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 u64 perf_reg_value(struct pt_regs *regs, int idx)
61 {
62 struct x86_perf_regs *perf_regs;
63
64 if (idx >= PERF_REG_X86_XMM0 && idx < PERF_REG_X86_XMM_MAX) {
65 perf_regs = container_of(regs, struct x86_perf_regs, regs);
66 if (!perf_regs->xmm_regs)
67 return 0;
68 return perf_regs->xmm_regs[idx - PERF_REG_X86_XMM0];
69 }
70
71 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset)))
72 return 0;
73
74 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 int perf_reg_validate(u64 mask)
116 {
117 if (!mask || (mask & (REG_NOSUPPORT | PERF_REG_X86_RESERVED)))
118 return -EINVAL;
119
120 return 0;
121 }
122
123 u64 perf_reg_abi(struct task_struct *task)
124 {
125 if (!user_64bit_mode(task_pt_regs(task)))
126 return PERF_SAMPLE_REGS_ABI_32;
127 else
128 return PERF_SAMPLE_REGS_ABI_64;
129 }
130
131 static DEFINE_PER_CPU(struct pt_regs, nmi_user_regs);
132
133 void perf_get_regs_user(struct perf_regs *regs_user,
134 struct pt_regs *regs)
135 {
136 struct pt_regs *regs_user_copy = this_cpu_ptr(&nmi_user_regs);
137 struct pt_regs *user_regs = task_pt_regs(current);
138
139 if (!in_nmi()) {
140 regs_user->regs = user_regs;
141 regs_user->abi = perf_reg_abi(current);
142 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 if (regs->sp > (unsigned long)&user_regs->r11 &&
152 regs->sp <= (unsigned long)(user_regs + 1)) {
153 regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
154 regs_user->regs = NULL;
155 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 regs_user_copy->ip = user_regs->ip;
163 regs_user_copy->ax = user_regs->ax;
164 regs_user_copy->cx = user_regs->cx;
165 regs_user_copy->dx = user_regs->dx;
166 regs_user_copy->si = user_regs->si;
167 regs_user_copy->di = user_regs->di;
168 regs_user_copy->r8 = user_regs->r8;
169 regs_user_copy->r9 = user_regs->r9;
170 regs_user_copy->r10 = user_regs->r10;
171 regs_user_copy->r11 = user_regs->r11;
172 regs_user_copy->orig_ax = user_regs->orig_ax;
173 regs_user_copy->flags = user_regs->flags;
174 regs_user_copy->sp = user_regs->sp;
175 regs_user_copy->cs = user_regs->cs;
176 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 regs_user_copy->bp = user_regs->bp;
184
185 regs_user_copy->bx = -1;
186 regs_user_copy->r12 = -1;
187 regs_user_copy->r13 = -1;
188 regs_user_copy->r14 = -1;
189 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 regs_user->abi = user_64bit_mode(user_regs) ?
198 PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32;
199
200 regs_user->regs = regs_user_copy;
201 }
202 #endif /* CONFIG_X86_32 */
203
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.