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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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