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1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
3
4#include <linux/perf_event.h>
5#include <linux/uaccess.h>
6
7/* Kernel callchain */
8struct stackframe {
9 unsigned long fp;
10 unsigned long lr;
11};
12
13static int unwind_frame_kernel(struct stackframe *frame)
14{
15 unsigned long low = (unsigned long)task_stack_page(current);
16 unsigned long high = low + THREAD_SIZE;
17
18 if (unlikely(frame->fp < low || frame->fp > high))
19 return -EPERM;
20
21 if (kstack_end((void *)frame->fp) || frame->fp & 0x3)
22 return -EPERM;
23
24 *frame = *(struct stackframe *)frame->fp;
25
26 if (__kernel_text_address(frame->lr)) {
27 int graph = 0;
28
29 frame->lr = ftrace_graph_ret_addr(NULL, &graph, frame->lr,
30 NULL);
31 }
32 return 0;
33}
34
35static void notrace walk_stackframe(struct stackframe *fr,
36 struct perf_callchain_entry_ctx *entry)
37{
38 do {
39 perf_callchain_store(entry, fr->lr);
40 } while (unwind_frame_kernel(fr) >= 0);
41}
42
43/*
44 * Get the return address for a single stackframe and return a pointer to the
45 * next frame tail.
46 */
47static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
48 unsigned long fp, unsigned long reg_lr)
49{
50 struct stackframe buftail;
51 unsigned long lr = 0;
52 unsigned long __user *user_frame_tail = (unsigned long __user *)fp;
53
54 /* Check accessibility of one struct frame_tail beyond */
55 if (!access_ok(user_frame_tail, sizeof(buftail)))
56 return 0;
57 if (__copy_from_user_inatomic(&buftail, user_frame_tail,
58 sizeof(buftail)))
59 return 0;
60
61 if (reg_lr != 0)
62 lr = reg_lr;
63 else
64 lr = buftail.lr;
65
66 fp = buftail.fp;
67 perf_callchain_store(entry, lr);
68
69 return fp;
70}
71
72/*
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()
77 *
78 * How to trigger perf_callchain_[user/kernel] :
79 * $ perf record -e cpu-clock --call-graph fp ./program
80 * $ perf report --call-graph
81 *
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.
85 */
86void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
87 struct pt_regs *regs)
88{
89 unsigned long fp = 0;
90
91 fp = regs->regs[4];
92 perf_callchain_store(entry, regs->pc);
93
94 /*
95 * While backtrace from leaf function, lr is normally
96 * not saved inside frame on C-SKY, so get lr from pt_regs
97 * at the sample point. However, lr value can be incorrect if
98 * lr is used as temp register
99 */
100 fp = user_backtrace(entry, fp, regs->lr);
101
102 while (fp && !(fp & 0x3) && entry->nr < entry->max_stack)
103 fp = user_backtrace(entry, fp, 0);
104}
105
106void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
107 struct pt_regs *regs)
108{
109 struct stackframe fr;
110
111 fr.fp = regs->regs[4];
112 fr.lr = regs->lr;
113 walk_stackframe(&fr, entry);
114}
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd.
3
4#include <linux/perf_event.h>
5#include <linux/uaccess.h>
6
7/* Kernel callchain */
8struct stackframe {
9 unsigned long fp;
10 unsigned long lr;
11};
12
13static int unwind_frame_kernel(struct stackframe *frame)
14{
15 if (kstack_end((void *)frame->fp))
16 return -EPERM;
17 if (frame->fp & 0x3 || frame->fp < TASK_SIZE)
18 return -EPERM;
19
20 *frame = *(struct stackframe *)frame->fp;
21 if (__kernel_text_address(frame->lr)) {
22 int graph = 0;
23
24 frame->lr = ftrace_graph_ret_addr(NULL, &graph, frame->lr,
25 NULL);
26 }
27 return 0;
28}
29
30static void notrace walk_stackframe(struct stackframe *fr,
31 struct perf_callchain_entry_ctx *entry)
32{
33 do {
34 perf_callchain_store(entry, fr->lr);
35 } while (unwind_frame_kernel(fr) >= 0);
36}
37
38/*
39 * Get the return address for a single stackframe and return a pointer to the
40 * next frame tail.
41 */
42static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
43 unsigned long fp, unsigned long reg_lr)
44{
45 struct stackframe buftail;
46 unsigned long lr = 0;
47 unsigned long *user_frame_tail = (unsigned long *)fp;
48
49 /* Check accessibility of one struct frame_tail beyond */
50 if (!access_ok(user_frame_tail, sizeof(buftail)))
51 return 0;
52 if (__copy_from_user_inatomic(&buftail, user_frame_tail,
53 sizeof(buftail)))
54 return 0;
55
56 if (reg_lr != 0)
57 lr = reg_lr;
58 else
59 lr = buftail.lr;
60
61 fp = buftail.fp;
62 perf_callchain_store(entry, lr);
63
64 return fp;
65}
66
67/*
68 * This will be called when the target is in user mode
69 * This function will only be called when we use
70 * "PERF_SAMPLE_CALLCHAIN" in
71 * kernel/events/core.c:perf_prepare_sample()
72 *
73 * How to trigger perf_callchain_[user/kernel] :
74 * $ perf record -e cpu-clock --call-graph fp ./program
75 * $ perf report --call-graph
76 *
77 * On C-SKY platform, the program being sampled and the C library
78 * need to be compiled with * -mbacktrace, otherwise the user
79 * stack will not contain function frame.
80 */
81void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
82 struct pt_regs *regs)
83{
84 unsigned long fp = 0;
85
86 /* C-SKY does not support virtualization. */
87 if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
88 return;
89
90 fp = regs->regs[4];
91 perf_callchain_store(entry, regs->pc);
92
93 /*
94 * While backtrace from leaf function, lr is normally
95 * not saved inside frame on C-SKY, so get lr from pt_regs
96 * at the sample point. However, lr value can be incorrect if
97 * lr is used as temp register
98 */
99 fp = user_backtrace(entry, fp, regs->lr);
100
101 while (fp && !(fp & 0x3) && entry->nr < entry->max_stack)
102 fp = user_backtrace(entry, fp, 0);
103}
104
105void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
106 struct pt_regs *regs)
107{
108 struct stackframe fr;
109
110 /* C-SKY does not support virtualization. */
111 if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
112 pr_warn("C-SKY does not support perf in guest mode!");
113 return;
114 }
115
116 fr.fp = regs->regs[4];
117 fr.lr = regs->lr;
118 walk_stackframe(&fr, entry);
119}