cpuid.c File Reference

x86 CPU feature detection More...

#include <string.h>
#include <errno.h>
#include <ipxe/cpuid.h>

Go to the source code of this file.

Macros
#define	colour   0x861d
	Colour for debug messages. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
	FILE_SECBOOT (PERMITTED)
static int	cpuid_instruction_supported (void)
	Check whether or not CPUID instruction is supported. More...
int	cpuid_supported (uint32_t function)
	Check whether or not CPUID function is supported. More...
static void	x86_intel_features (struct x86_features *features)
	Get Intel-defined x86 CPU features. More...
static void	x86_amd_features (struct x86_features *features)
	Get AMD-defined x86 CPU features. More...
void	x86_features (struct x86_features *features)
	Get x86 CPU features. More...

Detailed Description

x86 CPU feature detection

Definition in file cpuid.c.

Macro Definition Documentation

colour

#define colour   0x861d

Colour for debug messages.

Definition at line 38 of file cpuid.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

FILE_SECBOOT()

FILE_SECBOOT

(

PERMITTED

)

cpuid_instruction_supported()

static int cpuid_instruction_supported ( void  )

static

Check whether or not CPUID instruction is supported.

Return values

rc	Return status code

Definition at line 45 of file cpuid.c.

                                                {
        unsigned long original;
        unsigned long inverted;

        /* Check for instruction existence via flag modifiability */
        __asm__ ( "pushf\n\t"
                  "pushf\n\t"
                  "pop %0\n\t"
                  "mov %0,%1\n\t"
                  "xor %2,%1\n\t"
                  "push %1\n\t"
                  "popf\n\t"
                  "pushf\n\t"
                  "pop %1\n\t"
                  "popf\n\t"
                  : "=&r" ( original ), "=&r" ( inverted )
                  : "ir" ( CPUID_FLAG ) );
        if ( ! ( ( original ^ inverted ) & CPUID_FLAG ) ) {
                DBGC ( colour, "CPUID instruction is not supported\n" );
                return -ENOTSUP;
        }

        return 0;
}

References __asm__(), colour, CPUID_FLAG, DBGC, and ENOTSUP.

Referenced by cpuid_supported().

cpuid_supported()

int cpuid_supported

(

uint32_t

function

)

Check whether or not CPUID function is supported.

Parameters

function

CPUID function

Return values

rc	Return status code

Definition at line 76 of file cpuid.c.

                                          {
        uint32_t max_function;
        uint32_t discard_b;
        uint32_t discard_c;
        uint32_t discard_d;
        int rc;

        /* Check that CPUID instruction is available */
        if ( ( rc = cpuid_instruction_supported() ) != 0 )
                return rc;

        /* Find highest supported function number within this family */
        cpuid ( ( function & ( CPUID_EXTENDED | CPUID_HYPERVISOR ) ), 0,
                  &max_function, &discard_b, &discard_c, &discard_d );

        /* Fail if maximum function number is meaningless (e.g. if we
         * are attempting to call an extended function on a CPU which
         * does not support them).
         */
        if ( ( max_function & CPUID_AMD_CHECK_MASK ) !=
             ( function & CPUID_AMD_CHECK_MASK ) ) {
                DBGC ( colour, "CPUID invalid maximum function %#08x\n",
                       max_function );
                return -EINVAL;
        }

        /* Fail if this function is not supported */
        if ( function > max_function ) {
                DBGC ( colour, "CPUID function %#08x not supported\n",
                       function );
                return -ENOTTY;
        }

        return 0;
}

References colour, CPUID_AMD_CHECK_MASK, CPUID_EXTENDED, CPUID_HYPERVISOR, cpuid_instruction_supported(), DBGC, discard_c, EINVAL, ENOTTY, and rc.

Referenced by cpuid_settings_fetch(), rdtsc_probe(), x86_amd_features(), and x86_intel_features().

x86_intel_features()

static void x86_intel_features ( struct x86_features *  features )

static

Get Intel-defined x86 CPU features.

Parameters

features

x86 CPU features to fill in

Definition at line 117 of file cpuid.c.

                                                                 {
        uint32_t discard_a;
        uint32_t discard_b;
        int rc;

        /* Check that features are available via CPUID */
        if ( ( rc = cpuid_supported ( CPUID_FEATURES ) ) != 0 ) {
                DBGC ( features, "CPUID has no Intel-defined features\n" );
                return;
        }

        /* Get features */
        cpuid ( CPUID_FEATURES, 0, &discard_a, &discard_b,
                &features->intel.ecx, &features->intel.edx );
        DBGC ( features, "CPUID Intel features: %%ecx=%08x, %%edx=%08x\n",
               features->intel.ecx, features->intel.edx );

}

References CPUID_FEATURES, cpuid_supported(), DBGC, features, and rc.

Referenced by x86_features().

x86_amd_features()

static void x86_amd_features ( struct x86_features *  features )

static

Get AMD-defined x86 CPU features.

Parameters

features

x86 CPU features to fill in

Definition at line 141 of file cpuid.c.

                                                               {
        uint32_t discard_a;
        uint32_t discard_b;
        int rc;

        /* Check that features are available via CPUID */
        if ( ( rc = cpuid_supported ( CPUID_AMD_FEATURES ) ) != 0 ) {
                DBGC ( features, "CPUID has no AMD-defined features\n" );
                return;
        }

        /* Get features */
        cpuid ( CPUID_AMD_FEATURES, 0, &discard_a, &discard_b,
                &features->amd.ecx, &features->amd.edx );
        DBGC ( features, "CPUID AMD features: %%ecx=%08x, %%edx=%08x\n",
               features->amd.ecx, features->amd.edx );
}

References CPUID_AMD_FEATURES, cpuid_supported(), DBGC, features, and rc.

Referenced by x86_features().

x86_features()

void x86_features

(

struct x86_features *

features

)

Get x86 CPU features.

Parameters

features

x86 CPU features to fill in

Definition at line 164 of file cpuid.c.

                                                    {

        /* Clear all features */
        memset ( features, 0, sizeof ( *features ) );

        /* Get Intel-defined features */
        x86_intel_features ( features );

        /* Get AMD-defined features */
        x86_amd_features ( features );
}

References features, memset(), x86_amd_features(), and x86_intel_features().

Referenced by check_fxsr(), cpuid_exec(), hv_check_hv(), rdrand_entropy_enable(), and rtc_entropy_enable().