154 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * dwarf-regs.c : Mapping of DWARF debug register numbers into register names.4 * Extracted from probe-finder.c5 *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 struct22 * field name of user's pt_regs), we make REG_OFFSET_NAME to accept23 * both string name and reg field name.24 *25 * - Since accessing x86_32's pt_regs from x86_64 building is difficult26 * and vise versa, we simply fill offset with -1, so27 * 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 allowed30 * to generate BPF prologue for a x86_64 kernel if perf is built for31 * x86_32. This is really a rare usecase.32 *33 * - Order is different from kernel's ptrace.c for get_arch_regstr(). Use34 * 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#else48# 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#endif51 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_table67#else68static 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_table89#endif90 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 name103 * @name: the name of a register104 *105 * regs_query_register_offset() returns the offset of a register in struct106 * 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