linux-kernel - [PATCH] ARM/hw_breakpoint: modify dead code for breakpoint

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Date:   Wed, 9 Oct 2019 17:27:00 +0800
From:   wangxu <wangxu72@...wei.com>
To:     <will@...nel.org>, <mark.rutland@....com>, <linux@...linux.org.uk>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] ARM/hw_breakpoint: modify dead code for breakpoint_handler()

From: Wang Xu <wangxu72@...wei.com>

In perf_event_alloc(), event->overflow_handler is initialized to a
non-null value, which makes enable_single_step(bp, addr) in
breakpoint_handler() never be executed.

As a matter of fact, the branch condition has been updated to
is_default_overflow_handler().

Signed-off-by: Wang Xu <wangxu72@...wei.com>
---
 arch/arm/kernel/hw_breakpoint.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index b0c195e..586a587 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -822,7 +822,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
 			info->trigger = addr;
 			pr_debug("breakpoint fired: address = 0x%x\n", addr);
 			perf_bp_event(bp, regs);
-			if (!bp->overflow_handler)
+			if (is_default_overflow_handler(bp))
 				enable_single_step(bp, addr);
 			goto unlock;
 		}
-- 
1.8.5.6