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authorOleg Nesterov <oleg@redhat.com>2014-04-07 16:22:58 +0200
committerOleg Nesterov <oleg@redhat.com>2014-04-17 21:58:25 +0200
commit6cc5e7ff2c38641060f20786a5caf2815edbca5f (patch)
tree393f386a447bf0c124a685c9eaa5d8e87b5d167d
parent8f95505bc18a026ef7d3dfdbce4e5b31b3e4fc1b (diff)
uprobes/x86: Emulate relative conditional "near" jmp's
Change branch_setup_xol_ops() to simply use opc1 = OPCODE2(insn) - 0x10 if OPCODE1() == 0x0f; this matches the "short" jmp which checks the same condition. Thanks to lib/insn.c, it does the rest correctly. branch->ilen/offs are correct no matter if this jmp is "near" or "short". Reported-by: Jonathan Lebon <jlebon@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
-rw-r--r--arch/x86/kernel/uprobes.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 0460d04f0ac..ace22916ade 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -599,6 +599,14 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
branch_clear_offset(auprobe, insn);
break;
+ case 0x0f:
+ if (insn->opcode.nbytes != 2)
+ return -ENOSYS;
+ /*
+ * If it is a "near" conditional jmp, OPCODE2() - 0x10 matches
+ * OPCODE1() of the "short" jmp which checks the same condition.
+ */
+ opc1 = OPCODE2(insn) - 0x10;
default:
if (!is_cond_jmp_opcode(opc1))
return -ENOSYS;