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    Subject[PATCH -tip -v11 04/11] kprobes: cleanup fix_riprel() using insn decoder on x86
    Date
    Cleanup fix_riprel() in arch/x86/kernel/kprobes.c by using x86 instruction
    decoder.

    Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
    Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Jim Keniston <jkenisto@us.ibm.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    ---

    arch/x86/kernel/kprobes.c | 128 ++++++++-------------------------------------
    1 files changed, 23 insertions(+), 105 deletions(-)

    diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
    index 5341842..b77e050 100644
    --- a/arch/x86/kernel/kprobes.c
    +++ b/arch/x86/kernel/kprobes.c
    @@ -109,50 +109,6 @@ static const u32 twobyte_is_boostable[256 / 32] = {
    /* ----------------------------------------------- */
    /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
    };
    -static const u32 onebyte_has_modrm[256 / 32] = {
    - /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
    - /* ----------------------------------------------- */
    - W(0x00, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 00 */
    - W(0x10, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) , /* 10 */
    - W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 20 */
    - W(0x30, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) , /* 30 */
    - W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */
    - W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */
    - W(0x60, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0) | /* 60 */
    - W(0x70, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 70 */
    - W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
    - W(0x90, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 90 */
    - W(0xa0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* a0 */
    - W(0xb0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* b0 */
    - W(0xc0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0) | /* c0 */
    - W(0xd0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
    - W(0xe0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* e0 */
    - W(0xf0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) /* f0 */
    - /* ----------------------------------------------- */
    - /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
    -};
    -static const u32 twobyte_has_modrm[256 / 32] = {
    - /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
    - /* ----------------------------------------------- */
    - W(0x00, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1) | /* 0f */
    - W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0) , /* 1f */
    - W(0x20, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 2f */
    - W(0x30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 3f */
    - W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 4f */
    - W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 5f */
    - W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 6f */
    - W(0x70, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1) , /* 7f */
    - W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 8f */
    - W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 9f */
    - W(0xa0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) | /* af */
    - W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1) , /* bf */
    - W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0) | /* cf */
    - W(0xd0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* df */
    - W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* ef */
    - W(0xf0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* ff */
    - /* ----------------------------------------------- */
    - /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
    -};
    #undef W

    struct kretprobe_blackpoint kretprobe_blacklist[] = {
    @@ -345,68 +301,30 @@ static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
    static void __kprobes fix_riprel(struct kprobe *p)
    {
    #ifdef CONFIG_X86_64
    - u8 *insn = p->ainsn.insn;
    - s64 disp;
    - int need_modrm;
    -
    - /* Skip legacy instruction prefixes. */
    - while (1) {
    - switch (*insn) {
    - case 0x66:
    - case 0x67:
    - case 0x2e:
    - case 0x3e:
    - case 0x26:
    - case 0x64:
    - case 0x65:
    - case 0x36:
    - case 0xf0:
    - case 0xf3:
    - case 0xf2:
    - ++insn;
    - continue;
    - }
    - break;
    - }
    + struct insn insn;
    + kernel_insn_init(&insn, p->ainsn.insn);

    - /* Skip REX instruction prefix. */
    - if (is_REX_prefix(insn))
    - ++insn;
    -
    - if (*insn == 0x0f) {
    - /* Two-byte opcode. */
    - ++insn;
    - need_modrm = test_bit(*insn,
    - (unsigned long *)twobyte_has_modrm);
    - } else
    - /* One-byte opcode. */
    - need_modrm = test_bit(*insn,
    - (unsigned long *)onebyte_has_modrm);
    -
    - if (need_modrm) {
    - u8 modrm = *++insn;
    - if ((modrm & 0xc7) == 0x05) {
    - /* %rip+disp32 addressing mode */
    - /* Displacement follows ModRM byte. */
    - ++insn;
    - /*
    - * The copied instruction uses the %rip-relative
    - * addressing mode. Adjust the displacement for the
    - * difference between the original location of this
    - * instruction and the location of the copy that will
    - * actually be run. The tricky bit here is making sure
    - * that the sign extension happens correctly in this
    - * calculation, since we need a signed 32-bit result to
    - * be sign-extended to 64 bits when it's added to the
    - * %rip value and yield the same 64-bit result that the
    - * sign-extension of the original signed 32-bit
    - * displacement would have given.
    - */
    - disp = (u8 *) p->addr + *((s32 *) insn) -
    - (u8 *) p->ainsn.insn;
    - BUG_ON((s64) (s32) disp != disp); /* Sanity check. */
    - *(s32 *)insn = (s32) disp;
    - }
    + if (insn_rip_relative(&insn)) {
    + s64 newdisp;
    + u8 *disp;
    + insn_get_displacement(&insn);
    + /*
    + * The copied instruction uses the %rip-relative addressing
    + * mode. Adjust the displacement for the difference between
    + * the original location of this instruction and the location
    + * of the copy that will actually be run. The tricky bit here
    + * is making sure that the sign extension happens correctly in
    + * this calculation, since we need a signed 32-bit result to
    + * be sign-extended to 64 bits when it's added to the %rip
    + * value and yield the same 64-bit result that the sign-
    + * extension of the original signed 32-bit displacement would
    + * have given.
    + */
    + newdisp = (u8 *) p->addr + (s64) insn.displacement.value -
    + (u8 *) p->ainsn.insn;
    + BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
    + disp = (u8 *) p->ainsn.insn + INSN_DISPLACEMENT_OFFS(&insn);
    + *(s32 *) disp = (s32) newdisp;
    }
    #endif
    }

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America), Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com


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