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arm64: Return early when break handler is found on linked-list

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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.

Signed-off-by: Liao Chang <liaochang1@huawei.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241024034120.3814224-1-liaochang1@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Liao Chang 2024-10-24 03:41:20 +00:00 committed by Catalin Marinas
parent f8192813dc
commit 9a0e3b92b0
1 changed files with 2 additions and 3 deletions
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5
arch/arm64/kernel/debug-monitors.c
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@ -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);