linux-kernel - [PATCH] csky: kprobe: fix unreachable code in simulate

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Date:   Mon, 11 Jan 2021 06:25:17 -0800
From:   menglong8.dong@...il.com
To:     guoren@...nel.org
Cc:     dong.menglong@....com.cn, linux-csky@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] csky: kprobe: fix unreachable code in simulate_blz32

From: Menglong Dong <dong.menglong@....com.cn>

The type of 'val' is 'unsigned long' in simulate_blz32, so 'val < 0'
can't be true.

When 'csky_insn_reg_get_val' fails, 'false' will be returned. We
can directly use its return value here.

Fixes: 33e53ae1ce41 ("csky: Add kprobes supported")
Signed-off-by: Menglong Dong <dong.menglong@....com.cn>
---
 arch/csky/kernel/probes/simulate-insn.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/csky/kernel/probes/simulate-insn.c b/arch/csky/kernel/probes/simulate-insn.c
index 4e464fed52ec..b09ddcbcfa18 100644
--- a/arch/csky/kernel/probes/simulate-insn.c
+++ b/arch/csky/kernel/probes/simulate-insn.c
@@ -346,9 +346,7 @@ simulate_blz32(u32 opcode, long addr, struct pt_regs *regs)
 	unsigned long tmp = opcode & 0x1f;
 	unsigned long val;
 
-	csky_insn_reg_get_val(regs, tmp, &val);
-
-	if (val < 0) {
+	if (!csky_insn_reg_get_val(regs, tmp, &val)) {
 		instruction_pointer_set(regs,
 			addr + sign_extend32((opcode & 0xffff0000) >> 15, 15));
 	} else
-- 
2.17.1