Re: [PATCH v17 07/16] tracing: Add ftrace_fill_perf_regs() for perf event

[Google]

On Mon, 21 Oct 2024 18:01:21 +0100
Will Deacon <will@xxxxxxxxxx> wrote:

> On Wed, Oct 16, 2024 at 09:59:12AM +0900, Masami Hiramatsu (Google) wrote:
> > From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> > 
> > Add ftrace_fill_perf_regs() which should be compatible with the
> > perf_fetch_caller_regs(). In other words, the pt_regs returned from the
> > ftrace_fill_perf_regs() must satisfy 'user_mode(regs) == false' and can be
> > used for stack tracing.
> > 
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Cc: Will Deacon <will@xxxxxxxxxx>
> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> > Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> > Cc: Naveen N Rao <naveen@xxxxxxxxxx>
> > Cc: Madhavan Srinivasan <maddy@xxxxxxxxxxxxx>
> > Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
> > Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
> > Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
> > Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
> > Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: Borislav Petkov <bp@xxxxxxxxx>
> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> > 
> > ---
> >   Changes in v16:
> >    - Fix s390 to clear psw.mask according to Heiko's suggestion.
> > ---
> >  arch/arm64/include/asm/ftrace.h   |    7 +++++++
> >  arch/powerpc/include/asm/ftrace.h |    7 +++++++
> >  arch/s390/include/asm/ftrace.h    |    6 ++++++
> >  arch/x86/include/asm/ftrace.h     |    7 +++++++
> >  include/linux/ftrace.h            |   31 +++++++++++++++++++++++++++++++
> >  5 files changed, 58 insertions(+)
> > 
> > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
> > index d344c69eb01e..6493a575664f 100644
> > --- a/arch/arm64/include/asm/ftrace.h
> > +++ b/arch/arm64/include/asm/ftrace.h
> > @@ -146,6 +146,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
> >  	return regs;
> >  }
> >  
> > +#define arch_ftrace_fill_perf_regs(fregs, _regs) do {		\
> > +		(_regs)->pc = arch_ftrace_regs(fregs)->pc;			\
> > +		(_regs)->regs[29] = arch_ftrace_regs(fregs)->fp;		\
> > +		(_regs)->sp = arch_ftrace_regs(fregs)->sp;			\
> > +		(_regs)->pstate = PSR_MODE_EL1h;		\
> > +	} while (0)
> 
> arm64 bit looks correct to me:
> 
> Acked-by: Will Deacon <will@xxxxxxxxxx>

Thank you!

> 
> Will


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>