From: Andi Kleen <a...@linux.intel.com> gcc 5 has a new no_reorder attribute that prevents top level reordering only for that symbol.
Kernels don't like any reordering of initcalls between files, as several initcalls depend on each other. Add a __noreorder wrapper for the no_reorder attribute and use it for initcalls. LTO previously needed to use -fno-toplevel-reordering to prevent boot failures, but with noreorder this is not needed. I believe the patch is useful even without LTO because it clearly documents this dependency in the source. Signed-off-by: Andi Kleen <a...@linux.intel.com> --- include/linux/compiler_attributes.h | 11 +++++++++++ include/linux/init.h | 2 +- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 6b318efd8a74..1c44ef9034bb 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -39,6 +39,7 @@ # define __GCC4_has_attribute___externally_visible__ 1 # define __GCC4_has_attribute___noclone__ 1 # define __GCC4_has_attribute___nonstring__ 0 +# define __GCC4_has_attribute___no_reorder__ 0 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8) #endif @@ -253,4 +254,14 @@ */ #define __weak __attribute__((__weak__)) +/* + * https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes + */ + +#if __has_attribute(__no_reorder__) +#define __noreorder __attribute__((no_reorder)) +#else +#define __noreorder +#endif + #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ diff --git a/include/linux/init.h b/include/linux/init.h index 5255069f5a9f..49d032916604 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -190,7 +190,7 @@ extern bool initcall_debug; ".previous \n"); #else #define ___define_initcall(fn, id, __sec) \ - static initcall_t __initcall_##fn##id __used \ + static initcall_t __initcall_##fn##id __used __noreorder \ __attribute__((__section__(#__sec ".init"))) = fn; #endif -- 2.20.1
