1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * arm64 callchain support |
4 | * |
5 | * Copyright (C) 2015 ARM Limited |
6 | */ |
7 | #include <linux/perf_event.h> |
8 | #include <linux/stacktrace.h> |
9 | #include <linux/uaccess.h> |
10 | |
11 | #include <asm/pointer_auth.h> |
12 | |
13 | struct frame_tail { |
14 | struct frame_tail __user *fp; |
15 | unsigned long lr; |
16 | } __attribute__((packed)); |
17 | |
18 | /* |
19 | * Get the return address for a single stackframe and return a pointer to the |
20 | * next frame tail. |
21 | */ |
22 | static struct frame_tail __user * |
23 | user_backtrace(struct frame_tail __user *tail, |
24 | struct perf_callchain_entry_ctx *entry) |
25 | { |
26 | struct frame_tail buftail; |
27 | unsigned long err; |
28 | unsigned long lr; |
29 | |
30 | /* Also check accessibility of one struct frame_tail beyond */ |
31 | if (!access_ok(tail, sizeof(buftail))) |
32 | return NULL; |
33 | |
34 | pagefault_disable(); |
35 | err = __copy_from_user_inatomic(to: &buftail, from: tail, n: sizeof(buftail)); |
36 | pagefault_enable(); |
37 | |
38 | if (err) |
39 | return NULL; |
40 | |
41 | lr = ptrauth_strip_user_insn_pac(buftail.lr); |
42 | |
43 | perf_callchain_store(ctx: entry, ip: lr); |
44 | |
45 | /* |
46 | * Frame pointers should strictly progress back up the stack |
47 | * (towards higher addresses). |
48 | */ |
49 | if (tail >= buftail.fp) |
50 | return NULL; |
51 | |
52 | return buftail.fp; |
53 | } |
54 | |
55 | #ifdef CONFIG_COMPAT |
56 | /* |
57 | * The registers we're interested in are at the end of the variable |
58 | * length saved register structure. The fp points at the end of this |
59 | * structure so the address of this struct is: |
60 | * (struct compat_frame_tail *)(xxx->fp)-1 |
61 | * |
62 | * This code has been adapted from the ARM OProfile support. |
63 | */ |
64 | struct compat_frame_tail { |
65 | compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */ |
66 | u32 sp; |
67 | u32 lr; |
68 | } __attribute__((packed)); |
69 | |
70 | static struct compat_frame_tail __user * |
71 | compat_user_backtrace(struct compat_frame_tail __user *tail, |
72 | struct perf_callchain_entry_ctx *entry) |
73 | { |
74 | struct compat_frame_tail buftail; |
75 | unsigned long err; |
76 | |
77 | /* Also check accessibility of one struct frame_tail beyond */ |
78 | if (!access_ok(tail, sizeof(buftail))) |
79 | return NULL; |
80 | |
81 | pagefault_disable(); |
82 | err = __copy_from_user_inatomic(to: &buftail, from: tail, n: sizeof(buftail)); |
83 | pagefault_enable(); |
84 | |
85 | if (err) |
86 | return NULL; |
87 | |
88 | perf_callchain_store(ctx: entry, ip: buftail.lr); |
89 | |
90 | /* |
91 | * Frame pointers should strictly progress back up the stack |
92 | * (towards higher addresses). |
93 | */ |
94 | if (tail + 1 >= (struct compat_frame_tail __user *) |
95 | compat_ptr(uptr: buftail.fp)) |
96 | return NULL; |
97 | |
98 | return (struct compat_frame_tail __user *)compat_ptr(uptr: buftail.fp) - 1; |
99 | } |
100 | #endif /* CONFIG_COMPAT */ |
101 | |
102 | void perf_callchain_user(struct perf_callchain_entry_ctx *entry, |
103 | struct pt_regs *regs) |
104 | { |
105 | if (perf_guest_state()) { |
106 | /* We don't support guest os callchain now */ |
107 | return; |
108 | } |
109 | |
110 | perf_callchain_store(ctx: entry, ip: regs->pc); |
111 | |
112 | if (!compat_user_mode(regs)) { |
113 | /* AARCH64 mode */ |
114 | struct frame_tail __user *tail; |
115 | |
116 | tail = (struct frame_tail __user *)regs->regs[29]; |
117 | |
118 | while (entry->nr < entry->max_stack && |
119 | tail && !((unsigned long)tail & 0x7)) |
120 | tail = user_backtrace(tail, entry); |
121 | } else { |
122 | #ifdef CONFIG_COMPAT |
123 | /* AARCH32 compat mode */ |
124 | struct compat_frame_tail __user *tail; |
125 | |
126 | tail = (struct compat_frame_tail __user *)regs->compat_fp - 1; |
127 | |
128 | while ((entry->nr < entry->max_stack) && |
129 | tail && !((unsigned long)tail & 0x3)) |
130 | tail = compat_user_backtrace(tail, entry); |
131 | #endif |
132 | } |
133 | } |
134 | |
135 | static bool callchain_trace(void *data, unsigned long pc) |
136 | { |
137 | struct perf_callchain_entry_ctx *entry = data; |
138 | return perf_callchain_store(ctx: entry, ip: pc) == 0; |
139 | } |
140 | |
141 | void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, |
142 | struct pt_regs *regs) |
143 | { |
144 | if (perf_guest_state()) { |
145 | /* We don't support guest os callchain now */ |
146 | return; |
147 | } |
148 | |
149 | arch_stack_walk(consume_entry: callchain_trace, cookie: entry, current, regs); |
150 | } |
151 | |
152 | unsigned long perf_instruction_pointer(struct pt_regs *regs) |
153 | { |
154 | if (perf_guest_state()) |
155 | return perf_guest_get_ip(); |
156 | |
157 | return instruction_pointer(regs); |
158 | } |
159 | |
160 | unsigned long perf_misc_flags(struct pt_regs *regs) |
161 | { |
162 | unsigned int guest_state = perf_guest_state(); |
163 | int misc = 0; |
164 | |
165 | if (guest_state) { |
166 | if (guest_state & PERF_GUEST_USER) |
167 | misc |= PERF_RECORD_MISC_GUEST_USER; |
168 | else |
169 | misc |= PERF_RECORD_MISC_GUEST_KERNEL; |
170 | } else { |
171 | if (user_mode(regs)) |
172 | misc |= PERF_RECORD_MISC_USER; |
173 | else |
174 | misc |= PERF_RECORD_MISC_KERNEL; |
175 | } |
176 | |
177 | return misc; |
178 | } |
179 | |