rockbox/firmware/thread.c
Frank Gevaerts 376d8d577f Add IO priority handling. Currently all IO has equal priority, except the dircache scanning thread which is lower. This fixes the slow boot problem for me, with the added benefit that actual audio playback also starts faster.
Lots of the changes are due to changing storage_(read|write)sectors() from macros to wrapper functions. This means that they have to be called with IF_MD2(drive,) again.

Flyspray: FS#11167
Author: Frank Gevaerts


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25459 a1c6a512-1295-4272-9138-f99709370657
2010-04-03 22:02:09 +00:00

3204 lines
106 KiB
C

/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Ulf Ralberg
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include <stdbool.h>
#include "thread.h"
#include "panic.h"
#include "sprintf.h"
#include "system.h"
#include "kernel.h"
#include "cpu.h"
#include "string.h"
#ifdef RB_PROFILE
#include <profile.h>
#endif
/****************************************************************************
* ATTENTION!! *
* See notes below on implementing processor-specific portions! *
***************************************************************************/
/* Define THREAD_EXTRA_CHECKS as 1 to enable additional state checks */
#ifdef DEBUG
#define THREAD_EXTRA_CHECKS 1 /* Always 1 for DEBUG */
#else
#define THREAD_EXTRA_CHECKS 0
#endif
/**
* General locking order to guarantee progress. Order must be observed but
* all stages are not nescessarily obligatory. Going from 1) to 3) is
* perfectly legal.
*
* 1) IRQ
* This is first because of the likelyhood of having an interrupt occur that
* also accesses one of the objects farther down the list. Any non-blocking
* synchronization done may already have a lock on something during normal
* execution and if an interrupt handler running on the same processor as
* the one that has the resource locked were to attempt to access the
* resource, the interrupt handler would wait forever waiting for an unlock
* that will never happen. There is no danger if the interrupt occurs on
* a different processor because the one that has the lock will eventually
* unlock and the other processor's handler may proceed at that time. Not
* nescessary when the resource in question is definitely not available to
* interrupt handlers.
*
* 2) Kernel Object
* 1) May be needed beforehand if the kernel object allows dual-use such as
* event queues. The kernel object must have a scheme to protect itself from
* access by another processor and is responsible for serializing the calls
* to block_thread(_w_tmo) and wakeup_thread both to themselves and to each
* other. Objects' queues are also protected here.
*
* 3) Thread Slot
* This locks access to the thread's slot such that its state cannot be
* altered by another processor when a state change is in progress such as
* when it is in the process of going on a blocked list. An attempt to wake
* a thread while it is still blocking will likely desync its state with
* the other resources used for that state.
*
* 4) Core Lists
* These lists are specific to a particular processor core and are accessible
* by all processor cores and interrupt handlers. The running (rtr) list is
* the prime example where a thread may be added by any means.
*/
/*---------------------------------------------------------------------------
* Processor specific: core_sleep/core_wake/misc. notes
*
* ARM notes:
* FIQ is not dealt with by the scheduler code and is simply restored if it
* must by masked for some reason - because threading modifies a register
* that FIQ may also modify and there's no way to accomplish it atomically.
* s3c2440 is such a case.
*
* Audio interrupts are generally treated at a higher priority than others
* usage of scheduler code with interrupts higher than HIGHEST_IRQ_LEVEL
* are not in general safe. Special cases may be constructed on a per-
* source basis and blocking operations are not available.
*
* core_sleep procedure to implement for any CPU to ensure an asychronous
* wakup never results in requiring a wait until the next tick (up to
* 10000uS!). May require assembly and careful instruction ordering.
*
* 1) On multicore, stay awake if directed to do so by another. If so, goto
* step 4.
* 2) If processor requires, atomically reenable interrupts and perform step
* 3.
* 3) Sleep the CPU core. If wakeup itself enables interrupts (stop #0x2000
* on Coldfire) goto step 5.
* 4) Enable interrupts.
* 5) Exit procedure.
*
* core_wake and multprocessor notes for sleep/wake coordination:
* If possible, to wake up another processor, the forcing of an interrupt on
* the woken core by the waker core is the easiest way to ensure a non-
* delayed wake and immediate execution of any woken threads. If that isn't
* available then some careful non-blocking synchonization is needed (as on
* PP targets at the moment).
*---------------------------------------------------------------------------
*/
/* Cast to the the machine pointer size, whose size could be < 4 or > 32
* (someday :). */
#define DEADBEEF ((uintptr_t)0xdeadbeefdeadbeefull)
struct core_entry cores[NUM_CORES] IBSS_ATTR;
struct thread_entry threads[MAXTHREADS] IBSS_ATTR;
static const char main_thread_name[] = "main";
extern uintptr_t stackbegin[];
extern uintptr_t stackend[];
static inline void core_sleep(IF_COP_VOID(unsigned int core))
__attribute__((always_inline));
void check_tmo_threads(void)
__attribute__((noinline));
static inline void block_thread_on_l(struct thread_entry *thread, unsigned state)
__attribute__((always_inline));
static void add_to_list_tmo(struct thread_entry *thread)
__attribute__((noinline));
static void core_schedule_wakeup(struct thread_entry *thread)
__attribute__((noinline));
#if NUM_CORES > 1
static inline void run_blocking_ops(
unsigned int core, struct thread_entry *thread)
__attribute__((always_inline));
#endif
static void thread_stkov(struct thread_entry *thread)
__attribute__((noinline));
static inline void store_context(void* addr)
__attribute__((always_inline));
static inline void load_context(const void* addr)
__attribute__((always_inline));
void switch_thread(void)
__attribute__((noinline));
/****************************************************************************
* Processor-specific section
*/
#if defined(MAX_PHYS_SECTOR_SIZE) && MEM == 64
/* Support a special workaround object for large-sector disks */
#define IF_NO_SKIP_YIELD(...) __VA_ARGS__
#else
#define IF_NO_SKIP_YIELD(...)
#endif
#if defined(CPU_ARM)
/*---------------------------------------------------------------------------
* Start the thread running and terminate it if it returns
*---------------------------------------------------------------------------
*/
static void __attribute__((naked,used)) start_thread(void)
{
/* r0 = context */
asm volatile (
"ldr sp, [r0, #32] \n" /* Load initial sp */
"ldr r4, [r0, #40] \n" /* start in r4 since it's non-volatile */
"mov r1, #0 \n" /* Mark thread as running */
"str r1, [r0, #40] \n"
#if NUM_CORES > 1
"ldr r0, =cpucache_invalidate \n" /* Invalidate this core's cache. */
"mov lr, pc \n" /* This could be the first entry into */
"bx r0 \n" /* plugin or codec code for this core. */
#endif
"mov lr, pc \n" /* Call thread function */
"bx r4 \n"
); /* No clobber list - new thread doesn't care */
thread_exit();
//asm volatile (".ltorg"); /* Dump constant pool */
}
/* For startup, place context pointer in r4 slot, start_thread pointer in r5
* slot, and thread function pointer in context.start. See load_context for
* what happens when thread is initially going to run. */
#define THREAD_STARTUP_INIT(core, thread, function) \
({ (thread)->context.r[0] = (uint32_t)&(thread)->context, \
(thread)->context.r[1] = (uint32_t)start_thread, \
(thread)->context.start = (uint32_t)function; })
/*---------------------------------------------------------------------------
* Store non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void store_context(void* addr)
{
asm volatile(
"stmia %0, { r4-r11, sp, lr } \n"
: : "r" (addr)
);
}
/*---------------------------------------------------------------------------
* Load non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void load_context(const void* addr)
{
asm volatile(
"ldr r0, [%0, #40] \n" /* Load start pointer */
"cmp r0, #0 \n" /* Check for NULL */
"ldmneia %0, { r0, pc } \n" /* If not already running, jump to start */
"ldmia %0, { r4-r11, sp, lr } \n" /* Load regs r4 to r14 from context */
: : "r" (addr) : "r0" /* only! */
);
}
#if defined (CPU_PP)
#if NUM_CORES > 1
extern uintptr_t cpu_idlestackbegin[];
extern uintptr_t cpu_idlestackend[];
extern uintptr_t cop_idlestackbegin[];
extern uintptr_t cop_idlestackend[];
static uintptr_t * const idle_stacks[NUM_CORES] =
{
[CPU] = cpu_idlestackbegin,
[COP] = cop_idlestackbegin
};
#if CONFIG_CPU == PP5002
/* Bytes to emulate the PP502x mailbox bits */
struct core_semaphores
{
volatile uint8_t intend_wake; /* 00h */
volatile uint8_t stay_awake; /* 01h */
volatile uint8_t intend_sleep; /* 02h */
volatile uint8_t unused; /* 03h */
};
static struct core_semaphores core_semaphores[NUM_CORES] IBSS_ATTR;
#endif /* CONFIG_CPU == PP5002 */
#endif /* NUM_CORES */
#if CONFIG_CORELOCK == SW_CORELOCK
/* Software core locks using Peterson's mutual exclusion algorithm */
/*---------------------------------------------------------------------------
* Initialize the corelock structure.
*---------------------------------------------------------------------------
*/
void corelock_init(struct corelock *cl)
{
memset(cl, 0, sizeof (*cl));
}
#if 1 /* Assembly locks to minimize overhead */
/*---------------------------------------------------------------------------
* Wait for the corelock to become free and acquire it when it does.
*---------------------------------------------------------------------------
*/
void corelock_lock(struct corelock *cl) __attribute__((naked));
void corelock_lock(struct corelock *cl)
{
/* Relies on the fact that core IDs are complementary bitmasks (0x55,0xaa) */
asm volatile (
"mov r1, %0 \n" /* r1 = PROCESSOR_ID */
"ldrb r1, [r1] \n"
"strb r1, [r0, r1, lsr #7] \n" /* cl->myl[core] = core */
"eor r2, r1, #0xff \n" /* r2 = othercore */
"strb r2, [r0, #2] \n" /* cl->turn = othercore */
"1: \n"
"ldrb r3, [r0, r2, lsr #7] \n" /* cl->myl[othercore] == 0 ? */
"cmp r3, #0 \n" /* yes? lock acquired */
"bxeq lr \n"
"ldrb r3, [r0, #2] \n" /* || cl->turn == core ? */
"cmp r3, r1 \n"
"bxeq lr \n" /* yes? lock acquired */
"b 1b \n" /* keep trying */
: : "i"(&PROCESSOR_ID)
);
(void)cl;
}
/*---------------------------------------------------------------------------
* Try to aquire the corelock. If free, caller gets it, otherwise return 0.
*---------------------------------------------------------------------------
*/
int corelock_try_lock(struct corelock *cl) __attribute__((naked));
int corelock_try_lock(struct corelock *cl)
{
/* Relies on the fact that core IDs are complementary bitmasks (0x55,0xaa) */
asm volatile (
"mov r1, %0 \n" /* r1 = PROCESSOR_ID */
"ldrb r1, [r1] \n"
"mov r3, r0 \n"
"strb r1, [r0, r1, lsr #7] \n" /* cl->myl[core] = core */
"eor r2, r1, #0xff \n" /* r2 = othercore */
"strb r2, [r0, #2] \n" /* cl->turn = othercore */
"ldrb r0, [r3, r2, lsr #7] \n" /* cl->myl[othercore] == 0 ? */
"eors r0, r0, r2 \n" /* yes? lock acquired */
"bxne lr \n"
"ldrb r0, [r3, #2] \n" /* || cl->turn == core? */
"ands r0, r0, r1 \n"
"streqb r0, [r3, r1, lsr #7] \n" /* if not, cl->myl[core] = 0 */
"bx lr \n" /* return result */
: : "i"(&PROCESSOR_ID)
);
return 0;
(void)cl;
}
/*---------------------------------------------------------------------------
* Release ownership of the corelock
*---------------------------------------------------------------------------
*/
void corelock_unlock(struct corelock *cl) __attribute__((naked));
void corelock_unlock(struct corelock *cl)
{
asm volatile (
"mov r1, %0 \n" /* r1 = PROCESSOR_ID */
"ldrb r1, [r1] \n"
"mov r2, #0 \n" /* cl->myl[core] = 0 */
"strb r2, [r0, r1, lsr #7] \n"
"bx lr \n"
: : "i"(&PROCESSOR_ID)
);
(void)cl;
}
#else /* C versions for reference */
/*---------------------------------------------------------------------------
* Wait for the corelock to become free and aquire it when it does.
*---------------------------------------------------------------------------
*/
void corelock_lock(struct corelock *cl)
{
const unsigned int core = CURRENT_CORE;
const unsigned int othercore = 1 - core;
cl->myl[core] = core;
cl->turn = othercore;
for (;;)
{
if (cl->myl[othercore] == 0 || cl->turn == core)
break;
}
}
/*---------------------------------------------------------------------------
* Try to aquire the corelock. If free, caller gets it, otherwise return 0.
*---------------------------------------------------------------------------
*/
int corelock_try_lock(struct corelock *cl)
{
const unsigned int core = CURRENT_CORE;
const unsigned int othercore = 1 - core;
cl->myl[core] = core;
cl->turn = othercore;
if (cl->myl[othercore] == 0 || cl->turn == core)
{
return 1;
}
cl->myl[core] = 0;
return 0;
}
/*---------------------------------------------------------------------------
* Release ownership of the corelock
*---------------------------------------------------------------------------
*/
void corelock_unlock(struct corelock *cl)
{
cl->myl[CURRENT_CORE] = 0;
}
#endif /* ASM / C selection */
#endif /* CONFIG_CORELOCK == SW_CORELOCK */
/*---------------------------------------------------------------------------
* Put core in a power-saving state if waking list wasn't repopulated and if
* no other core requested a wakeup for it to perform a task.
*---------------------------------------------------------------------------
*/
#ifdef CPU_PP502x
#if NUM_CORES == 1
static inline void core_sleep(void)
{
sleep_core(CURRENT_CORE);
enable_irq();
}
#else
static inline void core_sleep(unsigned int core)
{
#if 1
asm volatile (
"mov r0, #4 \n" /* r0 = 0x4 << core */
"mov r0, r0, lsl %[c] \n"
"str r0, [%[mbx], #4] \n" /* signal intent to sleep */
"ldr r1, [%[mbx], #0] \n" /* && !(MBX_MSG_STAT & (0x10<<core)) ? */
"tst r1, r0, lsl #2 \n"
"moveq r1, #0x80000000 \n" /* Then sleep */
"streq r1, [%[ctl], %[c], lsl #2] \n"
"moveq r1, #0 \n" /* Clear control reg */
"streq r1, [%[ctl], %[c], lsl #2] \n"
"orr r1, r0, r0, lsl #2 \n" /* Signal intent to wake - clear wake flag */
"str r1, [%[mbx], #8] \n"
"1: \n" /* Wait for wake procedure to finish */
"ldr r1, [%[mbx], #0] \n"
"tst r1, r0, lsr #2 \n"
"bne 1b \n"
:
: [ctl]"r"(&CPU_CTL), [mbx]"r"(MBX_BASE), [c]"r"(core)
: "r0", "r1");
#else /* C version for reference */
/* Signal intent to sleep */
MBX_MSG_SET = 0x4 << core;
/* Something waking or other processor intends to wake us? */
if ((MBX_MSG_STAT & (0x10 << core)) == 0)
{
sleep_core(core);
wake_core(core);
}
/* Signal wake - clear wake flag */
MBX_MSG_CLR = 0x14 << core;
/* Wait for other processor to finish wake procedure */
while (MBX_MSG_STAT & (0x1 << core));
#endif /* ASM/C selection */
enable_irq();
}
#endif /* NUM_CORES */
#elif CONFIG_CPU == PP5002
#if NUM_CORES == 1
static inline void core_sleep(void)
{
sleep_core(CURRENT_CORE);
enable_irq();
}
#else
/* PP5002 has no mailboxes - emulate using bytes */
static inline void core_sleep(unsigned int core)
{
#if 1
asm volatile (
"mov r0, #1 \n" /* Signal intent to sleep */
"strb r0, [%[sem], #2] \n"
"ldrb r0, [%[sem], #1] \n" /* && stay_awake == 0? */
"cmp r0, #0 \n"
"bne 2f \n"
/* Sleep: PP5002 crashes if the instruction that puts it to sleep is
* located at 0xNNNNNNN0. 4/8/C works. This sequence makes sure
* that the correct alternative is executed. Don't change the order
* of the next 4 instructions! */
"tst pc, #0x0c \n"
"mov r0, #0xca \n"
"strne r0, [%[ctl], %[c], lsl #2] \n"
"streq r0, [%[ctl], %[c], lsl #2] \n"
"nop \n" /* nop's needed because of pipeline */
"nop \n"
"nop \n"
"2: \n"
"mov r0, #0 \n" /* Clear stay_awake and sleep intent */
"strb r0, [%[sem], #1] \n"
"strb r0, [%[sem], #2] \n"
"1: \n" /* Wait for wake procedure to finish */
"ldrb r0, [%[sem], #0] \n"
"cmp r0, #0 \n"
"bne 1b \n"
:
: [sem]"r"(&core_semaphores[core]), [c]"r"(core),
[ctl]"r"(&CPU_CTL)
: "r0"
);
#else /* C version for reference */
/* Signal intent to sleep */
core_semaphores[core].intend_sleep = 1;
/* Something waking or other processor intends to wake us? */
if (core_semaphores[core].stay_awake == 0)
{
sleep_core(core);
}
/* Signal wake - clear wake flag */
core_semaphores[core].stay_awake = 0;
core_semaphores[core].intend_sleep = 0;
/* Wait for other processor to finish wake procedure */
while (core_semaphores[core].intend_wake != 0);
/* Enable IRQ */
#endif /* ASM/C selection */
enable_irq();
}
#endif /* NUM_CORES */
#endif /* PP CPU type */
/*---------------------------------------------------------------------------
* Wake another processor core that is sleeping or prevent it from doing so
* if it was already destined. FIQ, IRQ should be disabled before calling.
*---------------------------------------------------------------------------
*/
#if NUM_CORES == 1
/* Shared single-core build debugging version */
void core_wake(void)
{
/* No wakey - core already wakey */
}
#elif defined (CPU_PP502x)
void core_wake(unsigned int othercore)
{
#if 1
/* avoid r0 since that contains othercore */
asm volatile (
"mrs r3, cpsr \n" /* Disable IRQ */
"orr r1, r3, #0x80 \n"
"msr cpsr_c, r1 \n"
"mov r2, #0x11 \n" /* r2 = (0x11 << othercore) */
"mov r2, r2, lsl %[oc] \n" /* Signal intent to wake othercore */
"str r2, [%[mbx], #4] \n"
"1: \n" /* If it intends to sleep, let it first */
"ldr r1, [%[mbx], #0] \n" /* (MSG_MSG_STAT & (0x4 << othercore)) != 0 ? */
"eor r1, r1, #0xc \n"
"tst r1, r2, lsr #2 \n"
"ldr r1, [%[ctl], %[oc], lsl #2] \n" /* && (PROC_CTL(othercore) & PROC_SLEEP) == 0 ? */
"tsteq r1, #0x80000000 \n"
"beq 1b \n" /* Wait for sleep or wake */
"tst r1, #0x80000000 \n" /* If sleeping, wake it */
"movne r1, #0x0 \n"
"strne r1, [%[ctl], %[oc], lsl #2] \n"
"mov r1, r2, lsr #4 \n"
"str r1, [%[mbx], #8] \n" /* Done with wake procedure */
"msr cpsr_c, r3 \n" /* Restore IRQ */
:
: [ctl]"r"(&PROC_CTL(CPU)), [mbx]"r"(MBX_BASE),
[oc]"r"(othercore)
: "r1", "r2", "r3");
#else /* C version for reference */
/* Disable interrupts - avoid reentrancy from the tick */
int oldlevel = disable_irq_save();
/* Signal intent to wake other processor - set stay awake */
MBX_MSG_SET = 0x11 << othercore;
/* If it intends to sleep, wait until it does or aborts */
while ((MBX_MSG_STAT & (0x4 << othercore)) != 0 &&
(PROC_CTL(othercore) & PROC_SLEEP) == 0);
/* If sleeping, wake it up */
if (PROC_CTL(othercore) & PROC_SLEEP)
PROC_CTL(othercore) = 0;
/* Done with wake procedure */
MBX_MSG_CLR = 0x1 << othercore;
restore_irq(oldlevel);
#endif /* ASM/C selection */
}
#elif CONFIG_CPU == PP5002
/* PP5002 has no mailboxes - emulate using bytes */
void core_wake(unsigned int othercore)
{
#if 1
/* avoid r0 since that contains othercore */
asm volatile (
"mrs r3, cpsr \n" /* Disable IRQ */
"orr r1, r3, #0x80 \n"
"msr cpsr_c, r1 \n"
"mov r1, #1 \n" /* Signal intent to wake other core */
"orr r1, r1, r1, lsl #8 \n" /* and set stay_awake */
"strh r1, [%[sem], #0] \n"
"mov r2, #0x8000 \n"
"1: \n" /* If it intends to sleep, let it first */
"ldrb r1, [%[sem], #2] \n" /* intend_sleep != 0 ? */
"cmp r1, #1 \n"
"ldr r1, [%[st]] \n" /* && not sleeping ? */
"tsteq r1, r2, lsr %[oc] \n"
"beq 1b \n" /* Wait for sleep or wake */
"tst r1, r2, lsr %[oc] \n"
"ldrne r2, =0xcf004054 \n" /* If sleeping, wake it */
"movne r1, #0xce \n"
"strne r1, [r2, %[oc], lsl #2] \n"
"mov r1, #0 \n" /* Done with wake procedure */
"strb r1, [%[sem], #0] \n"
"msr cpsr_c, r3 \n" /* Restore IRQ */
:
: [sem]"r"(&core_semaphores[othercore]),
[st]"r"(&PROC_STAT),
[oc]"r"(othercore)
: "r1", "r2", "r3"
);
#else /* C version for reference */
/* Disable interrupts - avoid reentrancy from the tick */
int oldlevel = disable_irq_save();
/* Signal intent to wake other processor - set stay awake */
core_semaphores[othercore].intend_wake = 1;
core_semaphores[othercore].stay_awake = 1;
/* If it intends to sleep, wait until it does or aborts */
while (core_semaphores[othercore].intend_sleep != 0 &&
(PROC_STAT & PROC_SLEEPING(othercore)) == 0);
/* If sleeping, wake it up */
if (PROC_STAT & PROC_SLEEPING(othercore))
wake_core(othercore);
/* Done with wake procedure */
core_semaphores[othercore].intend_wake = 0;
restore_irq(oldlevel);
#endif /* ASM/C selection */
}
#endif /* CPU type */
#if NUM_CORES > 1
/*---------------------------------------------------------------------------
* Switches to a stack that always resides in the Rockbox core.
*
* Needed when a thread suicides on a core other than the main CPU since the
* stack used when idling is the stack of the last thread to run. This stack
* may not reside in the core firmware in which case the core will continue
* to use a stack from an unloaded module until another thread runs on it.
*---------------------------------------------------------------------------
*/
static inline void switch_to_idle_stack(const unsigned int core)
{
asm volatile (
"str sp, [%0] \n" /* save original stack pointer on idle stack */
"mov sp, %0 \n" /* switch stacks */
: : "r"(&idle_stacks[core][IDLE_STACK_WORDS-1]));
(void)core;
}
/*---------------------------------------------------------------------------
* Perform core switch steps that need to take place inside switch_thread.
*
* These steps must take place while before changing the processor and after
* having entered switch_thread since switch_thread may not do a normal return
* because the stack being used for anything the compiler saved will not belong
* to the thread's destination core and it may have been recycled for other
* purposes by the time a normal context load has taken place. switch_thread
* will also clobber anything stashed in the thread's context or stored in the
* nonvolatile registers if it is saved there before the call since the
* compiler's order of operations cannot be known for certain.
*/
static void core_switch_blk_op(unsigned int core, struct thread_entry *thread)
{
/* Flush our data to ram */
cpucache_flush();
/* Stash thread in r4 slot */
thread->context.r[0] = (uint32_t)thread;
/* Stash restart address in r5 slot */
thread->context.r[1] = thread->context.start;
/* Save sp in context.sp while still running on old core */
thread->context.sp = idle_stacks[core][IDLE_STACK_WORDS-1];
}
/*---------------------------------------------------------------------------
* Machine-specific helper function for switching the processor a thread is
* running on. Basically, the thread suicides on the departing core and is
* reborn on the destination. Were it not for gcc's ill-behavior regarding
* naked functions written in C where it actually clobbers non-volatile
* registers before the intended prologue code, this would all be much
* simpler. Generic setup is done in switch_core itself.
*/
/*---------------------------------------------------------------------------
* This actually performs the core switch.
*/
static void __attribute__((naked))
switch_thread_core(unsigned int core, struct thread_entry *thread)
{
/* Pure asm for this because compiler behavior isn't sufficiently predictable.
* Stack access also isn't permitted until restoring the original stack and
* context. */
asm volatile (
"stmfd sp!, { r4-r11, lr } \n" /* Stack all non-volatile context on current core */
"ldr r2, =idle_stacks \n" /* r2 = &idle_stacks[core][IDLE_STACK_WORDS] */
"ldr r2, [r2, r0, lsl #2] \n"
"add r2, r2, %0*4 \n"
"stmfd r2!, { sp } \n" /* save original stack pointer on idle stack */
"mov sp, r2 \n" /* switch stacks */
"adr r2, 1f \n" /* r2 = new core restart address */
"str r2, [r1, #40] \n" /* thread->context.start = r2 */
"ldr pc, =switch_thread \n" /* r0 = thread after call - see load_context */
"1: \n"
"ldr sp, [r0, #32] \n" /* Reload original sp from context structure */
"mov r1, #0 \n" /* Clear start address */
"str r1, [r0, #40] \n"
"ldr r0, =cpucache_invalidate \n" /* Invalidate new core's cache */
"mov lr, pc \n"
"bx r0 \n"
"ldmfd sp!, { r4-r11, pc } \n" /* Restore non-volatile context to new core and return */
".ltorg \n" /* Dump constant pool */
: : "i"(IDLE_STACK_WORDS)
);
(void)core; (void)thread;
}
/*---------------------------------------------------------------------------
* Do any device-specific inits for the threads and synchronize the kernel
* initializations.
*---------------------------------------------------------------------------
*/
static void core_thread_init(unsigned int core) INIT_ATTR;
static void core_thread_init(unsigned int core)
{
if (core == CPU)
{
/* Wake up coprocessor and let it initialize kernel and threads */
#ifdef CPU_PP502x
MBX_MSG_CLR = 0x3f;
#endif
wake_core(COP);
/* Sleep until COP has finished */
sleep_core(CPU);
}
else
{
/* Wake the CPU and return */
wake_core(CPU);
}
}
#endif /* NUM_CORES */
#elif defined(CPU_TCC780X) || defined(CPU_TCC77X) /* Single core only for now */ \
|| CONFIG_CPU == IMX31L || CONFIG_CPU == DM320 || CONFIG_CPU == AS3525 \
|| CONFIG_CPU == S3C2440 || CONFIG_CPU == S5L8701 || CONFIG_CPU == AS3525v2
/* Use the generic ARMv4/v5/v6 wait for IRQ */
static inline void core_sleep(void)
{
asm volatile (
"mcr p15, 0, %0, c7, c0, 4" /* Wait for interrupt */
: : "r"(0)
);
enable_irq();
}
#else
static inline void core_sleep(void)
{
#warning core_sleep not implemented, battery life will be decreased
enable_irq();
}
#endif /* CONFIG_CPU == */
#elif defined(CPU_COLDFIRE)
/*---------------------------------------------------------------------------
* Start the thread running and terminate it if it returns
*---------------------------------------------------------------------------
*/
void start_thread(void); /* Provide C access to ASM label */
static void __attribute__((used)) __start_thread(void)
{
/* a0=macsr, a1=context */
asm volatile (
"start_thread: \n" /* Start here - no naked attribute */
"move.l %a0, %macsr \n" /* Set initial mac status reg */
"lea.l 48(%a1), %a1 \n"
"move.l (%a1)+, %sp \n" /* Set initial stack */
"move.l (%a1), %a2 \n" /* Fetch thread function pointer */
"clr.l (%a1) \n" /* Mark thread running */
"jsr (%a2) \n" /* Call thread function */
);
thread_exit();
}
/* Set EMAC unit to fractional mode with saturation for each new thread,
* since that's what'll be the most useful for most things which the dsp
* will do. Codecs should still initialize their preferred modes
* explicitly. Context pointer is placed in d2 slot and start_thread
* pointer in d3 slot. thread function pointer is placed in context.start.
* See load_context for what happens when thread is initially going to
* run.
*/
#define THREAD_STARTUP_INIT(core, thread, function) \
({ (thread)->context.macsr = EMAC_FRACTIONAL | EMAC_SATURATE, \
(thread)->context.d[0] = (uint32_t)&(thread)->context, \
(thread)->context.d[1] = (uint32_t)start_thread, \
(thread)->context.start = (uint32_t)(function); })
/*---------------------------------------------------------------------------
* Store non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void store_context(void* addr)
{
asm volatile (
"move.l %%macsr,%%d0 \n"
"movem.l %%d0/%%d2-%%d7/%%a2-%%a7,(%0) \n"
: : "a" (addr) : "d0" /* only! */
);
}
/*---------------------------------------------------------------------------
* Load non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void load_context(const void* addr)
{
asm volatile (
"move.l 52(%0), %%d0 \n" /* Get start address */
"beq.b 1f \n" /* NULL -> already running */
"movem.l (%0), %%a0-%%a2 \n" /* a0=macsr, a1=context, a2=start_thread */
"jmp (%%a2) \n" /* Start the thread */
"1: \n"
"movem.l (%0), %%d0/%%d2-%%d7/%%a2-%%a7 \n" /* Load context */
"move.l %%d0, %%macsr \n"
: : "a" (addr) : "d0" /* only! */
);
}
/*---------------------------------------------------------------------------
* Put core in a power-saving state if waking list wasn't repopulated.
*---------------------------------------------------------------------------
*/
static inline void core_sleep(void)
{
/* Supervisor mode, interrupts enabled upon wakeup */
asm volatile ("stop #0x2000");
};
#elif CONFIG_CPU == SH7034
/*---------------------------------------------------------------------------
* Start the thread running and terminate it if it returns
*---------------------------------------------------------------------------
*/
void start_thread(void); /* Provide C access to ASM label */
static void __attribute__((used)) __start_thread(void)
{
/* r8 = context */
asm volatile (
"_start_thread: \n" /* Start here - no naked attribute */
"mov.l @(4, r8), r0 \n" /* Fetch thread function pointer */
"mov.l @(28, r8), r15 \n" /* Set initial sp */
"mov #0, r1 \n" /* Start the thread */
"jsr @r0 \n"
"mov.l r1, @(36, r8) \n" /* Clear start address */
);
thread_exit();
}
/* Place context pointer in r8 slot, function pointer in r9 slot, and
* start_thread pointer in context_start */
#define THREAD_STARTUP_INIT(core, thread, function) \
({ (thread)->context.r[0] = (uint32_t)&(thread)->context, \
(thread)->context.r[1] = (uint32_t)(function), \
(thread)->context.start = (uint32_t)start_thread; })
/*---------------------------------------------------------------------------
* Store non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void store_context(void* addr)
{
asm volatile (
"add #36, %0 \n" /* Start at last reg. By the time routine */
"sts.l pr, @-%0 \n" /* is done, %0 will have the original value */
"mov.l r15,@-%0 \n"
"mov.l r14,@-%0 \n"
"mov.l r13,@-%0 \n"
"mov.l r12,@-%0 \n"
"mov.l r11,@-%0 \n"
"mov.l r10,@-%0 \n"
"mov.l r9, @-%0 \n"
"mov.l r8, @-%0 \n"
: : "r" (addr)
);
}
/*---------------------------------------------------------------------------
* Load non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void load_context(const void* addr)
{
asm volatile (
"mov.l @(36, %0), r0 \n" /* Get start address */
"tst r0, r0 \n"
"bt .running \n" /* NULL -> already running */
"jmp @r0 \n" /* r8 = context */
".running: \n"
"mov.l @%0+, r8 \n" /* Executes in delay slot and outside it */
"mov.l @%0+, r9 \n"
"mov.l @%0+, r10 \n"
"mov.l @%0+, r11 \n"
"mov.l @%0+, r12 \n"
"mov.l @%0+, r13 \n"
"mov.l @%0+, r14 \n"
"mov.l @%0+, r15 \n"
"lds.l @%0+, pr \n"
: : "r" (addr) : "r0" /* only! */
);
}
/*---------------------------------------------------------------------------
* Put core in a power-saving state.
*---------------------------------------------------------------------------
*/
static inline void core_sleep(void)
{
asm volatile (
"and.b #0x7f, @(r0, gbr) \n" /* Clear SBY (bit 7) in SBYCR */
"mov #0, r1 \n" /* Enable interrupts */
"ldc r1, sr \n" /* Following instruction cannot be interrupted */
"sleep \n" /* Execute standby */
: : "z"(&SBYCR-GBR) : "r1");
}
#elif defined(CPU_MIPS) && CPU_MIPS == 32
/*---------------------------------------------------------------------------
* Start the thread running and terminate it if it returns
*---------------------------------------------------------------------------
*/
void start_thread(void); /* Provide C access to ASM label */
static void __attribute__((used)) _start_thread(void)
{
/* t1 = context */
asm volatile (
"start_thread: \n"
".set noreorder \n"
".set noat \n"
"lw $8, 4($9) \n" /* Fetch thread function pointer ($8 = t0, $9 = t1) */
"lw $29, 36($9) \n" /* Set initial sp(=$29) */
"jalr $8 \n" /* Start the thread */
"sw $0, 44($9) \n" /* Clear start address */
".set at \n"
".set reorder \n"
);
thread_exit();
}
/* Place context pointer in s0 slot, function pointer in s1 slot, and
* start_thread pointer in context_start */
#define THREAD_STARTUP_INIT(core, thread, function) \
({ (thread)->context.r[0] = (uint32_t)&(thread)->context, \
(thread)->context.r[1] = (uint32_t)(function), \
(thread)->context.start = (uint32_t)start_thread; })
/*---------------------------------------------------------------------------
* Store non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void store_context(void* addr)
{
asm volatile (
".set noreorder \n"
".set noat \n"
"sw $16, 0(%0) \n" /* s0 */
"sw $17, 4(%0) \n" /* s1 */
"sw $18, 8(%0) \n" /* s2 */
"sw $19, 12(%0) \n" /* s3 */
"sw $20, 16(%0) \n" /* s4 */
"sw $21, 20(%0) \n" /* s5 */
"sw $22, 24(%0) \n" /* s6 */
"sw $23, 28(%0) \n" /* s7 */
"sw $30, 32(%0) \n" /* fp */
"sw $29, 36(%0) \n" /* sp */
"sw $31, 40(%0) \n" /* ra */
".set at \n"
".set reorder \n"
: : "r" (addr)
);
}
/*---------------------------------------------------------------------------
* Load non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void load_context(const void* addr)
{
asm volatile (
".set noat \n"
".set noreorder \n"
"lw $8, 44(%0) \n" /* Get start address ($8 = t0) */
"beqz $8, running \n" /* NULL -> already running */
"nop \n"
"jr $8 \n"
"move $9, %0 \n" /* t1 = context */
"running: \n"
"lw $16, 0(%0) \n" /* s0 */
"lw $17, 4(%0) \n" /* s1 */
"lw $18, 8(%0) \n" /* s2 */
"lw $19, 12(%0) \n" /* s3 */
"lw $20, 16(%0) \n" /* s4 */
"lw $21, 20(%0) \n" /* s5 */
"lw $22, 24(%0) \n" /* s6 */
"lw $23, 28(%0) \n" /* s7 */
"lw $30, 32(%0) \n" /* fp */
"lw $29, 36(%0) \n" /* sp */
"lw $31, 40(%0) \n" /* ra */
".set at \n"
".set reorder \n"
: : "r" (addr) : "t0", "t1"
);
}
/*---------------------------------------------------------------------------
* Put core in a power-saving state.
*---------------------------------------------------------------------------
*/
static inline void core_sleep(void)
{
#if CONFIG_CPU == JZ4732
__cpm_idle_mode();
#endif
asm volatile(".set mips32r2 \n"
"mfc0 $8, $12 \n" /* mfc t0, $12 */
"move $9, $8 \n" /* move t1, t0 */
"la $10, 0x8000000 \n" /* la t2, 0x8000000 */
"or $8, $8, $10 \n" /* Enable reduced power mode */
"mtc0 $8, $12 \n" /* mtc t0, $12 */
"wait \n"
"mtc0 $9, $12 \n" /* mtc t1, $12 */
".set mips0 \n"
::: "t0", "t1", "t2"
);
enable_irq();
}
#endif /* CONFIG_CPU == */
/*
* End Processor-specific section
***************************************************************************/
#if THREAD_EXTRA_CHECKS
static void thread_panicf(const char *msg, struct thread_entry *thread)
{
IF_COP( const unsigned int core = thread->core; )
static char name[32];
thread_get_name(name, 32, thread);
panicf ("%s %s" IF_COP(" (%d)"), msg, name IF_COP(, core));
}
static void thread_stkov(struct thread_entry *thread)
{
thread_panicf("Stkov", thread);
}
#define THREAD_PANICF(msg, thread) \
thread_panicf(msg, thread)
#define THREAD_ASSERT(exp, msg, thread) \
({ if (!({ exp; })) thread_panicf((msg), (thread)); })
#else
static void thread_stkov(struct thread_entry *thread)
{
IF_COP( const unsigned int core = thread->core; )
static char name[32];
thread_get_name(name, 32, thread);
panicf("Stkov %s" IF_COP(" (%d)"), name IF_COP(, core));
}
#define THREAD_PANICF(msg, thread)
#define THREAD_ASSERT(exp, msg, thread)
#endif /* THREAD_EXTRA_CHECKS */
/* Thread locking */
#if NUM_CORES > 1
#define LOCK_THREAD(thread) \
({ corelock_lock(&(thread)->slot_cl); })
#define TRY_LOCK_THREAD(thread) \
({ corelock_try_lock(&thread->slot_cl); })
#define UNLOCK_THREAD(thread) \
({ corelock_unlock(&(thread)->slot_cl); })
#define UNLOCK_THREAD_AT_TASK_SWITCH(thread) \
({ unsigned int _core = (thread)->core; \
cores[_core].blk_ops.flags |= TBOP_UNLOCK_CORELOCK; \
cores[_core].blk_ops.cl_p = &(thread)->slot_cl; })
#else
#define LOCK_THREAD(thread) \
({ })
#define TRY_LOCK_THREAD(thread) \
({ })
#define UNLOCK_THREAD(thread) \
({ })
#define UNLOCK_THREAD_AT_TASK_SWITCH(thread) \
({ })
#endif
/* RTR list */
#define RTR_LOCK(core) \
({ corelock_lock(&cores[core].rtr_cl); })
#define RTR_UNLOCK(core) \
({ corelock_unlock(&cores[core].rtr_cl); })
#ifdef HAVE_PRIORITY_SCHEDULING
#define rtr_add_entry(core, priority) \
prio_add_entry(&cores[core].rtr, (priority))
#define rtr_subtract_entry(core, priority) \
prio_subtract_entry(&cores[core].rtr, (priority))
#define rtr_move_entry(core, from, to) \
prio_move_entry(&cores[core].rtr, (from), (to))
#else
#define rtr_add_entry(core, priority)
#define rtr_add_entry_inl(core, priority)
#define rtr_subtract_entry(core, priority)
#define rtr_subtract_entry_inl(core, priotity)
#define rtr_move_entry(core, from, to)
#define rtr_move_entry_inl(core, from, to)
#endif
/*---------------------------------------------------------------------------
* Thread list structure - circular:
* +------------------------------+
* | |
* +--+---+<-+---+<-+---+<-+---+<-+
* Head->| T | | T | | T | | T |
* +->+---+->+---+->+---+->+---+--+
* | |
* +------------------------------+
*---------------------------------------------------------------------------
*/
/*---------------------------------------------------------------------------
* Adds a thread to a list of threads using "insert last". Uses the "l"
* links.
*---------------------------------------------------------------------------
*/
static void add_to_list_l(struct thread_entry **list,
struct thread_entry *thread)
{
struct thread_entry *l = *list;
if (l == NULL)
{
/* Insert into unoccupied list */
thread->l.prev = thread;
thread->l.next = thread;
*list = thread;
return;
}
/* Insert last */
thread->l.prev = l->l.prev;
thread->l.next = l;
l->l.prev->l.next = thread;
l->l.prev = thread;
}
/*---------------------------------------------------------------------------
* Removes a thread from a list of threads. Uses the "l" links.
*---------------------------------------------------------------------------
*/
static void remove_from_list_l(struct thread_entry **list,
struct thread_entry *thread)
{
struct thread_entry *prev, *next;
next = thread->l.next;
if (thread == next)
{
/* The only item */
*list = NULL;
return;
}
if (thread == *list)
{
/* List becomes next item */
*list = next;
}
prev = thread->l.prev;
/* Fix links to jump over the removed entry. */
next->l.prev = prev;
prev->l.next = next;
}
/*---------------------------------------------------------------------------
* Timeout list structure - circular reverse (to make "remove item" O(1)),
* NULL-terminated forward (to ease the far more common forward traversal):
* +------------------------------+
* | |
* +--+---+<-+---+<-+---+<-+---+<-+
* Head->| T | | T | | T | | T |
* +---+->+---+->+---+->+---+-X
*---------------------------------------------------------------------------
*/
/*---------------------------------------------------------------------------
* Add a thread from the core's timout list by linking the pointers in its
* tmo structure.
*---------------------------------------------------------------------------
*/
static void add_to_list_tmo(struct thread_entry *thread)
{
struct thread_entry *tmo = cores[IF_COP_CORE(thread->core)].timeout;
THREAD_ASSERT(thread->tmo.prev == NULL,
"add_to_list_tmo->already listed", thread);
thread->tmo.next = NULL;
if (tmo == NULL)
{
/* Insert into unoccupied list */
thread->tmo.prev = thread;
cores[IF_COP_CORE(thread->core)].timeout = thread;
return;
}
/* Insert Last */
thread->tmo.prev = tmo->tmo.prev;
tmo->tmo.prev->tmo.next = thread;
tmo->tmo.prev = thread;
}
/*---------------------------------------------------------------------------
* Remove a thread from the core's timout list by unlinking the pointers in
* its tmo structure. Sets thread->tmo.prev to NULL to indicate the timeout
* is cancelled.
*---------------------------------------------------------------------------
*/
static void remove_from_list_tmo(struct thread_entry *thread)
{
struct thread_entry **list = &cores[IF_COP_CORE(thread->core)].timeout;
struct thread_entry *prev = thread->tmo.prev;
struct thread_entry *next = thread->tmo.next;
THREAD_ASSERT(prev != NULL, "remove_from_list_tmo->not listed", thread);
if (next != NULL)
next->tmo.prev = prev;
if (thread == *list)
{
/* List becomes next item and empty if next == NULL */
*list = next;
/* Mark as unlisted */
thread->tmo.prev = NULL;
}
else
{
if (next == NULL)
(*list)->tmo.prev = prev;
prev->tmo.next = next;
/* Mark as unlisted */
thread->tmo.prev = NULL;
}
}
#ifdef HAVE_PRIORITY_SCHEDULING
/*---------------------------------------------------------------------------
* Priority distribution structure (one category for each possible priority):
*
* +----+----+----+ ... +-----+
* hist: | F0 | F1 | F2 | | F31 |
* +----+----+----+ ... +-----+
* mask: | b0 | b1 | b2 | | b31 |
* +----+----+----+ ... +-----+
*
* F = count of threads at priority category n (frequency)
* b = bitmask of non-zero priority categories (occupancy)
*
* / if H[n] != 0 : 1
* b[n] = |
* \ else : 0
*
*---------------------------------------------------------------------------
* Basic priority inheritance priotocol (PIP):
*
* Mn = mutex n, Tn = thread n
*
* A lower priority thread inherits the priority of the highest priority
* thread blocked waiting for it to complete an action (such as release a
* mutex or respond to a message via queue_send):
*
* 1) T2->M1->T1
*
* T1 owns M1, T2 is waiting for M1 to realease M1. If T2 has a higher
* priority than T1 then T1 inherits the priority of T2.
*
* 2) T3
* \/
* T2->M1->T1
*
* Situation is like 1) but T2 and T3 are both queued waiting for M1 and so
* T1 inherits the higher of T2 and T3.
*
* 3) T3->M2->T2->M1->T1
*
* T1 owns M1, T2 owns M2. If T3 has a higher priority than both T1 and T2,
* then T1 inherits the priority of T3 through T2.
*
* Blocking chains can grow arbitrarily complex (though it's best that they
* not form at all very often :) and build-up from these units.
*---------------------------------------------------------------------------
*/
/*---------------------------------------------------------------------------
* Increment frequency at category "priority"
*---------------------------------------------------------------------------
*/
static inline unsigned int prio_add_entry(
struct priority_distribution *pd, int priority)
{
unsigned int count;
/* Enough size/instruction count difference for ARM makes it worth it to
* use different code (192 bytes for ARM). Only thing better is ASM. */
#ifdef CPU_ARM
count = pd->hist[priority];
if (++count == 1)
pd->mask |= 1 << priority;
pd->hist[priority] = count;
#else /* This one's better for Coldfire */
if ((count = ++pd->hist[priority]) == 1)
pd->mask |= 1 << priority;
#endif
return count;
}
/*---------------------------------------------------------------------------
* Decrement frequency at category "priority"
*---------------------------------------------------------------------------
*/
static inline unsigned int prio_subtract_entry(
struct priority_distribution *pd, int priority)
{
unsigned int count;
#ifdef CPU_ARM
count = pd->hist[priority];
if (--count == 0)
pd->mask &= ~(1 << priority);
pd->hist[priority] = count;
#else
if ((count = --pd->hist[priority]) == 0)
pd->mask &= ~(1 << priority);
#endif
return count;
}
/*---------------------------------------------------------------------------
* Remove from one category and add to another
*---------------------------------------------------------------------------
*/
static inline void prio_move_entry(
struct priority_distribution *pd, int from, int to)
{
uint32_t mask = pd->mask;
#ifdef CPU_ARM
unsigned int count;
count = pd->hist[from];
if (--count == 0)
mask &= ~(1 << from);
pd->hist[from] = count;
count = pd->hist[to];
if (++count == 1)
mask |= 1 << to;
pd->hist[to] = count;
#else
if (--pd->hist[from] == 0)
mask &= ~(1 << from);
if (++pd->hist[to] == 1)
mask |= 1 << to;
#endif
pd->mask = mask;
}
/*---------------------------------------------------------------------------
* Change the priority and rtr entry for a running thread
*---------------------------------------------------------------------------
*/
static inline void set_running_thread_priority(
struct thread_entry *thread, int priority)
{
const unsigned int core = IF_COP_CORE(thread->core);
RTR_LOCK(core);
rtr_move_entry(core, thread->priority, priority);
thread->priority = priority;
RTR_UNLOCK(core);
}
/*---------------------------------------------------------------------------
* Finds the highest priority thread in a list of threads. If the list is
* empty, the PRIORITY_IDLE is returned.
*
* It is possible to use the struct priority_distribution within an object
* instead of scanning the remaining threads in the list but as a compromise,
* the resulting per-object memory overhead is saved at a slight speed
* penalty under high contention.
*---------------------------------------------------------------------------
*/
static int find_highest_priority_in_list_l(
struct thread_entry * const thread)
{
if (LIKELY(thread != NULL))
{
/* Go though list until the ending up at the initial thread */
int highest_priority = thread->priority;
struct thread_entry *curr = thread;
do
{
int priority = curr->priority;
if (priority < highest_priority)
highest_priority = priority;
curr = curr->l.next;
}
while (curr != thread);
return highest_priority;
}
return PRIORITY_IDLE;
}
/*---------------------------------------------------------------------------
* Register priority with blocking system and bubble it down the chain if
* any until we reach the end or something is already equal or higher.
*
* NOTE: A simultaneous circular wait could spin deadlock on multiprocessor
* targets but that same action also guarantees a circular block anyway and
* those are prevented, right? :-)
*---------------------------------------------------------------------------
*/
static struct thread_entry *
blocker_inherit_priority(struct thread_entry *current)
{
const int priority = current->priority;
struct blocker *bl = current->blocker;
struct thread_entry * const tstart = current;
struct thread_entry *bl_t = bl->thread;
/* Blocker cannot change since the object protection is held */
LOCK_THREAD(bl_t);
for (;;)
{
struct thread_entry *next;
int bl_pr = bl->priority;
if (priority >= bl_pr)
break; /* Object priority already high enough */
bl->priority = priority;
/* Add this one */
prio_add_entry(&bl_t->pdist, priority);
if (bl_pr < PRIORITY_IDLE)
{
/* Not first waiter - subtract old one */
prio_subtract_entry(&bl_t->pdist, bl_pr);
}
if (priority >= bl_t->priority)
break; /* Thread priority high enough */
if (bl_t->state == STATE_RUNNING)
{
/* Blocking thread is a running thread therefore there are no
* further blockers. Change the "run queue" on which it
* resides. */
set_running_thread_priority(bl_t, priority);
break;
}
bl_t->priority = priority;
/* If blocking thread has a blocker, apply transitive inheritance */
bl = bl_t->blocker;
if (bl == NULL)
break; /* End of chain or object doesn't support inheritance */
next = bl->thread;
if (UNLIKELY(next == tstart))
break; /* Full-circle - deadlock! */
UNLOCK_THREAD(current);
#if NUM_CORES > 1
for (;;)
{
LOCK_THREAD(next);
/* Blocker could change - retest condition */
if (LIKELY(bl->thread == next))
break;
UNLOCK_THREAD(next);
next = bl->thread;
}
#endif
current = bl_t;
bl_t = next;
}
UNLOCK_THREAD(bl_t);
return current;
}
/*---------------------------------------------------------------------------
* Readjust priorities when waking a thread blocked waiting for another
* in essence "releasing" the thread's effect on the object owner. Can be
* performed from any context.
*---------------------------------------------------------------------------
*/
struct thread_entry *
wakeup_priority_protocol_release(struct thread_entry *thread)
{
const int priority = thread->priority;
struct blocker *bl = thread->blocker;
struct thread_entry * const tstart = thread;
struct thread_entry *bl_t = bl->thread;
/* Blocker cannot change since object will be locked */
LOCK_THREAD(bl_t);
thread->blocker = NULL; /* Thread not blocked */
for (;;)
{
struct thread_entry *next;
int bl_pr = bl->priority;
if (priority > bl_pr)
break; /* Object priority higher */
next = *thread->bqp;
if (next == NULL)
{
/* No more threads in queue */
prio_subtract_entry(&bl_t->pdist, bl_pr);
bl->priority = PRIORITY_IDLE;
}
else
{
/* Check list for highest remaining priority */
int queue_pr = find_highest_priority_in_list_l(next);
if (queue_pr == bl_pr)
break; /* Object priority not changing */
/* Change queue priority */
prio_move_entry(&bl_t->pdist, bl_pr, queue_pr);
bl->priority = queue_pr;
}
if (bl_pr > bl_t->priority)
break; /* thread priority is higher */
bl_pr = find_first_set_bit(bl_t->pdist.mask);
if (bl_pr == bl_t->priority)
break; /* Thread priority not changing */
if (bl_t->state == STATE_RUNNING)
{
/* No further blockers */
set_running_thread_priority(bl_t, bl_pr);
break;
}
bl_t->priority = bl_pr;
/* If blocking thread has a blocker, apply transitive inheritance */
bl = bl_t->blocker;
if (bl == NULL)
break; /* End of chain or object doesn't support inheritance */
next = bl->thread;
if (UNLIKELY(next == tstart))
break; /* Full-circle - deadlock! */
UNLOCK_THREAD(thread);
#if NUM_CORES > 1
for (;;)
{
LOCK_THREAD(next);
/* Blocker could change - retest condition */
if (LIKELY(bl->thread == next))
break;
UNLOCK_THREAD(next);
next = bl->thread;
}
#endif
thread = bl_t;
bl_t = next;
}
UNLOCK_THREAD(bl_t);
#if NUM_CORES > 1
if (UNLIKELY(thread != tstart))
{
/* Relock original if it changed */
LOCK_THREAD(tstart);
}
#endif
return cores[CURRENT_CORE].running;
}
/*---------------------------------------------------------------------------
* Transfer ownership to a thread waiting for an objects and transfer
* inherited priority boost from other waiters. This algorithm knows that
* blocking chains may only unblock from the very end.
*
* Only the owning thread itself may call this and so the assumption that
* it is the running thread is made.
*---------------------------------------------------------------------------
*/
struct thread_entry *
wakeup_priority_protocol_transfer(struct thread_entry *thread)
{
/* Waking thread inherits priority boost from object owner */
struct blocker *bl = thread->blocker;
struct thread_entry *bl_t = bl->thread;
struct thread_entry *next;
int bl_pr;
THREAD_ASSERT(cores[CURRENT_CORE].running == bl_t,
"UPPT->wrong thread", cores[CURRENT_CORE].running);
LOCK_THREAD(bl_t);
bl_pr = bl->priority;
/* Remove the object's boost from the owning thread */
if (prio_subtract_entry(&bl_t->pdist, bl_pr) == 0 &&
bl_pr <= bl_t->priority)
{
/* No more threads at this priority are waiting and the old level is
* at least the thread level */
int priority = find_first_set_bit(bl_t->pdist.mask);
if (priority != bl_t->priority)
{
/* Adjust this thread's priority */
set_running_thread_priority(bl_t, priority);
}
}
next = *thread->bqp;
if (LIKELY(next == NULL))
{
/* Expected shortcut - no more waiters */
bl_pr = PRIORITY_IDLE;
}
else
{
if (thread->priority <= bl_pr)
{
/* Need to scan threads remaining in queue */
bl_pr = find_highest_priority_in_list_l(next);
}
if (prio_add_entry(&thread->pdist, bl_pr) == 1 &&
bl_pr < thread->priority)
{
/* Thread priority must be raised */
thread->priority = bl_pr;
}
}
bl->thread = thread; /* This thread pwns */
bl->priority = bl_pr; /* Save highest blocked priority */
thread->blocker = NULL; /* Thread not blocked */
UNLOCK_THREAD(bl_t);
return bl_t;
}
/*---------------------------------------------------------------------------
* No threads must be blocked waiting for this thread except for it to exit.
* The alternative is more elaborate cleanup and object registration code.
* Check this for risk of silent data corruption when objects with
* inheritable blocking are abandoned by the owner - not precise but may
* catch something.
*---------------------------------------------------------------------------
*/
static void check_for_obj_waiters(const char *function, struct thread_entry *thread)
{
/* Only one bit in the mask should be set with a frequency on 1 which
* represents the thread's own base priority */
uint32_t mask = thread->pdist.mask;
if ((mask & (mask - 1)) != 0 ||
thread->pdist.hist[find_first_set_bit(mask)] > 1)
{
unsigned char name[32];
thread_get_name(name, 32, thread);
panicf("%s->%s with obj. waiters", function, name);
}
}
#endif /* HAVE_PRIORITY_SCHEDULING */
/*---------------------------------------------------------------------------
* Move a thread back to a running state on its core.
*---------------------------------------------------------------------------
*/
static void core_schedule_wakeup(struct thread_entry *thread)
{
const unsigned int core = IF_COP_CORE(thread->core);
RTR_LOCK(core);
thread->state = STATE_RUNNING;
add_to_list_l(&cores[core].running, thread);
rtr_add_entry(core, thread->priority);
RTR_UNLOCK(core);
#if NUM_CORES > 1
if (core != CURRENT_CORE)
core_wake(core);
#endif
}
/*---------------------------------------------------------------------------
* Check the core's timeout list when at least one thread is due to wake.
* Filtering for the condition is done before making the call. Resets the
* tick when the next check will occur.
*---------------------------------------------------------------------------
*/
void check_tmo_threads(void)
{
const unsigned int core = CURRENT_CORE;
const long tick = current_tick; /* snapshot the current tick */
long next_tmo_check = tick + 60*HZ; /* minimum duration: once/minute */
struct thread_entry *next = cores[core].timeout;
/* If there are no processes waiting for a timeout, just keep the check
tick from falling into the past. */
/* Break the loop once we have walked through the list of all
* sleeping processes or have removed them all. */
while (next != NULL)
{
/* Check sleeping threads. Allow interrupts between checks. */
enable_irq();
struct thread_entry *curr = next;
next = curr->tmo.next;
/* Lock thread slot against explicit wakeup */
disable_irq();
LOCK_THREAD(curr);
unsigned state = curr->state;
if (state < TIMEOUT_STATE_FIRST)
{
/* Cleanup threads no longer on a timeout but still on the
* list. */
remove_from_list_tmo(curr);
}
else if (LIKELY(TIME_BEFORE(tick, curr->tmo_tick)))
{
/* Timeout still pending - this will be the usual case */
if (TIME_BEFORE(curr->tmo_tick, next_tmo_check))
{
/* Earliest timeout found so far - move the next check up
to its time */
next_tmo_check = curr->tmo_tick;
}
}
else
{
/* Sleep timeout has been reached so bring the thread back to
* life again. */
if (state == STATE_BLOCKED_W_TMO)
{
#if NUM_CORES > 1
/* Lock the waiting thread's kernel object */
struct corelock *ocl = curr->obj_cl;
if (UNLIKELY(corelock_try_lock(ocl) == 0))
{
/* Need to retry in the correct order though the need is
* unlikely */
UNLOCK_THREAD(curr);
corelock_lock(ocl);
LOCK_THREAD(curr);
if (UNLIKELY(curr->state != STATE_BLOCKED_W_TMO))
{
/* Thread was woken or removed explicitely while slot
* was unlocked */
corelock_unlock(ocl);
remove_from_list_tmo(curr);
UNLOCK_THREAD(curr);
continue;
}
}
#endif /* NUM_CORES */
remove_from_list_l(curr->bqp, curr);
#ifdef HAVE_WAKEUP_EXT_CB
if (curr->wakeup_ext_cb != NULL)
curr->wakeup_ext_cb(curr);
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
if (curr->blocker != NULL)
wakeup_priority_protocol_release(curr);
#endif
corelock_unlock(ocl);
}
/* else state == STATE_SLEEPING */
remove_from_list_tmo(curr);
RTR_LOCK(core);
curr->state = STATE_RUNNING;
add_to_list_l(&cores[core].running, curr);
rtr_add_entry(core, curr->priority);
RTR_UNLOCK(core);
}
UNLOCK_THREAD(curr);
}
cores[core].next_tmo_check = next_tmo_check;
}
/*---------------------------------------------------------------------------
* Performs operations that must be done before blocking a thread but after
* the state is saved.
*---------------------------------------------------------------------------
*/
#if NUM_CORES > 1
static inline void run_blocking_ops(
unsigned int core, struct thread_entry *thread)
{
struct thread_blk_ops *ops = &cores[core].blk_ops;
const unsigned flags = ops->flags;
if (LIKELY(flags == TBOP_CLEAR))
return;
switch (flags)
{
case TBOP_SWITCH_CORE:
core_switch_blk_op(core, thread);
/* Fall-through */
case TBOP_UNLOCK_CORELOCK:
corelock_unlock(ops->cl_p);
break;
}
ops->flags = TBOP_CLEAR;
}
#endif /* NUM_CORES > 1 */
#ifdef RB_PROFILE
void profile_thread(void)
{
profstart(cores[CURRENT_CORE].running - threads);
}
#endif
/*---------------------------------------------------------------------------
* Prepares a thread to block on an object's list and/or for a specified
* duration - expects object and slot to be appropriately locked if needed
* and interrupts to be masked.
*---------------------------------------------------------------------------
*/
static inline void block_thread_on_l(struct thread_entry *thread,
unsigned state)
{
/* If inlined, unreachable branches will be pruned with no size penalty
because state is passed as a constant parameter. */
const unsigned int core = IF_COP_CORE(thread->core);
/* Remove the thread from the list of running threads. */
RTR_LOCK(core);
remove_from_list_l(&cores[core].running, thread);
rtr_subtract_entry(core, thread->priority);
RTR_UNLOCK(core);
/* Add a timeout to the block if not infinite */
switch (state)
{
case STATE_BLOCKED:
case STATE_BLOCKED_W_TMO:
/* Put the thread into a new list of inactive threads. */
add_to_list_l(thread->bqp, thread);
if (state == STATE_BLOCKED)
break;
/* Fall-through */
case STATE_SLEEPING:
/* If this thread times out sooner than any other thread, update
next_tmo_check to its timeout */
if (TIME_BEFORE(thread->tmo_tick, cores[core].next_tmo_check))
{
cores[core].next_tmo_check = thread->tmo_tick;
}
if (thread->tmo.prev == NULL)
{
add_to_list_tmo(thread);
}
/* else thread was never removed from list - just keep it there */
break;
}
/* Remember the the next thread about to block. */
cores[core].block_task = thread;
/* Report new state. */
thread->state = state;
}
/*---------------------------------------------------------------------------
* Switch thread in round robin fashion for any given priority. Any thread
* that removed itself from the running list first must specify itself in
* the paramter.
*
* INTERNAL: Intended for use by kernel and not for programs.
*---------------------------------------------------------------------------
*/
void switch_thread(void)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *block = cores[core].block_task;
struct thread_entry *thread = cores[core].running;
/* Get context to save - next thread to run is unknown until all wakeups
* are evaluated */
if (block != NULL)
{
cores[core].block_task = NULL;
#if NUM_CORES > 1
if (UNLIKELY(thread == block))
{
/* This was the last thread running and another core woke us before
* reaching here. Force next thread selection to give tmo threads or
* other threads woken before this block a first chance. */
block = NULL;
}
else
#endif
{
/* Blocking task is the old one */
thread = block;
}
}
#ifdef RB_PROFILE
profile_thread_stopped(thread->id & THREAD_ID_SLOT_MASK);
#endif
/* Begin task switching by saving our current context so that we can
* restore the state of the current thread later to the point prior
* to this call. */
store_context(&thread->context);
/* Check if the current thread stack is overflown */
if (UNLIKELY(thread->stack[0] != DEADBEEF))
thread_stkov(thread);
#if NUM_CORES > 1
/* Run any blocking operations requested before switching/sleeping */
run_blocking_ops(core, thread);
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
IF_NO_SKIP_YIELD( if (thread->skip_count != -1) )
/* Reset the value of thread's skip count */
thread->skip_count = 0;
#endif
for (;;)
{
/* If there are threads on a timeout and the earliest wakeup is due,
* check the list and wake any threads that need to start running
* again. */
if (!TIME_BEFORE(current_tick, cores[core].next_tmo_check))
{
check_tmo_threads();
}
disable_irq();
RTR_LOCK(core);
thread = cores[core].running;
if (UNLIKELY(thread == NULL))
{
/* Enter sleep mode to reduce power usage - woken up on interrupt
* or wakeup request from another core - expected to enable
* interrupts. */
RTR_UNLOCK(core);
core_sleep(IF_COP(core));
}
else
{
#ifdef HAVE_PRIORITY_SCHEDULING
/* Select the new task based on priorities and the last time a
* process got CPU time relative to the highest priority runnable
* task. */
struct priority_distribution *pd = &cores[core].rtr;
int max = find_first_set_bit(pd->mask);
if (block == NULL)
{
/* Not switching on a block, tentatively select next thread */
thread = thread->l.next;
}
for (;;)
{
int priority = thread->priority;
int diff;
/* This ridiculously simple method of aging seems to work
* suspiciously well. It does tend to reward CPU hogs (under
* yielding) but that's generally not desirable at all. On the
* plus side, it, relatively to other threads, penalizes excess
* yielding which is good if some high priority thread is
* performing no useful work such as polling for a device to be
* ready. Of course, aging is only employed when higher and lower
* priority threads are runnable. The highest priority runnable
* thread(s) are never skipped. */
if (LIKELY(priority <= max) ||
IF_NO_SKIP_YIELD( thread->skip_count == -1 || )
(diff = priority - max, ++thread->skip_count > diff*diff))
{
cores[core].running = thread;
break;
}
thread = thread->l.next;
}
#else
/* Without priority use a simple FCFS algorithm */
if (block == NULL)
{
/* Not switching on a block, select next thread */
thread = thread->l.next;
cores[core].running = thread;
}
#endif /* HAVE_PRIORITY_SCHEDULING */
RTR_UNLOCK(core);
enable_irq();
break;
}
}
/* And finally give control to the next thread. */
load_context(&thread->context);
#ifdef RB_PROFILE
profile_thread_started(thread->id & THREAD_ID_SLOT_MASK);
#endif
}
/*---------------------------------------------------------------------------
* Sleeps a thread for at least a specified number of ticks with zero being
* a wait until the next tick.
*
* INTERNAL: Intended for use by kernel and not for programs.
*---------------------------------------------------------------------------
*/
void sleep_thread(int ticks)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
LOCK_THREAD(current);
/* Set our timeout, remove from run list and join timeout list. */
current->tmo_tick = current_tick + ticks + 1;
block_thread_on_l(current, STATE_SLEEPING);
UNLOCK_THREAD(current);
}
/*---------------------------------------------------------------------------
* Indefinitely block a thread on a blocking queue for explicit wakeup.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
void block_thread(struct thread_entry *current)
{
/* Set the state to blocked and take us off of the run queue until we
* are explicitly woken */
LOCK_THREAD(current);
/* Set the list for explicit wakeup */
block_thread_on_l(current, STATE_BLOCKED);
#ifdef HAVE_PRIORITY_SCHEDULING
if (current->blocker != NULL)
{
/* Object supports PIP */
current = blocker_inherit_priority(current);
}
#endif
UNLOCK_THREAD(current);
}
/*---------------------------------------------------------------------------
* Block a thread on a blocking queue for a specified time interval or until
* explicitly woken - whichever happens first.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
void block_thread_w_tmo(struct thread_entry *current, int timeout)
{
/* Get the entry for the current running thread. */
LOCK_THREAD(current);
/* Set the state to blocked with the specified timeout */
current->tmo_tick = current_tick + timeout;
/* Set the list for explicit wakeup */
block_thread_on_l(current, STATE_BLOCKED_W_TMO);
#ifdef HAVE_PRIORITY_SCHEDULING
if (current->blocker != NULL)
{
/* Object supports PIP */
current = blocker_inherit_priority(current);
}
#endif
UNLOCK_THREAD(current);
}
/*---------------------------------------------------------------------------
* Explicitly wakeup a thread on a blocking queue. Only effects threads of
* STATE_BLOCKED and STATE_BLOCKED_W_TMO.
*
* This code should be considered a critical section by the caller meaning
* that the object's corelock should be held.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
unsigned int wakeup_thread(struct thread_entry **list)
{
struct thread_entry *thread = *list;
unsigned int result = THREAD_NONE;
/* Check if there is a blocked thread at all. */
if (thread == NULL)
return result;
LOCK_THREAD(thread);
/* Determine thread's current state. */
switch (thread->state)
{
case STATE_BLOCKED:
case STATE_BLOCKED_W_TMO:
remove_from_list_l(list, thread);
result = THREAD_OK;
#ifdef HAVE_PRIORITY_SCHEDULING
struct thread_entry *current;
struct blocker *bl = thread->blocker;
if (bl == NULL)
{
/* No inheritance - just boost the thread by aging */
IF_NO_SKIP_YIELD( if (thread->skip_count != -1) )
thread->skip_count = thread->priority;
current = cores[CURRENT_CORE].running;
}
else
{
/* Call the specified unblocking PIP */
current = bl->wakeup_protocol(thread);
}
if (current != NULL && thread->priority < current->priority
IF_COP( && thread->core == current->core ))
{
/* Woken thread is higher priority and exists on the same CPU core;
* recommend a task switch. Knowing if this is an interrupt call
* would be helpful here. */
result |= THREAD_SWITCH;
}
#endif /* HAVE_PRIORITY_SCHEDULING */
core_schedule_wakeup(thread);
break;
/* Nothing to do. State is not blocked. */
#if THREAD_EXTRA_CHECKS
default:
THREAD_PANICF("wakeup_thread->block invalid", thread);
case STATE_RUNNING:
case STATE_KILLED:
break;
#endif
}
UNLOCK_THREAD(thread);
return result;
}
/*---------------------------------------------------------------------------
* Wakeup an entire queue of threads - returns bitwise-or of return bitmask
* from each operation or THREAD_NONE of nothing was awakened. Object owning
* the queue must be locked first.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
unsigned int thread_queue_wake(struct thread_entry **list)
{
unsigned result = THREAD_NONE;
for (;;)
{
unsigned int rc = wakeup_thread(list);
if (rc == THREAD_NONE)
break; /* No more threads */
result |= rc;
}
return result;
}
/*---------------------------------------------------------------------------
* Assign the thread slot a new ID. Version is 1-255.
*---------------------------------------------------------------------------
*/
static void new_thread_id(unsigned int slot_num,
struct thread_entry *thread)
{
unsigned int version =
(thread->id + (1u << THREAD_ID_VERSION_SHIFT))
& THREAD_ID_VERSION_MASK;
/* If wrapped to 0, make it 1 */
if (version == 0)
version = 1u << THREAD_ID_VERSION_SHIFT;
thread->id = version | (slot_num & THREAD_ID_SLOT_MASK);
}
/*---------------------------------------------------------------------------
* Find an empty thread slot or MAXTHREADS if none found. The slot returned
* will be locked on multicore.
*---------------------------------------------------------------------------
*/
static struct thread_entry * find_empty_thread_slot(void)
{
/* Any slot could be on an interrupt-accessible list */
IF_COP( int oldlevel = disable_irq_save(); )
struct thread_entry *thread = NULL;
int n;
for (n = 0; n < MAXTHREADS; n++)
{
/* Obtain current slot state - lock it on multicore */
struct thread_entry *t = &threads[n];
LOCK_THREAD(t);
if (t->state == STATE_KILLED IF_COP( && t->name != THREAD_DESTRUCT ))
{
/* Slot is empty - leave it locked and caller will unlock */
thread = t;
break;
}
/* Finished examining slot - no longer busy - unlock on multicore */
UNLOCK_THREAD(t);
}
IF_COP( restore_irq(oldlevel); ) /* Reenable interrups - this slot is
not accesible to them yet */
return thread;
}
/*---------------------------------------------------------------------------
* Return the thread_entry pointer for a thread_id. Return the current
* thread if the ID is 0 (alias for current).
*---------------------------------------------------------------------------
*/
struct thread_entry * thread_id_entry(unsigned int thread_id)
{
return (thread_id == THREAD_ID_CURRENT) ?
cores[CURRENT_CORE].running :
&threads[thread_id & THREAD_ID_SLOT_MASK];
}
/*---------------------------------------------------------------------------
* Place the current core in idle mode - woken up on interrupt or wake
* request from another core.
*---------------------------------------------------------------------------
*/
void core_idle(void)
{
IF_COP( const unsigned int core = CURRENT_CORE; )
disable_irq();
core_sleep(IF_COP(core));
}
/*---------------------------------------------------------------------------
* Create a thread. If using a dual core architecture, specify which core to
* start the thread on.
*
* Return ID if context area could be allocated, else NULL.
*---------------------------------------------------------------------------
*/
unsigned int create_thread(void (*function)(void),
void* stack, size_t stack_size,
unsigned flags, const char *name
IF_PRIO(, int priority)
IF_COP(, unsigned int core))
{
unsigned int i;
unsigned int stack_words;
uintptr_t stackptr, stackend;
struct thread_entry *thread;
unsigned state;
int oldlevel;
thread = find_empty_thread_slot();
if (thread == NULL)
{
return 0;
}
oldlevel = disable_irq_save();
/* Munge the stack to make it easy to spot stack overflows */
stackptr = ALIGN_UP((uintptr_t)stack, sizeof (uintptr_t));
stackend = ALIGN_DOWN((uintptr_t)stack + stack_size, sizeof (uintptr_t));
stack_size = stackend - stackptr;
stack_words = stack_size / sizeof (uintptr_t);
for (i = 0; i < stack_words; i++)
{
((uintptr_t *)stackptr)[i] = DEADBEEF;
}
/* Store interesting information */
thread->name = name;
thread->stack = (uintptr_t *)stackptr;
thread->stack_size = stack_size;
thread->queue = NULL;
#ifdef HAVE_WAKEUP_EXT_CB
thread->wakeup_ext_cb = NULL;
#endif
#ifdef HAVE_SCHEDULER_BOOSTCTRL
thread->cpu_boost = 0;
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
memset(&thread->pdist, 0, sizeof(thread->pdist));
thread->blocker = NULL;
thread->base_priority = priority;
thread->priority = priority;
thread->skip_count = priority;
prio_add_entry(&thread->pdist, priority);
#endif
#ifdef HAVE_IO_PRIORITY
/* Default to high (foreground) priority */
thread->io_priority = IO_PRIORITY_IMMEDIATE;
#endif
#if NUM_CORES > 1
thread->core = core;
/* Writeback stack munging or anything else before starting */
if (core != CURRENT_CORE)
{
cpucache_flush();
}
#endif
/* Thread is not on any timeout list but be a bit paranoid */
thread->tmo.prev = NULL;
state = (flags & CREATE_THREAD_FROZEN) ?
STATE_FROZEN : STATE_RUNNING;
thread->context.sp = (typeof (thread->context.sp))stackend;
/* Load the thread's context structure with needed startup information */
THREAD_STARTUP_INIT(core, thread, function);
thread->state = state;
i = thread->id; /* Snapshot while locked */
if (state == STATE_RUNNING)
core_schedule_wakeup(thread);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
return i;
}
#ifdef HAVE_SCHEDULER_BOOSTCTRL
/*---------------------------------------------------------------------------
* Change the boost state of a thread boosting or unboosting the CPU
* as required.
*---------------------------------------------------------------------------
*/
static inline void boost_thread(struct thread_entry *thread, bool boost)
{
if ((thread->cpu_boost != 0) != boost)
{
thread->cpu_boost = boost;
cpu_boost(boost);
}
}
void trigger_cpu_boost(void)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
boost_thread(current, true);
}
void cancel_cpu_boost(void)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
boost_thread(current, false);
}
#endif /* HAVE_SCHEDULER_BOOSTCTRL */
/*---------------------------------------------------------------------------
* Block the current thread until another thread terminates. A thread may
* wait on itself to terminate which prevents it from running again and it
* will need to be killed externally.
* Parameter is the ID as returned from create_thread().
*---------------------------------------------------------------------------
*/
void thread_wait(unsigned int thread_id)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
struct thread_entry *thread = thread_id_entry(thread_id);
/* Lock thread-as-waitable-object lock */
corelock_lock(&thread->waiter_cl);
/* Be sure it hasn't been killed yet */
if (thread_id == THREAD_ID_CURRENT ||
(thread->id == thread_id && thread->state != STATE_KILLED))
{
IF_COP( current->obj_cl = &thread->waiter_cl; )
current->bqp = &thread->queue;
disable_irq();
block_thread(current);
corelock_unlock(&thread->waiter_cl);
switch_thread();
return;
}
corelock_unlock(&thread->waiter_cl);
}
/*---------------------------------------------------------------------------
* Exit the current thread. The Right Way to Do Things (TM).
*---------------------------------------------------------------------------
*/
void thread_exit(void)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *current = cores[core].running;
/* Cancel CPU boost if any */
cancel_cpu_boost();
disable_irq();
corelock_lock(&current->waiter_cl);
LOCK_THREAD(current);
#if defined (ALLOW_REMOVE_THREAD) && NUM_CORES > 1
if (current->name == THREAD_DESTRUCT)
{
/* Thread being killed - become a waiter */
unsigned int id = current->id;
UNLOCK_THREAD(current);
corelock_unlock(&current->waiter_cl);
thread_wait(id);
THREAD_PANICF("thread_exit->WK:*R", current);
}
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
check_for_obj_waiters("thread_exit", current);
#endif
if (current->tmo.prev != NULL)
{
/* Cancel pending timeout list removal */
remove_from_list_tmo(current);
}
/* Switch tasks and never return */
block_thread_on_l(current, STATE_KILLED);
#if NUM_CORES > 1
/* Switch to the idle stack if not on the main core (where "main"
* runs) - we can hope gcc doesn't need the old stack beyond this
* point. */
if (core != CPU)
{
switch_to_idle_stack(core);
}
cpucache_flush();
/* At this point, this thread isn't using resources allocated for
* execution except the slot itself. */
#endif
/* Update ID for this slot */
new_thread_id(current->id, current);
current->name = NULL;
/* Signal this thread */
thread_queue_wake(&current->queue);
corelock_unlock(&current->waiter_cl);
/* Slot must be unusable until thread is really gone */
UNLOCK_THREAD_AT_TASK_SWITCH(current);
switch_thread();
/* This should never and must never be reached - if it is, the
* state is corrupted */
THREAD_PANICF("thread_exit->K:*R", current);
}
#ifdef ALLOW_REMOVE_THREAD
/*---------------------------------------------------------------------------
* Remove a thread from the scheduler. Not The Right Way to Do Things in
* normal programs.
*
* Parameter is the ID as returned from create_thread().
*
* Use with care on threads that are not under careful control as this may
* leave various objects in an undefined state.
*---------------------------------------------------------------------------
*/
void remove_thread(unsigned int thread_id)
{
#if NUM_CORES > 1
/* core is not constant here because of core switching */
unsigned int core = CURRENT_CORE;
unsigned int old_core = NUM_CORES;
struct corelock *ocl = NULL;
#else
const unsigned int core = CURRENT_CORE;
#endif
struct thread_entry *current = cores[core].running;
struct thread_entry *thread = thread_id_entry(thread_id);
unsigned state;
int oldlevel;
if (thread == current)
thread_exit(); /* Current thread - do normal exit */
oldlevel = disable_irq_save();
corelock_lock(&thread->waiter_cl);
LOCK_THREAD(thread);
state = thread->state;
if (thread->id != thread_id || state == STATE_KILLED)
goto thread_killed;
#if NUM_CORES > 1
if (thread->name == THREAD_DESTRUCT)
{
/* Thread being killed - become a waiter */
UNLOCK_THREAD(thread);
corelock_unlock(&thread->waiter_cl);
restore_irq(oldlevel);
thread_wait(thread_id);
return;
}
thread->name = THREAD_DESTRUCT; /* Slot can't be used for now */
#ifdef HAVE_PRIORITY_SCHEDULING
check_for_obj_waiters("remove_thread", thread);
#endif
if (thread->core != core)
{
/* Switch cores and safely extract the thread there */
/* Slot HAS to be unlocked or a deadlock could occur which means other
* threads have to be guided into becoming thread waiters if they
* attempt to remove it. */
unsigned int new_core = thread->core;
corelock_unlock(&thread->waiter_cl);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
old_core = switch_core(new_core);
oldlevel = disable_irq_save();
corelock_lock(&thread->waiter_cl);
LOCK_THREAD(thread);
state = thread->state;
core = new_core;
/* Perform the extraction and switch ourselves back to the original
processor */
}
#endif /* NUM_CORES > 1 */
if (thread->tmo.prev != NULL)
{
/* Clean thread off the timeout list if a timeout check hasn't
* run yet */
remove_from_list_tmo(thread);
}
#ifdef HAVE_SCHEDULER_BOOSTCTRL
/* Cancel CPU boost if any */
boost_thread(thread, false);
#endif
IF_COP( retry_state: )
switch (state)
{
case STATE_RUNNING:
RTR_LOCK(core);
/* Remove thread from ready to run tasks */
remove_from_list_l(&cores[core].running, thread);
rtr_subtract_entry(core, thread->priority);
RTR_UNLOCK(core);
break;
case STATE_BLOCKED:
case STATE_BLOCKED_W_TMO:
/* Remove thread from the queue it's blocked on - including its
* own if waiting there */
#if NUM_CORES > 1
if (&thread->waiter_cl != thread->obj_cl)
{
ocl = thread->obj_cl;
if (UNLIKELY(corelock_try_lock(ocl) == 0))
{
UNLOCK_THREAD(thread);
corelock_lock(ocl);
LOCK_THREAD(thread);
if (UNLIKELY(thread->state != state))
{
/* Something woke the thread */
state = thread->state;
corelock_unlock(ocl);
goto retry_state;
}
}
}
#endif
remove_from_list_l(thread->bqp, thread);
#ifdef HAVE_WAKEUP_EXT_CB
if (thread->wakeup_ext_cb != NULL)
thread->wakeup_ext_cb(thread);
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
if (thread->blocker != NULL)
{
/* Remove thread's priority influence from its chain */
wakeup_priority_protocol_release(thread);
}
#endif
#if NUM_CORES > 1
if (ocl != NULL)
corelock_unlock(ocl);
#endif
break;
/* Otherwise thread is frozen and hasn't run yet */
}
new_thread_id(thread_id, thread);
thread->state = STATE_KILLED;
/* If thread was waiting on itself, it will have been removed above.
* The wrong order would result in waking the thread first and deadlocking
* since the slot is already locked. */
thread_queue_wake(&thread->queue);
thread->name = NULL;
thread_killed: /* Thread was already killed */
/* Removal complete - safe to unlock and reenable interrupts */
corelock_unlock(&thread->waiter_cl);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
#if NUM_CORES > 1
if (old_core < NUM_CORES)
{
/* Did a removal on another processor's thread - switch back to
native core */
switch_core(old_core);
}
#endif
}
#endif /* ALLOW_REMOVE_THREAD */
#ifdef HAVE_PRIORITY_SCHEDULING
/*---------------------------------------------------------------------------
* Sets the thread's relative base priority for the core it runs on. Any
* needed inheritance changes also may happen.
*---------------------------------------------------------------------------
*/
int thread_set_priority(unsigned int thread_id, int priority)
{
int old_base_priority = -1;
struct thread_entry *thread = thread_id_entry(thread_id);
/* A little safety measure */
if (priority < HIGHEST_PRIORITY || priority > LOWEST_PRIORITY)
return -1;
/* Thread could be on any list and therefore on an interrupt accessible
one - disable interrupts */
int oldlevel = disable_irq_save();
LOCK_THREAD(thread);
/* Make sure it's not killed */
if (thread_id == THREAD_ID_CURRENT ||
(thread->id == thread_id && thread->state != STATE_KILLED))
{
int old_priority = thread->priority;
old_base_priority = thread->base_priority;
thread->base_priority = priority;
prio_move_entry(&thread->pdist, old_base_priority, priority);
priority = find_first_set_bit(thread->pdist.mask);
if (old_priority == priority)
{
/* No priority change - do nothing */
}
else if (thread->state == STATE_RUNNING)
{
/* This thread is running - change location on the run
* queue. No transitive inheritance needed. */
set_running_thread_priority(thread, priority);
}
else
{
thread->priority = priority;
if (thread->blocker != NULL)
{
/* Bubble new priority down the chain */
struct blocker *bl = thread->blocker; /* Blocker struct */
struct thread_entry *bl_t = bl->thread; /* Blocking thread */
struct thread_entry * const tstart = thread; /* Initial thread */
const int highest = MIN(priority, old_priority); /* Higher of new or old */
for (;;)
{
struct thread_entry *next; /* Next thread to check */
int bl_pr; /* Highest blocked thread */
int queue_pr; /* New highest blocked thread */
#if NUM_CORES > 1
/* Owner can change but thread cannot be dislodged - thread
* may not be the first in the queue which allows other
* threads ahead in the list to be given ownership during the
* operation. If thread is next then the waker will have to
* wait for us and the owner of the object will remain fixed.
* If we successfully grab the owner -- which at some point
* is guaranteed -- then the queue remains fixed until we
* pass by. */
for (;;)
{
LOCK_THREAD(bl_t);
/* Double-check the owner - retry if it changed */
if (LIKELY(bl->thread == bl_t))
break;
UNLOCK_THREAD(bl_t);
bl_t = bl->thread;
}
#endif
bl_pr = bl->priority;
if (highest > bl_pr)
break; /* Object priority won't change */
/* This will include the thread being set */
queue_pr = find_highest_priority_in_list_l(*thread->bqp);
if (queue_pr == bl_pr)
break; /* Object priority not changing */
/* Update thread boost for this object */
bl->priority = queue_pr;
prio_move_entry(&bl_t->pdist, bl_pr, queue_pr);
bl_pr = find_first_set_bit(bl_t->pdist.mask);
if (bl_t->priority == bl_pr)
break; /* Blocking thread priority not changing */
if (bl_t->state == STATE_RUNNING)
{
/* Thread not blocked - we're done */
set_running_thread_priority(bl_t, bl_pr);
break;
}
bl_t->priority = bl_pr;
bl = bl_t->blocker; /* Blocking thread has a blocker? */
if (bl == NULL)
break; /* End of chain */
next = bl->thread;
if (UNLIKELY(next == tstart))
break; /* Full-circle */
UNLOCK_THREAD(thread);
thread = bl_t;
bl_t = next;
} /* for (;;) */
UNLOCK_THREAD(bl_t);
}
}
}
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
return old_base_priority;
}
/*---------------------------------------------------------------------------
* Returns the current base priority for a thread.
*---------------------------------------------------------------------------
*/
int thread_get_priority(unsigned int thread_id)
{
struct thread_entry *thread = thread_id_entry(thread_id);
int base_priority = thread->base_priority;
/* Simply check without locking slot. It may or may not be valid by the
* time the function returns anyway. If all tests pass, it is the
* correct value for when it was valid. */
if (thread_id != THREAD_ID_CURRENT &&
(thread->id != thread_id || thread->state == STATE_KILLED))
base_priority = -1;
return base_priority;
}
#endif /* HAVE_PRIORITY_SCHEDULING */
#ifdef HAVE_IO_PRIORITY
int thread_get_io_priority(unsigned int thread_id)
{
struct thread_entry *thread = thread_id_entry(thread_id);
return thread->io_priority;
}
void thread_set_io_priority(unsigned int thread_id,int io_priority)
{
struct thread_entry *thread = thread_id_entry(thread_id);
thread->io_priority = io_priority;
}
#endif
/*---------------------------------------------------------------------------
* Starts a frozen thread - similar semantics to wakeup_thread except that
* the thread is on no scheduler or wakeup queue at all. It exists simply by
* virtue of the slot having a state of STATE_FROZEN.
*---------------------------------------------------------------------------
*/
void thread_thaw(unsigned int thread_id)
{
struct thread_entry *thread = thread_id_entry(thread_id);
int oldlevel = disable_irq_save();
LOCK_THREAD(thread);
/* If thread is the current one, it cannot be frozen, therefore
* there is no need to check that. */
if (thread->id == thread_id && thread->state == STATE_FROZEN)
core_schedule_wakeup(thread);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
}
/*---------------------------------------------------------------------------
* Return the ID of the currently executing thread.
*---------------------------------------------------------------------------
*/
unsigned int thread_get_current(void)
{
return cores[CURRENT_CORE].running->id;
}
#if NUM_CORES > 1
/*---------------------------------------------------------------------------
* Switch the processor that the currently executing thread runs on.
*---------------------------------------------------------------------------
*/
unsigned int switch_core(unsigned int new_core)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *current = cores[core].running;
if (core == new_core)
{
/* No change - just return same core */
return core;
}
int oldlevel = disable_irq_save();
LOCK_THREAD(current);
if (current->name == THREAD_DESTRUCT)
{
/* Thread being killed - deactivate and let process complete */
unsigned int id = current->id;
UNLOCK_THREAD(current);
restore_irq(oldlevel);
thread_wait(id);
/* Should never be reached */
THREAD_PANICF("switch_core->D:*R", current);
}
/* Get us off the running list for the current core */
RTR_LOCK(core);
remove_from_list_l(&cores[core].running, current);
rtr_subtract_entry(core, current->priority);
RTR_UNLOCK(core);
/* Stash return value (old core) in a safe place */
current->retval = core;
/* If a timeout hadn't yet been cleaned-up it must be removed now or
* the other core will likely attempt a removal from the wrong list! */
if (current->tmo.prev != NULL)
{
remove_from_list_tmo(current);
}
/* Change the core number for this thread slot */
current->core = new_core;
/* Do not use core_schedule_wakeup here since this will result in
* the thread starting to run on the other core before being finished on
* this one. Delay the list unlock to keep the other core stuck
* until this thread is ready. */
RTR_LOCK(new_core);
rtr_add_entry(new_core, current->priority);
add_to_list_l(&cores[new_core].running, current);
/* Make a callback into device-specific code, unlock the wakeup list so
* that execution may resume on the new core, unlock our slot and finally
* restore the interrupt level */
cores[core].blk_ops.flags = TBOP_SWITCH_CORE;
cores[core].blk_ops.cl_p = &cores[new_core].rtr_cl;
cores[core].block_task = current;
UNLOCK_THREAD(current);
/* Alert other core to activity */
core_wake(new_core);
/* Do the stack switching, cache_maintenence and switch_thread call -
requires native code */
switch_thread_core(core, current);
/* Finally return the old core to caller */
return current->retval;
}
#endif /* NUM_CORES > 1 */
/*---------------------------------------------------------------------------
* Initialize threading API. This assumes interrupts are not yet enabled. On
* multicore setups, no core is allowed to proceed until create_thread calls
* are safe to perform.
*---------------------------------------------------------------------------
*/
void init_threads(void)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *thread;
if (core == CPU)
{
/* Initialize core locks and IDs in all slots */
int n;
for (n = 0; n < MAXTHREADS; n++)
{
thread = &threads[n];
corelock_init(&thread->waiter_cl);
corelock_init(&thread->slot_cl);
thread->id = THREAD_ID_INIT(n);
}
}
/* CPU will initialize first and then sleep */
thread = find_empty_thread_slot();
if (thread == NULL)
{
/* WTF? There really must be a slot available at this stage.
* This can fail if, for example, .bss isn't zero'ed out by the loader
* or threads is in the wrong section. */
THREAD_PANICF("init_threads->no slot", NULL);
}
/* Initialize initially non-zero members of core */
cores[core].next_tmo_check = current_tick; /* Something not in the past */
/* Initialize initially non-zero members of slot */
UNLOCK_THREAD(thread); /* No sync worries yet */
thread->name = main_thread_name;
thread->state = STATE_RUNNING;
IF_COP( thread->core = core; )
#ifdef HAVE_PRIORITY_SCHEDULING
corelock_init(&cores[core].rtr_cl);
thread->base_priority = PRIORITY_USER_INTERFACE;
prio_add_entry(&thread->pdist, PRIORITY_USER_INTERFACE);
thread->priority = PRIORITY_USER_INTERFACE;
rtr_add_entry(core, PRIORITY_USER_INTERFACE);
#endif
add_to_list_l(&cores[core].running, thread);
if (core == CPU)
{
thread->stack = stackbegin;
thread->stack_size = (uintptr_t)stackend - (uintptr_t)stackbegin;
#if NUM_CORES > 1 /* This code path will not be run on single core targets */
/* Wait for other processors to finish their inits since create_thread
* isn't safe to call until the kernel inits are done. The first
* threads created in the system must of course be created by CPU.
* Another possible approach is to initialize all cores and slots
* for each core by CPU, let the remainder proceed in parallel and
* signal CPU when all are finished. */
core_thread_init(CPU);
}
else
{
/* Initial stack is the idle stack */
thread->stack = idle_stacks[core];
thread->stack_size = IDLE_STACK_SIZE;
/* After last processor completes, it should signal all others to
* proceed or may signal the next and call thread_exit(). The last one
* to finish will signal CPU. */
core_thread_init(core);
/* Other cores do not have a main thread - go idle inside switch_thread
* until a thread can run on the core. */
thread_exit();
#endif /* NUM_CORES */
}
}
/* Shared stack scan helper for thread_stack_usage and idle_stack_usage */
#if NUM_CORES == 1
static inline int stack_usage(uintptr_t *stackptr, size_t stack_size)
#else
static int stack_usage(uintptr_t *stackptr, size_t stack_size)
#endif
{
unsigned int stack_words = stack_size / sizeof (uintptr_t);
unsigned int i;
int usage = 0;
for (i = 0; i < stack_words; i++)
{
if (stackptr[i] != DEADBEEF)
{
usage = ((stack_words - i) * 100) / stack_words;
break;
}
}
return usage;
}
/*---------------------------------------------------------------------------
* Returns the maximum percentage of stack a thread ever used while running.
* NOTE: Some large buffer allocations that don't use enough the buffer to
* overwrite stackptr[0] will not be seen.
*---------------------------------------------------------------------------
*/
int thread_stack_usage(const struct thread_entry *thread)
{
return stack_usage(thread->stack, thread->stack_size);
}
#if NUM_CORES > 1
/*---------------------------------------------------------------------------
* Returns the maximum percentage of the core's idle stack ever used during
* runtime.
*---------------------------------------------------------------------------
*/
int idle_stack_usage(unsigned int core)
{
return stack_usage(idle_stacks[core], IDLE_STACK_SIZE);
}
#endif
/*---------------------------------------------------------------------------
* Fills in the buffer with the specified thread's name. If the name is NULL,
* empty, or the thread is in destruct state a formatted ID is written
* instead.
*---------------------------------------------------------------------------
*/
void thread_get_name(char *buffer, int size,
struct thread_entry *thread)
{
if (size <= 0)
return;
*buffer = '\0';
if (thread)
{
/* Display thread name if one or ID if none */
const char *name = thread->name;
const char *fmt = "%s";
if (name == NULL IF_COP(|| name == THREAD_DESTRUCT) || *name == '\0')
{
name = (const char *)thread;
fmt = "%08lX";
}
snprintf(buffer, size, fmt, name);
}
}