Re: [PATCH v3 08/19] unwind/x86: Enable CONFIG_HAVE_UNWIND_USER_FP

[Peter Zijlstra]

On Tue, Oct 29, 2024 at 09:31:10AM -0700, Josh Poimboeuf wrote:
> On Tue, Oct 29, 2024 at 02:13:03PM +0100, Peter Zijlstra wrote:

> > > +#define ARCH_INIT_USER_FP_FRAME							\
> > > +	.ra_off		= (s32)sizeof(long) * -1,				\
> > > +	.cfa_off	= (s32)sizeof(long) * 2,				\
> > > +	.fp_off		= (s32)sizeof(long) * -2,				\
> > > +	.use_fp		= true,
> > > +
> > > +#endif /* _ASM_X86_UNWIND_USER_H */
> > 
> > What about compat / 32bit userspace?
> 
> Sframe doesn't support 32-bit binaries at the moment.  Does anybody
> actually care?

Dunno, I think the only 32bit code I've recently ran is in selftests and
wine32 -- because Monkey Island rules :-)

> You're right this regresses existing perf behavior for the frame pointer
> case.  I'll try to fix that.

Thanks, this patch is the frame pointer unwinder, that really should do
32bit.