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Message-ID: <20241024034120.3814224-1-liaochang1@huawei.com>
Date: Thu, 24 Oct 2024 03:41:20 +0000
From: Liao Chang <liaochang1@...wei.com>
To: <mark.rutland@....com>, <catalin.marinas@....com>, <will@...nel.org>,
<oliver.upton@...ux.dev>, <kristina.martsenko@....com>, <ptosi@...gle.com>,
<liaochang1@...wei.com>
CC: <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] arm64: Return early when break handler is found on linked-list
The search for breakpoint handlers iterate through the entire
linked list. Given that all registered hook has a valid fn field, and no
registered hooks share the same mask and imm. This commit optimize the
efficiency slightly by returning early as a matching handler is found.
v2->v1:
Remove all WARN_ON(!hook->fn) in v1 as Will suggested.
Signed-off-by: Liao Chang <liaochang1@...wei.com>
---
arch/arm64/kernel/debug-monitors.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
index c60a4a90c6a5..58f047de3e1c 100644
--- a/arch/arm64/kernel/debug-monitors.c
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -303,7 +303,6 @@ static int call_break_hook(struct pt_regs *regs, unsigned long esr)
{
struct break_hook *hook;
struct list_head *list;
- int (*fn)(struct pt_regs *regs, unsigned long esr) = NULL;
list = user_mode(regs) ? &user_break_hook : &kernel_break_hook;
@@ -313,10 +312,10 @@ static int call_break_hook(struct pt_regs *regs, unsigned long esr)
*/
list_for_each_entry_rcu(hook, list, node) {
if ((esr_brk_comment(esr) & ~hook->mask) == hook->imm)
- fn = hook->fn;
+ return hook->fn(regs, esr);
}
- return fn ? fn(regs, esr) : DBG_HOOK_ERROR;
+ return DBG_HOOK_ERROR;
}
NOKPROBE_SYMBOL(call_break_hook);
--
2.34.1
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