0xeb and 0xe9. Anything else?

TODO: move ->fixup into the union along with rip_rela_target_address.

Reported-by: Jonathan Lebon <jle...@redhat.com>
Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
 arch/x86/include/asm/uprobes.h |    8 +++++++-
 arch/x86/kernel/uprobes.c      |   38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 9f8210b..cca62c5 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -44,9 +44,15 @@ struct arch_uprobe {
        u16                             fixups;
        const struct uprobe_xol_ops     *ops;
 
+       union {
 #ifdef CONFIG_X86_64
-       unsigned long                   rip_rela_target_address;
+               unsigned long                   rip_rela_target_address;
 #endif
+               struct {
+                       s32     disp;
+                       u8      ilen;
+               }                               ttt;
+       };
 };
 
 struct arch_uprobe_task {
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index ef59ef9..1cdc379 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -461,6 +461,40 @@ static struct uprobe_xol_ops default_xol_ops = {
        .post_xol = default_post_xol_op,
 };
 
+static bool ttt_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+       regs->ip += auprobe->ttt.ilen + auprobe->ttt.disp;
+       return true;
+}
+
+static struct uprobe_xol_ops ttt_xol_ops = {
+       .emulate  = ttt_emulate_op,
+};
+
+/* Returns -ENOSYS if ttt_xol_ops doesn't handle this insn */
+static int ttt_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
+{
+
+       switch (OPCODE1(insn)) {
+       case 0xeb:      /* jmp 8 */
+       case 0xe9:      /* jmp 32 */
+               break;
+       default:
+               return -ENOSYS;
+       }
+
+       /* has the side-effect of processing the entire instruction */
+       insn_get_length(insn);
+       if (WARN_ON_ONCE(!insn_complete(insn)))
+               return -ENOEXEC;
+
+       auprobe->ttt.ilen = insn->length;
+       auprobe->ttt.disp = insn->immediate.value;
+
+       auprobe->ops = &ttt_xol_ops;
+       return 0;
+}
+
 /**
  * arch_uprobe_analyze_insn - instruction analysis including validity and 
fixups.
  * @mm: the probed address space.
@@ -478,6 +512,10 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, 
struct mm_struct *mm,
        if (ret)
                return ret;
 
+       ret = ttt_setup_xol_ops(auprobe, &insn);
+       if (ret != -ENOSYS)
+               return ret;
+
        /*
         * Figure out which fixups arch_uprobe_post_xol() will need to perform,
         * and annotate arch_uprobe->fixups accordingly. To start with, ->fixups
-- 
1.5.5.1

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