Linus Torvalds 4356e9f841 work around gcc bugs with 'asm goto' with outputs ... We've had issues with gcc and 'asm goto' before, and we created a 'asm_volatile_goto()' macro for that in the past: see commits 3f0116c323 ("compiler/gcc4: Add quirk for 'asm goto' miscompilation bug") and a9f180345f ("compiler/gcc4: Make quirk for asm_volatile_goto() unconditional"). Then, much later, we ended up removing the workaround in commit 43c249ea0b ("compiler-gcc.h: remove ancient workaround for gcc PR 58670") because we no longer supported building the kernel with the affected gcc versions, but we left the macro uses around. Now, Sean Christopherson reports a new version of a very similar problem, which is fixed by re-applying that ancient workaround. But the problem in question is limited to only the 'asm goto with outputs' cases, so instead of re-introducing the old workaround as-is, let's rename and limit the workaround to just that much less common case. It looks like there are at least two separate issues that all hit in this area: (a) some versions of gcc don't mark the asm goto as 'volatile' when it has outputs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420 which is easy to work around by just adding the 'volatile' by hand. (b) Internal compiler errors: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422 which are worked around by adding the extra empty 'asm' as a barrier, as in the original workaround. but the problem Sean sees may be a third thing since it involves bad code generation (not an ICE) even with the manually added 'volatile'. but the same old workaround works for this case, even if this feels a bit like voodoo programming and may only be hiding the issue. Reported-and-tested-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/ Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Uros Bizjak <ubizjak@gmail.com> Cc: Jakub Jelinek <jakub@redhat.com> Cc: Andrew Pinski <quic_apinski@quicinc.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2024-02-09 15:57:48 -08:00
..
appldata	S390: Remove now superfluous sentinel elem from ctl_table arrays	2023-10-10 15:22:02 -07:00
boot	s390/boot: always align vmalloc area on segment boundary	2023-11-22 14:07:28 +01:00
configs	vfs-6.8.netfs	2024-01-19 09:10:23 -08:00
crypto	s390 updates for 6.8 merge window	2024-01-10 18:18:20 -08:00
hypfs	hypfs: convert to new timestamp accessors	2023-10-18 13:26:15 +02:00
include	work around gcc bugs with 'asm goto' with outputs	2024-02-09 15:57:48 -08:00
kernel	s390 updates for 6.8 merge window part 2	2024-01-18 14:11:25 -08:00
kvm	pqap instruction missing cc fix	2024-01-26 12:57:12 -05:00
lib	s390/nmi: implement and use local_mcck_save() / local_mcck_restore()	2023-12-11 14:33:05 +01:00
mm	pqap instruction missing cc fix	2024-01-26 12:57:12 -05:00
net	s390/bpf: Fix gotol with large offsets	2024-01-04 11:35:40 -08:00
pci	s390/pci: fix max size calculation in zpci_memcpy_toio()	2024-01-11 18:22:58 +01:00
purgatory	s390 updates for 6.5 merge window part 2	2023-07-06 13:18:30 -07:00
tools	s390/als: add vector facility to z13 architecture level set	2023-12-11 14:33:07 +01:00
Kbuild	- An extensive rework of kexec and crash Kconfig from Eric DeVolder	2023-08-29 14:53:51 -07:00
Kconfig	s390/kexec: do not automatically select KEXEC option	2024-01-11 18:22:58 +01:00
Kconfig.debug	s390/Kconfig.debug: fix indentation	2022-06-01 12:03:15 +02:00
Makefile	kbuild: unify vdso_install rules	2023-10-28 21:09:02 +09:00