# git rev-parse -q --verify 4356e9f841f7fbb945521cef3577ba394c65f3fc^{commit}
4356e9f841f7fbb945521cef3577ba394c65f3fc
already have revision, skipping fetch
# git checkout -q -f -B kisskb 4356e9f841f7fbb945521cef3577ba394c65f3fc
# git clean -qxdf
# < git log -1
# commit 4356e9f841f7fbb945521cef3577ba394c65f3fc
# Author: Linus Torvalds <torvalds@linux-foundation.org>
# Date:   Fri Feb 9 12:39:31 2024 -0800
# 
#     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
#     3f0116c3238a ("compiler/gcc4: Add quirk for 'asm goto' miscompilation
#     bug") and a9f180345f53 ("compiler/gcc4: Make quirk for
#     asm_volatile_goto() unconditional").
#     
#     Then, much later, we ended up removing the workaround in commit
#     43c249ea0b1e ("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>
# < /opt/cross/kisskb/korg/gcc-13.1.0-nolibc/sh4-linux/bin/sh4-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-13.1.0-nolibc/sh4-linux/bin/sh4-linux-ld --version
# < git log --format=%s --max-count=1 4356e9f841f7fbb945521cef3577ba394c65f3fc
# make -s -j 24 ARCH=sh O=/kisskb/build/linus_se7619_defconfig_sh4-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/sh4-linux/bin/sh4-linux-  se7619_defconfig
# < make -s -j 24 ARCH=sh O=/kisskb/build/linus_se7619_defconfig_sh4-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/sh4-linux/bin/sh4-linux-  help
# make -s -j 24 ARCH=sh O=/kisskb/build/linus_se7619_defconfig_sh4-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/sh4-linux/bin/sh4-linux-  olddefconfig
# make -s -j 24 ARCH=sh O=/kisskb/build/linus_se7619_defconfig_sh4-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/sh4-linux/bin/sh4-linux-  
  Generating include/generated/machtypes.h
<stdin>:1519:2: warning: #warning syscall clone3 not implemented [-Wcpp]
/kisskb/src/arch/sh/kernel/cpu/init.c:99:29: warning: no previous prototype for 'l2_cache_init' [-Wmissing-prototypes]
   99 | void __attribute__ ((weak)) l2_cache_init(void)
      |                             ^~~~~~~~~~~~~
/kisskb/src/arch/sh/mm/cache-sh2.c:85:13: warning: no previous prototype for 'sh2_cache_init' [-Wmissing-prototypes]
   85 | void __init sh2_cache_init(void)
      |             ^~~~~~~~~~~~~~
/kisskb/src/arch/sh/mm/nommu.c:76:13: warning: no previous prototype for 'kmap_coherent_init' [-Wmissing-prototypes]
   76 | void __init kmap_coherent_init(void)
      |             ^~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sh/mm/nommu.c:80:7: warning: no previous prototype for 'kmap_coherent' [-Wmissing-prototypes]
   80 | void *kmap_coherent(struct page *page, unsigned long addr)
      |       ^~~~~~~~~~~~~
/kisskb/src/arch/sh/mm/nommu.c:86:6: warning: no previous prototype for 'kunmap_coherent' [-Wmissing-prototypes]
   86 | void kunmap_coherent(void *kvaddr)
      |      ^~~~~~~~~~~~~~~
/kisskb/src/arch/sh/kernel/return_address.c:49:7: warning: no previous prototype for 'return_address' [-Wmissing-prototypes]
   49 | void *return_address(unsigned int depth)
      |       ^~~~~~~~~~~~~~
/kisskb/src/arch/sh/kernel/sys_sh.c:58:16: warning: no previous prototype for 'sys_cacheflush' [-Wmissing-prototypes]
   58 | asmlinkage int sys_cacheflush(unsigned long addr, unsigned long len, int op)
      |                ^~~~~~~~~~~~~~
/kisskb/src/arch/sh/kernel/traps_32.c:735:6: warning: no previous prototype for 'per_cpu_trap_init' [-Wmissing-prototypes]
  735 | void per_cpu_trap_init(void)
      |      ^~~~~~~~~~~~~~~~~
/kisskb/src/arch/sh/kernel/hw_breakpoint.c:135:5: warning: no previous prototype for 'arch_bp_generic_fields' [-Wmissing-prototypes]
  135 | int arch_bp_generic_fields(int sh_len, int sh_type,
      |     ^~~~~~~~~~~~~~~~~~~~~~
Completed OK
# rm -rf /kisskb/build/linus_se7619_defconfig_sh4-gcc13
# Build took: 0:00:50.888909