The following commit has been merged into the perf/core branch of tip:
Commit-ID: 9fcad995c6c52cc9791f7ee9f1386a5684055f9c
Gitweb: https://git.kernel.org/tip/9fcad995c6c52cc9791f7ee9f1386a5684055f9c
Author: Chuang Wang <nashuiliang@xxxxxxxxx>
AuthorDate: Tue, 29 Nov 2022 16:39:51 +08:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 10 Jan 2023 12:37:14 +01:00
x86/kprobes: Use switch-case for 0xFF opcodes in prepare_emulation
For the `FF /digit` opcodes in prepare_emulation, use switch-case
instead of hand-written code to make the logic easier to understand.
Signed-off-by: Chuang Wang <nashuiliang@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221129084022.718355-1-nashuiliang@xxxxxxxxx
---
arch/x86/kernel/kprobes/core.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 33390ed..fd0420a 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -655,17 +655,19 @@ static int prepare_emulation(struct kprobe *p, struct insn *insn)
* is determined by the MOD/RM byte.
*/
opcode = insn->modrm.bytes[0];
- if ((opcode & 0x30) == 0x10) {
- if ((opcode & 0x8) == 0x8)
- return -EOPNOTSUPP; /* far call */
- /* call absolute, indirect */
+ switch (X86_MODRM_REG(opcode)) {
+ case 0b010: /* FF /2, call near, absolute indirect */
p->ainsn.emulate_op = kprobe_emulate_call_indirect;
- } else if ((opcode & 0x30) == 0x20) {
- if ((opcode & 0x8) == 0x8)
- return -EOPNOTSUPP; /* far jmp */
- /* jmp near absolute indirect */
+ break;
+ case 0b100: /* FF /4, jmp near, absolute indirect */
p->ainsn.emulate_op = kprobe_emulate_jmp_indirect;
- } else
+ break;
+ case 0b011: /* FF /3, call far, absolute indirect */
+ case 0b101: /* FF /5, jmp far, absolute indirect */
+ return -EOPNOTSUPP;
+ }
+
+ if (!p->ainsn.emulate_op)
break;
if (insn->addr_bytes != sizeof(unsigned long))
|