On Tue, Feb 18, 2025 at 8:23 PM Richard Biener <rguent...@suse.de> wrote: > > > > > Am 18.02.2025 um 20:07 schrieb Roman Kagan <rka...@amazon.de>: > > > > On Tue, Feb 18, 2025 at 07:17:24PM +0100, Uros Bizjak wrote: > >>> On Mon, Feb 17, 2025 at 6:19 PM Roman Kagan <rka...@amazon.de> wrote: > >>> > >>> On Thu, Jan 02, 2025 at 04:32:17PM +0100, Roman Kagan wrote: > >>>> When gcc is built for x86_64-linux-musl target, stack unwinding from > >>>> within signal handler stops at the innermost signal frame. The reason > >>>> for this behaviro is that the signal trampoline is not accompanied with > >>>> appropiate CFI directives, and the fallback path in libgcc to recognize > >>>> it by the code sequence is only enabled for glibc except 2.0. The > >>>> latter is motivated by the lack of sys/ucontext.h in that glibc version. > >>>> > >>>> Given that all relevant libc-s ship sys/ucontext.h for over a decade, > >>>> and that other arches aren't shy of unconditionally using it, follow > >>>> suit and remove the preprocessor condition, too. > >> > >> "Relevant libc"-s for x86 linux are LIBC_GLIBC, LIBC_UCLIBC, > >> LIBC_BIONIC and LIBC_MUSL. As far as glibc is concerned, the latest > >> glibc 2.0.x version was released in 1997 [1], so I guess we can remove > >> the condition for version 2.0. Based on your claim, the other > >> mentioned libcs also provide the required header for a long time. > > > > Ah, good point, for completeness I should've supplied evidence from > > their respective git repos, here you go: > > > > uclibc(-ng): > > libc/sysdeps/linux/i386/sys/ucontext.h > > > > commit 9cee42f10dbc5b33866ff137b926a74abd7c1a5b > > Author: Eric Andersen <ander...@codepoet.org> > > Date: Fri Mar 1 20:46:26 2002 +0000 > > > > Major rework of the include files to eliminate redundancy > > and to better support each arch. This is a really big patch... > > -Erik > > > > libc/sysdeps/linux/i386/sys/ucontext.h > > > > commit 1fef64b22811709b2e640d341237bce1c8081203 > > Author: Mike Frysinger <vap...@gentoo.org> > > Date: Tue Feb 15 01:27:10 2005 +0000 > > > > headers for x86_64 > > > > bionic: > > libc/include/sys/ucontext.h > > > > commit e61d106008f7d77fa1c0de43ac27311320225135 > > Author: Pavel Chupin <pavel.v.chu...@intel.com> > > Date: Mon Jan 27 17:56:43 2014 +0400 > > > > Add x86_64 ucontext.h for better compatibility > > > > As suggested here: https://android-review.googlesource.com/#/c/71267/ > > it may be used for x86_64 libunwind enabling. > > > > Change-Id: I21623261a48ea7099e030d33932556e294d226ff > > Signed-off-by: Pavel Chupin <pavel.v.chu...@intel.com> > > > > commit 677a07cb9a3f5964e9ead4d37b9f775d971c61e0 > > Author: Elliott Hughes <e...@google.com> > > Date: Wed Jan 29 16:46:00 2014 -0800 > > > > Add x86 <sys/ucontext.h>. > > > > Change-Id: I43e72604f7a932f134733b78094b577415a5edb7 > > > > musl: > > arch/i386/bits/signal.h > > arch/x86_64/bits/signal.h > > include/ucontext.h > > > > commit ad2fe25041622b6cf426b0f98af0e52c2c9727f6 > > Author: Rich Felker <dal...@aerifal.cx> > > Date: Fri Feb 18 22:03:03 2011 -0500 > > > > support the ugly and deprecated ucontext and sigcontext header > > stuff... > > > > only the structures, not the functions from ucontext.h, are supported > > at this point. the main goal of this commit is to make modern gcc > > with > > dwarf2 unwinding build without errors. > > > > honestly, it probably doesn't matter how we define these as long as > > they have members with the right names to prevent errors while > > compiling libgcc. the only time they will be used is for propagating > > exceptions across signal-handler boundaries, which invokes undefined > > behavior anyway. but as-is, they're probably correct and may be > > useful > > to various low-level applications dealing with virtualization, jit > > code generation, and so on... > > > >> I have no objection to the patch, but I think that this patch is a bit > >> late for gcc-15 and should be committed early in the gcc-16 > >> development cycle. But let's hear release managers (CC'd). > > It’s fine for 15, or rather I’m leaving it for you to decide.
OK, based on the above research, I'll commit it to gcc-15. Thanks, Uros.
