Re: [PATCH] compiler.h: Fix barrier_data() on clang

Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Andreas Schwab]

On Okt 14 2020, Arvind Sankar wrote:

> Commit
>   815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
>
> neglected to copy barrier_data() from compiler-gcc.h into
> compiler-clang.h. The definition in compiler-gcc.h was really to work
> around clang's more aggressive optimization, so this broke
> barrier_data() on clang, and consequently memzero_explicit() as well.
>
> For example, this results in at least the memzero_explicit() call in
> lib/crypto/sha256.c:sha256_transform() being optimized away by clang.
>
> Fix this by moving the definition of barrier_data() into compiler.h.
>
> Also move the gcc/clang definition of barrier() into compiler.h,
> __memory_barrier() is icc-specific (and barrier() is already defined
> using it in compiler-intel.h) and doesn't belong in compiler.h.
>
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
> Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")

This breaks build on riscv:

  CC [M]  drivers/net/ethernet/emulex/benet/be_main.o
In file included from ./include/vdso/processor.h:10,
                 from ./arch/riscv/include/asm/processor.h:11,
                 from ./include/linux/prefetch.h:15,
                 from drivers/net/ethernet/emulex/benet/be_main.c:14:
./arch/riscv/include/asm/vdso/processor.h: In function 'cpu_relax':
./arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier' [-Werror=implicit-function-declaration]
   14 |  barrier();
      |  ^~~~~~~
cc1: some warnings being treated as errors
make[5]: *** [scripts/Makefile.build:283: drivers/net/ethernet/emulex/benet/be_main.o] Error 1
make[4]: *** [scripts/Makefile.build:500: drivers/net/ethernet/emulex/benet] Error 2
make[3]: *** [scripts/Makefile.build:500: drivers/net/ethernet/emulex] Error 2
make[2]: *** [scripts/Makefile.build:500: drivers/net/ethernet] Error 2
make[1]: *** [scripts/Makefile.build:500: drivers/net] Error 2
make: *** [Makefile:1799: drivers] Error 2

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

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Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Randy Dunlap]

On 11/16/20 9:47 AM, Andreas Schwab wrote:
> On Okt 14 2020, Arvind Sankar wrote:
> 
>> Commit
>>   815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
>>
>> neglected to copy barrier_data() from compiler-gcc.h into
>> compiler-clang.h. The definition in compiler-gcc.h was really to work
>> around clang's more aggressive optimization, so this broke
>> barrier_data() on clang, and consequently memzero_explicit() as well.
>>
>> For example, this results in at least the memzero_explicit() call in
>> lib/crypto/sha256.c:sha256_transform() being optimized away by clang.
>>
>> Fix this by moving the definition of barrier_data() into compiler.h.
>>
>> Also move the gcc/clang definition of barrier() into compiler.h,
>> __memory_barrier() is icc-specific (and barrier() is already defined
>> using it in compiler-intel.h) and doesn't belong in compiler.h.
>>
>> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
>> Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
> 
> This breaks build on riscv:
> 
>   CC [M]  drivers/net/ethernet/emulex/benet/be_main.o
> In file included from ./include/vdso/processor.h:10,
>                  from ./arch/riscv/include/asm/processor.h:11,
>                  from ./include/linux/prefetch.h:15,
>                  from drivers/net/ethernet/emulex/benet/be_main.c:14:
> ./arch/riscv/include/asm/vdso/processor.h: In function 'cpu_relax':
> ./arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier' [-Werror=implicit-function-declaration]
>    14 |  barrier();
>       |  ^~~~~~~
> cc1: some warnings being treated as errors
> make[5]: *** [scripts/Makefile.build:283: drivers/net/ethernet/emulex/benet/be_main.o] Error 1
> make[4]: *** [scripts/Makefile.build:500: drivers/net/ethernet/emulex/benet] Error 2
> make[3]: *** [scripts/Makefile.build:500: drivers/net/ethernet/emulex] Error 2
> make[2]: *** [scripts/Makefile.build:500: drivers/net/ethernet] Error 2
> make[1]: *** [scripts/Makefile.build:500: drivers/net] Error 2
> make: *** [Makefile:1799: drivers] Error 2

Hi,
What kernel version are you building?
This should be fixed in 5.10-rc4 by
commit 3347acc6fcd4ee71ad18a9ff9d9dac176b517329;
specifically this portion of it:

diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 798027bb89be..640f09479bdf 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -13,6 +13,7 @@
 
 #ifndef __ASSEMBLY__
 
+#include <linux/compiler.h>
 #include <asm/rwonce.h>
 
 #ifndef nop



-- 
~Randy


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Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Andreas Schwab]

On Nov 16 2020, Randy Dunlap wrote:

> What kernel version are you building?

5.10-rc4

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

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Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Randy Dunlap]

On 11/16/20 10:30 AM, Andreas Schwab wrote:
> On Nov 16 2020, Randy Dunlap wrote:
> 
>> What kernel version are you building?
> 
> 5.10-rc4
> 
> Andreas.

OK, thanks.

My build machine is slow, but I have a patch that I am testing:

---
From: Randy Dunlap <rdunlap@infradead.org>

riscv's <vdso/processor.h> uses barrier() so it should
#include <asm/barrier.h> to prevent build errors.

Reported-by: Andreas Schwab <schwab@linux-m68k.org>
---
  arch/riscv/include/asm/vdso/processor.h |    2 ++
  1 file changed, 2 insertions(+)

--- lnx-510-rc4.orig/arch/riscv/include/asm/vdso/processor.h
+++ lnx-510-rc4/arch/riscv/include/asm/vdso/processor.h
@@ -4,6 +4,8 @@

  #ifndef __ASSEMBLY__

+#include <asm/barrier.h>
+
  static inline void cpu_relax(void)
  {
  #ifdef __riscv_muldiv






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Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Nick Desaulniers]

On Mon, Nov 16, 2020 at 9:47 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Okt 14 2020, Arvind Sankar wrote:
>
> > Commit
> >   815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
> >
> > neglected to copy barrier_data() from compiler-gcc.h into
> > compiler-clang.h. The definition in compiler-gcc.h was really to work
> > around clang's more aggressive optimization, so this broke
> > barrier_data() on clang, and consequently memzero_explicit() as well.
> >
> > For example, this results in at least the memzero_explicit() call in
> > lib/crypto/sha256.c:sha256_transform() being optimized away by clang.
> >
> > Fix this by moving the definition of barrier_data() into compiler.h.
> >
> > Also move the gcc/clang definition of barrier() into compiler.h,
> > __memory_barrier() is icc-specific (and barrier() is already defined
> > using it in compiler-intel.h) and doesn't belong in compiler.h.
> >
> > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
> > Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
>
> This breaks build on riscv:
>
>   CC [M]  drivers/net/ethernet/emulex/benet/be_main.o
> In file included from ./include/vdso/processor.h:10,
>                  from ./arch/riscv/include/asm/processor.h:11,
>                  from ./include/linux/prefetch.h:15,
>                  from drivers/net/ethernet/emulex/benet/be_main.c:14:
> ./arch/riscv/include/asm/vdso/processor.h: In function 'cpu_relax':
> ./arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier' [-Werror=implicit-function-declaration]
>    14 |  barrier();
>       |  ^~~~~~~
> cc1: some warnings being treated as errors
> make[5]: *** [scripts/Makefile.build:283: drivers/net/ethernet/emulex/benet/be_main.o] Error 1
> make[4]: *** [scripts/Makefile.build:500: drivers/net/ethernet/emulex/benet] Error 2
> make[3]: *** [scripts/Makefile.build:500: drivers/net/ethernet/emulex] Error 2
> make[2]: *** [scripts/Makefile.build:500: drivers/net/ethernet] Error 2
> make[1]: *** [scripts/Makefile.build:500: drivers/net] Error 2
> make: *** [Makefile:1799: drivers] Error 2
>
> Andreas.

A lot of VDSO's reset KBUILD_CFLAGS or use a new variable for their
compiler flags.  As such, they're missing `-include` command line flag
that injects include/linux/compiler_types.h, which `#includes`
numerous other headers if `__KERNEL__` is defined (`-D__KERNEL__`).
So the RISCV VDSO Makefile might need to `-include
$(srctree)/include/linux/compiler_types.h -D__KERNEL__`, or `#include
<linux/compiler.h>"` directly in
arch/riscv/include/asm/vdso/processor.h.
-- 
Thanks,
~Nick Desaulniers

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Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Andreas Schwab]

On Nov 16 2020, Nick Desaulniers wrote:

> A lot of VDSO's reset KBUILD_CFLAGS or use a new variable for their
> compiler flags.  As such, they're missing `-include` command line flag
> that injects include/linux/compiler_types.h,

It's not missing here.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

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Re: [PATCH] compiler.h: Fix barrier_data() on clang

[Randy Dunlap]

On 11/16/20 11:28 AM, Randy Dunlap wrote:
> On 11/16/20 10:30 AM, Andreas Schwab wrote:
>> On Nov 16 2020, Randy Dunlap wrote:
>>
>>> What kernel version are you building?
>>
>> 5.10-rc4
>>
>> Andreas.
> 
> OK, thanks.
> 
> My build machine is slow, but I have a patch that I am testing:
> 
> ---
> From: Randy Dunlap <rdunlap@infradead.org>
> 
> riscv's <vdso/processor.h> uses barrier() so it should
> #include <asm/barrier.h> to prevent build errors.
> 
> Reported-by: Andreas Schwab <schwab@linux-m68k.org>
> ---
>  arch/riscv/include/asm/vdso/processor.h |    2 ++
>  1 file changed, 2 insertions(+)
> 
> --- lnx-510-rc4.orig/arch/riscv/include/asm/vdso/processor.h
> +++ lnx-510-rc4/arch/riscv/include/asm/vdso/processor.h
> @@ -4,6 +4,8 @@
> 
>  #ifndef __ASSEMBLY__
> 
> +#include <asm/barrier.h>
> +
>  static inline void cpu_relax(void)
>  {
>  #ifdef __riscv_muldiv


This fixes the emulex/benet/ driver build.
I'm still building allmodconfig to see if there are any
other issues.

-- 
~Randy


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