powerpc/kprobes: Remove redundant code

At the time being we have something like

	if (something) {
		p = get();
		if (p) {
			if (something_wrong)
				goto out;
			...
			return;
		} else if (a != b) {
			if (some_error)
				goto out;
			...
		}
		goto out;
	}
	p = get();
	if (!p) {
		if (a != b) {
			if (some_error)
				goto out;
			...
		}
		goto out;
	}

This is similar to

	p = get();
	if (!p) {
		if (a != b) {
			if (some_error)
				goto out;
			...
		}
		goto out;
	}
	if (something) {
		if (something_wrong)
			goto out;
		...
		return;
	}

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Reflow the comment that was moved]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/07a17425743600460ce35fa9432d42487a825583.1582099499.git.christophe.leroy@c-s.fr

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 2d27ec4..3aaff33 100644 (file)
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -271,54 +271,6 @@ int kprobe_handler(struct pt_regs *regs)
        preempt_disable();
        kcb = get_kprobe_ctlblk();
 
-       /* Check we're not actually recursing */
-       if (kprobe_running()) {
-               p = get_kprobe(addr);
-               if (p) {
-                       kprobe_opcode_t insn = *p->ainsn.insn;
-                       if (kcb->kprobe_status == KPROBE_HIT_SS &&
-                                       is_trap(insn)) {
-                               /* Turn off 'trace' bits */
-                               regs->msr &= ~MSR_SINGLESTEP;
-                               regs->msr |= kcb->kprobe_saved_msr;
-                               goto no_kprobe;
-                       }
-                       /* We have reentered the kprobe_handler(), since
-                        * another probe was hit while within the handler.
-                        * We here save the original kprobes variables and
-                        * just single step on the instruction of the new probe
-                        * without calling any user handlers.
-                        */
-                       save_previous_kprobe(kcb);
-                       set_current_kprobe(p, regs, kcb);
-                       kprobes_inc_nmissed_count(p);
-                       kcb->kprobe_status = KPROBE_REENTER;
-                       if (p->ainsn.boostable >= 0) {
-                               ret = try_to_emulate(p, regs);
-
-                               if (ret > 0) {
-                                       restore_previous_kprobe(kcb);
-                                       preempt_enable_no_resched();
-                                       return 1;
-                               }
-                       }
-                       prepare_singlestep(p, regs);
-                       return 1;
-               } else if (*addr != BREAKPOINT_INSTRUCTION) {
-                       /* If trap variant, then it belongs not to us */
-                       kprobe_opcode_t cur_insn = *addr;
-
-                       if (is_trap(cur_insn))
-                               goto no_kprobe;
-                       /* The breakpoint instruction was removed by
-                        * another cpu right after we hit, no further
-                        * handling of this interrupt is appropriate
-                        */
-                       ret = 1;
-               }
-               goto no_kprobe;
-       }
-
        p = get_kprobe(addr);
        if (!p) {
                if (*addr != BREAKPOINT_INSTRUCTION) {
@@ -343,6 +295,39 @@ int kprobe_handler(struct pt_regs *regs)
                goto no_kprobe;
        }
 
+       /* Check we're not actually recursing */
+       if (kprobe_running()) {
+               kprobe_opcode_t insn = *p->ainsn.insn;
+               if (kcb->kprobe_status == KPROBE_HIT_SS && is_trap(insn)) {
+                       /* Turn off 'trace' bits */
+                       regs->msr &= ~MSR_SINGLESTEP;
+                       regs->msr |= kcb->kprobe_saved_msr;
+                       goto no_kprobe;
+               }
+
+               /*
+                * We have reentered the kprobe_handler(), since another probe
+                * was hit while within the handler. We here save the original
+                * kprobes variables and just single step on the instruction of
+                * the new probe without calling any user handlers.
+                */
+               save_previous_kprobe(kcb);
+               set_current_kprobe(p, regs, kcb);
+               kprobes_inc_nmissed_count(p);
+               kcb->kprobe_status = KPROBE_REENTER;
+               if (p->ainsn.boostable >= 0) {
+                       ret = try_to_emulate(p, regs);
+
+                       if (ret > 0) {
+                               restore_previous_kprobe(kcb);
+                               preempt_enable_no_resched();
+                               return 1;
+                       }
+               }
+               prepare_singlestep(p, regs);
+               return 1;
+       }
+
        kcb->kprobe_status = KPROBE_HIT_ACTIVE;
        set_current_kprobe(p, regs, kcb);
        if (p->pre_handler && p->pre_handler(p, regs)) {