[PATCH v3 08/21] lib/crc: Switch ARM and arm64 to 'ksimd' scoped guard API

Ard Biesheuvel
2025-10-08T15:46:55Z

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/crc/arm/crc-t10dif.h | 16 +++++-----------
lib/crc/arm/crc32.h | 11 ++++-------
lib/crc/arm64/crc-t10dif.h | 16 +++++-----------
lib/crc/arm64/crc32.h | 16 ++++++----------
4 files changed, 20 insertions(+), 39 deletions(-)

diff --git a/lib/crc/arm/crc-t10dif.h b/lib/crc/arm/crc-t10dif.h
index 63441de5e3f1..7f02a767f675 100644
--- a/lib/crc/arm/crc-t10dif.h
+++ b/lib/crc/arm/crc-t10dif.h
@@ -5,7 +5,6 @@
* Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org>
*/

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

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
@@ -20,21 +19,16 @@ asmlinkage void crc_t10dif_pmull8(u16 init_crc, const u8 *buf, size_t len,
static inline u16 crc_t10dif_arch(u16 crc, const u8 *data, size_t length)
{
if (length >= CRC_T10DIF_PMULL_CHUNK_SIZE) {
- if (static_branch_likely(&have_pmull)) {
- if (likely(may_use_simd())) {
- kernel_neon_begin();
- crc = crc_t10dif_pmull64(crc, data, length);
- kernel_neon_end();
- return crc;
- }
+ if (static_branch_likely(&have_pmull) && likely(may_use_simd()) {
+ scoped_ksimd()
+ return crc_t10dif_pmull64(crc, data, length);
} else if (length > CRC_T10DIF_PMULL_CHUNK_SIZE &&
static_branch_likely(&have_neon) &&
likely(may_use_simd())) {
u8 buf[16] __aligned(16);

- kernel_neon_begin();
- crc_t10dif_pmull8(crc, data, length, buf);
- kernel_neon_end();
+ scoped_ksimd()
+ crc_t10dif_pmull8(crc, data, length, buf);

return crc_t10dif_generic(0, buf, sizeof(buf));
}
diff --git a/lib/crc/arm/crc32.h b/lib/crc/arm/crc32.h
index 7b76f52f6907..f33de6b22cd4 100644
--- a/lib/crc/arm/crc32.h
+++ b/lib/crc/arm/crc32.h
@@ -8,7 +8,6 @@
#include <linux/cpufeature.h>

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

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_crc32);
@@ -42,9 +41,8 @@ static inline u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)
len -= n;
}
n = round_down(len, 16);
- kernel_neon_begin();
- crc = crc32_pmull_le(p, n, crc);
- kernel_neon_end();
+ scoped_ksimd()
+ crc = crc32_pmull_le(p, n, crc);
p += n;
len -= n;
}
@@ -71,9 +69,8 @@ static inline u32 crc32c_arch(u32 crc, const u8 *p, size_t len)
len -= n;
}
n = round_down(len, 16);
- kernel_neon_begin();
- crc = crc32c_pmull_le(p, n, crc);
- kernel_neon_end();
+ scoped_ksimd()
+ crc = crc32c_pmull_le(p, n, crc);
p += n;
len -= n;
}
diff --git a/lib/crc/arm64/crc-t10dif.h b/lib/crc/arm64/crc-t10dif.h
index f88db2971805..0de03ab1aeab 100644
--- a/lib/crc/arm64/crc-t10dif.h
+++ b/lib/crc/arm64/crc-t10dif.h
@@ -7,7 +7,6 @@

#include <linux/cpufeature.h>

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

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_asimd);
@@ -22,21 +21,16 @@ asmlinkage u16 crc_t10dif_pmull_p64(u16 init_crc, const u8 *buf, size_t len);
static inline u16 crc_t10dif_arch(u16 crc, const u8 *data, size_t length)
{
if (length >= CRC_T10DIF_PMULL_CHUNK_SIZE) {
- if (static_branch_likely(&have_pmull)) {
- if (likely(may_use_simd())) {
- kernel_neon_begin();
- crc = crc_t10dif_pmull_p64(crc, data, length);
- kernel_neon_end();
- return crc;
- }
+ if (static_branch_likely(&have_pmull) && likely(may_use_simd())) {
+ scoped_ksimd()
+ return crc_t10dif_pmull_p64(crc, data, length);
} else if (length > CRC_T10DIF_PMULL_CHUNK_SIZE &&
static_branch_likely(&have_asimd) &&
likely(may_use_simd())) {
u8 buf[16];

- kernel_neon_begin();
- crc_t10dif_pmull_p8(crc, data, length, buf);
- kernel_neon_end();
+ scoped_ksimd()
+ crc_t10dif_pmull_p8(crc, data, length, buf);

return crc_t10dif_generic(0, buf, sizeof(buf));
}
diff --git a/lib/crc/arm64/crc32.h b/lib/crc/arm64/crc32.h
index 31e649cd40a2..1939a5dee477 100644
--- a/lib/crc/arm64/crc32.h
+++ b/lib/crc/arm64/crc32.h
@@ -2,7 +2,6 @@

#include <asm/alternative.h>
#include <asm/cpufeature.h>
-#include <asm/neon.h>
#include <asm/simd.h>

// The minimum input length to consider the 4-way interleaved code path
@@ -23,9 +22,8 @@ static inline u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)

if (len >= min_len && cpu_have_named_feature(PMULL) &&
likely(may_use_simd())) {
- kernel_neon_begin();
- crc = crc32_le_arm64_4way(crc, p, len);
- kernel_neon_end();
+ scoped_ksimd()
+ crc = crc32_le_arm64_4way(crc, p, len);

p += round_down(len, 64);
len %= 64;
@@ -44,9 +42,8 @@ static inline u32 crc32c_arch(u32 crc, const u8 *p, size_t len)

if (len >= min_len && cpu_have_named_feature(PMULL) &&
likely(may_use_simd())) {
- kernel_neon_begin();
- crc = crc32c_le_arm64_4way(crc, p, len);
- kernel_neon_end();
+ scoped_ksimd()
+ crc = crc32c_le_arm64_4way(crc, p, len);

p += round_down(len, 64);
len %= 64;
@@ -65,9 +62,8 @@ static inline u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)

if (len >= min_len && cpu_have_named_feature(PMULL) &&
likely(may_use_simd())) {
- kernel_neon_begin();
- crc = crc32_be_arm64_4way(crc, p, len);
- kernel_neon_end();
+ scoped_ksimd()
+ crc = crc32_be_arm64_4way(crc, p, len);

p += round_down(len, 64);
len %= 64;
--
2.51.0.710.ga91ca5db03-goog