@@ -3,6 +3,7 @@
#define _LINUX_CRC_T10DIF_H
#include <linux/types.h>
+#include <linux/static_call.h>
#define CRC_T10DIF_DIGEST_SIZE 2
#define CRC_T10DIF_BLOCK_SIZE 1
@@ -10,7 +11,23 @@
extern __u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer,
size_t len);
-extern __u16 crc_t10dif(unsigned char const *, size_t);
-extern __u16 crc_t10dif_update(__u16 crc, unsigned char const *, size_t);
+
+DECLARE_STATIC_CALL(crc_t10dif_arch, crc_t10dif_generic);
+
+static inline __u16 crc_t10dif_update(__u16 crc, unsigned char const *buffer,
+ size_t len)
+{
+ return static_call(crc_t10dif_arch)(crc, buffer, len);
+}
+
+static inline __u16 crc_t10dif(unsigned char const *buffer, size_t len)
+{
+ return crc_t10dif_update(0, buffer, len);
+}
+
+int crc_t10dif_register(__u16 (*)(__u16, const unsigned char *, size_t),
+ const char *name);
+
+int crc_t10dif_unregister(void);
#endif
@@ -18,6 +18,11 @@
#include <linux/static_key.h>
#include <linux/notifier.h>
+DEFINE_STATIC_CALL(crc_t10dif_arch, crc_t10dif_generic);
+EXPORT_STATIC_CALL(crc_t10dif_arch);
+
+static char const *crc_t10dif_arch_name;
+
/* Table generated using the following polynomium:
* x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
* gt: 0x8bb7
@@ -68,21 +73,32 @@ __u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len)
}
EXPORT_SYMBOL(crc_t10dif_generic);
-__u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
+int crc_t10dif_register(__u16 (*func)(__u16, const unsigned char *, size_t),
+ const char *name)
{
- return crc_t10dif_generic(crc, buffer, len);
+ if (!name || cmpxchg(&crc_t10dif_arch_name, NULL, name) != NULL)
+ return -EBUSY;
+
+ static_call_update(crc_t10dif_arch, func);
+ return 0;
}
-EXPORT_SYMBOL(crc_t10dif_update);
+EXPORT_SYMBOL_NS(crc_t10dif_register, CRYPTO_INTERNAL);
-__u16 crc_t10dif(const unsigned char *buffer, size_t len)
+int crc_t10dif_unregister(void)
{
- return crc_t10dif_update(0, buffer, len);
+ // revert to generic implementation
+ static_call_update(crc_t10dif_arch, crc_t10dif_generic);
+ crc_t10dif_arch_name = NULL;
+
+ // wait for all potential callers of the unregistered routine to finish
+ synchronize_rcu_tasks();
+ return 0;
}
-EXPORT_SYMBOL(crc_t10dif);
+EXPORT_SYMBOL_NS(crc_t10dif_unregister, CRYPTO_INTERNAL);
static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
{
- return sprintf(buffer, "fallback\n");
+ return sprintf(buffer, "%s\n", crc_t10dif_arch_name ?: "fallback");
}
module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0444);
Wire up the new static call facility to the CRC-T10DIF library code, so that optimized implementations can be swapped in easily, without having to rely on the complexity of the crypto API shash infrastructure. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- include/linux/crc-t10dif.h | 21 ++++++++++++-- lib/crc-t10dif.c | 30 +++++++++++++++----- 2 files changed, 42 insertions(+), 9 deletions(-)