Messages in this thread Patch in this message | | | From | Alexey Dobriyan <> | Subject | [PATCH 2/5] x86_64, -march=native: POPCNT support | Date | Thu, 4 Jul 2019 23:47:34 +0300 |
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Detect POPCNT instruction support and inline hweigth*() functions if it is supported by CPU.
Detect POPCNT at boot time and conditionally refuse to boot.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> --- arch/x86/include/asm/arch_hweight.h | 24 ++++++++++++++++++++++++ arch/x86/include/asm/segment.h | 1 + arch/x86/kernel/verify_cpu.S | 8 ++++++++ arch/x86/lib/Makefile | 5 ++++- include/linux/bitops.h | 2 ++ lib/Makefile | 2 ++ scripts/kconfig/cpuid.c | 7 +++++++ scripts/march-native.sh | 2 ++ 8 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h index ba88edd0d58b..3797aa57baa5 100644 --- a/arch/x86/include/asm/arch_hweight.h +++ b/arch/x86/include/asm/arch_hweight.h @@ -2,6 +2,28 @@ #ifndef _ASM_X86_HWEIGHT_H #define _ASM_X86_HWEIGHT_H +#ifdef CONFIG_MARCH_NATIVE_POPCNT +static inline unsigned int __arch_hweight64(uint64_t x) +{ + return __builtin_popcountll(x); +} + +static inline unsigned int __arch_hweight32(uint32_t x) +{ + return __builtin_popcount(x); +} + +static inline unsigned int __arch_hweight16(uint16_t x) +{ + return __builtin_popcount(x); +} + +static inline unsigned int __arch_hweight8(uint8_t x) +{ + return __builtin_popcount(x); +} +#else + #include <asm/cpufeatures.h> #ifdef CONFIG_64BIT @@ -53,3 +75,5 @@ static __always_inline unsigned long __arch_hweight64(__u64 w) #endif /* CONFIG_X86_32 */ #endif + +#endif diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index ac3892920419..d314c6b9b632 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -4,6 +4,7 @@ #include <linux/const.h> #include <asm/alternative.h> +#include <asm/cpufeatures.h> /* * Constructor for a conventional segment GDT (or LDT) entry. diff --git a/arch/x86/kernel/verify_cpu.S b/arch/x86/kernel/verify_cpu.S index a024c4f7ba56..a9be8904faa3 100644 --- a/arch/x86/kernel/verify_cpu.S +++ b/arch/x86/kernel/verify_cpu.S @@ -134,6 +134,14 @@ ENTRY(verify_cpu) movl $1,%eax ret .Lverify_cpu_sse_ok: + +#ifdef CONFIG_MARCH_NATIVE_POPCNT + mov $1, %eax + cpuid + bt $23, %ecx + jnc .Lverify_cpu_no_longmode +#endif + popf # Restore caller passed flags xorl %eax, %eax ret diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index 5246db42de45..7dc0e71b0ef3 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -40,7 +40,10 @@ lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o lib-$(CONFIG_RETPOLINE) += retpoline.o -obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o +obj-y += msr.o msr-reg.o msr-reg-export.o +ifneq ($(CONFIG_MARCH_NATIVE_POPCNT),y) + obj-y += hweight.o +endif obj-y += iomem.o ifeq ($(CONFIG_X86_32),y) diff --git a/include/linux/bitops.h b/include/linux/bitops.h index cf074bce3eb3..655b120bba66 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -7,10 +7,12 @@ #define BITS_PER_TYPE(type) (sizeof(type) * BITS_PER_BYTE) #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_TYPE(long)) +#ifndef CONFIG_MARCH_NATIVE_POPCNT extern unsigned int __sw_hweight8(unsigned int w); extern unsigned int __sw_hweight16(unsigned int w); extern unsigned int __sw_hweight32(unsigned int w); extern unsigned long __sw_hweight64(__u64 w); +#endif /* * Include this here because some architectures need generic_ffs/fls in diff --git a/lib/Makefile b/lib/Makefile index fb7697031a79..87e7b974cab1 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -112,7 +112,9 @@ obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o obj-y += logic_pio.o +ifneq ($(CONFIG_MARCH_NATIVE_POPCNT),y) obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o +endif obj-$(CONFIG_BTREE) += btree.o obj-$(CONFIG_INTERVAL_TREE) += interval_tree.o diff --git a/scripts/kconfig/cpuid.c b/scripts/kconfig/cpuid.c index 81b292382e26..9efc0d9464d8 100644 --- a/scripts/kconfig/cpuid.c +++ b/scripts/kconfig/cpuid.c @@ -43,6 +43,8 @@ static inline void cpuid2(uint32_t eax0, uint32_t ecx0, uint32_t *eax, uint32_t ); } +static bool popcnt = false; + static uint32_t eax0_max; static void intel(void) @@ -52,6 +54,10 @@ static void intel(void) if (eax0_max >= 1) { cpuid(1, &eax, &ecx, &edx, &ebx); // printf("%08x %08x %08x %08x\n", eax, ecx, edx, ebx); + + if (ecx & (1 << 23)) { + popcnt = true; + } } } @@ -72,6 +78,7 @@ int main(int argc, char *argv[]) } #define _(x) if (streq(opt, #x)) return x ? EXIT_SUCCESS : EXIT_FAILURE + _(popcnt); #undef _ return EXIT_FAILURE; diff --git a/scripts/march-native.sh b/scripts/march-native.sh index 29a33c80b62b..c3059f93ed2b 100755 --- a/scripts/march-native.sh +++ b/scripts/march-native.sh @@ -41,6 +41,8 @@ COLLECT_GCC_OPTIONS=$( ) echo "-march=native: $COLLECT_GCC_OPTIONS" +"$CPUID" popcnt && option "CONFIG_MARCH_NATIVE_POPCNT" + for i in $COLLECT_GCC_OPTIONS; do case $i in */cc1|-E|-quiet|-v|/dev/null|--param|-fstack-protector*) -- 2.21.0
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