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git.ipfire.org Git - thirdparty/linux.git/blob - arch/csky/kernel/perf_callchain.c
1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
4 #include <linux/perf_event.h>
5 #include <linux/uaccess.h>
13 static int unwind_frame_kernel(struct stackframe
*frame
)
15 unsigned long low
= (unsigned long)task_stack_page(current
);
16 unsigned long high
= low
+ THREAD_SIZE
;
18 if (unlikely(frame
->fp
< low
|| frame
->fp
> high
))
21 if (kstack_end((void *)frame
->fp
) || frame
->fp
& 0x3)
24 *frame
= *(struct stackframe
*)frame
->fp
;
26 if (__kernel_text_address(frame
->lr
)) {
29 frame
->lr
= ftrace_graph_ret_addr(NULL
, &graph
, frame
->lr
,
35 static void notrace
walk_stackframe(struct stackframe
*fr
,
36 struct perf_callchain_entry_ctx
*entry
)
39 perf_callchain_store(entry
, fr
->lr
);
40 } while (unwind_frame_kernel(fr
) >= 0);
44 * Get the return address for a single stackframe and return a pointer to the
47 static unsigned long user_backtrace(struct perf_callchain_entry_ctx
*entry
,
48 unsigned long fp
, unsigned long reg_lr
)
50 struct stackframe buftail
;
52 unsigned long *user_frame_tail
= (unsigned long *)fp
;
54 /* Check accessibility of one struct frame_tail beyond */
55 if (!access_ok(user_frame_tail
, sizeof(buftail
)))
57 if (__copy_from_user_inatomic(&buftail
, user_frame_tail
,
67 perf_callchain_store(entry
, lr
);
73 * This will be called when the target is in user mode
74 * This function will only be called when we use
75 * "PERF_SAMPLE_CALLCHAIN" in
76 * kernel/events/core.c:perf_prepare_sample()
78 * How to trigger perf_callchain_[user/kernel] :
79 * $ perf record -e cpu-clock --call-graph fp ./program
80 * $ perf report --call-graph
82 * On C-SKY platform, the program being sampled and the C library
83 * need to be compiled with * -mbacktrace, otherwise the user
84 * stack will not contain function frame.
86 void perf_callchain_user(struct perf_callchain_entry_ctx
*entry
,
91 /* C-SKY does not support virtualization. */
92 if (perf_guest_cbs
&& perf_guest_cbs
->is_in_guest())
96 perf_callchain_store(entry
, regs
->pc
);
99 * While backtrace from leaf function, lr is normally
100 * not saved inside frame on C-SKY, so get lr from pt_regs
101 * at the sample point. However, lr value can be incorrect if
102 * lr is used as temp register
104 fp
= user_backtrace(entry
, fp
, regs
->lr
);
106 while (fp
&& !(fp
& 0x3) && entry
->nr
< entry
->max_stack
)
107 fp
= user_backtrace(entry
, fp
, 0);
110 void perf_callchain_kernel(struct perf_callchain_entry_ctx
*entry
,
111 struct pt_regs
*regs
)
113 struct stackframe fr
;
115 /* C-SKY does not support virtualization. */
116 if (perf_guest_cbs
&& perf_guest_cbs
->is_in_guest()) {
117 pr_warn("C-SKY does not support perf in guest mode!");
121 fr
.fp
= regs
->regs
[4];
123 walk_stackframe(&fr
, entry
);