mirror of https://gitee.com/openkylin/linux.git
413 lines
14 KiB
C
413 lines
14 KiB
C
/*
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* Userspace Probes (UProbes) for x86
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2008-2011
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* Authors:
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* Srikar Dronamraju
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* Jim Keniston
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/ptrace.h>
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#include <linux/uprobes.h>
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#include <linux/kdebug.h>
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#include <asm/insn.h>
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/* Post-execution fixups. */
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/* No fixup needed */
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#define UPROBES_FIX_NONE 0x0
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/* Adjust IP back to vicinity of actual insn */
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#define UPROBES_FIX_IP 0x1
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/* Adjust the return address of a call insn */
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#define UPROBES_FIX_CALL 0x2
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#define UPROBES_FIX_RIP_AX 0x8000
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#define UPROBES_FIX_RIP_CX 0x4000
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/* Adaptations for mhiramat x86 decoder v14. */
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#define OPCODE1(insn) ((insn)->opcode.bytes[0])
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#define OPCODE2(insn) ((insn)->opcode.bytes[1])
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#define OPCODE3(insn) ((insn)->opcode.bytes[2])
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#define MODRM_REG(insn) X86_MODRM_REG(insn->modrm.value)
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#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
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(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
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(b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
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(b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
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(bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
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<< (row % 32))
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#ifdef CONFIG_X86_64
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static volatile u32 good_insns_64[256 / 32] = {
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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/* ---------------------------------------------- */
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W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */
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W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */
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W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */
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W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */
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W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */
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W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
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W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
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W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
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W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
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W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
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W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
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W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
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W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
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W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
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W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
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W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */
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/* ---------------------------------------------- */
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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};
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#endif
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/* Good-instruction tables for 32-bit apps */
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static volatile u32 good_insns_32[256 / 32] = {
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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/* ---------------------------------------------- */
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W(0x00, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) | /* 00 */
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W(0x10, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 10 */
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W(0x20, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* 20 */
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W(0x30, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) , /* 30 */
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W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
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W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
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W(0x60, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
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W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
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W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
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W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
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W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
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W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
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W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
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W(0xd0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
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W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
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W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */
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/* ---------------------------------------------- */
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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};
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/* Using this for both 64-bit and 32-bit apps */
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static volatile u32 good_2byte_insns[256 / 32] = {
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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/* ---------------------------------------------- */
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W(0x00, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1) | /* 00 */
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W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* 10 */
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W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */
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W(0x30, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
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W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
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W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
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W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */
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W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
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W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
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W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
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W(0xa0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */
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W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
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W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
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W(0xd0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
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W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */
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W(0xf0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* f0 */
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/* ---------------------------------------------- */
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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};
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#undef W
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/*
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* opcodes we'll probably never support:
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* 6c-6d, e4-e5, ec-ed - in
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* 6e-6f, e6-e7, ee-ef - out
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* cc, cd - int3, int
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* cf - iret
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* d6 - illegal instruction
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* f1 - int1/icebp
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* f4 - hlt
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* fa, fb - cli, sti
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* 0f - lar, lsl, syscall, clts, sysret, sysenter, sysexit, invd, wbinvd, ud2
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*
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* invalid opcodes in 64-bit mode:
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* 06, 0e, 16, 1e, 27, 2f, 37, 3f, 60-62, 82, c4-c5, d4-d5
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*
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* 63 - we support this opcode in x86_64 but not in i386.
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*
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* opcodes we may need to refine support for:
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* 0f - 2-byte instructions: For many of these instructions, the validity
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* depends on the prefix and/or the reg field. On such instructions, we
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* just consider the opcode combination valid if it corresponds to any
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* valid instruction.
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* 8f - Group 1 - only reg = 0 is OK
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* c6-c7 - Group 11 - only reg = 0 is OK
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* d9-df - fpu insns with some illegal encodings
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* f2, f3 - repnz, repz prefixes. These are also the first byte for
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* certain floating-point instructions, such as addsd.
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* fe - Group 4 - only reg = 0 or 1 is OK
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* ff - Group 5 - only reg = 0-6 is OK
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*
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* others -- Do we need to support these?
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* 0f - (floating-point?) prefetch instructions
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* 07, 17, 1f - pop es, pop ss, pop ds
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* 26, 2e, 36, 3e - es:, cs:, ss:, ds: segment prefixes --
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* but 64 and 65 (fs: and gs:) seem to be used, so we support them
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* 67 - addr16 prefix
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* ce - into
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* f0 - lock prefix
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*/
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/*
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* TODO:
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* - Where necessary, examine the modrm byte and allow only valid instructions
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* in the different Groups and fpu instructions.
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*/
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static bool is_prefix_bad(struct insn *insn)
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{
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int i;
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for (i = 0; i < insn->prefixes.nbytes; i++) {
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switch (insn->prefixes.bytes[i]) {
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case 0x26: /*INAT_PFX_ES */
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case 0x2E: /*INAT_PFX_CS */
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case 0x36: /*INAT_PFX_DS */
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case 0x3E: /*INAT_PFX_SS */
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case 0xF0: /*INAT_PFX_LOCK */
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return true;
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}
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}
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return false;
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}
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static int validate_insn_32bits(struct uprobe *uprobe, struct insn *insn)
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{
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insn_init(insn, uprobe->insn, false);
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/* Skip good instruction prefixes; reject "bad" ones. */
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insn_get_opcode(insn);
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if (is_prefix_bad(insn))
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return -ENOTSUPP;
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if (test_bit(OPCODE1(insn), (unsigned long *)good_insns_32))
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return 0;
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if (insn->opcode.nbytes == 2) {
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if (test_bit(OPCODE2(insn), (unsigned long *)good_2byte_insns))
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return 0;
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}
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return -ENOTSUPP;
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}
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/*
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* Figure out which fixups post_xol() will need to perform, and annotate
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* uprobe->arch_info.fixups accordingly. To start with,
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* uprobe->arch_info.fixups is either zero or it reflects rip-related
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* fixups.
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*/
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static void prepare_fixups(struct uprobe *uprobe, struct insn *insn)
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{
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bool fix_ip = true, fix_call = false; /* defaults */
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int reg;
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insn_get_opcode(insn); /* should be a nop */
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switch (OPCODE1(insn)) {
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case 0xc3: /* ret/lret */
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case 0xcb:
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case 0xc2:
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case 0xca:
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/* ip is correct */
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fix_ip = false;
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break;
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case 0xe8: /* call relative - Fix return addr */
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fix_call = true;
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break;
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case 0x9a: /* call absolute - Fix return addr, not ip */
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fix_call = true;
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fix_ip = false;
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break;
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case 0xff:
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insn_get_modrm(insn);
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reg = MODRM_REG(insn);
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if (reg == 2 || reg == 3) {
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/* call or lcall, indirect */
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/* Fix return addr; ip is correct. */
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fix_call = true;
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fix_ip = false;
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} else if (reg == 4 || reg == 5) {
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/* jmp or ljmp, indirect */
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/* ip is correct. */
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fix_ip = false;
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}
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break;
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case 0xea: /* jmp absolute -- ip is correct */
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fix_ip = false;
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break;
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default:
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break;
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}
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if (fix_ip)
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uprobe->arch_info.fixups |= UPROBES_FIX_IP;
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if (fix_call)
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uprobe->arch_info.fixups |= UPROBES_FIX_CALL;
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}
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#ifdef CONFIG_X86_64
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/*
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* If uprobe->insn doesn't use rip-relative addressing, return
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* immediately. Otherwise, rewrite the instruction so that it accesses
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* its memory operand indirectly through a scratch register. Set
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* uprobe->arch_info.fixups and uprobe->arch_info.rip_rela_target_address
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* accordingly. (The contents of the scratch register will be saved
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* before we single-step the modified instruction, and restored
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* afterward.)
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*
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* We do this because a rip-relative instruction can access only a
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* relatively small area (+/- 2 GB from the instruction), and the XOL
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* area typically lies beyond that area. At least for instructions
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* that store to memory, we can't execute the original instruction
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* and "fix things up" later, because the misdirected store could be
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* disastrous.
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*
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* Some useful facts about rip-relative instructions:
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* - There's always a modrm byte.
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* - There's never a SIB byte.
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* - The displacement is always 4 bytes.
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*/
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static void handle_riprel_insn(struct mm_struct *mm, struct uprobe *uprobe,
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struct insn *insn)
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{
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u8 *cursor;
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u8 reg;
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if (mm->context.ia32_compat)
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return;
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uprobe->arch_info.rip_rela_target_address = 0x0;
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if (!insn_rip_relative(insn))
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return;
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/*
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* insn_rip_relative() would have decoded rex_prefix, modrm.
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* Clear REX.b bit (extension of MODRM.rm field):
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* we want to encode rax/rcx, not r8/r9.
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*/
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if (insn->rex_prefix.nbytes) {
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cursor = uprobe->insn + insn_offset_rex_prefix(insn);
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*cursor &= 0xfe; /* Clearing REX.B bit */
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}
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/*
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* Point cursor at the modrm byte. The next 4 bytes are the
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* displacement. Beyond the displacement, for some instructions,
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* is the immediate operand.
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*/
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cursor = uprobe->insn + insn_offset_modrm(insn);
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insn_get_length(insn);
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/*
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* Convert from rip-relative addressing to indirect addressing
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* via a scratch register. Change the r/m field from 0x5 (%rip)
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* to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field.
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*/
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reg = MODRM_REG(insn);
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if (reg == 0) {
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/*
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* The register operand (if any) is either the A register
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* (%rax, %eax, etc.) or (if the 0x4 bit is set in the
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* REX prefix) %r8. In any case, we know the C register
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* is NOT the register operand, so we use %rcx (register
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* #1) for the scratch register.
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*/
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uprobe->arch_info.fixups = UPROBES_FIX_RIP_CX;
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/* Change modrm from 00 000 101 to 00 000 001. */
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*cursor = 0x1;
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} else {
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/* Use %rax (register #0) for the scratch register. */
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uprobe->arch_info.fixups = UPROBES_FIX_RIP_AX;
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/* Change modrm from 00 xxx 101 to 00 xxx 000 */
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*cursor = (reg << 3);
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}
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/* Target address = address of next instruction + (signed) offset */
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uprobe->arch_info.rip_rela_target_address = (long)insn->length
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+ insn->displacement.value;
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/* Displacement field is gone; slide immediate field (if any) over. */
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if (insn->immediate.nbytes) {
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cursor++;
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memmove(cursor, cursor + insn->displacement.nbytes,
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insn->immediate.nbytes);
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}
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return;
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}
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static int validate_insn_64bits(struct uprobe *uprobe, struct insn *insn)
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{
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insn_init(insn, uprobe->insn, true);
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/* Skip good instruction prefixes; reject "bad" ones. */
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insn_get_opcode(insn);
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if (is_prefix_bad(insn))
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return -ENOTSUPP;
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if (test_bit(OPCODE1(insn), (unsigned long *)good_insns_64))
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return 0;
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if (insn->opcode.nbytes == 2) {
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if (test_bit(OPCODE2(insn), (unsigned long *)good_2byte_insns))
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return 0;
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}
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return -ENOTSUPP;
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}
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static int validate_insn_bits(struct mm_struct *mm, struct uprobe *uprobe,
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struct insn *insn)
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{
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if (mm->context.ia32_compat)
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return validate_insn_32bits(uprobe, insn);
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return validate_insn_64bits(uprobe, insn);
|
|
}
|
|
#else
|
|
static void handle_riprel_insn(struct mm_struct *mm, struct uprobe *uprobe,
|
|
struct insn *insn)
|
|
{
|
|
return;
|
|
}
|
|
|
|
static int validate_insn_bits(struct mm_struct *mm, struct uprobe *uprobe,
|
|
struct insn *insn)
|
|
{
|
|
return validate_insn_32bits(uprobe, insn);
|
|
}
|
|
#endif /* CONFIG_X86_64 */
|
|
|
|
/**
|
|
* analyze_insn - instruction analysis including validity and fixups.
|
|
* @mm: the probed address space.
|
|
* @uprobe: the probepoint information.
|
|
* Return 0 on success or a -ve number on error.
|
|
*/
|
|
int analyze_insn(struct mm_struct *mm, struct uprobe *uprobe)
|
|
{
|
|
int ret;
|
|
struct insn insn;
|
|
|
|
uprobe->arch_info.fixups = 0;
|
|
ret = validate_insn_bits(mm, uprobe, &insn);
|
|
if (ret != 0)
|
|
return ret;
|
|
handle_riprel_insn(mm, uprobe, &insn);
|
|
prepare_fixups(uprobe, &insn);
|
|
return 0;
|
|
}
|