Messages in this thread Patch in this message | | | Date | Sun, 13 Apr 2014 19:46:13 +0200 | From | Oleg Nesterov <> | Subject | [PATCH v3 15/15] uprobes/x86: Emulate relative conditional "near" jmp's |
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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> --- arch/x86/kernel/uprobes.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index b5f2fa4..d7e9d04 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; -- 1.5.5.1
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