[1/4] lib/crc32: make core crc32() routines weak so they can be overridden

Commit Message

Ard Biesheuvel Aug. 27, 2018, 11:02 a.m. UTC

Allow architectures to drop in accelerated CRC32 routines by making
the crc32_le/__crc32c_le entry points weak, and exposing non-weak
aliases for them that may be used by the accelerated versions as
fallbacks in case the instructions they rely upon are not available.

Signed-off-by: Ard Biesheuvel <[e-mail]>
---
 lib/crc32.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Comments

Herbert Xu Sept. 4, 2018, 9:44 a.m. UTC | #1

On Mon, Aug 27, 2018 at 01:02:42PM +0200, Ard Biesheuvel wrote:
> Allow architectures to drop in accelerated CRC32 routines by making
> the crc32_le/__crc32c_le entry points weak, and exposing non-weak
> aliases for them that may be used by the accelerated versions as
> fallbacks in case the instructions they rely upon are not available.
> 
> Signed-off-by: Ard Biesheuvel <[e-mail]>

Acked-by: Herbert Xu <[e-mail]>

Thanks,

Patch

diff --git a/lib/crc32.c b/lib/crc32.c
index a6c9afafc8c8..45b1d67a1767 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -183,21 +183,21 @@  static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
 }
 
 #if CRC_LE_BITS == 1
-u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE);
 }
-u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
 }
 #else
-u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len,
 			(const u32 (*)[256])crc32table_le, CRC32_POLY_LE);
 }
-u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len,
 			(const u32 (*)[256])crc32ctable_le, CRC32C_POLY_LE);
@@ -206,6 +206,9 @@  u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
 EXPORT_SYMBOL(crc32_le);
 EXPORT_SYMBOL(__crc32c_le);
 
+u32 crc32_le_base(u32, unsigned char const *, size_t) __alias(crc32_le);
+u32 __crc32c_le_base(u32, unsigned char const *, size_t) __alias(__crc32c_le);
+
 /*
  * This multiplies the polynomials x and y modulo the given modulus.
  * This follows the "little-endian" CRC convention that the lsbit