Commit bec50077 authored by Arvind Sankar's avatar Arvind Sankar Committed by Ingo Molnar
Browse files

lib/string: Make memzero_explicit() inline instead of external 



With the use of the barrier implied by barrier_data(), there is no need
for memzero_explicit() to be extern. Making it inline saves the overhead
of a function call, and allows the code to be reused in arch/*/purgatory
without having to duplicate the implementation.

Tested-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarArvind Sankar <nivedita@alum.mit.edu>
Reviewed-by: default avatarHans de Goede <hdegoede@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephan Mueller <smueller@chronox.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-crypto@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Fixes: 906a4bb9 ("crypto: sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit")
Link: https://lkml.kernel.org/r/20191007220000.GA408752@rani.riverdale.lan


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent fbcfb8f0

include/linux/string.h

+20 −1
Original line number Diff line number Diff line
@@ -227,7 +227,26 @@ static inline bool strstarts(const char *str, const char *prefix) 
}



size_t memweight(const void *ptr, size_t bytes);

void memzero_explicit(void *s, size_t count);



/**

 * memzero_explicit - Fill a region of memory (e.g. sensitive

 *		      keying data) with 0s.

 * @s: Pointer to the start of the area.

 * @count: The size of the area.

 *

 * Note: usually using memset() is just fine (!), but in cases

 * where clearing out _local_ data at the end of a scope is

 * necessary, memzero_explicit() should be used instead in

 * order to prevent the compiler from optimising away zeroing.

 *

 * memzero_explicit() doesn't need an arch-specific version as

 * it just invokes the one of memset() implicitly.

 */

static inline void memzero_explicit(void *s, size_t count)

{

	memset(s, 0, count);

	barrier_data(s);

}



/**

 * kbasename - return the last part of a pathname.

lib/string.c

+0 −21
Original line number Diff line number Diff line
@@ -748,27 +748,6 @@ void *memset(void *s, int c, size_t count) 
EXPORT_SYMBOL(memset);

#endif



/**

 * memzero_explicit - Fill a region of memory (e.g. sensitive

 *		      keying data) with 0s.

 * @s: Pointer to the start of the area.

 * @count: The size of the area.

 *

 * Note: usually using memset() is just fine (!), but in cases

 * where clearing out _local_ data at the end of a scope is

 * necessary, memzero_explicit() should be used instead in

 * order to prevent the compiler from optimising away zeroing.

 *

 * memzero_explicit() doesn't need an arch-specific version as

 * it just invokes the one of memset() implicitly.

 */

void memzero_explicit(void *s, size_t count)

{

	memset(s, 0, count);

	barrier_data(s);

}

EXPORT_SYMBOL(memzero_explicit);



#ifndef __HAVE_ARCH_MEMSET16

/**

 * memset16() - Fill a memory area with a uint16_t

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