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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - arch/arm/kernel/stacktrace.c
1 #include <linux/export.h>
2 #include <linux/sched.h>
3 #include <linux/stacktrace.h>
5 #include <asm/stacktrace.h>
7 #if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
9 * Unwind the current stack frame and store the new register values in the
10 * structure passed as argument. Unwinding is equivalent to a function return,
11 * hence the new PC value rather than LR should be used for backtrace.
13 * With framepointer enabled, a simple function prologue looks like this:
15 * stmdb sp!, {fp, ip, lr, pc}
18 * A simple function epilogue looks like this:
19 * ldm sp, {fp, sp, pc}
21 * Note that with framepointer enabled, even the leaf functions have the same
22 * prologue and epilogue, therefore we can ignore the LR value in this case.
24 int notrace
unwind_frame(struct stackframe
*frame
)
26 unsigned long high
, low
;
27 unsigned long fp
= frame
->fp
;
29 /* only go to a higher address on the stack */
31 high
= ALIGN(low
, THREAD_SIZE
);
33 /* check current frame pointer is within bounds */
34 if (fp
< (low
+ 12) || fp
+ 4 >= high
)
37 /* restore the registers from the stack frame */
38 frame
->fp
= *(unsigned long *)(fp
- 12);
39 frame
->sp
= *(unsigned long *)(fp
- 8);
40 frame
->pc
= *(unsigned long *)(fp
- 4);
46 void notrace
walk_stackframe(struct stackframe
*frame
,
47 int (*fn
)(struct stackframe
*, void *), void *data
)
54 ret
= unwind_frame(frame
);
59 EXPORT_SYMBOL(walk_stackframe
);
61 #ifdef CONFIG_STACKTRACE
62 struct stack_trace_data
{
63 struct stack_trace
*trace
;
64 unsigned int no_sched_functions
;
68 static int save_trace(struct stackframe
*frame
, void *d
)
70 struct stack_trace_data
*data
= d
;
71 struct stack_trace
*trace
= data
->trace
;
72 unsigned long addr
= frame
->pc
;
74 if (data
->no_sched_functions
&& in_sched_functions(addr
))
81 trace
->entries
[trace
->nr_entries
++] = addr
;
83 return trace
->nr_entries
>= trace
->max_entries
;
86 void save_stack_trace_tsk(struct task_struct
*tsk
, struct stack_trace
*trace
)
88 struct stack_trace_data data
;
89 struct stackframe frame
;
92 data
.skip
= trace
->skip
;
97 * What guarantees do we have here that 'tsk' is not
98 * running on another CPU? For now, ignore it as we
99 * can't guarantee we won't explode.
101 if (trace
->nr_entries
< trace
->max_entries
)
102 trace
->entries
[trace
->nr_entries
++] = ULONG_MAX
;
105 data
.no_sched_functions
= 1;
106 frame
.fp
= thread_saved_fp(tsk
);
107 frame
.sp
= thread_saved_sp(tsk
);
108 frame
.lr
= 0; /* recovered from the stack */
109 frame
.pc
= thread_saved_pc(tsk
);
112 register unsigned long current_sp
asm ("sp");
114 data
.no_sched_functions
= 0;
115 frame
.fp
= (unsigned long)__builtin_frame_address(0);
116 frame
.sp
= current_sp
;
117 frame
.lr
= (unsigned long)__builtin_return_address(0);
118 frame
.pc
= (unsigned long)save_stack_trace_tsk
;
121 walk_stackframe(&frame
, save_trace
, &data
);
122 if (trace
->nr_entries
< trace
->max_entries
)
123 trace
->entries
[trace
->nr_entries
++] = ULONG_MAX
;
126 void save_stack_trace(struct stack_trace
*trace
)
128 save_stack_trace_tsk(current
, trace
);
130 EXPORT_SYMBOL_GPL(save_stack_trace
);