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| author | Oleg Nesterov <oleg@redhat.com> | 2022-12-04 18:39:33 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-12-05 11:55:18 +0100 |
| commit | cefa72129e45313655d53a065b8055aaeb01a0c9 (patch) | |
| tree | 8bcf7483e6a5f7874f5fe77782ff812fe337f8f0 /arch/x86/kernel/uprobes.c | |
| parent | 023e59d4cee91dd3ca811eb01db2c5fb9f783dc2 (diff) | |
| download | linux-cefa72129e45313655d53a065b8055aaeb01a0c9.tar.gz linux-cefa72129e45313655d53a065b8055aaeb01a0c9.tar.bz2 linux-cefa72129e45313655d53a065b8055aaeb01a0c9.zip | |
uprobes/x86: Allow to probe a NOP instruction with 0x66 prefix
Intel ICC -hotpatch inserts 2-byte "0x66 0x90" NOP at the start of each
function to reserve extra space for hot-patching, and currently it is not
possible to probe these functions because branch_setup_xol_ops() wrongly
rejects NOP with REP prefix as it treats them like word-sized branch
instructions.
Fixes: 250bbd12c2fe ("uprobes/x86: Refuse to attach uprobe to "word-sized" branch insns")
Reported-by: Seiji Nishikawa <snishika@redhat.com>
Suggested-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20221204173933.GA31544@redhat.com
Diffstat (limited to 'arch/x86/kernel/uprobes.c')
| -rw-r--r-- | arch/x86/kernel/uprobes.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index b63cf8f7745e..6c07f6daaa22 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -722,8 +722,9 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) switch (opc1) { case 0xeb: /* jmp 8 */ case 0xe9: /* jmp 32 */ - case 0x90: /* prefix* + nop; same as jmp with .offs = 0 */ break; + case 0x90: /* prefix* + nop; same as jmp with .offs = 0 */ + goto setup; case 0xe8: /* call relative */ branch_clear_offset(auprobe, insn); @@ -753,6 +754,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) return -ENOTSUPP; } +setup: auprobe->branch.opc1 = opc1; auprobe->branch.ilen = insn->length; auprobe->branch.offs = insn->immediate.value; |