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Subject[PATCH 2/5] x86_64, -march=native: POPCNT support
Date
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 +++-
.../drm/i915/display/intel_display_power.c | 2 +-
drivers/misc/sgi-gru/grumain.c | 2 +-
fs/btrfs/tree-checker.c | 4 ++--
include/linux/bitops.h | 2 ++
lib/Makefile | 2 ++
scripts/kconfig/cpuid.c | 7 ++++++
scripts/march-native.sh | 2 ++
11 files changed, 54 insertions(+), 5 deletions(-)

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/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index c93ad512014c..9066105f2fea 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -1570,7 +1570,7 @@ static void print_power_domains(struct i915_power_domains *power_domains,
{
enum intel_display_power_domain domain;

- DRM_DEBUG_DRIVER("%s (%lu):\n", prefix, hweight64(mask));
+ DRM_DEBUG_DRIVER("%s (%u):\n", prefix, hweight64(mask));
for_each_power_domain(domain, mask)
DRM_DEBUG_DRIVER("%s use_count %d\n",
intel_display_power_domain_str(domain),
diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
index 40ac59dd018c..30cfeeb28e74 100644
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -833,7 +833,7 @@ void gru_steal_context(struct gru_thread_state *gts)
}
gru_dbg(grudev,
"stole gid %d, ctxnum %d from gts %p. Need cb %d, ds %d;"
- " avail cb %ld, ds %ld\n",
+ " avail cb %u, ds %u\n",
gru->gs_gid, ctxnum, ngts, cbr, dsr, hweight64(gru->gs_cbr_map),
hweight64(gru->gs_dsr_map));
}
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index ccd5706199d7..2d33c6ae0e61 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -478,7 +478,7 @@ static int check_block_group_item(struct extent_buffer *leaf,
flags = btrfs_block_group_flags(&bgi);
if (hweight64(flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) > 1) {
block_group_err(leaf, slot,
-"invalid profile flags, have 0x%llx (%lu bits set) expect no more than 1 bit set",
+"invalid profile flags, have 0x%llx (%u bits set) expect no more than 1 bit set",
flags & BTRFS_BLOCK_GROUP_PROFILE_MASK,
hweight64(flags & BTRFS_BLOCK_GROUP_PROFILE_MASK));
return -EUCLEAN;
@@ -491,7 +491,7 @@ static int check_block_group_item(struct extent_buffer *leaf,
type != (BTRFS_BLOCK_GROUP_METADATA |
BTRFS_BLOCK_GROUP_DATA)) {
block_group_err(leaf, slot,
-"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
+"invalid type, have 0x%llx (%u bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
type, hweight64(type),
BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA,
BTRFS_BLOCK_GROUP_SYSTEM,
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 095601ce371d..32400f3a3328 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -114,7 +114,9 @@ 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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