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Fix preemption.

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Consider the sequence:

   chx_handle_intr -> chx_handle_intr -> preempt

We can't use R0 passing as an argument to preempt.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
This commit is contained in:
NIIBE Yutaka
2021-02-05 11:03:35 +09:00
parent c3f00e1c69
commit b0986cdb09
2 changed files with 16 additions and 34 deletions
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28
chopstx-cortex-m.c
View File

@@ -257,34 +257,31 @@ chx_cpu_sched_unlock (void)
}
static struct chx_thread *
static void
chx_request_preemption_possibly (struct chx_thread *tp_next)
{
if (!tp_next)
return NULL;
return;
if (preempting)
{
chx_ready_push (tp_next);
return NULL;
}
else
{
preempting = tp_next;
*ICSR = (1 << 28);
asm volatile ("" : : : "memory");
return tp_next;
}
}
struct chx_thread *
void
chx_timer_handler (void)
{
struct chx_thread *tp_next;
tp_next = chx_timer_expired ();
return chx_request_preemption_possibly (tp_next);
chx_request_preemption_possibly (tp_next);
}
struct chx_thread *
void
chx_handle_intr (void)
{
register uint32_t irq_num;
@@ -295,7 +292,7 @@ chx_handle_intr (void)
: "=r" (irq_num) : /* no input */ : "memory");
tp_next = chx_recv_irq (irq_num);
return chx_request_preemption_possibly (tp_next);
chx_request_preemption_possibly (tp_next);
}
static void
@@ -485,20 +482,19 @@ chopstx_create_arch (uintptr_t stack_addr, size_t stack_size,
*/
void __attribute__ ((naked))
preempt (struct chx_thread * tp_next)
preempt (void)
{
register struct chx_thread *tp_next asm ("r0");
register struct chx_thread *tp_current asm ("r1");
asm (
"mov r1, #0\n\t"
"ldr r2, =preempting\n\t"
#if defined(__ARM_ARCH_6M__)
"ldr r0, [r2]\n\t"
#endif
"str r1, [r2]\n\t"
"ldr r2, =running\n\t"
"ldr r1, [r2]"
: "=r" (tp_current)
: "=r" (tp_next), "=r" (tp_current)
: /* no input */
: "r2");
@@ -558,7 +554,7 @@ preempt (struct chx_thread * tp_next)
#endif
"mov r0, #0\n\t"
"sub r0, #3\n\t" /* EXC_RETURN to a thread with PSP */
"bx r0\n"
"bx r0"
: /* no output */ : "r" (tp_next) : "memory");
}

14
entry-cortex-m.c
View File

@@ -65,22 +65,8 @@ extern uint8_t __main_stack_end__;
extern void svc (void);
#endif
/*
* In ARMv6-M Architecture Reference Manual and ARM v7-M Architecture
* Reference Manual, you can find a section B1.5.12 for tail-chaining.
*
* B1.5.12 Exceptions on exception return, and tail-chaining exceptions
*/
/*
* Because it is tail-chained, the preempt function has an argument
* with type of (struct chx_thread *), in fact.
*/
extern void preempt (void);
/*
* Following functions return type of (struct chx_thread *) for
* tail-chained function (the preempt function), for its argument.
*/
extern void chx_timer_handler (void);
extern void chx_handle_intr (void);