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1a59d1b8 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
cd932c59 IM |
2 | /* |
3 | * dwarf-regs.c : Mapping of DWARF debug register numbers into register names. | |
4 | * Extracted from probe-finder.c | |
5 | * | |
6 | * Written by Masami Hiramatsu <mhiramat@redhat.com> | |
cd932c59 IM |
7 | */ |
8 | ||
861e10be | 9 | #include <stddef.h> |
bbbe6bf6 WN |
10 | #include <errno.h> /* for EINVAL */ |
11 | #include <string.h> /* for strcmp */ | |
12 | #include <linux/ptrace.h> /* for struct pt_regs */ | |
13 | #include <linux/kernel.h> /* for offsetof */ | |
cd932c59 IM |
14 | #include <dwarf-regs.h> |
15 | ||
16 | /* | |
bbbe6bf6 WN |
17 | * See arch/x86/kernel/ptrace.c. |
18 | * Different from it: | |
19 | * | |
20 | * - Since struct pt_regs is defined differently for user and kernel, | |
21 | * but we want to use 'ax, bx' instead of 'rax, rbx' (which is struct | |
22 | * field name of user's pt_regs), we make REG_OFFSET_NAME to accept | |
23 | * both string name and reg field name. | |
24 | * | |
25 | * - Since accessing x86_32's pt_regs from x86_64 building is difficult | |
26 | * and vise versa, we simply fill offset with -1, so | |
27 | * get_arch_regstr() still works but regs_query_register_offset() | |
28 | * returns error. | |
29 | * The only inconvenience caused by it now is that we are not allowed | |
30 | * to generate BPF prologue for a x86_64 kernel if perf is built for | |
31 | * x86_32. This is really a rare usecase. | |
32 | * | |
33 | * - Order is different from kernel's ptrace.c for get_arch_regstr(). Use | |
34 | * the order defined by dwarf. | |
cd932c59 IM |
35 | */ |
36 | ||
bbbe6bf6 WN |
37 | struct pt_regs_offset { |
38 | const char *name; | |
39 | int offset; | |
40 | }; | |
41 | ||
42 | #define REG_OFFSET_END {.name = NULL, .offset = 0} | |
43 | ||
44 | #ifdef __x86_64__ | |
45 | # define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} | |
46 | # define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = -1} | |
47 | #else | |
48 | # define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = -1} | |
49 | # define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} | |
50 | #endif | |
51 | ||
62aa0e17 ACM |
52 | /* TODO: switching by dwarf address size */ |
53 | #ifndef __x86_64__ | |
bbbe6bf6 WN |
54 | static const struct pt_regs_offset x86_32_regoffset_table[] = { |
55 | REG_OFFSET_NAME_32("%ax", eax), | |
56 | REG_OFFSET_NAME_32("%cx", ecx), | |
57 | REG_OFFSET_NAME_32("%dx", edx), | |
58 | REG_OFFSET_NAME_32("%bx", ebx), | |
59 | REG_OFFSET_NAME_32("$stack", esp), /* Stack address instead of %sp */ | |
60 | REG_OFFSET_NAME_32("%bp", ebp), | |
61 | REG_OFFSET_NAME_32("%si", esi), | |
62 | REG_OFFSET_NAME_32("%di", edi), | |
63 | REG_OFFSET_END, | |
cd932c59 IM |
64 | }; |
65 | ||
62aa0e17 ACM |
66 | #define regoffset_table x86_32_regoffset_table |
67 | #else | |
bbbe6bf6 WN |
68 | static const struct pt_regs_offset x86_64_regoffset_table[] = { |
69 | REG_OFFSET_NAME_64("%ax", rax), | |
70 | REG_OFFSET_NAME_64("%dx", rdx), | |
71 | REG_OFFSET_NAME_64("%cx", rcx), | |
72 | REG_OFFSET_NAME_64("%bx", rbx), | |
73 | REG_OFFSET_NAME_64("%si", rsi), | |
74 | REG_OFFSET_NAME_64("%di", rdi), | |
75 | REG_OFFSET_NAME_64("%bp", rbp), | |
76 | REG_OFFSET_NAME_64("%sp", rsp), | |
77 | REG_OFFSET_NAME_64("%r8", r8), | |
78 | REG_OFFSET_NAME_64("%r9", r9), | |
79 | REG_OFFSET_NAME_64("%r10", r10), | |
80 | REG_OFFSET_NAME_64("%r11", r11), | |
81 | REG_OFFSET_NAME_64("%r12", r12), | |
82 | REG_OFFSET_NAME_64("%r13", r13), | |
83 | REG_OFFSET_NAME_64("%r14", r14), | |
84 | REG_OFFSET_NAME_64("%r15", r15), | |
85 | REG_OFFSET_END, | |
cd932c59 IM |
86 | }; |
87 | ||
bbbe6bf6 | 88 | #define regoffset_table x86_64_regoffset_table |
cd932c59 IM |
89 | #endif |
90 | ||
bbbe6bf6 WN |
91 | /* Minus 1 for the ending REG_OFFSET_END */ |
92 | #define ARCH_MAX_REGS ((sizeof(regoffset_table) / sizeof(regoffset_table[0])) - 1) | |
93 | ||
cd932c59 IM |
94 | /* Return architecture dependent register string (for kprobe-tracer) */ |
95 | const char *get_arch_regstr(unsigned int n) | |
96 | { | |
bbbe6bf6 WN |
97 | return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL; |
98 | } | |
99 | ||
100 | /* Reuse code from arch/x86/kernel/ptrace.c */ | |
101 | /** | |
102 | * regs_query_register_offset() - query register offset from its name | |
103 | * @name: the name of a register | |
104 | * | |
105 | * regs_query_register_offset() returns the offset of a register in struct | |
106 | * pt_regs from its name. If the name is invalid, this returns -EINVAL; | |
107 | */ | |
108 | int regs_query_register_offset(const char *name) | |
109 | { | |
110 | const struct pt_regs_offset *roff; | |
111 | for (roff = regoffset_table; roff->name != NULL; roff++) | |
112 | if (!strcmp(roff->name, name)) | |
113 | return roff->offset; | |
114 | return -EINVAL; | |
cd932c59 | 115 | } |