[PATCH v3 09/21] lib/crypto: Switch ARM and arm64 to 'ksimd' scoped guard API

Ard Biesheuvel
2025-10-08T15:46:56Z

Before modifying the prototypes of kernel_neon_begin() and
kernel_neon_end() to accommodate kernel mode FP/SIMD state buffers
allocated on the stack, move arm64 to the new 'ksimd' scoped guard API,
which encapsulates the calls to those functions.

For symmetry, do the same for 32-bit ARM too.

Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
lib/crypto/arm/chacha.h | 6 ++----
lib/crypto/arm/poly1305.h | 6 ++----
lib/crypto/arm/sha1.h | 13 ++++++-------
lib/crypto/arm/sha256.h | 12 ++++++------
lib/crypto/arm/sha512.h | 6 ++----
lib/crypto/arm64/chacha.h | 11 ++++-------
lib/crypto/arm64/poly1305.h | 6 ++----
lib/crypto/arm64/sha1.h | 7 +++----
lib/crypto/arm64/sha256.h | 19 ++++++++-----------
lib/crypto/arm64/sha512.h | 8 ++++----
10 files changed, 39 insertions(+), 55 deletions(-)

diff --git a/lib/crypto/arm/chacha.h b/lib/crypto/arm/chacha.h
index 0cae30f8ee5d..b27ba00b3b23 100644
--- a/lib/crypto/arm/chacha.h
+++ b/lib/crypto/arm/chacha.h
@@ -12,7 +12,6 @@

#include <asm/cputype.h>
#include <asm/hwcap.h>
-#include <asm/neon.h>
#include <asm/simd.h>

asmlinkage void chacha_block_xor_neon(const struct chacha_state *state,
@@ -87,9 +86,8 @@ static void chacha_crypt_arch(struct chacha_state *state, u8 *dst,
do {
unsigned int todo = min_t(unsigned int, bytes, SZ_4K);

- kernel_neon_begin();
- chacha_doneon(state, dst, src, todo, nrounds);
- kernel_neon_end();
+ scoped_ksimd()
+ chacha_doneon(state, dst, src, todo, nrounds);

bytes -= todo;
src += todo;
diff --git a/lib/crypto/arm/poly1305.h b/lib/crypto/arm/poly1305.h
index 0021cf368307..0fe903d8de55 100644
--- a/lib/crypto/arm/poly1305.h
+++ b/lib/crypto/arm/poly1305.h
@@ -6,7 +6,6 @@
*/

#include <asm/hwcap.h>
-#include <asm/neon.h>
#include <asm/simd.h>
#include <linux/cpufeature.h>
#include <linux/jump_label.h>
@@ -32,9 +31,8 @@ static void poly1305_blocks(struct poly1305_block_state *state, const u8 *src,
do {
unsigned int todo = min_t(unsigned int, len, SZ_4K);

- kernel_neon_begin();
- poly1305_blocks_neon(state, src, todo, padbit);
- kernel_neon_end();
+ scoped_ksimd()
+ poly1305_blocks_neon(state, src, todo, padbit);

len -= todo;
src += todo;
diff --git a/lib/crypto/arm/sha1.h b/lib/crypto/arm/sha1.h
index 29f8bcad0447..3e2d8c7cab9f 100644
--- a/lib/crypto/arm/sha1.h
+++ b/lib/crypto/arm/sha1.h
@@ -4,7 +4,6 @@
*
* Copyright 2025 Google LLC
*/
-#include <asm/neon.h>
#include <asm/simd.h>

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
@@ -22,12 +21,12 @@ static void sha1_blocks(struct sha1_block_state *state,
{
if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
static_branch_likely(&have_neon) && likely(may_use_simd())) {
- kernel_neon_begin();
- if (static_branch_likely(&have_ce))
- sha1_ce_transform(state, data, nblocks);
- else
- sha1_transform_neon(state, data, nblocks);
- kernel_neon_end();
+ scoped_ksimd() {
+ if (static_branch_likely(&have_ce))
+ sha1_ce_transform(state, data, nblocks);
+ else
+ sha1_transform_neon(state, data, nblocks);
+ }
} else {
sha1_block_data_order(state, data, nblocks);
}
diff --git a/lib/crypto/arm/sha256.h b/lib/crypto/arm/sha256.h
index 7556457b3094..ae7e52dd6e3b 100644
--- a/lib/crypto/arm/sha256.h
+++ b/lib/crypto/arm/sha256.h
@@ -22,12 +22,12 @@ static void sha256_blocks(struct sha256_block_state *state,
{
if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
static_branch_likely(&have_neon) && likely(may_use_simd())) {
- kernel_neon_begin();
- if (static_branch_likely(&have_ce))
- sha256_ce_transform(state, data, nblocks);
- else
- sha256_block_data_order_neon(state, data, nblocks);
- kernel_neon_end();
+ scoped_ksimd() {
+ if (static_branch_likely(&have_ce))
+ sha256_ce_transform(state, data, nblocks);
+ else
+ sha256_block_data_order_neon(state, data, nblocks);
+ }
} else {
sha256_block_data_order(state, data, nblocks);
}
diff --git a/lib/crypto/arm/sha512.h b/lib/crypto/arm/sha512.h
index d1b485dd275d..8d3af965d2b3 100644
--- a/lib/crypto/arm/sha512.h
+++ b/lib/crypto/arm/sha512.h
@@ -18,10 +18,8 @@ static void sha512_blocks(struct sha512_block_state *state,
const u8 *data, size_t nblocks)
{
if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
- static_branch_likely(&have_neon) && likely(may_use_simd())) {
- kernel_neon_begin();
- sha512_block_data_order_neon(state, data, nblocks);
- kernel_neon_end();
+ scoped_ksimd()
+ sha512_block_data_order_neon(state, data, nblocks);
} else {
sha512_block_data_order(state, data, nblocks);
}
diff --git a/lib/crypto/arm64/chacha.h b/lib/crypto/arm64/chacha.h
index ba6c22d46086..ca8c6a8b0578 100644
--- a/lib/crypto/arm64/chacha.h
+++ b/lib/crypto/arm64/chacha.h
@@ -23,7 +23,6 @@
#include <linux/kernel.h>

#include <asm/hwcap.h>
-#include <asm/neon.h>
#include <asm/simd.h>

asmlinkage void chacha_block_xor_neon(const struct chacha_state *state,
@@ -65,9 +64,8 @@ static void hchacha_block_arch(const struct chacha_state *state,
if (!static_branch_likely(&have_neon) || !crypto_simd_usable()) {
hchacha_block_generic(state, out, nrounds);
} else {
- kernel_neon_begin();
- hchacha_block_neon(state, out, nrounds);
- kernel_neon_end();
+ scoped_ksimd()
+ hchacha_block_neon(state, out, nrounds);
}
}

@@ -81,9 +79,8 @@ static void chacha_crypt_arch(struct chacha_state *state, u8 *dst,
do {
unsigned int todo = min_t(unsigned int, bytes, SZ_4K);

- kernel_neon_begin();
- chacha_doneon(state, dst, src, todo, nrounds);
- kernel_neon_end();
+ scoped_ksimd()
+ chacha_doneon(state, dst, src, todo, nrounds);

bytes -= todo;
src += todo;
diff --git a/lib/crypto/arm64/poly1305.h b/lib/crypto/arm64/poly1305.h
index aed5921ccd9a..b77669767cd6 100644
--- a/lib/crypto/arm64/poly1305.h
+++ b/lib/crypto/arm64/poly1305.h
@@ -6,7 +6,6 @@
*/

#include <asm/hwcap.h>
-#include <asm/neon.h>
#include <asm/simd.h>
#include <linux/cpufeature.h>
#include <linux/jump_label.h>
@@ -31,9 +30,8 @@ static void poly1305_blocks(struct poly1305_block_state *state, const u8 *src,
do {
unsigned int todo = min_t(unsigned int, len, SZ_4K);

- kernel_neon_begin();
- poly1305_blocks_neon(state, src, todo, padbit);
- kernel_neon_end();
+ scoped_ksimd()
+ poly1305_blocks_neon(state, src, todo, padbit);

len -= todo;
src += todo;
diff --git a/lib/crypto/arm64/sha1.h b/lib/crypto/arm64/sha1.h
index aaef4ebfc5e3..bc7071f1be09 100644
--- a/lib/crypto/arm64/sha1.h
+++ b/lib/crypto/arm64/sha1.h
@@ -4,7 +4,6 @@
*
* Copyright 2025 Google LLC
*/
-#include <asm/neon.h>
#include <asm/simd.h>
#include <linux/cpufeature.h>

@@ -20,9 +19,9 @@ static void sha1_blocks(struct sha1_block_state *state,
do {
size_t rem;

- kernel_neon_begin();
- rem = __sha1_ce_transform(state, data, nblocks);
- kernel_neon_end();
+ scoped_ksimd()
+ rem = __sha1_ce_transform(state, data, nblocks);
+
data += (nblocks - rem) * SHA1_BLOCK_SIZE;
nblocks = rem;
} while (nblocks);
diff --git a/lib/crypto/arm64/sha256.h b/lib/crypto/arm64/sha256.h
index 80d06df27d3a..568dff0f276a 100644
--- a/lib/crypto/arm64/sha256.h
+++ b/lib/crypto/arm64/sha256.h
@@ -4,7 +4,6 @@
*
* Copyright 2025 Google LLC
*/
-#include <asm/neon.h>
#include <asm/simd.h>
#include <linux/cpufeature.h>

@@ -27,17 +26,16 @@ static void sha256_blocks(struct sha256_block_state *state,
do {
size_t rem;

- kernel_neon_begin();
- rem = __sha256_ce_transform(state,
- data, nblocks);
- kernel_neon_end();
+ scoped_ksimd()
+ rem = __sha256_ce_transform(state, data,
+ nblocks);
+
data += (nblocks - rem) * SHA256_BLOCK_SIZE;
nblocks = rem;
} while (nblocks);
} else {
- kernel_neon_begin();
- sha256_block_neon(state, data, nblocks);
- kernel_neon_end();
+ scoped_ksimd()
+ sha256_block_neon(state, data, nblocks);
}
} else {
sha256_block_data_order(state, data, nblocks);
@@ -66,9 +64,8 @@ static bool sha256_finup_2x_arch(const struct __sha256_ctx *ctx,
if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
static_branch_likely(&have_ce) && len >= SHA256_BLOCK_SIZE &&
len <= 65536 && likely(may_use_simd())) {
- kernel_neon_begin();
- sha256_ce_finup2x(ctx, data1, data2, len, out1, out2);
- kernel_neon_end();
+ scoped_ksimd()
+ sha256_ce_finup2x(ctx, data1, data2, len, out1, out2);
kmsan_unpoison_memory(out1, SHA256_DIGEST_SIZE);
kmsan_unpoison_memory(out2, SHA256_DIGEST_SIZE);
return true;
diff --git a/lib/crypto/arm64/sha512.h b/lib/crypto/arm64/sha512.h
index ddb0d256f73a..7eb7ef04d268 100644
--- a/lib/crypto/arm64/sha512.h
+++ b/lib/crypto/arm64/sha512.h
@@ -4,7 +4,7 @@
*
* Copyright 2025 Google LLC
*/
-#include <asm/neon.h>
+
#include <asm/simd.h>
#include <linux/cpufeature.h>

@@ -24,9 +24,9 @@ static void sha512_blocks(struct sha512_block_state *state,
do {
size_t rem;

- kernel_neon_begin();
- rem = __sha512_ce_transform(state, data, nblocks);
- kernel_neon_end();
+ scoped_ksimd()
+ rem = __sha512_ce_transform(state, data, nblocks);
+
data += (nblocks - rem) * SHA512_BLOCK_SIZE;
nblocks = rem;
} while (nblocks);
--
2.51.0.710.ga91ca5db03-goog