[PATCH 1/1] ARM: hw_breakpoint: Do not directly check the event's overflow_handler hook

[Will Deacon]

On Thu, Feb 18, 2021 at 10:03:22AM +0800, Leizhen (ThunderTown) wrote:
> 
> 
> On 2021/2/12 18:02, Will Deacon wrote:
> > On Sun, Feb 07, 2021 at 06:59:34PM +0800, Zhen Lei wrote:
> >> The commit 1879445dfa7b ("perf/core: Set event's default
> >> ::overflow_handler()") set a default event->overflow_handler in
> >> perf_event_alloc(), and replace the check event->overflow_handler with
> >> is_default_overflow_handler(), but one is missing.
> >>
> >> Currently, the bp->overflow_handler can not be NULL. As a result,
> >> enable_single_step() is always not invoked.
> >>
> >> Fixes: 1879445dfa7b ("perf/core: Set event's default ::overflow_handler()")
> >> Signed-off-by: Zhen Lei <thunder.leizhen at huawei.com>
> >> Cc: Wang Nan <wangnan0 at huawei.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 08660ae9dcbce1c..b1423fb130ea4a0 100644
> >> --- a/arch/arm/kernel/hw_breakpoint.c
> >> +++ b/arch/arm/kernel/hw_breakpoint.c
> >> @@ -886,7 +886,7 @@ 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;
> >>  		}
> > 
> > Acked-by: Will Deacon <will at kernel.org>
> > 
> > Please can you put this into the patch tracker?
> > 
> > https://www.arm.linux.org.uk/developer/patches/
> 
> I've added it.
> 
> https://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=9064/1

Thanks, although you forgot to add my Ack!

Will