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Commit fe13f95b authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Will Deacon
Browse files

arm64: pass a task parameter to unwind_frame() 



Function graph tracer modifies a return address (LR) in a stack frame
to hook a function's return. This will result in many useless entries
(return_to_handler) showing up in a call stack list.
We will fix this problem in a later patch ("arm64: ftrace: fix a stack
tracer's output under function graph tracer"). But since real return
addresses are saved in ret_stack[] array in struct task_struct,
unwind functions need to be notified of, in addition to a stack pointer
address, which task is being traced in order to find out real return
addresses.

This patch extends unwind functions' interfaces by adding an extra
argument of a pointer to task_struct.

Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 79fdee9b

arch/arm64/include/asm/stacktrace.h

+4 −2
Original line number Diff line number Diff line
@@ -16,14 +16,16 @@ 
#ifndef __ASM_STACKTRACE_H

#define __ASM_STACKTRACE_H



struct task_struct;



struct stackframe {

	unsigned long fp;

	unsigned long sp;

	unsigned long pc;

};



extern int unwind_frame(struct stackframe *frame);

extern void walk_stackframe(struct stackframe *frame,

extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);

extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,

			    int (*fn)(struct stackframe *, void *), void *data);



#endif	/* __ASM_STACKTRACE_H */

arch/arm64/kernel/perf_callchain.c

+1 −1
Original line number Diff line number Diff line
@@ -165,7 +165,7 @@ void perf_callchain_kernel(struct perf_callchain_entry *entry, 
	frame.sp = regs->sp;

	frame.pc = regs->pc;



	walk_stackframe(&frame, callchain_trace, entry);

	walk_stackframe(current, &frame, callchain_trace, entry);

}



unsigned long perf_instruction_pointer(struct pt_regs *regs)

arch/arm64/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -348,7 +348,7 @@ unsigned long get_wchan(struct task_struct *p) 
	do {

		if (frame.sp < stack_page ||

		    frame.sp >= stack_page + THREAD_SIZE ||

		    unwind_frame(&frame))

		    unwind_frame(p, &frame))

			return 0;

		if (!in_sched_functions(frame.pc))

			return frame.pc;

arch/arm64/kernel/return_address.c

+1 −1
Original line number Diff line number Diff line
@@ -44,7 +44,7 @@ void *return_address(unsigned int level) 
	frame.sp = current_stack_pointer;

	frame.pc = (unsigned long)return_address; /* dummy */



	walk_stackframe(&frame, save_return_addr, &data);

	walk_stackframe(current, &frame, save_return_addr, &data);



	if (!data.level)

		return data.addr;

arch/arm64/kernel/stacktrace.c

+4 −4
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ 
 *	ldp	x29, x30, [sp]

 *	add	sp, sp, #0x10

 */

int notrace unwind_frame(struct stackframe *frame)

int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)

{

	unsigned long high, low;

	unsigned long fp = frame->fp;
@@ -99,7 +99,7 @@ int notrace unwind_frame(struct stackframe *frame) 
	return 0;

}



void notrace walk_stackframe(struct stackframe *frame,

void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame,

		     int (*fn)(struct stackframe *, void *), void *data)

{

	while (1) {
@@ -107,7 +107,7 @@ void notrace walk_stackframe(struct stackframe *frame, 


		if (fn(frame, data))

			break;

		ret = unwind_frame(frame);

		ret = unwind_frame(tsk, frame);

		if (ret < 0)

			break;

	}
@@ -159,7 +159,7 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 
		frame.pc = (unsigned long)save_stack_trace_tsk;

	}



	walk_stackframe(&frame, save_trace, &data);

	walk_stackframe(tsk, &frame, save_trace, &data);

	if (trace->nr_entries < trace->max_entries)

		trace->entries[trace->nr_entries++] = ULONG_MAX;

}