Commit 6756dd9b authored by Vasily Gorbik's avatar Vasily Gorbik
Browse files

s390/process: avoid custom stack unwinding in get_wchan 



Currently get_wchan uses custom stack unwinding implementation which
relies on back_chain presence. Replace it with more abstract stack
unwinding api usage.

Suggested-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent ea3f6dcf

arch/s390/kernel/process.c

+16 −20
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#include <asm/stacktrace.h>

#include <asm/switch_to.h>

#include <asm/runtime_instr.h>

#include <asm/unwind.h>

#include "entry.h"



asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
@@ -178,9 +179,8 @@ EXPORT_SYMBOL(dump_fpu); 


unsigned long get_wchan(struct task_struct *p)

{

	struct stack_frame *sf, *low, *high;

	unsigned long return_address;

	int count;

	struct unwind_state state;

	unsigned long ip = 0;



	if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p))

		return 0;
@@ -188,26 +188,22 @@ unsigned long get_wchan(struct task_struct *p) 
	if (!try_get_task_stack(p))

		return 0;



	low = task_stack_page(p);

	high = (struct stack_frame *) task_pt_regs(p);

	sf = (struct stack_frame *) p->thread.ksp;

	if (sf <= low || sf > high) {

		return_address = 0;

		goto out;

	unwind_for_each_frame(&state, p, NULL, 0) {

		if (state.stack_info.type != STACK_TYPE_TASK) {

			ip = 0;

			break;

		}

	for (count = 0; count < 16; count++) {

		sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain);

		if (sf <= low || sf > high) {

			return_address = 0;

			goto out;

		}

		return_address = READ_ONCE_NOCHECK(sf->gprs[8]);

		if (!in_sched_functions(return_address))

			goto out;



		ip = unwind_get_return_address(&state);

		if (!ip)

			break;



		if (!in_sched_functions(ip))

			break;

	}

out:



	put_task_stack(p);

	return return_address;

	return ip;

}



unsigned long arch_align_stack(unsigned long sp)