arch/x86/include/asm/cpufeature.h

#ifndef _ASM_X86_CPUFEATURE_H
#define _ASM_X86_CPUFEATURE_H

#include <asm/processor.h>

#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

#include <asm/asm.h>
#include <linux/bitops.h>

enum cpuid_leafs
{
	CPUID_1_EDX		= 0,
	CPUID_8000_0001_EDX,
	CPUID_8086_0001_EDX,
	CPUID_LNX_1,
	CPUID_1_ECX,
	CPUID_C000_0001_EDX,
	CPUID_8000_0001_ECX,
	CPUID_LNX_2,
	CPUID_LNX_3,
	CPUID_7_0_EBX,
	CPUID_D_1_EAX,
	CPUID_F_0_EDX,
	CPUID_F_1_EDX,
	CPUID_8000_0008_EBX,
	CPUID_6_EAX,
	CPUID_8000_000A_EDX,
	CPUID_7_ECX,
	CPUID_8000_0007_EBX,
};

#ifdef CONFIG_X86_FEATURE_NAMES
extern const char * const x86_cap_flags[NCAPINTS*32];
extern const char * const x86_power_flags[32];
#define X86_CAP_FMT "%s"
#define x86_cap_flag(flag) x86_cap_flags[flag]
#else
#define X86_CAP_FMT "%d:%d"
#define x86_cap_flag(flag) ((flag) >> 5), ((flag) & 31)
#endif

/*
 * In order to save room, we index into this array by doing
 * X86_BUG_<name> - NCAPINTS*32.
 */
extern const char * const x86_bug_flags[NBUGINTS*32];

#define test_cpu_cap(c, bit)						\
	 test_bit(bit, (unsigned long *)((c)->x86_capability))

/*
 * There are 32 bits/features in each mask word.  The high bits
 * (selected with (bit>>5) give us the word number and the low 5
 * bits give us the bit/feature number inside the word.
 * (1UL<<((bit)&31) gives us a mask for the feature_bit so we can
 * see if it is set in the mask word.
 */
#define CHECK_BIT_IN_MASK_WORD(maskname, word, bit)	\
	(((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))

#define REQUIRED_MASK_BIT_SET(feature_bit)		\
	 ( CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  0, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  1, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  2, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  3, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  4, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  5, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  6, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  7, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  8, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  9, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 10, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 11, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 12, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 13, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 14, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 15, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 16, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 17, feature_bit) ||	\
	   REQUIRED_MASK_CHECK					  ||	\
	   BUILD_BUG_ON_ZERO(NCAPINTS != 18))

#define DISABLED_MASK_BIT_SET(feature_bit)				\
	 ( CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  0, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  1, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  2, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  3, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  4, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  5, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  6, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  7, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  8, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  9, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 10, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 11, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 12, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 13, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 14, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 15, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 16, feature_bit) ||	\
	   CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 17, feature_bit) ||	\
	   DISABLED_MASK_CHECK					  ||	\
	   BUILD_BUG_ON_ZERO(NCAPINTS != 18))

#define cpu_has(c, bit)							\
	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 :	\
	 test_cpu_cap(c, bit))

#define this_cpu_has(bit)						\
	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : 	\
	 x86_this_cpu_test_bit(bit, (unsigned long *)&cpu_info.x86_capability))

/*
 * This macro is for detection of features which need kernel
 * infrastructure to be used.  It may *not* directly test the CPU
 * itself.  Use the cpu_has() family if you want true runtime
 * testing of CPU features, like in hypervisor code where you are
 * supporting a possible guest feature where host support for it
 * is not relevant.
 */
#define cpu_feature_enabled(bit)	\
	(__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit))

#define boot_cpu_has(bit)	cpu_has(&boot_cpu_data, bit)

#define set_cpu_cap(c, bit)	set_bit(bit, (unsigned long *)((c)->x86_capability))
#define clear_cpu_cap(c, bit)	clear_bit(bit, (unsigned long *)((c)->x86_capability))
#define setup_clear_cpu_cap(bit) do { \
	clear_cpu_cap(&boot_cpu_data, bit);	\
	set_bit(bit, (unsigned long *)cpu_caps_cleared); \
} while (0)
#define setup_force_cpu_cap(bit) do { \
	set_cpu_cap(&boot_cpu_data, bit);	\
	set_bit(bit, (unsigned long *)cpu_caps_set);	\
} while (0)

#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_X86_FAST_FEATURE_TESTS)
/*
 * Static testing of CPU features.  Used the same as boot_cpu_has().
 * These will statically patch the target code for additional
 * performance.
 */
static __always_inline __pure bool _static_cpu_has(u16 bit)
{
		asm_volatile_goto("1: jmp 6f\n"
			 "2:\n"
			 ".skip -(((5f-4f) - (2b-1b)) > 0) * "
			         "((5f-4f) - (2b-1b)),0x90\n"
			 "3:\n"
			 ".section .altinstructions,\"a\"\n"
			 " .long 1b - .\n"		/* src offset */
			 " .long 4f - .\n"		/* repl offset */
			 " .word %P1\n"			/* always replace */
			 " .byte 3b - 1b\n"		/* src len */
			 " .byte 5f - 4f\n"		/* repl len */
			 " .byte 3b - 2b\n"		/* pad len */
			 ".previous\n"
			 ".section .altinstr_replacement,\"ax\"\n"
			 "4: jmp %l[t_no]\n"
			 "5:\n"
			 ".previous\n"
			 ".section .altinstructions,\"a\"\n"
			 " .long 1b - .\n"		/* src offset */
			 " .long 0\n"			/* no replacement */
			 " .word %P0\n"			/* feature bit */
			 " .byte 3b - 1b\n"		/* src len */
			 " .byte 0\n"			/* repl len */
			 " .byte 0\n"			/* pad len */
			 ".previous\n"
			 ".section .altinstr_aux,\"ax\"\n"
			 "6:\n"
			 " testb %[bitnum],%[cap_byte]\n"
			 " jnz %l[t_yes]\n"
			 " jmp %l[t_no]\n"
			 ".previous\n"
			 : : "i" (bit), "i" (X86_FEATURE_ALWAYS),
			     [bitnum] "i" (1 << (bit & 7)),
			     [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
			 : : t_yes, t_no);
	t_yes:
		return true;
	t_no:
		return false;
}

#define static_cpu_has(bit)					\
(								\
	__builtin_constant_p(boot_cpu_has(bit)) ?		\
		boot_cpu_has(bit) :				\
		_static_cpu_has(bit)				\
)
#else
/*
 * Fall back to dynamic for gcc versions which don't support asm goto. Should be
 * a minority now anyway.
 */
#define static_cpu_has(bit)		boot_cpu_has(bit)
#endif

#define cpu_has_bug(c, bit)		cpu_has(c, (bit))
#define set_cpu_bug(c, bit)		set_cpu_cap(c, (bit))
#define clear_cpu_bug(c, bit)		clear_cpu_cap(c, (bit))

#define static_cpu_has_bug(bit)		static_cpu_has((bit))
#define boot_cpu_has_bug(bit)		cpu_has_bug(&boot_cpu_data, (bit))

#define MAX_CPU_FEATURES		(NCAPINTS * 32)
#define cpu_have_feature		boot_cpu_has

#define CPU_FEATURE_TYPEFMT		"x86,ven%04Xfam%04Xmod%04X"
#define CPU_FEATURE_TYPEVAL		boot_cpu_data.x86_vendor, boot_cpu_data.x86, \
					boot_cpu_data.x86_model

#endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */
#endif /* _ASM_X86_CPUFEATURE_H */