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>

Pull percpu updates from Dennis Zhou:
 "Enable percpu page allocator for RISC-V.

  There are RISC-V configurations with sparse NUMA configurations and
  small vmalloc space causing dynamic percpu allocations to fail as the
  backing chunk stride is too far apart"

* tag 'percpu-for-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
  riscv: Enable pcpu page first chunk allocator
  mm: Introduce flush_cache_vmap_early()

Pull Xtensa updates from Max Filippov:

 - small cleanups in the xtensa PCI and asmmacro code

 - fix kernel build with FDPIC toolchain

* tag 'xtensa-20240117' of https://github.com/jcmvbkbc/linux-xtensa:
  xtensa: don't produce FDPIC output with fdpic toolchain
  xtensa: Use PCI_HEADER_TYPE_MFD instead of literal
  xtensa: replace <asm-generic/export.h> with <linux/export.h>
  xtensa: fix variants path in the Kconfig help

Common KASAN code might rely on the definitions of the shadow mapping
start, end, and size.  Define KASAN_SHADOW_END in addition to
KASAN_SHADOW_START and KASAN_SHADOW_SIZE.

Link: https://lkml.kernel.org/r/20231225151924.5422-1-andrey.konovalov@linux.dev
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312240755.MqsWuTno-lkp@intel.com/
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The pcpu setup when using the page allocator sets up a new vmalloc
mapping very early in the boot process, so early that it cannot use the
flush_cache_vmap() function which may depend on structures not yet
initialized (for example in riscv, we currently send an IPI to flush
other cpus TLB).

But on some architectures, we must call flush_cache_vmap(): for example,
in riscv, some uarchs can cache invalid TLB entries so we need to flush
the new established mapping to avoid taking an exception.

So fix this by introducing a new function flush_cache_vmap_early() which
is called right after setting the new page table entry and before
accessing this new mapping. This new function implements a local flush
tlb on riscv and is no-op for other architectures (same as today).

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Dennis Zhou <dennis@kernel.org>

Commit ddb5cdbafaaa ("kbuild: generate KSYMTAB entries by modpost")
deprecated <asm-generic/export.h>, which is now a wrapper of
<linux/export.h>.

Replace #include <asm-generic/export.h> with #include <linux/export.h>.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Message-Id: <20231126151222.1556761-1-masahiroy@kernel.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Add the prototype for check_tlb_sanity() to <asm/tlb.h> and use that
header to prevent a build warning:

arch/xtensa/mm/tlb.c:273:6: warning: no previous prototype for 'check_tlb_sanity' [-Wmissing-prototypes]
  273 | void check_tlb_sanity(void)

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20230920052139.10570-13-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Add the prototype for restore_dbreak() to <asm/hw_breakpoint.h> and use
that header in hw_breakpoint.c to prevent a build warning:

arch/xtensa/kernel/hw_breakpoint.c:263:6: warning: no previous prototype for 'restore_dbreak' [-Wmissing-prototypes]
  263 | void restore_dbreak(void)

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20230920052139.10570-12-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Use <asm/smp.h> to provide the prototype for secondary_start_kernel().
Use <linux/profile.h> to provide the prototype for
setup_profiling_timer().

arch/xtensa/kernel/smp.c:119:6: warning: no previous prototype for 'secondary_start_kernel' [-Wmissing-prototypes]
  119 | void secondary_start_kernel(void)
arch/xtensa/kernel/smp.c:461:5: warning: no previous prototype for 'setup_profiling_timer' [-Wmissing-prototypes]
  461 | int setup_profiling_timer(unsigned int multiplier)

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20230920052139.10570-11-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Add <asm/syscall.h> to satisfy the xtensa_rt_sigreturn() prototype
warning.
Add <asm/processor.h> to satisfy the do_notify_resume() prototype
warning.

arch/xtensa/kernel/signal.c:246:17: warning: no previous prototype for 'xtensa_rt_sigreturn' [-Wmissing-prototypes]
arch/xtensa/kernel/signal.c:525:6: warning: no previous prototype for 'do_notify_resume' [-Wmissing-prototypes]
  525 | void do_notify_resume(struct pt_regs *regs)

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20230920052139.10570-7-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>