Merge tag 'compiler-attributes-for-linus-v5.0-rc7' of git://github.com/ojeda/linux

torvalds · torvalds · commit 0b999ae3614d · 2019-02-16T10:28:05.000-08:00
Pull compiler attributes fixes from Miguel Ojeda: "Clean the new GCC 9 -Wmissing-attributes warnings The upcoming GCC 9 release extends the -Wmissing-attributes warnings (enabled by -Wall) to C and aliases: it warns when particular function attributes are missing in the aliases but not in their target, e.g.: void __cold f(void) {} void __alias("f") g(void); diagnoses: warning: 'g' specifies less restrictive attribute than its target 'f': 'cold' [-Wmissing-attributes] These patch series clean these new warnings. Most of them are caused by the module_init/exit macros" Link: https://lore.kernel.org/lkml/20190125104353.2791-1-labbott@redhat.com/ * tag 'compiler-attributes-for-linus-v5.0-rc7' of git://github.com/ojeda/linux: include/linux/module.h: copy __init/__exit attrs to init/cleanup_module Compiler Attributes: add support for __copy (gcc >= 9) lib/crc32.c: mark crc32_le_base/__crc32c_le_base aliases as __pure
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
@@ -34,6 +34,7 @@
 #ifndef __has_attribute
 # define __has_attribute(x) __GCC4_has_attribute_##x
 # define __GCC4_has_attribute___assume_aligned__      (__GNUC_MINOR__ >= 9)
+# define __GCC4_has_attribute___copy__                0
 # define __GCC4_has_attribute___designated_init__     0
 # define __GCC4_has_attribute___externally_visible__  1
 # define __GCC4_has_attribute___noclone__             1
@@ -100,6 +101,19 @@
  */
 #define __attribute_const__             __attribute__((__const__))
 
+/*
+ * Optional: only supported since gcc >= 9
+ * Optional: not supported by clang
+ * Optional: not supported by icc
+ *
+ *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute
+ */
+#if __has_attribute(__copy__)
+# define __copy(symbol)                 __attribute__((__copy__(symbol)))
+#else
+# define __copy(symbol)
+#endif
+
 /*
  * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated'
  * attribute warnings entirely and for good") for more information.
diff --git a/include/linux/module.h b/include/linux/module.h
@@ -129,13 +129,13 @@ extern void cleanup_module(void);
 #define module_init(initfn)					\
 	static inline initcall_t __maybe_unused __inittest(void)		\
 	{ return initfn; }					\
-	int init_module(void) __attribute__((alias(#initfn)));
+	int init_module(void) __copy(initfn) __attribute__((alias(#initfn)));
 
 /* This is only required if you want to be unloadable. */
 #define module_exit(exitfn)					\
 	static inline exitcall_t __maybe_unused __exittest(void)		\
 	{ return exitfn; }					\
-	void cleanup_module(void) __attribute__((alias(#exitfn)));
+	void cleanup_module(void) __copy(exitfn) __attribute__((alias(#exitfn)));
 
 #endif
 
diff --git a/lib/crc32.c b/lib/crc32.c
@@ -206,8 +206,8 @@ u32 __pure __weak __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);
+u32 __pure crc32_le_base(u32, unsigned char const *, size_t) __alias(crc32_le);
+u32 __pure __crc32c_le_base(u32, unsigned char const *, size_t) __alias(__crc32c_le);
 
 /*
  * This multiplies the polynomials x and y modulo the given modulus.
