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Commit 3240dd57 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

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: default avatarVineet Gupta <vgupta@synopsys.com>
parent 13648b01

arch/arc/include/asm/processor.h

+2 −3
Original line number Diff line number Diff line
@@ -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);

arch/arc/kernel/process.c

+0 −23
Original line number Diff line number Diff line
@@ -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;