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authorBorislav Petkov <bp@suse.de>2016-05-30 12:56:27 +0200
committerIngo Molnar <mingo@kernel.org>2016-06-08 15:01:02 +0200
commitf5967101e9de12addcda4510dfbac66d7c5779c3 (patch)
tree2f01f9e5eb430728ebecd5abff9851fafb5c8c62 /lib
parent08dd8cd06ed95625b9e2fac43c78fcb45b7eaf94 (diff)
downloadlinux-f5967101e9de12addcda4510dfbac66d7c5779c3.tar.bz2
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 <hpa@zytor.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1464605787-20603-1-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Makefile5
-rw-r--r--lib/hweight.c4
2 files changed, 4 insertions, 5 deletions
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