xref: /openbmc/linux/arch/x86/kernel/perf_regs.c (revision d7a3d85e)
1 #include <linux/errno.h>
2 #include <linux/kernel.h>
3 #include <linux/sched.h>
4 #include <linux/perf_event.h>
5 #include <linux/bug.h>
6 #include <linux/stddef.h>
7 #include <asm/perf_regs.h>
8 #include <asm/ptrace.h>
9 
10 #ifdef CONFIG_X86_32
11 #define PERF_REG_X86_MAX PERF_REG_X86_32_MAX
12 #else
13 #define PERF_REG_X86_MAX PERF_REG_X86_64_MAX
14 #endif
15 
16 #define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r)
17 
18 static unsigned int pt_regs_offset[PERF_REG_X86_MAX] = {
19 	PT_REGS_OFFSET(PERF_REG_X86_AX, ax),
20 	PT_REGS_OFFSET(PERF_REG_X86_BX, bx),
21 	PT_REGS_OFFSET(PERF_REG_X86_CX, cx),
22 	PT_REGS_OFFSET(PERF_REG_X86_DX, dx),
23 	PT_REGS_OFFSET(PERF_REG_X86_SI, si),
24 	PT_REGS_OFFSET(PERF_REG_X86_DI, di),
25 	PT_REGS_OFFSET(PERF_REG_X86_BP, bp),
26 	PT_REGS_OFFSET(PERF_REG_X86_SP, sp),
27 	PT_REGS_OFFSET(PERF_REG_X86_IP, ip),
28 	PT_REGS_OFFSET(PERF_REG_X86_FLAGS, flags),
29 	PT_REGS_OFFSET(PERF_REG_X86_CS, cs),
30 	PT_REGS_OFFSET(PERF_REG_X86_SS, ss),
31 #ifdef CONFIG_X86_32
32 	PT_REGS_OFFSET(PERF_REG_X86_DS, ds),
33 	PT_REGS_OFFSET(PERF_REG_X86_ES, es),
34 	PT_REGS_OFFSET(PERF_REG_X86_FS, fs),
35 	PT_REGS_OFFSET(PERF_REG_X86_GS, gs),
36 #else
37 	/*
38 	 * The pt_regs struct does not store
39 	 * ds, es, fs, gs in 64 bit mode.
40 	 */
41 	(unsigned int) -1,
42 	(unsigned int) -1,
43 	(unsigned int) -1,
44 	(unsigned int) -1,
45 #endif
46 #ifdef CONFIG_X86_64
47 	PT_REGS_OFFSET(PERF_REG_X86_R8, r8),
48 	PT_REGS_OFFSET(PERF_REG_X86_R9, r9),
49 	PT_REGS_OFFSET(PERF_REG_X86_R10, r10),
50 	PT_REGS_OFFSET(PERF_REG_X86_R11, r11),
51 	PT_REGS_OFFSET(PERF_REG_X86_R12, r12),
52 	PT_REGS_OFFSET(PERF_REG_X86_R13, r13),
53 	PT_REGS_OFFSET(PERF_REG_X86_R14, r14),
54 	PT_REGS_OFFSET(PERF_REG_X86_R15, r15),
55 #endif
56 };
57 
58 u64 perf_reg_value(struct pt_regs *regs, int idx)
59 {
60 	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(pt_regs_offset)))
61 		return 0;
62 
63 	return regs_get_register(regs, pt_regs_offset[idx]);
64 }
65 
66 #define REG_RESERVED (~((1ULL << PERF_REG_X86_MAX) - 1ULL))
67 
68 #ifdef CONFIG_X86_32
69 int perf_reg_validate(u64 mask)
70 {
71 	if (!mask || mask & REG_RESERVED)
72 		return -EINVAL;
73 
74 	return 0;
75 }
76 
77 u64 perf_reg_abi(struct task_struct *task)
78 {
79 	return PERF_SAMPLE_REGS_ABI_32;
80 }
81 
82 void perf_get_regs_user(struct perf_regs *regs_user,
83 			struct pt_regs *regs,
84 			struct pt_regs *regs_user_copy)
85 {
86 	regs_user->regs = task_pt_regs(current);
87 	regs_user->abi = perf_reg_abi(current);
88 }
89 #else /* CONFIG_X86_64 */
90 #define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \
91 		       (1ULL << PERF_REG_X86_ES) | \
92 		       (1ULL << PERF_REG_X86_FS) | \
93 		       (1ULL << PERF_REG_X86_GS))
94 
95 int perf_reg_validate(u64 mask)
96 {
97 	if (!mask || mask & REG_RESERVED)
98 		return -EINVAL;
99 
100 	if (mask & REG_NOSUPPORT)
101 		return -EINVAL;
102 
103 	return 0;
104 }
105 
106 u64 perf_reg_abi(struct task_struct *task)
107 {
108 	if (test_tsk_thread_flag(task, TIF_IA32))
109 		return PERF_SAMPLE_REGS_ABI_32;
110 	else
111 		return PERF_SAMPLE_REGS_ABI_64;
112 }
113 
114 void perf_get_regs_user(struct perf_regs *regs_user,
115 			struct pt_regs *regs,
116 			struct pt_regs *regs_user_copy)
117 {
118 	struct pt_regs *user_regs = task_pt_regs(current);
119 
120 	/*
121 	 * If we're in an NMI that interrupted task_pt_regs setup, then
122 	 * we can't sample user regs at all.  This check isn't really
123 	 * sufficient, though, as we could be in an NMI inside an interrupt
124 	 * that happened during task_pt_regs setup.
125 	 */
126 	if (regs->sp > (unsigned long)&user_regs->r11 &&
127 	    regs->sp <= (unsigned long)(user_regs + 1)) {
128 		regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
129 		regs_user->regs = NULL;
130 		return;
131 	}
132 
133 	/*
134 	 * These registers are always saved on 64-bit syscall entry.
135 	 * On 32-bit entry points, they are saved too except r8..r11.
136 	 */
137 	regs_user_copy->ip = user_regs->ip;
138 	regs_user_copy->ax = user_regs->ax;
139 	regs_user_copy->cx = user_regs->cx;
140 	regs_user_copy->dx = user_regs->dx;
141 	regs_user_copy->si = user_regs->si;
142 	regs_user_copy->di = user_regs->di;
143 	regs_user_copy->r8 = user_regs->r8;
144 	regs_user_copy->r9 = user_regs->r9;
145 	regs_user_copy->r10 = user_regs->r10;
146 	regs_user_copy->r11 = user_regs->r11;
147 	regs_user_copy->orig_ax = user_regs->orig_ax;
148 	regs_user_copy->flags = user_regs->flags;
149 	regs_user_copy->sp = user_regs->sp;
150 	regs_user_copy->cs = user_regs->cs;
151 	regs_user_copy->ss = user_regs->ss;
152 
153 	/*
154 	 * Most system calls don't save these registers, don't report them.
155 	 */
156 	regs_user_copy->bx = -1;
157 	regs_user_copy->bp = -1;
158 	regs_user_copy->r12 = -1;
159 	regs_user_copy->r13 = -1;
160 	regs_user_copy->r14 = -1;
161 	regs_user_copy->r15 = -1;
162 
163 	/*
164 	 * For this to be at all useful, we need a reasonable guess for
165 	 * the ABI.  Be careful: we're in NMI context, and we're
166 	 * considering current to be the current task, so we should
167 	 * be careful not to look at any other percpu variables that might
168 	 * change during context switches.
169 	 */
170 	regs_user->abi = user_64bit_mode(user_regs) ?
171 		PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32;
172 
173 	regs_user->regs = regs_user_copy;
174 }
175 #endif /* CONFIG_X86_32 */
176