From: Ingo Molnar Date: Sat, 22 Jan 2022 12:39:15 +0000 (+0100) Subject: x86/bitops: Remove unused __sw_hweight64() assembly implementation on x86-32 X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ad424743256b0119bd60a9248db4df5d998000a4;p=linux.git x86/bitops: Remove unused __sw_hweight64() assembly implementation on x86-32 Header cleanups in the fast-headers tree highlighted that we have an unused assembly implementation for __sw_hweight64(): WARNING: modpost: EXPORT symbol "__sw_hweight64" [vmlinux] version ... __arch_hweight64() on x86-32 is defined in the arch/x86/include/asm/arch_hweight.h header as an inline, using __arch_hweight32(): #ifdef CONFIG_X86_32 static inline unsigned long __arch_hweight64(__u64 w) { return __arch_hweight32((u32)w) + __arch_hweight32((u32)(w >> 32)); } *But* there's also a __sw_hweight64() assembly implementation: arch/x86/lib/hweight.S SYM_FUNC_START(__sw_hweight64) #ifdef CONFIG_X86_64 ... #else /* CONFIG_X86_32 */ /* We're getting an u64 arg in (%eax,%edx): unsigned long hweight64(__u64 w) */ pushl %ecx call __sw_hweight32 movl %eax, %ecx # stash away result movl %edx, %eax # second part of input call __sw_hweight32 addl %ecx, %eax # result popl %ecx ret #endif But this __sw_hweight64 assembly implementation is unused - and it's essentially doing the same thing that the inline wrapper does. Remove the assembly version and add a comment about it. Reported-by: Nathan Chancellor Signed-off-by: Ingo Molnar Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org --- diff --git a/arch/x86/lib/hweight.S b/arch/x86/lib/hweight.S index 12c16c6aa44a3..0a152e51d3f5b 100644 --- a/arch/x86/lib/hweight.S +++ b/arch/x86/lib/hweight.S @@ -36,8 +36,12 @@ SYM_FUNC_START(__sw_hweight32) SYM_FUNC_END(__sw_hweight32) EXPORT_SYMBOL(__sw_hweight32) -SYM_FUNC_START(__sw_hweight64) +/* + * No 32-bit variant, because it's implemented as an inline wrapper + * on top of __arch_hweight32(): + */ #ifdef CONFIG_X86_64 +SYM_FUNC_START(__sw_hweight64) pushq %rdi pushq %rdx @@ -66,18 +70,6 @@ SYM_FUNC_START(__sw_hweight64) popq %rdx popq %rdi RET -#else /* CONFIG_X86_32 */ - /* We're getting an u64 arg in (%eax,%edx): unsigned long hweight64(__u64 w) */ - pushl %ecx - - call __sw_hweight32 - movl %eax, %ecx # stash away result - movl %edx, %eax # second part of input - call __sw_hweight32 - addl %ecx, %eax # result - - popl %ecx - RET -#endif SYM_FUNC_END(__sw_hweight64) EXPORT_SYMBOL(__sw_hweight64) +#endif