michaelh/zephyr
1
0
Fork 0
Code Releases Activity

arm64: simplify the code around the call to z_get_next_switch_handle()

Browse source 
Remove the special SMP workaround and the extra wrapper.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2022-03-16 21:54:46 -04:00 • committed by Anas Nashif
commit 47e4a4487f
3 changed files with 16 additions and 65 deletions
Download patch file Download diff file Expand all files Collapse all files

53
arch/arm64/core/isr_wrapper.S
View file

@ -117,49 +117,28 @@ z_arm64_irq_done:
bne exit
/* No more nested: retrieve the task's stack. */
ldr x0, [sp]
mov sp, x0
ldr x1, [sp]
mov sp, x1
/* retrieve pointer to the current thread */
ldr x1, [x0, #___cpu_t_current_OFFSET]
/*
* z_arch_get_next_switch_handle() is returning:
*
* - The next thread to schedule in x0
* - The current thread in x1. This value is returned using the
* **old_thread parameter, so we need to make space on the stack for
* that.
* Get next thread to schedule with z_get_next_switch_handle().
* We pass it a NULL as we didn't save the whole thread context yet.
* If no scheduling is necessary then NULL will be returned.
*/
sub sp, sp, #16
mov x0, sp
bl z_arch_get_next_switch_handle
ldp x1, xzr, [sp], #16
str x1, [sp, #-16]!
mov x0, xzr
bl z_get_next_switch_handle
ldr x1, [sp], #16
cbz x0, exit
/*
* x0: 1st thread in the ready queue
* x1: _current thread
* Switch thread
* x0: new thread
* x1: old thread
*/
#ifdef CONFIG_SMP
/*
* 2 possibilities here:
* - x0 != NULL (implies x0 != x1): we need to context switch and set
* the switch_handle in the context switch code
* - x0 == NULL: no context switch
*/
cmp x0, #0x0
bne switch
/*
* No context switch. Restore x0 from x1 (they are the same thread).
* See also comments to z_arch_get_next_switch_handle()
*/
mov x0, x1
b exit
switch:
#else
cmp x0, x1
beq exit
#endif
/* Switch thread */
bl z_arm64_context_switch
exit:

2
arch/arm64/core/switch.S
View file

@ -68,12 +68,10 @@ SECTION_FUNC(TEXT, z_arm64_context_switch)
ldp x0, x1, [sp], #16
#endif
#ifdef CONFIG_SMP
/* save old thread into switch handle which is required by
* wait_for_switch
*/
str x1, [x1, #___thread_t_switch_handle_OFFSET]
#endif
#ifdef CONFIG_THREAD_LOCAL_STORAGE
/* Grab the TLS pointer */

26
arch/arm64/core/thread.c
View file

@ -120,32 +120,6 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
thread->switch_handle = thread;
}
void *z_arch_get_next_switch_handle(struct k_thread **old_thread)
{
/*
* When returning from this function we will have the current thread
* onto the stack to be popped in x1 and the next thread in x0 returned
* from z_get_next_switch_handle() (see isr_wrapper.S)
*/
*old_thread = _current;
#ifdef CONFIG_SMP
/*
* XXX: see thread in #41840 and #40795
*
* The scheduler API requires a complete switch handle here, but arm64
* optimizes things such that the callee-save registers are still
* unsaved here (they get written out in z_arm64_context_switch()
* below). So pass a NULL instead, which the scheduler will store into
* the thread switch_handle field. The resulting thread won't be
* switched into until we write that ourselves.
*/
return z_get_next_switch_handle(NULL);
#else
return z_get_next_switch_handle(*old_thread);
#endif
}
#ifdef CONFIG_USERSPACE
FUNC_NORETURN void arch_user_mode_enter(k_thread_entry_t user_entry,
void *p1, void *p2, void *p3)