cpuid_settings.c

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/*
 * Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );

#include <string.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/init.h>
#include <ipxe/settings.h>
#include <ipxe/cpuid.h>

/** @file
 *
 * x86 CPUID settings
 *
 * CPUID settings are numerically encoded as:
 *
 *  Bit  31     Extended function
 *  Bits 30-24  (bit 22 = 1) Subfunction number
 *  Bit  30     (bit 22 = 0) Hypervisor function
 *  Bits 29-24  (bit 22 = 0) Number of consecutive functions to call, minus one
 *  Bit  23     Return result as little-endian (used for strings)
 *  Bit  22     Interpret bits 30-24 as a subfunction number
 *  Bits 21-18  Unused
 *  Bits 17-16  Number of registers in register array, minus one
 *  Bits 15-8   Array of register indices.  First entry in array is in
 *              bits 9-8.  Indices are 0-%eax, 1-%ebx, 2-%ecx, 3-%edx.
 *  Bits 7-0    Starting function number (excluding "extended" bit)
 *
 * This encoding scheme is designed to allow the common case of
 * extracting a single register from a single function to be encoded
 * using "cpuid/<register>.<function>", e.g. "cpuid/2.0x80000001" to
 * retrieve the value of %ecx from calling CPUID with %eax=0x80000001.
 *
 * A subfunction (i.e. an input value for %ecx) may be specified using
 * "cpuid/<subfunction>.0x40.<register>.<function>".  This slightly
 * cumbersome syntax is required in order to maintain backwards
 * compatibility with older scripts.
 */

/** CPUID setting tag register indices */
enum cpuid_registers {
        CPUID_EAX = 0,
        CPUID_EBX = 1,
        CPUID_ECX = 2,
        CPUID_EDX = 3,
};

/** CPUID setting tag flags */
enum cpuid_flags {
        CPUID_LITTLE_ENDIAN = 0x00800000UL,
        CPUID_USE_SUBFUNCTION = 0x00400000UL,
};

/**
 * Construct CPUID setting tag
 *
 * @v function          Starting function number
 * @v subfunction       Subfunction, or number of consecutive functions minus 1
 * @v flags             Flags
 * @v num_registers     Number of registers in register array
 * @v register1         First register in register array (or zero, if empty)
 * @v register2         Second register in register array (or zero, if empty)
 * @v register3         Third register in register array (or zero, if empty)
 * @v register4         Fourth register in register array (or zero, if empty)
 * @ret tag             Setting tag
 */
#define CPUID_TAG( function, subfunction, flags, num_registers,         \
                   register1, register2, register3, register4 )         \
        ( (function) | ( (subfunction) << 24 ) | (flags) |              \
          ( ( (num_registers) - 1 ) << 16 ) |                           \
          ( (register1) << 8 ) | ( (register2) << 10 ) |                \
          ( (register3) << 12 ) | ( (register4) << 14 ) )

/**
 * Extract starting function number from CPUID setting tag
 *
 * @v tag               Setting tag
 * @ret function        Starting function number
 */
#define CPUID_FUNCTION( tag ) ( (tag) & 0xc00000ffUL )

/**
 * Extract subfunction number from CPUID setting tag
 *
 * @v tag               Setting tag
 * @ret subfunction     Subfunction number
 */
#define CPUID_SUBFUNCTION( tag ) ( ( (tag) >> 24 ) & 0x7f )

/**
 * Extract number of consecutive functions from CPUID setting tag
 *
 * @v tag               Setting tag
 * @ret num_functions   Number of consecutive functions
 */
#define CPUID_NUM_FUNCTIONS( tag ) ( ( ( (tag) >> 24 ) & 0x3f ) + 1 )

/**
 * Extract register array from CPUID setting tag
 *
 * @v tag               Setting tag
 * @ret registers       Register array
 */
#define CPUID_REGISTERS( tag ) ( ( (tag) >> 8 ) & 0xff )

/**
 * Extract number of registers from CPUID setting tag
 *
 * @v tag               Setting tag
 * @ret num_registers   Number of registers within register array
 */
#define CPUID_NUM_REGISTERS( tag ) ( ( ( (tag) >> 16 ) & 0x3 ) + 1 )

/** CPUID settings scope */
static const struct settings_scope cpuid_settings_scope;

/**
 * Check applicability of CPUID setting
 *
 * @v settings          Settings block
 * @v setting           Setting
 * @ret applies         Setting applies within this settings block
 */
static int cpuid_settings_applies ( struct settings *settings __unused,
                                    const struct setting *setting ) {

        return ( setting->scope == &cpuid_settings_scope );
}

/**
 * Fetch value of CPUID setting
 *
 * @v settings          Settings block
 * @v setting           Setting to fetch
 * @v data              Buffer to fill with setting data
 * @v len               Length of buffer
 * @ret len             Length of setting data, or negative error
 */
static int cpuid_settings_fetch ( struct settings *settings,
                                  struct setting *setting,
                                  void *data, size_t len ) {
        uint32_t function;
        uint32_t subfunction;
        uint32_t num_functions;
        uint32_t registers;
        uint32_t num_registers;
        uint32_t buf[4];
        uint32_t output;
        size_t frag_len;
        size_t result_len = 0;
        int rc;

        /* Call each function in turn */
        function = CPUID_FUNCTION ( setting->tag );
        if ( setting->tag & CPUID_USE_SUBFUNCTION ) {
                function &= ~CPUID_HYPERVISOR;
                subfunction = CPUID_SUBFUNCTION ( setting->tag );
                num_functions = 1;
        } else {
                subfunction = 0;
                num_functions = CPUID_NUM_FUNCTIONS ( setting->tag );
        }
        for ( ; num_functions-- ; function++ ) {

                /* Fail if this function is not supported */
                if ( ( rc = cpuid_supported ( function ) ) != 0 ) {
                        DBGC ( settings, "CPUID function %#08x not supported: "
                               "%s\n", function, strerror ( rc ) );
                        return rc;
                }

                /* Issue CPUID */
                cpuid ( function, subfunction, &buf[CPUID_EAX],
                        &buf[CPUID_EBX], &buf[CPUID_ECX], &buf[CPUID_EDX] );
                DBGC ( settings, "CPUID %#08x:%x => %#08x:%#08x:%#08x:%#08x\n",
                       function, subfunction, buf[0], buf[1], buf[2], buf[3] );

                /* Copy results to buffer */
                registers = CPUID_REGISTERS ( setting->tag );
                num_registers = CPUID_NUM_REGISTERS ( setting->tag );
                for ( ; num_registers-- ; registers >>= 2 ) {
                        output = buf[ registers & 0x3 ];
                        if ( ! ( setting->tag & CPUID_LITTLE_ENDIAN ) )
                                output = cpu_to_be32 ( output );
                        frag_len = sizeof ( output );
                        if ( frag_len > len )
                                frag_len = len;
                        memcpy ( data, &output, frag_len );
                        data += frag_len;
                        len -= frag_len;
                        result_len += sizeof ( output );
                }
        }

        /* Set type if not already specified */
        if ( ! setting->type )
                setting->type = &setting_type_hexraw;

        return result_len;
}

/** CPUID settings operations */
static struct settings_operations cpuid_settings_operations = {
        .applies = cpuid_settings_applies,
        .fetch = cpuid_settings_fetch,
};

/** CPUID settings */
static struct settings cpuid_settings = {
        .refcnt = NULL,
        .siblings = LIST_HEAD_INIT ( cpuid_settings.siblings ),
        .children = LIST_HEAD_INIT ( cpuid_settings.children ),
        .op = &cpuid_settings_operations,
        .default_scope = &cpuid_settings_scope,
};

/** Initialise CPUID settings */
static void cpuid_settings_init ( void ) {
        int rc;

        if ( ( rc = register_settings ( &cpuid_settings, NULL,
                                        "cpuid" ) ) != 0 ) {
                DBG ( "CPUID could not register settings: %s\n",
                      strerror ( rc ) );
                return;
        }
}

/** CPUID settings initialiser */
struct init_fn cpuid_settings_init_fn __init_fn ( INIT_NORMAL ) = {
        .name = "cpuid",
        .initialise = cpuid_settings_init,
};

/** CPU vendor setting */
const struct setting cpuvendor_setting __setting ( SETTING_HOST_EXTRA,
                                                   cpuvendor ) = {
        .name = "cpuvendor",
        .description = "CPU vendor",
        .tag = CPUID_TAG ( CPUID_VENDOR_ID, 0, CPUID_LITTLE_ENDIAN, 3,
                           CPUID_EBX, CPUID_EDX, CPUID_ECX, 0 ),
        .type = &setting_type_string,
        .scope = &cpuid_settings_scope,
};

/** CPU model setting */
const struct setting cpumodel_setting __setting ( SETTING_HOST_EXTRA,
                                                  cpumodel ) = {
        .name = "cpumodel",
        .description = "CPU model",
        .tag = CPUID_TAG ( CPUID_MODEL, 2, CPUID_LITTLE_ENDIAN, 4,
                           CPUID_EAX, CPUID_EBX, CPUID_ECX, CPUID_EDX ),
        .type = &setting_type_string,
        .scope = &cpuid_settings_scope,
};