[PATCH 36/36] lib/crypto: aes: Drop 'volatile' from aes_sbox and aes_inv_sbox
From: Eric Biggers <ebiggers@kernel.org>
Date: 2026-01-05 05:15:14
Also in:
linux-arm-kernel, linux-crypto, linux-riscv, linux-s390, lkml, sparclinux
Subsystem:
crypto library, library code, the rest · Maintainers:
Eric Biggers, Jason A. Donenfeld, Ard Biesheuvel, Andrew Morton, Linus Torvalds
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. Signed-off-by: Eric Biggers <ebiggers@kernel.org> --- lib/crypto/aes.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/lib/crypto/aes.c b/lib/crypto/aes.c
index 98ade1758735..e85c905296f1 100644
--- a/lib/crypto/aes.c
+++ b/lib/crypto/aes.c@@ -9,15 +9,11 @@ #include <linux/crypto.h> #include <linux/export.h> #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, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
@@ -48,11 +44,11 @@ static volatile const u8 __cacheline_aligned aes_sbox[] = { 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 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, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb, 0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d,
@@ -428,11 +424,11 @@ static void __maybe_unused aes_decrypt_generic(const u32 inv_rndkeys[], w[1] = w1; w[2] = w2; 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]); put_unaligned_le32(declast_quarterround(w, 3, *rkp++), &out[12]); }
--
2.52.0