lib/crc32: make core crc32() routines weak so they can be overridden

Ard Biesheuvel · ctmarinas · commit 9784d82db3eb · 2018-09-10T16:09:27.000+01:00
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.

Acked-by: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
diff --git 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

Original file line number	Diff line number	Diff line change
`@@ -183,21 +183,21 @@ static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,`
`183`	`183`	`}`
`184`	`184`
`185`	`185`	`#if CRC_LE_BITS == 1`
`186`		`-u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)`
	`186`	`+u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len)`
`187`	`187`	`{`
`188`	`188`	`return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE);`
`189`	`189`	`}`
`190`		`-u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)`
	`190`	`+u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len)`
`191`	`191`	`{`
`192`	`192`	`return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);`
`193`	`193`	`}`
`194`	`194`	`#else`
`195`		`-u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)`
	`195`	`+u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len)`
`196`	`196`	`{`
`197`	`197`	`return crc32_le_generic(crc, p, len,`
`198`	`198`	`(const u32 (*)[256])crc32table_le, CRC32_POLY_LE);`
`199`	`199`	`}`
`200`		`-u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)`
	`200`	`+u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len)`
`201`	`201`	`{`
`202`	`202`	`return crc32_le_generic(crc, p, len,`
`203`	`203`	`(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)`
`206`	`206`	`EXPORT_SYMBOL(crc32_le);`
`207`	`207`	`EXPORT_SYMBOL(__crc32c_le);`
`208`	`208`
	`209`	`+u32 crc32_le_base(u32, unsigned char const *, size_t) __alias(crc32_le);`
	`210`	`+u32 __crc32c_le_base(u32, unsigned char const *, size_t) __alias(__crc32c_le);`
	`211`	`+`
`209`	`212`	`/*`
`210`	`213`	`* This multiplies the polynomials x and y modulo the given modulus.`
`211`	`214`	`* This follows the "little-endian" CRC convention that the lsbit`