arm64: pass a task parameter to unwind_frame()

AKASHI Takahiro · wildea01 · commit fe13f95b7200 · 2015-12-21T17:26:01.000Z
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: AKASHI Takahiro &lt;takahiro.akashi@linaro.org&gt;
Signed-off-by: Will Deacon &lt;will.deacon@arm.com&gt;
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
@@ -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 */
diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
@@ -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)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
@@ -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;
diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c
@@ -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;
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
@@ -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;
@@ -99,15 +99,15 @@ 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) {
 		int ret;
 
 		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;
 }
diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c
@@ -53,7 +53,7 @@ unsigned long profile_pc(struct pt_regs *regs)
 	frame.sp = regs->sp;
 	frame.pc = regs->pc;
 	do {
-		int ret = unwind_frame(&frame);
+		int ret = unwind_frame(NULL, &frame);
 		if (ret < 0)
 			return 0;
 	} while (in_lock_functions(frame.pc));
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
@@ -177,7 +177,7 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 		int ret;
 
 		dump_backtrace_entry(where);
-		ret = unwind_frame(&frame);
+		ret = unwind_frame(tsk, &frame);
 		if (ret < 0)
 			break;
 		stack = frame.sp;

Original file line number	Diff line number	Diff line change
`@@ -165,7 +165,7 @@ void perf_callchain_kernel(struct perf_callchain_entry *entry,`
`165`	`165`	`frame.sp = regs->sp;`
`166`	`166`	`frame.pc = regs->pc;`
`167`	`167`
`168`		`- walk_stackframe(&frame, callchain_trace, entry);`
	`168`	`+ walk_stackframe(current, &frame, callchain_trace, entry);`
`169`	`169`	`}`
`170`	`170`
`171`	`171`	`unsigned long perf_instruction_pointer(struct pt_regs *regs)`
Original file line number	Diff line number	Diff line change
`@@ -36,7 +36,7 @@`
`36`	`36`	`* ldp x29, x30, [sp]`
`37`	`37`	`* add sp, sp, #0x10`
`38`	`38`	`*/`
`39`		`-int notrace unwind_frame(struct stackframe *frame)`
	`39`	`+int notrace unwind_frame(struct task_struct tsk, struct stackframe frame)`
`40`	`40`	`{`
`41`	`41`	`unsigned long high, low;`
`42`	`42`	`unsigned long fp = frame->fp;`
`@@ -99,15 +99,15 @@ int notrace unwind_frame(struct stackframe *frame)`
`99`	`99`	`return 0;`
`100`	`100`	`}`
`101`	`101`
`102`		`-void notrace walk_stackframe(struct stackframe *frame,`
	`102`	`+void notrace walk_stackframe(struct task_struct tsk, struct stackframe frame,`
`103`	`103`	`int (fn)(struct stackframe , void ), void data)`
`104`	`104`	`{`
`105`	`105`	`while (1) {`
`106`	`106`	`int ret;`
`107`	`107`
`108`	`108`	`if (fn(frame, data))`
`109`	`109`	`break;`
`110`		`- ret = unwind_frame(frame);`
	`110`	`+ ret = unwind_frame(tsk, frame);`
`111`	`111`	`if (ret < 0)`
`112`	`112`	`break;`
`113`	`113`	`}`
`@@ -159,7 +159,7 @@ void save_stack_trace_tsk(struct task_struct tsk, struct stack_trace trace)`
`159`	`159`	`frame.pc = (unsigned long)save_stack_trace_tsk;`
`160`	`160`	`}`
`161`	`161`
`162`		`- walk_stackframe(&frame, save_trace, &data);`
	`162`	`+ walk_stackframe(tsk, &frame, save_trace, &data);`
`163`	`163`	`if (trace->nr_entries < trace->max_entries)`
`164`	`164`	`trace->entries[trace->nr_entries++] = ULONG_MAX;`
`165`	`165`	`}`