# 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-11.3.0-nolibc/sparc64-linux/bin/sparc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-11.3.0-nolibc/sparc64-linux/bin/sparc64-linux-ld --version
# < git log --format=%s --max-count=1 4356e9f841f7fbb945521cef3577ba394c65f3fc
# make -s -j 160 ARCH=sparc64 O=/kisskb/build/linus_defconfig_sparc64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.3.0-nolibc/sparc64-linux/bin/sparc64-linux-  defconfig
# < make -s -j 160 ARCH=sparc64 O=/kisskb/build/linus_defconfig_sparc64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.3.0-nolibc/sparc64-linux/bin/sparc64-linux-  help
# make -s -j 160 ARCH=sparc64 O=/kisskb/build/linus_defconfig_sparc64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.3.0-nolibc/sparc64-linux/bin/sparc64-linux-  olddefconfig
# make -s -j 160 ARCH=sparc64 O=/kisskb/build/linus_defconfig_sparc64-gcc11 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-11.3.0-nolibc/sparc64-linux/bin/sparc64-linux-  
<stdin>:1519:2: warning: #warning syscall clone3 not implemented [-Wcpp]
/kisskb/src/arch/sparc/vdso/vclock_gettime.c:254:1: warning: no previous prototype for '__vdso_clock_gettime' [-Wmissing-prototypes]
  254 | __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
      | ^~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vclock_gettime.c:282:1: warning: no previous prototype for '__vdso_clock_gettime_stick' [-Wmissing-prototypes]
  282 | __vdso_clock_gettime_stick(clockid_t clock, struct __kernel_old_timespec *ts)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vclock_gettime.c:307:1: warning: no previous prototype for '__vdso_gettimeofday' [-Wmissing-prototypes]
  307 | __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
      | ^~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vclock_gettime.c:343:1: warning: no previous prototype for '__vdso_gettimeofday_stick' [-Wmissing-prototypes]
  343 | __vdso_gettimeofday_stick(struct __kernel_old_timeval *tv, struct timezone *tz)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /kisskb/src/arch/sparc/vdso/vdso32/vclock_gettime.c:22:
/kisskb/src/arch/sparc/vdso/vdso32/../vclock_gettime.c:254:1: warning: no previous prototype for '__vdso_clock_gettime' [-Wmissing-prototypes]
  254 | __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
      | ^~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vdso32/../vclock_gettime.c:282:1: warning: no previous prototype for '__vdso_clock_gettime_stick' [-Wmissing-prototypes]
  282 | __vdso_clock_gettime_stick(clockid_t clock, struct __kernel_old_timespec *ts)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vdso32/../vclock_gettime.c:307:1: warning: no previous prototype for '__vdso_gettimeofday' [-Wmissing-prototypes]
  307 | __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
      | ^~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vdso32/../vclock_gettime.c:343:1: warning: no previous prototype for '__vdso_gettimeofday_stick' [-Wmissing-prototypes]
  343 | __vdso_gettimeofday_stick(struct __kernel_old_timeval *tv, struct timezone *tz)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/vdso/vma.c:246:12: warning: no previous prototype for 'init_vdso_image' [-Wmissing-prototypes]
  246 | int __init init_vdso_image(const struct vdso_image *image,
      |            ^~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/prom/p1275.c:52:6: warning: no previous prototype for 'prom_cif_init' [-Wmissing-prototypes]
   52 | void prom_cif_init(void *cif_handler, void *cif_stack)
      |      ^~~~~~~~~~~~~
/kisskb/src/arch/sparc/prom/misc_64.c:165:5: warning: no previous prototype for 'prom_get_mmu_ihandle' [-Wmissing-prototypes]
  165 | int prom_get_mmu_ihandle(void)
      |     ^~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/traps_64.c:253:6: warning: no previous prototype for 'is_no_fault_exception' [-Wmissing-prototypes]
  253 | bool is_no_fault_exception(struct pt_regs *regs)
      |      ^~~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/mm/init_64.c:2644:6: warning: no previous prototype for 'vmemmap_free' [-Wmissing-prototypes]
 2644 | void vmemmap_free(unsigned long start, unsigned long end,
      |      ^~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/traps_64.c:2035:6: warning: no previous prototype for 'do_mcd_err' [-Wmissing-prototypes]
 2035 | void do_mcd_err(struct pt_regs *regs, struct sun4v_error_entry ent)
      |      ^~~~~~~~~~
/kisskb/src/arch/sparc/kernel/traps_64.c:2153:6: warning: no previous prototype for 'sun4v_nonresum_error_user_handled' [-Wmissing-prototypes]
 2153 | bool sun4v_nonresum_error_user_handled(struct pt_regs *regs,
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/setup_64.c:602:13: warning: no previous prototype for 'alloc_irqstack_bootmem' [-Wmissing-prototypes]
  602 | void __init alloc_irqstack_bootmem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/time_64.c:880:20: warning: no previous prototype for 'sched_clock' [-Wmissing-prototypes]
  880 | unsigned long long sched_clock(void)
      |                    ^~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/adi_64.c:124:21: warning: no previous prototype for 'find_tag_store' [-Wmissing-prototypes]
  124 | tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
      |                     ^~~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/adi_64.c:156:21: warning: no previous prototype for 'alloc_tag_store' [-Wmissing-prototypes]
  156 | tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
      |                     ^~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/adi_64.c:299:6: warning: no previous prototype for 'del_tag_store' [-Wmissing-prototypes]
  299 | void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
      |      ^~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/pci_sun4v.c:259:15: warning: no previous prototype for 'dma_4v_iotsb_bind' [-Wmissing-prototypes]
  259 | unsigned long dma_4v_iotsb_bind(unsigned long devhandle,
      |               ^~~~~~~~~~~~~~~~~
/kisskb/src/arch/sparc/kernel/uprobes.c:237:17: warning: no previous prototype for 'uprobe_trap' [-Wmissing-prototypes]
  237 | asmlinkage void uprobe_trap(struct pt_regs *regs,
      |                 ^~~~~~~~~~~
WARNING: modpost: EXPORT symbol "_mcount" [vmlinux] version generation failed, symbol will not be versioned.
Is "_mcount" prototyped in <asm/asm-prototypes.h>?
Completed OK
# rm -rf /kisskb/build/linus_defconfig_sparc64-gcc11
# Build took: 0:01:22.938794