linux-kernel - Re: [PATCH v6 17/22] arm64: mm: Add page fault trace points

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Message-ID: <20250516150928.4Y7is6pg@linutronix.de>
Date: Fri, 16 May 2025 17:09:28 +0200
From: Nam Cao <namcao@...utronix.de>
To: Will Deacon <will@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
	Gabriele Monaco <gmonaco@...hat.com>,
	linux-trace-kernel@...r.kernel.org, linux-kernel@...r.kernel.org,
	john.ogness@...utronix.de,
	Catalin Marinas <catalin.marinas@....com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 17/22] arm64: mm: Add page fault trace points

On Fri, May 16, 2025 at 03:04:50PM +0100, Will Deacon wrote:
> On Wed, Apr 30, 2025 at 01:02:32PM +0200, Nam Cao wrote:
> > Add page fault trace points, which are useful to implement RV monitor which
> > watches page faults.
> > 
> > Signed-off-by: Nam Cao <namcao@...utronix.de>
> > ---
> > Cc: Catalin Marinas <catalin.marinas@....com>
> > Cc: Will Deacon <will@...nel.org>
> > Cc: linux-arm-kernel@...ts.infradead.org
> > ---
> >  arch/arm64/mm/fault.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> > index ef63651099a9..e3f096b0dffd 100644
> > --- a/arch/arm64/mm/fault.c
> > +++ b/arch/arm64/mm/fault.c
> > @@ -44,6 +44,9 @@
> >  #include <asm/tlbflush.h>
> >  #include <asm/traps.h>
> >  
> > +#define CREATE_TRACE_POINTS
> > +#include <trace/events/exceptions.h>
> > +
> >  struct fault_info {
> >  	int	(*fn)(unsigned long far, unsigned long esr,
> >  		      struct pt_regs *regs);
> > @@ -559,6 +562,11 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
> >  	if (kprobe_page_fault(regs, esr))
> >  		return 0;
> >  
> > +	if (user_mode(regs))
> > +		trace_page_fault_user(addr, regs, esr);
> > +	else
> > +		trace_page_fault_kernel(addr, regs, esr);
> 
> Why is this after kprobe_page_fault()?

This is me being incompetent, sorry about that. It is more logical to put
them at the beginning.

Best regards,
Nam