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
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acrn
auxdisplay
binderfs
bpf	work around gcc bugs with 'asm goto' with outputs	2024-02-09 15:57:48 -08:00
cgroup	samples/cgroup: add .gitignore file for generated samples	2024-01-24 11:52:40 -08:00
configfs
connector
coresight
fanotify
fprobe
ftrace	RISC-V Patches for the 6.8 Merge Window, Part 4	2024-01-20 11:06:04 -08:00
hid
hidraw
hw_breakpoint
kdb
kfifo
kmemleak
kobject
kprobes
landlock
livepatch
mei
nitro_enclaves
pfsm
pidfd
pktgen
qmi
rpmsg
rust
seccomp
timers
trace_events	samples: Replace strlcpy() with strscpy()	2023-11-30 12:20:53 -08:00
trace_printk
uhid
user_events
v4l	media updates for v6.8-rc1	2024-01-12 14:29:48 -08:00
vfio-mdev	eventfd: simplify eventfd_signal()	2023-11-28 14:08:38 +01:00
vfs
watch_queue
watchdog
Kconfig	samples: introduce new samples subdir for cgroup	2023-12-10 16:51:54 -08:00
Makefile	samples: introduce new samples subdir for cgroup	2023-12-10 16:51:54 -08:00