uprobes/x86: Conditionalize the usage of handle_riprel_insn()

arch_uprobe_analyze_insn() calls handle_riprel_insn() at the start,
but only "0xff" and "default" cases need the UPROBE_FIX_RIP_ logic.
Move the callsite into "default" case and change the "0xff" case to
fall-through.

We are going to add the various hooks to handle the rip-relative
jmp/call instructions (and more), we need this change to enforce the
fact that the new code can not conflict with is_riprel_insn() logic
which, after this change, can only be used by default_xol_ops.

Note: arch_uprobe_abort_xol() still calls handle_riprel_post_xol()
directly. This is fine unless another _xol_ops we may add later will
need to reuse "UPROBE_FIX_RIP_AX|UPROBE_FIX_RIP_CX" bits in ->fixup.
In this case we can add uprobe_xol_ops->abort() hook, which (perhaps)
we will need anyway in the long term.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 13ad8a38c2d9b6cbb1eb0617a5f02f84b8890bfd..08cdb82815feb5dc935849a89ca922bb7f3f76ba 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -482,8 +482,6 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
         * and annotate arch_uprobe->fixups accordingly. To start with, ->fixups
         * is either zero or it reflects rip-related fixups.
         */
-       handle_riprel_insn(auprobe, &insn);
-
        switch (OPCODE1(&insn)) {
        case 0x9d:              /* popf */
                auprobe->fixups |= UPROBE_FIX_SETF;
@@ -512,9 +510,9 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
                case 4: case 5:                 /* jmp or ljmp, indirect */
                        fix_ip = false;
                }
-               break;
+               /* fall through */
        default:
-               break;
+               handle_riprel_insn(auprobe, &insn);
        }
 
        if (fix_ip)