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lib/crypto: aes: Drop 'volatile' from aes_sbox and aes_inv_sbox

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The volatile keyword is no longer necessary or useful on aes_sbox and
aes_inv_sbox, since the table prefetching is now done using a helper
function that casts to volatile itself and also includes an optimization
barrier.  Since it prevents some compiler optimizations, remove it.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260112192035.10427-36-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers
2026-01-12 11:20:33 -08:00
parent 953f2db0bf
commit fbfeca7404
1 changed files with 3 additions and 7 deletions
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10
lib/crypto/aes.c
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@@ -11,11 +11,7 @@
#include <linux/module.h>
#include <linux/unaligned.h>
/*
* Emit the sbox as volatile const to prevent the compiler from doing
* constant folding on sbox references involving fixed indexes.
*/
static volatile const u8 ____cacheline_aligned aes_sbox[] = {
static const u8 ____cacheline_aligned aes_sbox[] = {
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
@@ -50,7 +46,7 @@ static volatile const u8 ____cacheline_aligned aes_sbox[] = {
0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16,
};
static volatile const u8 ____cacheline_aligned aes_inv_sbox[] = {
static const u8 ____cacheline_aligned aes_inv_sbox[] = {
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38,
0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87,
@@ -430,7 +426,7 @@ static void __maybe_unused aes_decrypt_generic(const u32 inv_rndkeys[],
w[3] = w3;
} while (--n);
aes_prefetch((const void *)aes_inv_sbox, sizeof(aes_inv_sbox));
aes_prefetch(aes_inv_sbox, sizeof(aes_inv_sbox));
put_unaligned_le32(declast_quarterround(w, 0, *rkp++), &out[0]);
put_unaligned_le32(declast_quarterround(w, 1, *rkp++), &out[4]);
put_unaligned_le32(declast_quarterround(w, 2, *rkp++), &out[8]);