lib/crc32: don't bother with pure and const function attributes

ebiggers · ebiggers · commit bc2736fe7e0b · 2025-02-08T20:06:30.000-08:00
Drop the use of __pure and __attribute_const__ from the CRC32 library functions that had them. Both of these are unusual optimizations that don't help properly written code. They seem more likely to cause problems than have any real benefit. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250208024911.14936-4-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>
diff --git a/arch/arm64/lib/crc32-glue.c b/arch/arm64/lib/crc32-glue.c
@@ -22,7 +22,7 @@ asmlinkage u32 crc32_le_arm64_4way(u32 crc, unsigned char const *p, size_t len);
 asmlinkage u32 crc32c_le_arm64_4way(u32 crc, unsigned char const *p, size_t len);
 asmlinkage u32 crc32_be_arm64_4way(u32 crc, unsigned char const *p, size_t len);
 
-u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len)
+u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)
 {
 	if (!alternative_has_cap_likely(ARM64_HAS_CRC32))
 		return crc32_le_base(crc, p, len);
@@ -43,7 +43,7 @@ u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len)
 }
 EXPORT_SYMBOL(crc32_le_arch);
 
-u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len)
+u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len)
 {
 	if (!alternative_has_cap_likely(ARM64_HAS_CRC32))
 		return crc32c_le_base(crc, p, len);
@@ -64,7 +64,7 @@ u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len)
 }
 EXPORT_SYMBOL(crc32c_le_arch);
 
-u32 __pure crc32_be_arch(u32 crc, const u8 *p, size_t len)
+u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)
 {
 	if (!alternative_has_cap_likely(ARM64_HAS_CRC32))
 		return crc32_be_base(crc, p, len);
diff --git a/arch/riscv/lib/crc32-riscv.c b/arch/riscv/lib/crc32-riscv.c
@@ -175,10 +175,9 @@ static inline u32 crc32_le_unaligned(u32 crc, unsigned char const *p,
 	return crc;
 }
 
-static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
-					  size_t len, u32 poly,
-					  unsigned long poly_qt,
-					  fallback crc_fb)
+static inline u32 crc32_le_generic(u32 crc, unsigned char const *p, size_t len,
+				   u32 poly, unsigned long poly_qt,
+				   fallback crc_fb)
 {
 	size_t offset, head_len, tail_len;
 	unsigned long const *p_ul;
@@ -218,14 +217,14 @@ static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
 	return crc_fb(crc, p, len);
 }
 
-u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len)
+u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len, CRC32_POLY_LE, CRC32_POLY_QT_LE,
 				crc32_le_base);
 }
 EXPORT_SYMBOL(crc32_le_arch);
 
-u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len)
+u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len)
 {
 	return crc32_le_generic(crc, p, len, CRC32C_POLY_LE,
 				CRC32C_POLY_QT_LE, crc32c_le_base);
@@ -256,7 +255,7 @@ static inline u32 crc32_be_unaligned(u32 crc, unsigned char const *p,
 	return crc;
 }
 
-u32 __pure crc32_be_arch(u32 crc, const u8 *p, size_t len)
+u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)
 {
 	size_t offset, head_len, tail_len;
 	unsigned long const *p_ul;
diff --git a/include/linux/crc32.h b/include/linux/crc32.h
@@ -8,29 +8,29 @@
 #include <linux/types.h>
 #include <linux/bitrev.h>
 
-u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len);
-u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len);
-u32 __pure crc32_be_arch(u32 crc, const u8 *p, size_t len);
-u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len);
-u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len);
-u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len);
+u32 crc32_le_arch(u32 crc, const u8 *p, size_t len);
+u32 crc32_le_base(u32 crc, const u8 *p, size_t len);
+u32 crc32_be_arch(u32 crc, const u8 *p, size_t len);
+u32 crc32_be_base(u32 crc, const u8 *p, size_t len);
+u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len);
+u32 crc32c_le_base(u32 crc, const u8 *p, size_t len);
 
-static inline u32 __pure crc32_le(u32 crc, const void *p, size_t len)
+static inline u32 crc32_le(u32 crc, const void *p, size_t len)
 {
 	if (IS_ENABLED(CONFIG_CRC32_ARCH))
 		return crc32_le_arch(crc, p, len);
 	return crc32_le_base(crc, p, len);
 }
 
-static inline u32 __pure crc32_be(u32 crc, const void *p, size_t len)
+static inline u32 crc32_be(u32 crc, const void *p, size_t len)
 {
 	if (IS_ENABLED(CONFIG_CRC32_ARCH))
 		return crc32_be_arch(crc, p, len);
 	return crc32_be_base(crc, p, len);
 }
 
 /* TODO: leading underscores should be dropped once callers have been updated */
-static inline u32 __pure __crc32c_le(u32 crc, const void *p, size_t len)
+static inline u32 __crc32c_le(u32 crc, const void *p, size_t len)
 {
 	if (IS_ENABLED(CONFIG_CRC32_ARCH))
 		return crc32c_le_arch(crc, p, len);
@@ -70,7 +70,7 @@ static inline u32 crc32_optimizations(void) { return 0; }
  * 	   with the same initializer as crc1, and crc2 seed was 0. See
  * 	   also crc32_combine_test().
  */
-u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len);
+u32 crc32_le_shift(u32 crc, size_t len);
 
 static inline u32 crc32_le_combine(u32 crc1, u32 crc2, size_t len2)
 {
@@ -95,7 +95,7 @@ static inline u32 crc32_le_combine(u32 crc1, u32 crc2, size_t len2)
  * 	   seeded with the same initializer as crc1, and crc2 seed
  * 	   was 0. See also crc32c_combine_test().
  */
-u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len);
+u32 __crc32c_le_shift(u32 crc, size_t len);
 
 static inline u32 __crc32c_le_combine(u32 crc1, u32 crc2, size_t len2)
 {
diff --git a/lib/crc32.c b/lib/crc32.c
@@ -37,15 +37,15 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
 MODULE_DESCRIPTION("Various CRC32 calculations");
 MODULE_LICENSE("GPL");
 
-u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len)
+u32 crc32_le_base(u32 crc, const u8 *p, size_t len)
 {
 	while (len--)
 		crc = (crc >> 8) ^ crc32table_le[(crc & 255) ^ *p++];
 	return crc;
 }
 EXPORT_SYMBOL(crc32_le_base);
 
-u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len)
+u32 crc32c_le_base(u32 crc, const u8 *p, size_t len)
 {
 	while (len--)
 		crc = (crc >> 8) ^ crc32ctable_le[(crc & 255) ^ *p++];
@@ -58,7 +58,7 @@ EXPORT_SYMBOL(crc32c_le_base);
  * This follows the "little-endian" CRC convention that the lsbit
  * represents the highest power of x, and the msbit represents x^0.
  */
-static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)
+static u32 gf2_multiply(u32 x, u32 y, u32 modulus)
 {
 	u32 product = x & 1 ? y : 0;
 	int i;
@@ -84,8 +84,7 @@ static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)
  * as appending len bytes of zero to the data), in time proportional
  * to log(len).
  */
-static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,
-						   u32 polynomial)
+static u32 crc32_generic_shift(u32 crc, size_t len, u32 polynomial)
 {
 	u32 power = polynomial;	/* CRC of x^32 */
 	int i;
@@ -114,19 +113,19 @@ static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,
 	return crc;
 }
 
-u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len)
+u32 crc32_le_shift(u32 crc, size_t len)
 {
 	return crc32_generic_shift(crc, len, CRC32_POLY_LE);
 }
 
-u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)
+u32 __crc32c_le_shift(u32 crc, size_t len)
 {
 	return crc32_generic_shift(crc, len, CRC32C_POLY_LE);
 }
 EXPORT_SYMBOL(crc32_le_shift);
 EXPORT_SYMBOL(__crc32c_le_shift);
 
-u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len)
+u32 crc32_be_base(u32 crc, const u8 *p, size_t len)
 {
 	while (len--)
 		crc = (crc << 8) ^ crc32table_be[(crc >> 24) ^ *p++];

Original file line number	Diff line number	Diff line change
`@@ -22,7 +22,7 @@ asmlinkage u32 crc32_le_arm64_4way(u32 crc, unsigned char const *p, size_t len);`
`22`	`22`	`asmlinkage u32 crc32c_le_arm64_4way(u32 crc, unsigned char const *p, size_t len);`
`23`	`23`	`asmlinkage u32 crc32_be_arm64_4way(u32 crc, unsigned char const *p, size_t len);`
`24`	`24`
`25`		`-u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len)`
	`25`	`+u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)`
`26`	`26`	`{`
`27`	`27`	`if (!alternative_has_cap_likely(ARM64_HAS_CRC32))`
`28`	`28`	`return crc32_le_base(crc, p, len);`
`@@ -43,7 +43,7 @@ u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len)`
`43`	`43`	`}`
`44`	`44`	`EXPORT_SYMBOL(crc32_le_arch);`
`45`	`45`
`46`		`-u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len)`
	`46`	`+u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len)`
`47`	`47`	`{`
`48`	`48`	`if (!alternative_has_cap_likely(ARM64_HAS_CRC32))`
`49`	`49`	`return crc32c_le_base(crc, p, len);`
`@@ -64,7 +64,7 @@ u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len)`
`64`	`64`	`}`
`65`	`65`	`EXPORT_SYMBOL(crc32c_le_arch);`
`66`	`66`
`67`		`-u32 __pure crc32_be_arch(u32 crc, const u8 *p, size_t len)`
	`67`	`+u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)`
`68`	`68`	`{`
`69`	`69`	`if (!alternative_has_cap_likely(ARM64_HAS_CRC32))`
`70`	`70`	`return crc32_be_base(crc, p, len);`
Original file line number	Diff line number	Diff line change
`@@ -175,10 +175,9 @@ static inline u32 crc32_le_unaligned(u32 crc, unsigned char const *p,`
`175`	`175`	`return crc;`
`176`	`176`	`}`
`177`	`177`
`178`		`-static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,`
`179`		`- size_t len, u32 poly,`
`180`		`- unsigned long poly_qt,`
`181`		`- fallback crc_fb)`
	`178`	`+static inline u32 crc32_le_generic(u32 crc, unsigned char const *p, size_t len,`
	`179`	`+ u32 poly, unsigned long poly_qt,`
	`180`	`+ fallback crc_fb)`
`182`	`181`	`{`
`183`	`182`	`size_t offset, head_len, tail_len;`
`184`	`183`	`unsigned long const *p_ul;`
`@@ -218,14 +217,14 @@ static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,`
`218`	`217`	`return crc_fb(crc, p, len);`
`219`	`218`	`}`
`220`	`219`
`221`		`-u32 __pure crc32_le_arch(u32 crc, const u8 *p, size_t len)`
	`220`	`+u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)`
`222`	`221`	`{`
`223`	`222`	`return crc32_le_generic(crc, p, len, CRC32_POLY_LE, CRC32_POLY_QT_LE,`
`224`	`223`	`crc32_le_base);`
`225`	`224`	`}`
`226`	`225`	`EXPORT_SYMBOL(crc32_le_arch);`
`227`	`226`
`228`		`-u32 __pure crc32c_le_arch(u32 crc, const u8 *p, size_t len)`
	`227`	`+u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len)`
`229`	`228`	`{`
`230`	`229`	`return crc32_le_generic(crc, p, len, CRC32C_POLY_LE,`
`231`	`230`	`CRC32C_POLY_QT_LE, crc32c_le_base);`
`@@ -256,7 +255,7 @@ static inline u32 crc32_be_unaligned(u32 crc, unsigned char const *p,`
`256`	`255`	`return crc;`
`257`	`256`	`}`
`258`	`257`
`259`		`-u32 __pure crc32_be_arch(u32 crc, const u8 *p, size_t len)`
	`258`	`+u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)`
`260`	`259`	`{`
`261`	`260`	`size_t offset, head_len, tail_len;`
`262`	`261`	`unsigned long const *p_ul;`
Original file line number	Diff line number	Diff line change
`@@ -37,15 +37,15 @@ MODULE_AUTHOR("Matt Domsch <[email protected]>");`
`37`	`37`	`MODULE_DESCRIPTION("Various CRC32 calculations");`
`38`	`38`	`MODULE_LICENSE("GPL");`
`39`	`39`
`40`		`-u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len)`
	`40`	`+u32 crc32_le_base(u32 crc, const u8 *p, size_t len)`
`41`	`41`	`{`
`42`	`42`	`while (len--)`
`43`	`43`	`crc = (crc >> 8) ^ crc32table_le[(crc & 255) ^ *p++];`
`44`	`44`	`return crc;`
`45`	`45`	`}`
`46`	`46`	`EXPORT_SYMBOL(crc32_le_base);`
`47`	`47`
`48`		`-u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len)`
	`48`	`+u32 crc32c_le_base(u32 crc, const u8 *p, size_t len)`
`49`	`49`	`{`
`50`	`50`	`while (len--)`
`51`	`51`	`crc = (crc >> 8) ^ crc32ctable_le[(crc & 255) ^ *p++];`
`@@ -58,7 +58,7 @@ EXPORT_SYMBOL(crc32c_le_base);`
`58`	`58`	`* This follows the "little-endian" CRC convention that the lsbit`
`59`	`59`	`* represents the highest power of x, and the msbit represents x^0.`
`60`	`60`	`*/`
`61`		`-static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)`
	`61`	`+static u32 gf2_multiply(u32 x, u32 y, u32 modulus)`
`62`	`62`	`{`
`63`	`63`	`u32 product = x & 1 ? y : 0;`
`64`	`64`	`int i;`
`@@ -84,8 +84,7 @@ static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)`
`84`	`84`	`* as appending len bytes of zero to the data), in time proportional`
`85`	`85`	`* to log(len).`
`86`	`86`	`*/`
`87`		`-static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,`
`88`		`- u32 polynomial)`
	`87`	`+static u32 crc32_generic_shift(u32 crc, size_t len, u32 polynomial)`
`89`	`88`	`{`
`90`	`89`	`u32 power = polynomial; /* CRC of x^32 */`
`91`	`90`	`int i;`
`@@ -114,19 +113,19 @@ static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,`
`114`	`113`	`return crc;`
`115`	`114`	`}`
`116`	`115`
`117`		`-u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len)`
	`116`	`+u32 crc32_le_shift(u32 crc, size_t len)`
`118`	`117`	`{`
`119`	`118`	`return crc32_generic_shift(crc, len, CRC32_POLY_LE);`
`120`	`119`	`}`
`121`	`120`
`122`		`-u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)`
	`121`	`+u32 __crc32c_le_shift(u32 crc, size_t len)`
`123`	`122`	`{`
`124`	`123`	`return crc32_generic_shift(crc, len, CRC32C_POLY_LE);`
`125`	`124`	`}`
`126`	`125`	`EXPORT_SYMBOL(crc32_le_shift);`
`127`	`126`	`EXPORT_SYMBOL(__crc32c_le_shift);`
`128`	`127`
`129`		`-u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len)`
	`128`	`+u32 crc32_be_base(u32 crc, const u8 *p, size_t len)`
`130`	`129`	`{`
`131`	`130`	`while (len--)`
`132`	`131`	`crc = (crc << 8) ^ crc32table_be[(crc >> 24) ^ *p++];`