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d39976f0 MR |
1 | /* |
2 | * ARM callchain support | |
3 | * | |
4 | * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles | |
5 | * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com> | |
6 | * | |
7 | * This code is based on the ARM OProfile backtrace code. | |
8 | */ | |
9 | #include <linux/perf_event.h> | |
10 | #include <linux/uaccess.h> | |
11 | ||
12 | #include <asm/stacktrace.h> | |
13 | ||
14 | /* | |
15 | * The registers we're interested in are at the end of the variable | |
16 | * length saved register structure. The fp points at the end of this | |
17 | * structure so the address of this struct is: | |
18 | * (struct frame_tail *)(xxx->fp)-1 | |
19 | * | |
20 | * This code has been adapted from the ARM OProfile support. | |
21 | */ | |
22 | struct frame_tail { | |
23 | struct frame_tail __user *fp; | |
24 | unsigned long sp; | |
25 | unsigned long lr; | |
26 | } __attribute__((packed)); | |
27 | ||
28 | /* | |
29 | * Get the return address for a single stackframe and return a pointer to the | |
30 | * next frame tail. | |
31 | */ | |
32 | static struct frame_tail __user * | |
33 | user_backtrace(struct frame_tail __user *tail, | |
cfbcf468 | 34 | struct perf_callchain_entry_ctx *entry) |
d39976f0 MR |
35 | { |
36 | struct frame_tail buftail; | |
37 | unsigned long err; | |
38 | ||
39 | if (!access_ok(VERIFY_READ, tail, sizeof(buftail))) | |
40 | return NULL; | |
41 | ||
42 | pagefault_disable(); | |
43 | err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail)); | |
44 | pagefault_enable(); | |
45 | ||
46 | if (err) | |
47 | return NULL; | |
48 | ||
49 | perf_callchain_store(entry, buftail.lr); | |
50 | ||
51 | /* | |
52 | * Frame pointers should strictly progress back up the stack | |
53 | * (towards higher addresses). | |
54 | */ | |
55 | if (tail + 1 >= buftail.fp) | |
56 | return NULL; | |
57 | ||
58 | return buftail.fp - 1; | |
59 | } | |
60 | ||
61 | void | |
cfbcf468 | 62 | perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) |
d39976f0 MR |
63 | { |
64 | struct frame_tail __user *tail; | |
65 | ||
66 | if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { | |
67 | /* We don't support guest os callchain now */ | |
68 | return; | |
69 | } | |
70 | ||
71 | perf_callchain_store(entry, regs->ARM_pc); | |
72 | ||
73 | if (!current->mm) | |
74 | return; | |
75 | ||
76 | tail = (struct frame_tail __user *)regs->ARM_fp - 1; | |
77 | ||
3b1fff08 | 78 | while ((entry->nr < entry->max_stack) && |
d39976f0 MR |
79 | tail && !((unsigned long)tail & 0x3)) |
80 | tail = user_backtrace(tail, entry); | |
81 | } | |
82 | ||
83 | /* | |
84 | * Gets called by walk_stackframe() for every stackframe. This will be called | |
85 | * whist unwinding the stackframe and is like a subroutine return so we use | |
86 | * the PC. | |
87 | */ | |
88 | static int | |
89 | callchain_trace(struct stackframe *fr, | |
90 | void *data) | |
91 | { | |
cfbcf468 | 92 | struct perf_callchain_entry_ctx *entry = data; |
d39976f0 MR |
93 | perf_callchain_store(entry, fr->pc); |
94 | return 0; | |
95 | } | |
96 | ||
97 | void | |
cfbcf468 | 98 | perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs) |
d39976f0 MR |
99 | { |
100 | struct stackframe fr; | |
101 | ||
102 | if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { | |
103 | /* We don't support guest os callchain now */ | |
104 | return; | |
105 | } | |
106 | ||
107 | arm_get_current_stackframe(regs, &fr); | |
108 | walk_stackframe(&fr, callchain_trace, entry); | |
109 | } | |
110 | ||
111 | unsigned long perf_instruction_pointer(struct pt_regs *regs) | |
112 | { | |
113 | if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) | |
114 | return perf_guest_cbs->get_guest_ip(); | |
115 | ||
116 | return instruction_pointer(regs); | |
117 | } | |
118 | ||
119 | unsigned long perf_misc_flags(struct pt_regs *regs) | |
120 | { | |
121 | int misc = 0; | |
122 | ||
123 | if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { | |
124 | if (perf_guest_cbs->is_user_mode()) | |
125 | misc |= PERF_RECORD_MISC_GUEST_USER; | |
126 | else | |
127 | misc |= PERF_RECORD_MISC_GUEST_KERNEL; | |
128 | } else { | |
129 | if (user_mode(regs)) | |
130 | misc |= PERF_RECORD_MISC_USER; | |
131 | else | |
132 | misc |= PERF_RECORD_MISC_KERNEL; | |
133 | } | |
134 | ||
135 | return misc; | |
136 | } |