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crypto: x86/sha1 - fix stack alignment of AVX2 variant 

The AVX2 implementation might waste up to a page of stack memory because
of a wrong alignment calculation. This will, in the worst case, increase
the stack usage of sha1_transform_avx2() alone to 5.4 kB -- way to big
for a kernel function. Even worse, it might also allocate *less* bytes
than needed if the stack pointer is already aligned bacause in that case
the 'sub %rbx, %rsp' is effectively moving the stack pointer upwards,
not downwards.

Fix those issues by changing and simplifying the alignment calculation
to use a 32 byte alignment, the alignment really needed.

Cc: Chandramouli Narayanan <mouli@linux.intel.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Reviewed-by: H. Peter Anvin <hpa@linux.intel.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Mathias Krause 2014-03-24 17:10:38 +01:00 committed by Herbert Xu
parent 6ca5afb8c2
commit 6c8c17cc7a
1 changed files with 2 additions and 5 deletions
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7
arch/x86/crypto/sha1_avx2_x86_64_asm.S
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@ -636,9 +636,7 @@ _loop3:
/* Align stack */
mov %rsp, %rbx
and $(0x1000-1), %rbx
sub $(8+32), %rbx
sub %rbx, %rsp
and $~(0x20-1), %rsp
push %rbx
sub $RESERVE_STACK, %rsp
@ -665,8 +663,7 @@ _loop3:
avx2_zeroupper
add $RESERVE_STACK, %rsp
pop %rbx
add %rbx, %rsp
pop %rsp
pop %r15
pop %r14