LXR linux/tools/perf/arch/x86/util/dwarf-regs.c

   1/*
   2 * dwarf-regs.c : Mapping of DWARF debug register numbers into register names.
   3 * Extracted from probe-finder.c
   4 *
   5 * Written by Masami Hiramatsu <mhiramat@redhat.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License as published by
   9 * the Free Software Foundation; either version 2 of the License, or
  10 * (at your option) any later version.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20 *
  21 */
  22
  23#include <stddef.h>
  24#include <errno.h> /* for EINVAL */
  25#include <string.h> /* for strcmp */
  26#include <linux/ptrace.h> /* for struct pt_regs */
  27#include <linux/kernel.h> /* for offsetof */
  28#include <dwarf-regs.h>
  29
  30/*
  31 * See arch/x86/kernel/ptrace.c.
  32 * Different from it:
  33 *
  34 *  - Since struct pt_regs is defined differently for user and kernel,
  35 *    but we want to use 'ax, bx' instead of 'rax, rbx' (which is struct
  36 *    field name of user's pt_regs), we make REG_OFFSET_NAME to accept
  37 *    both string name and reg field name.
  38 *
  39 *  - Since accessing x86_32's pt_regs from x86_64 building is difficult
  40 *    and vise versa, we simply fill offset with -1, so
  41 *    get_arch_regstr() still works but regs_query_register_offset()
  42 *    returns error.
  43 *    The only inconvenience caused by it now is that we are not allowed
  44 *    to generate BPF prologue for a x86_64 kernel if perf is built for
  45 *    x86_32. This is really a rare usecase.
  46 *
  47 *  - Order is different from kernel's ptrace.c for get_arch_regstr(). Use
  48 *    the order defined by dwarf.
  49 */
  50
  51struct pt_regs_offset {
  52        const char *name;
  53        int offset;
  54};
  55
  56#define REG_OFFSET_END {.name = NULL, .offset = 0}
  57
  58#ifdef __x86_64__
  59# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)}
  60# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = -1}
  61#else
  62# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = -1}
  63# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)}
  64#endif
  65
  66/* TODO: switching by dwarf address size */
  67#ifndef __x86_64__
  68static const struct pt_regs_offset x86_32_regoffset_table[] = {
  69        REG_OFFSET_NAME_32("%ax",       eax),
  70        REG_OFFSET_NAME_32("%cx",       ecx),
  71        REG_OFFSET_NAME_32("%dx",       edx),
  72        REG_OFFSET_NAME_32("%bx",       ebx),
  73        REG_OFFSET_NAME_32("$stack",    esp),   /* Stack address instead of %sp */
  74        REG_OFFSET_NAME_32("%bp",       ebp),
  75        REG_OFFSET_NAME_32("%si",       esi),
  76        REG_OFFSET_NAME_32("%di",       edi),
  77        REG_OFFSET_END,
  78};
  79
  80#define regoffset_table x86_32_regoffset_table
  81#else
  82static const struct pt_regs_offset x86_64_regoffset_table[] = {
  83        REG_OFFSET_NAME_64("%ax",       rax),
  84        REG_OFFSET_NAME_64("%dx",       rdx),
  85        REG_OFFSET_NAME_64("%cx",       rcx),
  86        REG_OFFSET_NAME_64("%bx",       rbx),
  87        REG_OFFSET_NAME_64("%si",       rsi),
  88        REG_OFFSET_NAME_64("%di",       rdi),
  89        REG_OFFSET_NAME_64("%bp",       rbp),
  90        REG_OFFSET_NAME_64("%sp",       rsp),
  91        REG_OFFSET_NAME_64("%r8",       r8),
  92        REG_OFFSET_NAME_64("%r9",       r9),
  93        REG_OFFSET_NAME_64("%r10",      r10),
  94        REG_OFFSET_NAME_64("%r11",      r11),
  95        REG_OFFSET_NAME_64("%r12",      r12),
  96        REG_OFFSET_NAME_64("%r13",      r13),
  97        REG_OFFSET_NAME_64("%r14",      r14),
  98        REG_OFFSET_NAME_64("%r15",      r15),
  99        REG_OFFSET_END,
 100};
 101
 102#define regoffset_table x86_64_regoffset_table
 103#endif
 104
 105/* Minus 1 for the ending REG_OFFSET_END */
 106#define ARCH_MAX_REGS ((sizeof(regoffset_table) / sizeof(regoffset_table[0])) - 1)
 107
 108/* Return architecture dependent register string (for kprobe-tracer) */
 109const char *get_arch_regstr(unsigned int n)
 110{
 111        return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL;
 112}
 113
 114/* Reuse code from arch/x86/kernel/ptrace.c */
 115/**
 116 * regs_query_register_offset() - query register offset from its name
 117 * @name:       the name of a register
 118 *
 119 * regs_query_register_offset() returns the offset of a register in struct
 120 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
 121 */
 122int regs_query_register_offset(const char *name)
 123{
 124        const struct pt_regs_offset *roff;
 125        for (roff = regoffset_table; roff->name != NULL; roff++)
 126                if (!strcmp(roff->name, name))
 127                        return roff->offset;
 128        return -EINVAL;
 129}
 130