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ARC: Fix thread_saved_pc() 

The old implementation assumed that SP at the time of __switch_to() is
right above pt_regs which is almost certainly not the case as there will
be some stack build up between entry into kernel and leading up to
__switch_to

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2015-02-27 10:59:31 +05:30
parent 13648b0118
commit 3240dd57e5
2 changed files with 2 additions and 26 deletions
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5
arch/arc/include/asm/processor.h
View File

@ -47,9 +47,6 @@ struct thread_struct {
/* Forward declaration, a strange C thing */
struct task_struct;
/* Return saved PC of a blocked thread */
unsigned long thread_saved_pc(struct task_struct *t);
#define task_pt_regs(p) \
((struct pt_regs *)(THREAD_SIZE + (void *)task_stack_page(p)) - 1)
@ -86,6 +83,8 @@ unsigned long thread_saved_pc(struct task_struct *t);
#define TSK_K_BLINK(tsk) TSK_K_REG(tsk, 4)
#define TSK_K_FP(tsk) TSK_K_REG(tsk, 0)
#define thread_saved_pc(tsk) TSK_K_BLINK(tsk)
extern void start_thread(struct pt_regs * regs, unsigned long pc,
unsigned long usp);

23
arch/arc/kernel/process.c
View File

@ -192,29 +192,6 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
return 0;
}
/*
* API: expected by schedular Code: If thread is sleeping where is that.
* What is this good for? it will be always the scheduler or ret_from_fork.
* So we hard code that anyways.
*/
unsigned long thread_saved_pc(struct task_struct *t)
{
struct pt_regs *regs = task_pt_regs(t);
unsigned long blink = 0;
/*
* If the thread being queried for in not itself calling this, then it
* implies it is not executing, which in turn implies it is sleeping,
* which in turn implies it got switched OUT by the schedular.
* In that case, it's kernel mode blink can reliably retrieved as per
* the picture above (right above pt_regs).
*/
if (t != current && t->state != TASK_RUNNING)
blink = *((unsigned int *)regs - 1);
return blink;
}
int elf_check_arch(const struct elf32_hdr *x)
{
unsigned int eflags;