From f5967101e9de12addcda4510dfbac66d7c5779c3 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 30 May 2016 12:56:27 +0200 Subject: x86/hweight: Get rid of the special calling convention People complained about ARCH_HWEIGHT_CFLAGS and how it throws a wrench into kcov, lto, etc, experimentations. Add asm versions for __sw_hweight{32,64}() and do explicit saving and restoring of clobbered registers. This gets rid of the special calling convention. We get to call those functions on !X86_FEATURE_POPCNT CPUs. We still need to hardcode POPCNT and register operands as some old gas versions which we support, do not know about POPCNT. Btw, remove redundant REX prefix from 32-bit POPCNT because alternatives can do padding now. Suggested-by: H. Peter Anvin Signed-off-by: Borislav Petkov Acked-by: Peter Zijlstra (Intel) Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1464605787-20603-1-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- lib/Makefile | 5 ----- lib/hweight.c | 4 ++++ 2 files changed, 4 insertions(+), 5 deletions(-) (limited to 'lib') diff --git a/lib/Makefile b/lib/Makefile index ff6a7a6c6395..07d06a8b9788 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -15,9 +15,6 @@ KCOV_INSTRUMENT_rbtree.o := n KCOV_INSTRUMENT_list_debug.o := n KCOV_INSTRUMENT_debugobjects.o := n KCOV_INSTRUMENT_dynamic_debug.o := n -# Kernel does not boot if we instrument this file as it uses custom calling -# convention (see CONFIG_ARCH_HWEIGHT_CFLAGS). -KCOV_INSTRUMENT_hweight.o := n lib-y := ctype.o string.o vsprintf.o cmdline.o \ rbtree.o radix-tree.o dump_stack.o timerqueue.o\ @@ -74,8 +71,6 @@ obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o obj-$(CONFIG_CHECK_SIGNATURE) += check_signature.o obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o -GCOV_PROFILE_hweight.o := n -CFLAGS_hweight.o = $(subst $(quote),,$(CONFIG_ARCH_HWEIGHT_CFLAGS)) obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o obj-$(CONFIG_BTREE) += btree.o diff --git a/lib/hweight.c b/lib/hweight.c index 9a5c1f221558..43273a7d83cf 100644 --- a/lib/hweight.c +++ b/lib/hweight.c @@ -9,6 +9,7 @@ * The Hamming Weight of a number is the total number of bits set in it. */ +#ifndef __HAVE_ARCH_SW_HWEIGHT unsigned int __sw_hweight32(unsigned int w) { #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER @@ -25,6 +26,7 @@ unsigned int __sw_hweight32(unsigned int w) #endif } EXPORT_SYMBOL(__sw_hweight32); +#endif unsigned int __sw_hweight16(unsigned int w) { @@ -43,6 +45,7 @@ unsigned int __sw_hweight8(unsigned int w) } EXPORT_SYMBOL(__sw_hweight8); +#ifndef __HAVE_ARCH_SW_HWEIGHT unsigned long __sw_hweight64(__u64 w) { #if BITS_PER_LONG == 32 @@ -65,3 +68,4 @@ unsigned long __sw_hweight64(__u64 w) #endif } EXPORT_SYMBOL(__sw_hweight64); +#endif -- cgit v1.2.3