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
..
boot	sparc: Use $(kecho) to announce kernel images being ready	2023-12-04 13:28:06 +01:00
configs	arch/*/configs/*defconfig: Replace AUTOFS4_FS by AUTOFS_FS	2023-07-29 14:08:22 -07:00
crypto	crypto: sparc/crc32c - stop using the shash alignmask	2023-10-27 18:04:24 +08:00
include	work around gcc bugs with 'asm goto' with outputs	2024-02-09 15:57:48 -08:00
kernel	sparc: Use device_get_match_data()	2024-01-19 08:08:53 -06:00
lib	arch: turn off -Werror for architectures with known warnings	2023-12-10 17:21:33 -08:00
math-emu	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
mm	Quite a lot of kexec work this time around. Many singleton patches in	2024-01-09 11:46:20 -08:00
net	net: remove skb->vlan_present	2022-11-11 18:18:05 -08:00
power	…
prom	arch: turn off -Werror for architectures with known warnings	2023-12-10 17:21:33 -08:00
vdso	sparc: vdso: use $(addprefix ) instead of $(foreach )	2023-12-10 15:34:37 +09:00
video	arch/sparc: Add module license and description for fbdev helpers	2023-06-29 13:30:02 +02:00
Kbuild	kbuild: use more subdir- for visiting subdirectories while cleaning	2021-10-24 13:49:46 +09:00
Kconfig	mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER	2024-01-08 15:27:15 -08:00
Kconfig.debug	watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64	2023-06-19 16:25:29 -07:00
Makefile	kbuild: unify vdso_install rules	2023-10-28 21:09:02 +09:00