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rockbox/firmware/thread.c

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/***************************************************************************
* __________ __ ___.
* 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-r12, 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-r12, 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)
{
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
/* 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 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, 40($9) \n" /* Set initial sp(=$29) */
"sw $0, 48($9) \n" /* Clear start address */
"jr $8 \n" /* Start the thread */
"nop \n"
".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"
"move $8, %0 \n"
"sw $16, 0($8) \n" /* $s0 */
"sw $17, 4($8) \n" /* $s1 */
"sw $18, 8($8) \n" /* $s2 */
"sw $19, 12($8) \n" /* $s3 */
"sw $20, 16($8) \n" /* $s4 */
"sw $21, 20($8) \n" /* $s5 */
"sw $22, 24($8) \n" /* $s6 */
"sw $23, 28($8) \n" /* $s7 */
"sw $28, 32($8) \n" /* gp */
"sw $30, 36($8) \n" /* fp */
"sw $29, 40($8) \n" /* sp */
"sw $31, 44($8) \n" /* ra */
".set at \n"
".set reorder \n"
: : "r" (addr) : "t0"
);
}
/*---------------------------------------------------------------------------
* Load non-volatile context.
*---------------------------------------------------------------------------
*/
static inline void load_context(const void* addr)
{
asm volatile (
".set noat \n"
".set noreorder \n"
"lw $8, 48(%0) \n" /* Get start address ($8 = $t0) */
"beqz $8, running \n" /* NULL -> already running */
"nop \n"
"move $9, %0 \n" /* $t1 = context */
"jr $8 \n"
"nop \n"
"running: \n"
"move $8, %0 \n"
"lw $16, 0($8) \n" /* $s0 */
"lw $17, 4($8) \n" /* $s1 */
"lw $18, 8($8) \n" /* $s2 */
"lw $19, 12($8) \n" /* $s3 */
"lw $20, 16($8) \n" /* $s4 */
"lw $21, 20($8) \n" /* $s5 */
"lw $22, 24($8) \n" /* $s6 */
"lw $23, 28($8) \n" /* $s7 */
"lw $28, 32($8) \n" /* gp */
"lw $30, 36($8) \n" /* fp */
"lw $29, 40($8) \n" /* sp */
"lw $31, 44($8) \n" /* ra */
".set at \n"
".set reorder \n"
: : "r" (addr) : "t0" /* only! */
);
}
/*---------------------------------------------------------------------------
* 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"
"wait \n"
"mtc0 $9, $12 \n"
".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
#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 */
/*---------------------------------------------------------------------------
* 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);
}
}
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