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ubifs: work around high stack usage with clang

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Building this file with clang can result in large stack usage as seen from
this warning:

fs/ubifs/auth.c:78:5: error: stack frame size of 1152 bytes in function 'ubifs_prepare_auth_node'

The problem is that inlining ubifs_hash_calc_hmac() leads to
two SHASH_DESC_ON_STACK() blocks in the same function, and clang
for some reason does not reuse the stack space as it should.

Putting the first declaration into a separate basic block avoids
this problem and reduces the stack allocation to 640 bytes.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Arnd Bergmann 2019-03-24 20:44:51 +01:00 committed by Richard Weinberger
parent fb9a5a3edb
commit f4844b35d6
1 changed files with 10 additions and 7 deletions
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17
fs/ubifs/auth.c
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@ -78,7 +78,6 @@ static int ubifs_hash_calc_hmac(const struct ubifs_info *c, const u8 *hash,
int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,
struct shash_desc *inhash)
{
SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);
struct ubifs_auth_node *auth = node;
u8 *hash;
int err;
@ -87,13 +86,17 @@ int ubifs_prepare_auth_node(struct ubifs_info *c, void *node,
if (!hash)
return -ENOMEM;
hash_desc->tfm = c->hash_tfm;
hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
ubifs_shash_copy_state(c, inhash, hash_desc);
{
SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);
err = crypto_shash_final(hash_desc, hash);
if (err)
goto out;
hash_desc->tfm = c->hash_tfm;
hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
ubifs_shash_copy_state(c, inhash, hash_desc);
err = crypto_shash_final(hash_desc, hash);
if (err)
goto out;
}
err = ubifs_hash_calc_hmac(c, hash, auth->hmac);
if (err)