[PATCH 1/2] powerpc/kprobes: Remove redundant code

Christophe Leroy christophe.leroy at c-s.fr
Sat Feb 15 00:44:15 AEDT 2020


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

Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
---
 arch/powerpc/kernel/kprobes.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index f8b848aa65bd..7a925eb76ec0 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -276,8 +276,8 @@ int kprobe_handler(struct pt_regs *regs)
 	kcb = get_kprobe_ctlblk();
 
 	/* Check we're not actually recursing */
+	p = get_kprobe(addr);
 	if (kprobe_running()) {
-		p = get_kprobe(addr);
 		if (p) {
 			kprobe_opcode_t insn = *p->ainsn.insn;
 			if (kcb->kprobe_status == KPROBE_HIT_SS &&
@@ -308,22 +308,9 @@ int kprobe_handler(struct pt_regs *regs)
 			}
 			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) {
 			/*
-- 
2.25.0



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