Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : #include <linux/errno.h>
3 : #include <linux/kernel.h>
4 : #include <linux/sched.h>
5 : #include <linux/sched/task_stack.h>
6 : #include <linux/perf_event.h>
7 : #include <linux/bug.h>
8 : #include <linux/stddef.h>
9 : #include <asm/perf_regs.h>
10 : #include <asm/ptrace.h>
11 :
12 : #ifdef CONFIG_X86_32
13 : #define PERF_REG_X86_MAX PERF_REG_X86_32_MAX
14 : #else
15 : #define PERF_REG_X86_MAX PERF_REG_X86_64_MAX
16 : #endif
17 :
18 : #define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r)
19 :
20 : static unsigned int pt_regs_offset[PERF_REG_X86_MAX] = {
21 : PT_REGS_OFFSET(PERF_REG_X86_AX, ax),
22 : PT_REGS_OFFSET(PERF_REG_X86_BX, bx),
23 : PT_REGS_OFFSET(PERF_REG_X86_CX, cx),
24 : PT_REGS_OFFSET(PERF_REG_X86_DX, dx),
25 : PT_REGS_OFFSET(PERF_REG_X86_SI, si),
26 : PT_REGS_OFFSET(PERF_REG_X86_DI, di),
27 : PT_REGS_OFFSET(PERF_REG_X86_BP, bp),
28 : PT_REGS_OFFSET(PERF_REG_X86_SP, sp),
29 : PT_REGS_OFFSET(PERF_REG_X86_IP, ip),
30 : PT_REGS_OFFSET(PERF_REG_X86_FLAGS, flags),
31 : PT_REGS_OFFSET(PERF_REG_X86_CS, cs),
32 : PT_REGS_OFFSET(PERF_REG_X86_SS, ss),
33 : #ifdef CONFIG_X86_32
34 : PT_REGS_OFFSET(PERF_REG_X86_DS, ds),
35 : PT_REGS_OFFSET(PERF_REG_X86_ES, es),
36 : PT_REGS_OFFSET(PERF_REG_X86_FS, fs),
37 : PT_REGS_OFFSET(PERF_REG_X86_GS, gs),
38 : #else
39 : /*
40 : * The pt_regs struct does not store
41 : * ds, es, fs, gs in 64 bit mode.
42 : */
43 : (unsigned int) -1,
44 : (unsigned int) -1,
45 : (unsigned int) -1,
46 : (unsigned int) -1,
47 : #endif
48 : #ifdef CONFIG_X86_64
49 : PT_REGS_OFFSET(PERF_REG_X86_R8, r8),
50 : PT_REGS_OFFSET(PERF_REG_X86_R9, r9),
51 : PT_REGS_OFFSET(PERF_REG_X86_R10, r10),
52 : PT_REGS_OFFSET(PERF_REG_X86_R11, r11),
53 : PT_REGS_OFFSET(PERF_REG_X86_R12, r12),
54 : PT_REGS_OFFSET(PERF_REG_X86_R13, r13),
55 : PT_REGS_OFFSET(PERF_REG_X86_R14, r14),
56 : PT_REGS_OFFSET(PERF_REG_X86_R15, r15),
57 : #endif
58 : };
59 :
60 0 : u64 perf_reg_value(struct pt_regs *regs, int idx)
61 : {
62 0 : struct x86_perf_regs *perf_regs;
63 :
64 0 : if (idx >= PERF_REG_X86_XMM0 && idx < PERF_REG_X86_XMM_MAX) {
65 0 : perf_regs = container_of(regs, struct x86_perf_regs, regs);
66 0 : if (!perf_regs->xmm_regs)
67 : return 0;
68 0 : return perf_regs->xmm_regs[idx - PERF_REG_X86_XMM0];
69 : }
70 :
71 0 : if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset)))
72 : return 0;
73 :
74 0 : return regs_get_register(regs, pt_regs_offset[idx]);
75 : }
76 :
77 : #define PERF_REG_X86_RESERVED (((1ULL << PERF_REG_X86_XMM0) - 1) & \
78 : ~((1ULL << PERF_REG_X86_MAX) - 1))
79 :
80 : #ifdef CONFIG_X86_32
81 : #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_R8) | \
82 : (1ULL << PERF_REG_X86_R9) | \
83 : (1ULL << PERF_REG_X86_R10) | \
84 : (1ULL << PERF_REG_X86_R11) | \
85 : (1ULL << PERF_REG_X86_R12) | \
86 : (1ULL << PERF_REG_X86_R13) | \
87 : (1ULL << PERF_REG_X86_R14) | \
88 : (1ULL << PERF_REG_X86_R15))
89 :
90 : int perf_reg_validate(u64 mask)
91 : {
92 : if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED)))
93 : return -EINVAL;
94 :
95 : return 0;
96 : }
97 :
98 : u64 perf_reg_abi(struct task_struct *task)
99 : {
100 : return PERF_SAMPLE_REGS_ABI_32;
101 : }
102 :
103 : void perf_get_regs_user(struct perf_regs *regs_user,
104 : struct pt_regs *regs)
105 : {
106 : regs_user->regs = task_pt_regs(current);
107 : regs_user->abi = perf_reg_abi(current);
108 : }
109 : #else /* CONFIG_X86_64 */
110 : #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \
111 : (1ULL << PERF_REG_X86_ES) | \
112 : (1ULL << PERF_REG_X86_FS) | \
113 : (1ULL << PERF_REG_X86_GS))
114 :
115 0 : int perf_reg_validate(u64 mask)
116 : {
117 0 : if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED)))
118 0 : return -EINVAL;
119 :
120 : return 0;
121 : }
122 :
123 0 : u64 perf_reg_abi(struct task_struct *task)
124 : {
125 0 : if (!user_64bit_mode(task_pt_regs(task)))
126 : return PERF_SAMPLE_REGS_ABI_32;
127 : else
128 0 : return PERF_SAMPLE_REGS_ABI_64;
129 : }
130 :
131 : static DEFINE_PER_CPU(struct pt_regs, nmi_user_regs);
132 :
133 0 : void perf_get_regs_user(struct perf_regs *regs_user,
134 : struct pt_regs *regs)
135 : {
136 0 : struct pt_regs *regs_user_copy = this_cpu_ptr(&nmi_user_regs);
137 0 : struct pt_regs *user_regs = task_pt_regs(current);
138 :
139 0 : if (!in_nmi()) {
140 0 : regs_user->regs = user_regs;
141 0 : regs_user->abi = perf_reg_abi(current);
142 0 : return;
143 : }
144 :
145 : /*
146 : * If we're in an NMI that interrupted task_pt_regs setup, then
147 : * we can't sample user regs at all. This check isn't really
148 : * sufficient, though, as we could be in an NMI inside an interrupt
149 : * that happened during task_pt_regs setup.
150 : */
151 0 : if (regs->sp > (unsigned long)&user_regs->r11 &&
152 0 : regs->sp <= (unsigned long)(user_regs + 1)) {
153 0 : regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
154 0 : regs_user->regs = NULL;
155 0 : return;
156 : }
157 :
158 : /*
159 : * These registers are always saved on 64-bit syscall entry.
160 : * On 32-bit entry points, they are saved too except r8..r11.
161 : */
162 0 : regs_user_copy->ip = user_regs->ip;
163 0 : regs_user_copy->ax = user_regs->ax;
164 0 : regs_user_copy->cx = user_regs->cx;
165 0 : regs_user_copy->dx = user_regs->dx;
166 0 : regs_user_copy->si = user_regs->si;
167 0 : regs_user_copy->di = user_regs->di;
168 0 : regs_user_copy->r8 = user_regs->r8;
169 0 : regs_user_copy->r9 = user_regs->r9;
170 0 : regs_user_copy->r10 = user_regs->r10;
171 0 : regs_user_copy->r11 = user_regs->r11;
172 0 : regs_user_copy->orig_ax = user_regs->orig_ax;
173 0 : regs_user_copy->flags = user_regs->flags;
174 0 : regs_user_copy->sp = user_regs->sp;
175 0 : regs_user_copy->cs = user_regs->cs;
176 0 : regs_user_copy->ss = user_regs->ss;
177 : /*
178 : * Store user space frame-pointer value on sample
179 : * to facilitate stack unwinding for cases when
180 : * user space executable code has such support
181 : * enabled at compile time:
182 : */
183 0 : regs_user_copy->bp = user_regs->bp;
184 :
185 0 : regs_user_copy->bx = -1;
186 0 : regs_user_copy->r12 = -1;
187 0 : regs_user_copy->r13 = -1;
188 0 : regs_user_copy->r14 = -1;
189 0 : regs_user_copy->r15 = -1;
190 : /*
191 : * For this to be at all useful, we need a reasonable guess for
192 : * the ABI. Be careful: we're in NMI context, and we're
193 : * considering current to be the current task, so we should
194 : * be careful not to look at any other percpu variables that might
195 : * change during context switches.
196 : */
197 0 : regs_user->abi = user_64bit_mode(user_regs) ?
198 0 : PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32;
199 :
200 0 : regs_user->regs = regs_user_copy;
201 : }
202 : #endif /* CONFIG_X86_32 */
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