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crypto: LLVMLinux: Add macro to remove use of VLAIS in crypto code

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Add a macro which replaces the use of a Variable Length Array In Struct (VLAIS)
with a C99 compliant equivalent. This macro instead allocates the appropriate
amount of memory using an char array.

The new code can be compiled with both gcc and clang.

struct shash_desc contains a flexible array member member ctx declared with
CRYPTO_MINALIGN_ATTR, so sizeof(struct shash_desc) aligns the beginning
of the array declared after struct shash_desc with long long.

No trailing padding is required because it is not a struct type that can
be used in an array.

The CRYPTO_MINALIGN_ATTR is required so that desc is aligned with long long
as would be the case for a struct containing a member with
CRYPTO_MINALIGN_ATTR.

If you want to get to the ctx at the end of the shash_desc as before you can do
so using shash_desc_ctx(shash)

Signed-off-by: Behan Webster <behanw@converseincode.com>
Reviewed-by: Mark Charlebois <charlebm@gmail.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michał Mirosław <mirqus@gmail.com>
This commit is contained in:
Behan Webster 2014-09-08 00:05:09 -05:00
parent 2d65a9f48f
commit a0a77af141
1 changed files with 5 additions and 0 deletions
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5
include/crypto/hash.h
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@ -58,6 +58,11 @@ struct shash_desc {
void *__ctx[] CRYPTO_MINALIGN_ATTR;
};
#define SHASH_DESC_ON_STACK(shash, ctx) \
char __##shash##_desc[sizeof(struct shash_desc) + \
crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \
struct shash_desc *shash = (struct shash_desc *)__##shash##_desc
struct shash_alg {
int (*init)(struct shash_desc *desc);
int (*update)(struct shash_desc *desc, const u8 *data,