1// SPDX-License-Identifier: GPL-2.0-or-later 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> 7 */ 8 9#include <stddef.h> 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 */ 14#include <dwarf-regs.h> 15 16/* 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. 35 */ 36 37struct 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 52/* TODO: switching by dwarf address size */ 53#ifndef __x86_64__ 54static 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, 64}; 65 66#define regoffset_table x86_32_regoffset_table 67#else 68static 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, 86}; 87 88#define regoffset_table x86_64_regoffset_table 89#endif 90 91/* Minus 1 for the ending REG_OFFSET_END */ 92#define ARCH_MAX_REGS ((sizeof(regoffset_table) / sizeof(regoffset_table[0])) - 1) 93 94/* Return architecture dependent register string (for kprobe-tracer) */ 95const char *get_arch_regstr(unsigned int n) 96{ 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 */ 108int 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; 115} 116 117struct dwarf_regs_idx { 118 const char *name; 119 int idx; 120}; 121 122static const struct dwarf_regs_idx x86_regidx_table[] = { 123 { "rax", 0 }, { "eax", 0 }, { "ax", 0 }, { "al", 0 }, 124 { "rdx", 1 }, { "edx", 1 }, { "dx", 1 }, { "dl", 1 }, 125 { "rcx", 2 }, { "ecx", 2 }, { "cx", 2 }, { "cl", 2 }, 126 { "rbx", 3 }, { "edx", 3 }, { "bx", 3 }, { "bl", 3 }, 127 { "rsi", 4 }, { "esi", 4 }, { "si", 4 }, { "sil", 4 }, 128 { "rdi", 5 }, { "edi", 5 }, { "di", 5 }, { "dil", 5 }, 129 { "rbp", 6 }, { "ebp", 6 }, { "bp", 6 }, { "bpl", 6 }, 130 { "rsp", 7 }, { "esp", 7 }, { "sp", 7 }, { "spl", 7 }, 131 { "r8", 8 }, { "r8d", 8 }, { "r8w", 8 }, { "r8b", 8 }, 132 { "r9", 9 }, { "r9d", 9 }, { "r9w", 9 }, { "r9b", 9 }, 133 { "r10", 10 }, { "r10d", 10 }, { "r10w", 10 }, { "r10b", 10 }, 134 { "r11", 11 }, { "r11d", 11 }, { "r11w", 11 }, { "r11b", 11 }, 135 { "r12", 12 }, { "r12d", 12 }, { "r12w", 12 }, { "r12b", 12 }, 136 { "r13", 13 }, { "r13d", 13 }, { "r13w", 13 }, { "r13b", 13 }, 137 { "r14", 14 }, { "r14d", 14 }, { "r14w", 14 }, { "r14b", 14 }, 138 { "r15", 15 }, { "r15d", 15 }, { "r15w", 15 }, { "r15b", 15 }, 139 { "rip", DWARF_REG_PC }, 140}; 141 142int get_arch_regnum(const char *name) 143{ 144 unsigned int i; 145 146 if (*name != '%') 147 return -EINVAL; 148 149 for (i = 0; i < ARRAY_SIZE(x86_regidx_table); i++) 150 if (!strcmp(x86_regidx_table[i].name, name + 1)) 151 return x86_regidx_table[i].idx; 152 return -ENOENT; 153} 154