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Message-ID: <20241029163110.xf5o2bvfbfcenlla@treble.attlocal.net>
Date: Tue, 29 Oct 2024 09:31:10 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
linux-kernel@...r.kernel.org, Indu Bhagat <indu.bhagat@...cle.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org, Mark Brown <broonie@...nel.org>,
linux-toolchains@...r.kernel.org, Jordan Rome <jordalgo@...a.com>,
Sam James <sam@...too.org>, linux-trace-kernel@...r.kerne.org,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Jens Remus <jremus@...ux.ibm.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Florian Weimer <fweimer@...hat.com>,
Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v3 08/19] unwind/x86: Enable CONFIG_HAVE_UNWIND_USER_FP
On Tue, Oct 29, 2024 at 02:13:03PM +0100, Peter Zijlstra wrote:
> On Mon, Oct 28, 2024 at 02:47:35PM -0700, Josh Poimboeuf wrote:
> > Use ARCH_INIT_USER_FP_FRAME to describe how frame pointers are unwound
> > on x86, and enable CONFIG_HAVE_UNWIND_USER_FP accordingly so the
> > unwind_user interfaces can be used.
> >
> > Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
> > ---
> > arch/x86/Kconfig | 1 +
> > arch/x86/include/asm/unwind_user.h | 11 +++++++++++
> > 2 files changed, 12 insertions(+)
> > create mode 100644 arch/x86/include/asm/unwind_user.h
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 0bdb7a394f59..f91098d6f535 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -289,6 +289,7 @@ config X86
> > select HAVE_SYSCALL_TRACEPOINTS
> > select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
> > select HAVE_UNSTABLE_SCHED_CLOCK
> > + select HAVE_UNWIND_USER_FP if X86_64
> > select HAVE_USER_RETURN_NOTIFIER
> > select HAVE_GENERIC_VDSO
> > select VDSO_GETRANDOM if X86_64
> > diff --git a/arch/x86/include/asm/unwind_user.h b/arch/x86/include/asm/unwind_user.h
> > new file mode 100644
> > index 000000000000..19df26a65132
> > --- /dev/null
> > +++ b/arch/x86/include/asm/unwind_user.h
> > @@ -0,0 +1,11 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _ASM_X86_UNWIND_USER_H
> > +#define _ASM_X86_UNWIND_USER_H
> > +
> > +#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?
You're right this regresses existing perf behavior for the frame pointer
case. I'll try to fix that.
--
Josh
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