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lib/crypto: arm64/sha256: Remove obsolete chunking logic

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Since commit aefbab8e77 ("arm64: fpsimd: Preserve/restore kernel mode
NEON at context switch"), kernel-mode NEON sections have been
preemptible on arm64.  And since commit 7dadeaa6e8 ("sched: Further
restrict the preemption modes"), voluntary preemption is no longer
supported on arm64 either.  Therefore, there's no longer any need to
limit the length of kernel-mode NEON sections on arm64.

Simplify the SHA-256 code accordingly.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260401000548.133151-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers 2026-03-31 17:05:45 -07:00
commit fe1233c2eb
2 changed files with 13 additions and 30 deletions
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14
lib/crypto/arm64/sha256-ce.S
View file

@ -79,11 +79,11 @@
.endm
/*
* size_t __sha256_ce_transform(struct sha256_block_state *state,
* const u8 *data, size_t nblocks);
* void sha256_ce_transform(struct sha256_block_state *state,
* const u8 *data, size_t nblocks);
*/
.text
SYM_FUNC_START(__sha256_ce_transform)
SYM_FUNC_START(sha256_ce_transform)
load_round_constants x8
@ -127,17 +127,13 @@ CPU_LE( rev32 v19.16b, v19.16b )
add dgav.4s, dgav.4s, dg0v.4s
add dgbv.4s, dgbv.4s, dg1v.4s
/* return early if voluntary preemption is needed */
cond_yield 1f, x5, x6
/* handled all input blocks? */
cbnz x2, 0b
/* store new state */
1: st1 {dgav.4s, dgbv.4s}, [x0]
mov x0, x2
st1 {dgav.4s, dgbv.4s}, [x0]
ret
SYM_FUNC_END(__sha256_ce_transform)
SYM_FUNC_END(sha256_ce_transform)
.unreq dga
.unreq dgav

29
lib/crypto/arm64/sha256.h
View file

@ -14,26 +14,17 @@ asmlinkage void sha256_block_data_order(struct sha256_block_state *state,
const u8 *data, size_t nblocks);
asmlinkage void sha256_block_neon(struct sha256_block_state *state,
const u8 *data, size_t nblocks);
asmlinkage size_t __sha256_ce_transform(struct sha256_block_state *state,
const u8 *data, size_t nblocks);
asmlinkage void sha256_ce_transform(struct sha256_block_state *state,
const u8 *data, size_t nblocks);
static void sha256_blocks(struct sha256_block_state *state,
const u8 *data, size_t nblocks)
{
if (static_branch_likely(&have_neon) && likely(may_use_simd())) {
if (static_branch_likely(&have_ce)) {
do {
size_t rem;
scoped_ksimd()
rem = __sha256_ce_transform(state, data,
nblocks);
data += (nblocks - rem) * SHA256_BLOCK_SIZE;
nblocks = rem;
} while (nblocks);
} else {
scoped_ksimd()
scoped_ksimd() {
if (static_branch_likely(&have_ce))
sha256_ce_transform(state, data, nblocks);
else
sha256_block_neon(state, data, nblocks);
}
} else {
@ -55,13 +46,9 @@ static bool sha256_finup_2x_arch(const struct __sha256_ctx *ctx,
u8 out1[SHA256_DIGEST_SIZE],
u8 out2[SHA256_DIGEST_SIZE])
{
/*
* The assembly requires len >= SHA256_BLOCK_SIZE && len <= INT_MAX.
* Further limit len to 65536 to avoid spending too long with preemption
* disabled. (Of course, in practice len is nearly always 4096 anyway.)
*/
/* The assembly requires len >= SHA256_BLOCK_SIZE && len <= INT_MAX. */
if (static_branch_likely(&have_ce) && len >= SHA256_BLOCK_SIZE &&
len <= 65536 && likely(may_use_simd())) {
len <= INT_MAX && likely(may_use_simd())) {
scoped_ksimd()
sha256_ce_finup2x(ctx, data1, data2, len, out1, out2);
kmsan_unpoison_memory(out1, SHA256_DIGEST_SIZE);