ich777/linux_media
1
0
Fork 0
mirror of https://github.com/tbsdtv/linux_media.git synced 2025-07-23 04:33:26 +02:00
Code Issues Packages Projects Releases Wiki Activity

crypto: crypto_xor - use helpers for unaligned accesses

Browse Source 
Dereferencing a misaligned pointer is undefined behavior in C, and may
result in codegen on architectures such as ARM that trigger alignments
traps and expensive fixups in software.

Instead, use the get_aligned()/put_aligned() accessors, which are cheap
or even completely free when CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y.

In the converse case, the prior alignment checks ensure that the casts
are safe, and so no unaligned accessors are necessary.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Ard Biesheuvel
2022-02-23 08:07:01 +01:00
committed by Herbert Xu
parent 4920a4a726
commit 7976c14925
2 changed files with 29 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
crypto/algapi.c
View File

@@ -1022,7 +1022,13 @@ void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
}
while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {
*(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;
if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
u64 l = get_unaligned((u64 *)src1) ^
get_unaligned((u64 *)src2);
put_unaligned(l, (u64 *)dst);
} else {
*(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;
}
dst += 8;
src1 += 8;
src2 += 8;
@@ -1030,7 +1036,13 @@ void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
}
while (len >= 4 && !(relalign & 3)) {
*(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
u32 l = get_unaligned((u32 *)src1) ^
get_unaligned((u32 *)src2);
put_unaligned(l, (u32 *)dst);
} else {
*(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
}
dst += 4;
src1 += 4;
src2 += 4;
@@ -1038,7 +1050,13 @@ void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
}
while (len >= 2 && !(relalign & 1)) {
*(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
u16 l = get_unaligned((u16 *)src1) ^
get_unaligned((u16 *)src2);
put_unaligned(l, (u16 *)dst);
} else {
*(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
}
dst += 2;
src1 += 2;
src2 += 2;