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115 lines
3.6 KiB
115 lines
3.6 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* dwarf-regs.c : Mapping of DWARF debug register numbers into register names. |
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* Extracted from probe-finder.c |
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* |
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* Written by Masami Hiramatsu <[email protected]> |
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*/ |
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#include <stddef.h> |
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#include <errno.h> /* for EINVAL */ |
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#include <string.h> /* for strcmp */ |
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#include <linux/ptrace.h> /* for struct pt_regs */ |
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#include <linux/kernel.h> /* for offsetof */ |
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#include <dwarf-regs.h> |
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/* |
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* See arch/x86/kernel/ptrace.c. |
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* Different from it: |
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* |
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* - Since struct pt_regs is defined differently for user and kernel, |
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* but we want to use 'ax, bx' instead of 'rax, rbx' (which is struct |
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* field name of user's pt_regs), we make REG_OFFSET_NAME to accept |
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* both string name and reg field name. |
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* |
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* - Since accessing x86_32's pt_regs from x86_64 building is difficult |
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* and vise versa, we simply fill offset with -1, so |
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* get_arch_regstr() still works but regs_query_register_offset() |
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* returns error. |
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* The only inconvenience caused by it now is that we are not allowed |
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* to generate BPF prologue for a x86_64 kernel if perf is built for |
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* x86_32. This is really a rare usecase. |
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* |
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* - Order is different from kernel's ptrace.c for get_arch_regstr(). Use |
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* the order defined by dwarf. |
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*/ |
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struct pt_regs_offset { |
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const char *name; |
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int offset; |
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}; |
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#define REG_OFFSET_END {.name = NULL, .offset = 0} |
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#ifdef __x86_64__ |
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# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} |
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# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = -1} |
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#else |
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# define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = -1} |
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# define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} |
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#endif |
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/* TODO: switching by dwarf address size */ |
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#ifndef __x86_64__ |
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static const struct pt_regs_offset x86_32_regoffset_table[] = { |
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REG_OFFSET_NAME_32("%ax", eax), |
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REG_OFFSET_NAME_32("%cx", ecx), |
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REG_OFFSET_NAME_32("%dx", edx), |
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REG_OFFSET_NAME_32("%bx", ebx), |
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REG_OFFSET_NAME_32("$stack", esp), /* Stack address instead of %sp */ |
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REG_OFFSET_NAME_32("%bp", ebp), |
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REG_OFFSET_NAME_32("%si", esi), |
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REG_OFFSET_NAME_32("%di", edi), |
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REG_OFFSET_END, |
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}; |
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#define regoffset_table x86_32_regoffset_table |
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#else |
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static const struct pt_regs_offset x86_64_regoffset_table[] = { |
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REG_OFFSET_NAME_64("%ax", rax), |
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REG_OFFSET_NAME_64("%dx", rdx), |
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REG_OFFSET_NAME_64("%cx", rcx), |
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REG_OFFSET_NAME_64("%bx", rbx), |
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REG_OFFSET_NAME_64("%si", rsi), |
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REG_OFFSET_NAME_64("%di", rdi), |
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REG_OFFSET_NAME_64("%bp", rbp), |
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REG_OFFSET_NAME_64("%sp", rsp), |
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REG_OFFSET_NAME_64("%r8", r8), |
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REG_OFFSET_NAME_64("%r9", r9), |
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REG_OFFSET_NAME_64("%r10", r10), |
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REG_OFFSET_NAME_64("%r11", r11), |
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REG_OFFSET_NAME_64("%r12", r12), |
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REG_OFFSET_NAME_64("%r13", r13), |
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REG_OFFSET_NAME_64("%r14", r14), |
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REG_OFFSET_NAME_64("%r15", r15), |
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REG_OFFSET_END, |
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}; |
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#define regoffset_table x86_64_regoffset_table |
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#endif |
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/* Minus 1 for the ending REG_OFFSET_END */ |
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#define ARCH_MAX_REGS ((sizeof(regoffset_table) / sizeof(regoffset_table[0])) - 1) |
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/* Return architecture dependent register string (for kprobe-tracer) */ |
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const char *get_arch_regstr(unsigned int n) |
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{ |
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return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL; |
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} |
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/* Reuse code from arch/x86/kernel/ptrace.c */ |
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/** |
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* regs_query_register_offset() - query register offset from its name |
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* @name: the name of a register |
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* |
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* regs_query_register_offset() returns the offset of a register in struct |
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* pt_regs from its name. If the name is invalid, this returns -EINVAL; |
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*/ |
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int regs_query_register_offset(const char *name) |
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{ |
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const struct pt_regs_offset *roff; |
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for (roff = regoffset_table; roff->name != NULL; roff++) |
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if (!strcmp(roff->name, name)) |
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return roff->offset; |
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return -EINVAL; |
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}
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