cregit-Linux how code gets into the kernel

Release 4.7 arch/x86/include/asm/arch_hweight.h

#ifndef _ASM_X86_HWEIGHT_H

#define _ASM_X86_HWEIGHT_H

#include <asm/cpufeatures.h>

#ifdef CONFIG_64BIT
/* popcnt %edi, %eax -- redundant REX prefix for alignment */

#define POPCNT32 ".byte 0xf3,0x40,0x0f,0xb8,0xc7"
/* popcnt %rdi, %rax */

#define POPCNT64 ".byte 0xf3,0x48,0x0f,0xb8,0xc7"

#define REG_IN "D"

#define REG_OUT "a"
#else
/* popcnt %eax, %eax */

#define POPCNT32 ".byte 0xf3,0x0f,0xb8,0xc0"

#define REG_IN "a"

#define REG_OUT "a"
#endif

/*
 * __sw_hweightXX are called from within the alternatives below
 * and callee-clobbered registers need to be taken care of. See
 * ARCH_HWEIGHT_CFLAGS in <arch/x86/Kconfig> for the respective
 * compiler switches.
 */

static __always_inline unsigned int __arch_hweight32(unsigned int w) { unsigned int res = 0; asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT) : "="REG_OUT (res) : REG_IN (w)); return res; }

Contributors

PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov2090.91%133.33%
h. peter anvinh. peter anvin14.55%133.33%
denys vlasenkodenys vlasenko14.55%133.33%
Total22100.00%3100.00%


static inline unsigned int __arch_hweight16(unsigned int w) { return __arch_hweight32(w & 0xffff); }

Contributors

PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov20100.00%1100.00%
Total20100.00%1100.00%


static inline unsigned int __arch_hweight8(unsigned int w) { return __arch_hweight32(w & 0xff); }

Contributors

PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov20100.00%1100.00%
Total20100.00%1100.00%

#ifdef CONFIG_X86_32
static inline unsigned long __arch_hweight64(__u64 w) { return __arch_hweight32((u32)w) + __arch_hweight32((u32)(w >> 32)); }

Contributors

PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov3196.88%150.00%
denys vlasenkodenys vlasenko13.12%150.00%
Total32100.00%2100.00%

#else
static __always_inline unsigned long __arch_hweight64(__u64 w) { unsigned long res = 0; asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT) : "="REG_OUT (res) : REG_IN (w)); return res; }

Contributors

PersonTokensPropCommitsCommitProp
denys vlasenkodenys vlasenko1676.19%133.33%
borislav petkovborislav petkov419.05%133.33%
h. peter anvinh. peter anvin14.76%133.33%
Total21100.00%3100.00%

#endif /* CONFIG_X86_32 */ #endif

Overall Contributors

PersonTokensPropCommitsCommitProp
borislav petkovborislav petkov14080.92%250.00%
denys vlasenkodenys vlasenko2413.87%125.00%
h. peter anvinh. peter anvin95.20%125.00%
Total173100.00%4100.00%
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