ucode.c

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/*
 * Copyright (C) 2024 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
 *
 * Microcode updates
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>
#include <ipxe/uaccess.h>
#include <ipxe/umalloc.h>
#include <ipxe/image.h>
#include <ipxe/cpuid.h>
#include <ipxe/msr.h>
#include <ipxe/mp.h>
#include <ipxe/timer.h>
#include <ipxe/ucode.h>

/**
 * Maximum number of hyperthread siblings
 *
 * Microcode updates must not be performed on hyperthread siblings at
 * the same time, since they share microcode storage.
 *
 * Hyperthread siblings are always the lowest level of the CPU
 * topology and correspond to the least significant bits of the APIC
 * ID.  We may therefore avoid collisions by performing the microcode
 * updates in batches, with each batch targeting just one value for
 * the least significant N bits of the APIC ID.
 *
 * We assume that no CPUs exist with more than this number of
 * hyperthread siblings.  (This must be a power of two.)
 */
#define UCODE_MAX_HT 8

/** Time to wait for a microcode update to complete */
#define UCODE_WAIT_MS 10

/** A CPU vendor string */
union ucode_vendor_id {
        /** CPUID registers */
        uint32_t dword[3];
        /** Human-readable string */
        uint8_t string[12];
};

/** A CPU vendor */
struct ucode_vendor {
        /** Vendor string */
        union ucode_vendor_id id;
        /** Microcode load trigger MSR */
        uint32_t trigger_msr;
        /** Microcode version requires manual clear */
        uint8_t ver_clear;
        /** Microcode version is reported via high dword */
        uint8_t ver_high;
};

/** A microcode update */
struct ucode_update {
        /** CPU vendor, if known */
        struct ucode_vendor *vendor;
        /** Boot processor CPU signature */
        uint32_t signature;
        /** Platform ID */
        uint32_t platform;
        /** Number of potentially relevant signatures found */
        unsigned int count;
        /** Update descriptors (if being populated) */
        struct ucode_descriptor *desc;
};

/** A microcode update summary */
struct ucode_summary {
        /** Number of CPUs processed */
        unsigned int count;
        /** Lowest observed microcode version */
        int32_t low;
        /** Highest observed microcode version */
        int32_t high;
};

/** Intel CPU vendor */
static struct ucode_vendor ucode_intel = {
        .id = { .string = "GenuineIntel" },
        .ver_clear = 1,
        .ver_high = 1,
        .trigger_msr = MSR_UCODE_TRIGGER_INTEL,
};

/** AMD CPU vendor */
static struct ucode_vendor ucode_amd = {
        .id = { .string = "AuthenticAMD" },
        .trigger_msr = MSR_UCODE_TRIGGER_AMD,
};

/** List of known CPU vendors */
static struct ucode_vendor *ucode_vendors[] = {
        &ucode_intel,
        &ucode_amd,
};

/**
 * Get CPU vendor name (for debugging)
 *
 * @v vendor            CPU vendor
 * @ret name            Name
 */
static const char * ucode_vendor_name ( const union ucode_vendor_id *vendor ) {
        static union {
                union ucode_vendor_id vendor;
                char text[ sizeof ( *vendor ) + 1 /* NUL */ ];
        } u;

        /* Construct name */
        memcpy ( &u.vendor, vendor, sizeof ( u.vendor ) );
        u.text[ sizeof ( u.text ) - 1 ] = '\0';
        return u.text;
}

/**
 * Check status report
 *
 * @v update            Microcode update
 * @v control           Microcode update control
 * @v summary           Microcode update summary
 * @v id                APIC ID
 * @v optional          Status report is optional
 * @ret rc              Return status code
 */
static int ucode_status ( struct ucode_update *update,
                          struct ucode_control *control,
                          struct ucode_summary *summary,
                          unsigned int id, int optional ) {
        struct ucode_status status;
        struct ucode_descriptor *desc;

        /* Sanity check */
        assert ( id <= control->apic_max );

        /* Read status report */
        copy_from_user ( &status, phys_to_user ( control->status ),
                         ( id * sizeof ( status ) ), sizeof ( status ) );

        /* Ignore empty optional status reports */
        if ( optional && ( ! status.signature ) )
                return 0;
        DBGC ( update, "UCODE %#08x signature %#08x ucode %#08x->%#08x\n",
               id, status.signature, status.before, status.after );

        /* Check CPU signature */
        if ( ! status.signature ) {
                DBGC2 ( update, "UCODE %#08x has no signature\n", id );
                return -ENOENT;
        }

        /* Check APIC ID is correct */
        if ( status.id != id ) {
                DBGC ( update, "UCODE %#08x wrong APIC ID %#08x\n",
                       id, status.id );
                return -EINVAL;
        }

        /* Check that maximum APIC ID was not exceeded */
        if ( control->apic_unexpected ) {
                DBGC ( update, "UCODE %#08x saw unexpected APIC ID %#08x\n",
                       id, control->apic_unexpected );
                return -ERANGE;
        }

        /* Check microcode was not downgraded */
        if ( status.after < status.before ) {
                DBGC ( update, "UCODE %#08x was downgraded %#08x->%#08x\n",
                       id, status.before, status.after );
                return -ENOTTY;
        }

        /* Check that expected updates (if any) were applied */
        for ( desc = update->desc ; desc->signature ; desc++ ) {
                if ( ( desc->signature == status.signature ) &&
                     ( status.after < desc->version ) ) {
                        DBGC ( update, "UCODE %#08x failed update %#08x->%#08x "
                               "(wanted %#08x)\n", id, status.before,
                               status.after, desc->version );
                        return -EIO;
                }
        }

        /* Update summary */
        summary->count++;
        if ( status.before < summary->low )
                summary->low = status.before;
        if ( status.after > summary->high )
                summary->high = status.after;

        return 0;
}

/**
 * Update microcode on all CPUs
 *
 * @v image             Microcode image
 * @v update            Microcode update
 * @v summary           Microcode update summary to fill in
 * @ret rc              Return status code
 */
static int ucode_update_all ( struct image *image,
                              struct ucode_update *update,
                              struct ucode_summary *summary ) {
        struct ucode_control control;
        struct ucode_vendor *vendor;
        userptr_t status;
        unsigned int max;
        unsigned int i;
        size_t len;
        int rc;

        /* Initialise summary */
        summary->count = 0;
        summary->low = UCODE_VERSION_MAX;
        summary->high = UCODE_VERSION_MIN;

        /* Allocate status reports */
        max = mp_max_cpuid();
        len = ( ( max + 1 ) * sizeof ( struct ucode_status ) );
        status = umalloc ( len );
        if ( ! status ) {
                DBGC ( image, "UCODE %s could not allocate %d status reports\n",
                       image->name, ( max + 1 ) );
                rc = -ENOMEM;
                goto err_alloc;
        }
        memset_user ( status, 0, 0, len );

        /* Construct control structure */
        memset ( &control, 0, sizeof ( control ) );
        control.desc = virt_to_phys ( update->desc );
        control.status = user_to_phys ( status, 0 );
        vendor = update->vendor;
        if ( vendor ) {
                control.ver_clear = vendor->ver_clear;
                control.ver_high = vendor->ver_high;
                control.trigger_msr = vendor->trigger_msr;
        } else {
                assert ( update->count == 0 );
        }
        control.apic_max = max;

        /* Update microcode on boot processor */
        mp_exec_boot ( ucode_update, &control );
        if ( ( rc = ucode_status ( update, &control, summary,
                                   mp_boot_cpuid(), 0 ) ) != 0 ) {
                DBGC ( image, "UCODE %s failed on boot processor: %s\n",
                       image->name, strerror ( rc ) );
                goto err_boot;
        }

        /* Update microcode on application processors, avoiding
         * simultaneous updates on hyperthread siblings.
         */
        build_assert ( ( UCODE_MAX_HT & ( UCODE_MAX_HT - 1 ) ) == 0 );
        control.apic_mask = ( UCODE_MAX_HT - 1 );
        for ( ; control.apic_test <= control.apic_mask ; control.apic_test++ ) {
                mp_start_all ( ucode_update, &control );
                mdelay ( UCODE_WAIT_MS );
        }

        /* Check status reports */
        summary->count = 0;
        for ( i = 0 ; i <= max ; i++ ) {
                if ( ( rc = ucode_status ( update, &control, summary,
                                           i, 1 ) ) != 0 ) {
                        goto err_status;
                }
        }

        /* Success */
        rc = 0;

 err_status:
 err_boot:
        ufree ( status );
 err_alloc:
        return rc;
}

/**
 * Add descriptor to list (if applicable)
 *
 * @v image             Microcode image
 * @v start             Starting offset within image
 * @v vendor            CPU vendor
 * @v desc              Microcode descriptor
 * @v platforms         Supported platforms, or 0 for all platforms
 * @v update            Microcode update
 */
static void ucode_describe ( struct image *image, size_t start,
                             const struct ucode_vendor *vendor,
                             const struct ucode_descriptor *desc,
                             uint32_t platforms, struct ucode_update *update ) {

        /* Dump descriptor information */
        DBGC2 ( image, "UCODE %s+%#04zx %s %#08x", image->name, start,
                ucode_vendor_name ( &vendor->id ), desc->signature );
        if ( platforms )
                DBGC2 ( image, " (%#02x)", platforms );
        DBGC2 ( image, " version %#08x\n", desc->version );

        /* Check applicability */
        if ( vendor != update->vendor )
                return;
        if ( ( desc->signature ^ update->signature ) & UCODE_SIGNATURE_MASK )
                return;
        if ( platforms && ( ! ( platforms & update->platform ) ) )
                return;

        /* Add descriptor, if applicable */
        if ( update->desc ) {
                memcpy ( &update->desc[update->count], desc, sizeof ( *desc ) );
                DBGC ( image, "UCODE %s+%#04zx found %s %#08x version %#08x\n",
                       image->name, start, ucode_vendor_name ( &vendor->id ),
                       desc->signature, desc->version );
        }
        update->count++;
}

/**
 * Verify checksum
 *
 * @v image             Microcode image
 * @v start             Starting offset
 * @v len               Length
 * @ret rc              Return status code
 */
static int ucode_verify ( struct image *image, size_t start, size_t len ) {
        uint32_t checksum = 0;
        uint32_t dword;
        size_t offset;

        /* Check length is a multiple of dwords */
        if ( ( len % sizeof ( dword ) ) != 0 ) {
                DBGC ( image, "UCODE %s+%#04zx invalid length %#zx\n",
                       image->name, start, len );
                return -EINVAL;
        }

        /* Calculate checksum */
        for ( offset = start ; len ;
              offset += sizeof ( dword ), len -= sizeof ( dword ) ) {
                copy_from_user ( &dword, image->data, offset,
                                 sizeof ( dword ) );
                checksum += dword;
        }
        if ( checksum != 0 ) {
                DBGC ( image, "UCODE %s+%#04zx bad checksum %#08x\n",
                       image->name, start, checksum );
                return -EINVAL;
        }

        return 0;
}

/**
 * Parse Intel microcode image
 *
 * @v image             Microcode image
 * @v start             Starting offset within image
 * @v update            Microcode update
 * @ret len             Length consumed, or negative error
 */
static int ucode_parse_intel ( struct image *image, size_t start,
                               struct ucode_update *update ) {
        struct intel_ucode_header hdr;
        struct intel_ucode_ext_header exthdr;
        struct intel_ucode_ext ext;
        struct ucode_descriptor desc;
        size_t remaining;
        size_t offset;
        size_t data_len;
        size_t len;
        unsigned int i;
        int rc;

        /* Read header */
        remaining = ( image->len - start );
        if ( remaining < sizeof ( hdr ) ) {
                DBGC ( image, "UCODE %s+%#04zx too small for Intel header\n",
                       image->name, start );
                return -ENOEXEC;
        }
        copy_from_user ( &hdr, image->data, start, sizeof ( hdr ) );

        /* Determine lengths */
        data_len = hdr.data_len;
        if ( ! data_len )
                data_len = INTEL_UCODE_DATA_LEN;
        len = hdr.len;
        if ( ! len )
                len = ( sizeof ( hdr ) + data_len );

        /* Verify a selection of fields */
        if ( ( hdr.hver != INTEL_UCODE_HVER ) ||
             ( hdr.lver != INTEL_UCODE_LVER ) ||
             ( len < sizeof ( hdr ) ) ||
             ( len > remaining ) ||
             ( data_len > ( len - sizeof ( hdr ) ) ) ||
             ( ( data_len % sizeof ( uint32_t ) ) != 0 ) ||
             ( ( len % INTEL_UCODE_ALIGN ) != 0 ) ) {
                DBGC2 ( image, "UCODE %s+%#04zx is not an Intel update\n",
                        image->name, start );
                return -EINVAL;
        }
        DBGC2 ( image, "UCODE %s+%#04zx is an Intel update\n",
                image->name, start );

        /* Verify checksum */
        if ( ( rc = ucode_verify ( image, start, len ) ) != 0 )
                return rc;

        /* Populate descriptor */
        desc.signature = hdr.signature;
        desc.version = hdr.version;
        desc.address = user_to_phys ( image->data,
                                      ( start + sizeof ( hdr ) ) );

        /* Add non-extended descriptor, if applicable */
        ucode_describe ( image, start, &ucode_intel, &desc, hdr.platforms,
                         update );

        /* Construct extended descriptors, if applicable */
        offset = ( sizeof ( hdr ) + data_len );
        if ( offset <= ( len - sizeof ( exthdr ) ) ) {

                /* Read extended header */
                copy_from_user ( &exthdr, image->data, ( start + offset ),
                                 sizeof ( exthdr ) );
                offset += sizeof ( exthdr );

                /* Read extended signatures */
                for ( i = 0 ; i < exthdr.count ; i++ ) {

                        /* Read extended signature */
                        if ( offset > ( len - sizeof ( ext ) ) ) {
                                DBGC ( image, "UCODE %s+%#04zx extended "
                                       "signature overrun\n",
                                       image->name, start );
                                return -EINVAL;
                        }
                        copy_from_user ( &ext, image->data, ( start + offset ),
                                         sizeof ( ext ) );
                        offset += sizeof ( ext );

                        /* Avoid duplicating non-extended descriptor */
                        if ( ( ext.signature == hdr.signature ) &&
                             ( ext.platforms == hdr.platforms ) ) {
                                continue;
                        }

                        /* Construct descriptor, if applicable */
                        desc.signature = ext.signature;
                        ucode_describe ( image, start, &ucode_intel, &desc,
                                         ext.platforms, update );
                }
        }

        return len;
}

/**
 * Parse AMD microcode image
 *
 * @v image             Microcode image
 * @v start             Starting offset within image
 * @v update            Microcode update
 * @ret len             Length consumed, or negative error
 */
static int ucode_parse_amd ( struct image *image, size_t start,
                             struct ucode_update *update ) {
        struct amd_ucode_header hdr;
        struct amd_ucode_equivalence equiv;
        struct amd_ucode_patch_header phdr;
        struct amd_ucode_patch patch;
        struct ucode_descriptor desc;
        size_t remaining;
        size_t offset;
        unsigned int count;
        unsigned int used;
        unsigned int i;

        /* Read header */
        remaining = ( image->len - start );
        if ( remaining < sizeof ( hdr ) ) {
                DBGC ( image, "UCODE %s+%#04zx too small for AMD header\n",
                       image->name, start );
                return -ENOEXEC;
        }
        copy_from_user ( &hdr, image->data, start, sizeof ( hdr ) );

        /* Check header */
        if ( hdr.magic != AMD_UCODE_MAGIC ) {
                DBGC2 ( image, "UCODE %s+%#04zx is not an AMD update\n",
                        image->name, start );
                return -ENOEXEC;
        }
        DBGC2 ( image, "UCODE %s+%#04zx is an AMD update\n",
                image->name, start );
        if ( hdr.type != AMD_UCODE_EQUIV_TYPE ) {
                DBGC ( image, "UCODE %s+%#04zx unsupported equivalence table "
                       "type %d\n", image->name, start, hdr.type );
                return -ENOTSUP;
        }
        if ( hdr.len > ( remaining - sizeof ( hdr ) ) ) {
                DBGC ( image, "UCODE %s+%#04zx truncated equivalence table\n",
                       image->name, start );
                return -EINVAL;
        }

        /* Count number of equivalence table entries */
        offset = sizeof ( hdr );
        for ( count = 0 ; offset < ( sizeof ( hdr ) + hdr.len ) ;
              count++, offset += sizeof ( equiv ) ) {
                copy_from_user ( &equiv, image->data, ( start + offset ),
                                 sizeof ( equiv ) );
                if ( ! equiv.signature )
                        break;
        }
        DBGC2 ( image, "UCODE %s+%#04zx has %d equivalence table entries\n",
                image->name, start, count );

        /* Parse available updates */
        offset = ( sizeof ( hdr ) + hdr.len );
        used = 0;
        while ( used < count ) {

                /* Read patch header */
                if ( ( offset + sizeof ( phdr ) ) > remaining ) {
                        DBGC ( image, "UCODE %s+%#04zx truncated patch "
                               "header\n", image->name, start );
                        return -EINVAL;
                }
                copy_from_user ( &phdr, image->data, ( start + offset ),
                                 sizeof ( phdr ) );
                offset += sizeof ( phdr );

                /* Validate patch header */
                if ( phdr.type != AMD_UCODE_PATCH_TYPE ) {
                        DBGC ( image, "UCODE %s+%#04zx unsupported patch type "
                               "%d\n", image->name, start, phdr.type );
                        return -ENOTSUP;
                }
                if ( phdr.len < sizeof ( patch ) ) {
                        DBGC ( image, "UCODE %s+%#04zx underlength patch\n",
                               image->name, start );
                        return -EINVAL;
                }
                if ( phdr.len > ( remaining - offset ) ) {
                        DBGC ( image, "UCODE %s+%#04zx truncated patch\n",
                               image->name, start );
                        return -EINVAL;
                }

                /* Read patch and construct descriptor */
                copy_from_user ( &patch, image->data, ( start + offset ),
                                 sizeof ( patch ) );
                desc.version = patch.version;
                desc.address = user_to_phys ( image->data, ( start + offset ) );
                offset += phdr.len;

                /* Parse equivalence table to find matching signatures */
                for ( i = 0 ; i < count ; i++ ) {
                        copy_from_user ( &equiv, image->data,
                                         ( start + sizeof ( hdr ) +
                                           ( i * ( sizeof ( equiv ) ) ) ),
                                         sizeof ( equiv ) );
                        if ( patch.id == equiv.id ) {
                                desc.signature = equiv.signature;
                                ucode_describe ( image, start, &ucode_amd,
                                                 &desc, 0, update );
                                used++;
                        }
                }
        }

        return offset;
}

/**
 * Parse microcode image
 *
 * @v image             Microcode image
 * @v update            Microcode update
 * @ret rc              Return status code
 */
static int ucode_parse ( struct image *image, struct ucode_update *update ) {
        size_t start;
        int len;

        /* Attempt to parse concatenated microcode updates */
        for ( start = 0 ; start < image->len ; start += len ) {

                /* Attempt to parse as Intel microcode */
                len = ucode_parse_intel ( image, start, update );
                if ( len > 0 )
                        continue;

                /* Attempt to parse as AMD microcode */
                len = ucode_parse_amd ( image, start, update );
                if ( len > 0 )
                        continue;

                /* Not a recognised microcode format */
                DBGC ( image, "UCODE %s+%zx not recognised\n",
                       image->name, start );
                return -ENOEXEC;
        }

        return 0;
}

/**
 * Execute microcode update
 *
 * @v image             Microcode image
 * @ret rc              Return status code
 */
static int ucode_exec ( struct image *image ) {
        struct ucode_update update;
        struct ucode_vendor *vendor;
        struct ucode_summary summary;
        union ucode_vendor_id id;
        uint64_t platform_id;
        uint32_t discard_a;
        uint32_t discard_b;
        uint32_t discard_c;
        uint32_t discard_d;
        unsigned int check;
        unsigned int i;
        size_t len;
        int rc;

        /* Initialise update */
        memset ( &update, 0, sizeof ( update ) );
        cpuid ( CPUID_VENDOR_ID, 0, &discard_a, &id.dword[0], &id.dword[2],
                &id.dword[1] );
        cpuid ( CPUID_FEATURES, 0, &update.signature, &discard_b,
                &discard_c, &discard_d );

        /* Identify CPU vendor, if recognised */
        for ( i = 0 ; i < ( sizeof ( ucode_vendors ) /
                            sizeof ( ucode_vendors[0] ) ) ; i++ ) {
                vendor = ucode_vendors[i];
                if ( memcmp ( &id, &vendor->id, sizeof ( id ) ) == 0 )
                        update.vendor = vendor;
        }

        /* Identify platform, if applicable */
        if ( update.vendor == &ucode_intel ) {
                platform_id = rdmsr ( MSR_PLATFORM_ID );
                update.platform =
                        ( 1 << MSR_PLATFORM_ID_VALUE ( platform_id ) );
        }

        /* Count number of matching update descriptors */
        DBGC ( image, "UCODE %s applying to %s %#08x",
               image->name, ucode_vendor_name ( &id ), update.signature );
        if ( update.platform )
                DBGC ( image, " (%#02x)", update.platform );
        DBGC ( image, "\n" );
        if ( ( rc = ucode_parse ( image, &update ) ) != 0 )
                goto err_count;
        DBGC ( image, "UCODE %s found %d matching update(s)\n",
               image->name, update.count );

        /* Allocate descriptors */
        len = ( ( update.count + 1 /* terminator */ ) *
                sizeof ( update.desc[0] ) );
        update.desc = zalloc ( len );
        if ( ! update.desc ) {
                rc = -ENOMEM;
                goto err_alloc;
        }

        /* Populate descriptors */
        check = update.count;
        update.count = 0;
        if ( ( rc = ucode_parse ( image, &update ) ) != 0 )
                goto err_parse;
        assert ( check == update.count );

        /* Perform update */
        if ( ( rc = ucode_update_all ( image, &update, &summary ) ) != 0 )
                goto err_update;

        /* Print summary if directed to do so */
        if ( image->cmdline && ( strstr ( image->cmdline, "-v" ) ) ) {
                printf ( "Microcode: " );
                if ( summary.low == summary.high ) {
                        printf ( "already version %#x", summary.low );
                } else {
                        printf ( "updated version %#x->%#x",
                                 summary.low, summary.high );
                }
                printf ( " (x%d)\n", summary.count );
        }

 err_update:
 err_parse:
        free ( update.desc );
 err_alloc:
 err_count:
        return rc;
}

/**
 * Probe microcode update image
 *
 * @v image             Microcode image
 * @ret rc              Return status code
 */
static int ucode_probe ( struct image *image ) {
        union {
                struct intel_ucode_header intel;
                struct amd_ucode_header amd;
        } header;

        /* Sanity check */
        if ( image->len < sizeof ( header )  ) {
                DBGC ( image, "UCODE %s too short\n", image->name );
                return -ENOEXEC;
        }

        /* Read first microcode image header */
        copy_from_user ( &header, image->data, 0, sizeof ( header ) );

        /* Check for something that looks like an Intel update
         *
         * Intel updates unfortunately have no magic signatures or
         * other easily verifiable fields.  We check a small selection
         * of header fields that can be easily verified.
         *
         * We do not attempt to fully parse the update, since we want
         * errors to be reported at the point of attempting to execute
         * the image, and do not want to have a microcode image
         * erroneously treated as a PXE boot executable.
         */
        if ( ( header.intel.hver == INTEL_UCODE_HVER ) &&
             ( header.intel.lver == INTEL_UCODE_LVER ) &&
             ( ( header.intel.date.century == 0x19 ) ||
               ( ( header.intel.date.century >= 0x20 ) &&
                 ( header.intel.date.century <= 0x29 ) ) ) ) {
                DBGC ( image, "UCODE %s+%#04zx looks like an Intel update\n",
                       image->name, ( ( size_t ) 0 ) );
                return 0;
        }

        /* Check for AMD update signature */
        if ( ( header.amd.magic == AMD_UCODE_MAGIC ) &&
             ( header.amd.type == AMD_UCODE_EQUIV_TYPE ) ) {
                DBGC ( image, "UCODE %s+%#04zx looks like an AMD update\n",
                       image->name, ( ( size_t ) 0 ) );
                return 0;
        }

        return -ENOEXEC;
}

/** Microcode update image type */
struct image_type ucode_image_type __image_type ( PROBE_NORMAL ) = {
        .name = "ucode",
        .probe = ucode_probe,
        .exec = ucode_exec,
};