fmap.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <boot_device.h>
#include <cbmem.h>
#include <console/console.h>
#include <fmap.h>
#include <metadata_hash.h>
#include <stddef.h>
#include <string.h>
#include <symbols.h>
#include <endian.h>
 
#include "fmap_config.h"
 
/*
 * See http://code.google.com/p/flashmap/ for more information on FMAP.
 */
 
static int fmap_print_once;
static struct region_device fmap_cache;
 
#define print_once(...) do { \
                if (!fmap_print_once) \
                        printk(__VA_ARGS__); \
        } while (0)
 
uint64_t get_fmap_flash_offset(void)
{
        return FMAP_OFFSET;
}
 
static int verify_fmap(const struct fmap *fmap)
{
        if (memcmp(fmap->signature, FMAP_SIGNATURE, sizeof(fmap->signature)))
                return -1;
 
        static bool done = false;
        if (!CONFIG(CBFS_VERIFICATION) || !ENV_INITIAL_STAGE || done)
                return 0;       /* Only need to check hash in first stage. */
 
        if (metadata_hash_verify_fmap(fmap, FMAP_SIZE) != VB2_SUCCESS)
                return -1;
 
        done = true;
        return 0;
}
 
static void report(const struct fmap *fmap)
{
        print_once(BIOS_DEBUG, "FMAP: Found \"%s\" version %d.%d at %#x.\n",
               fmap->name, fmap->ver_major, fmap->ver_minor, FMAP_OFFSET);
        print_once(BIOS_DEBUG, "FMAP: base = %#llx size = %#x #areas = %d\n",
               (long long)le64toh(fmap->base), le32toh(fmap->size),
               le16toh(fmap->nareas));
        fmap_print_once = 1;
}
 
static void setup_preram_cache(struct region_device *cache_rdev)
{
        if (CONFIG(NO_FMAP_CACHE))
                return;
 
        /* No need to use FMAP cache in SMM */
        if (ENV_SMM)
                return;
 
        if (!ENV_ROMSTAGE_OR_BEFORE) {
                /* We get here if ramstage makes an FMAP access before calling
                   cbmem_initialize(). We should avoid letting it come to that,
                   so print a warning. */
                print_once(BIOS_WARNING,
                        "WARNING: Post-RAM FMAP access too early for cache!\n");
                return;
        }
 
        struct fmap *fmap = (struct fmap *)_fmap_cache;
        if (!(ENV_INITIAL_STAGE)) {
                /* NOTE: This assumes that the first stage will make
                   at least one FMAP access (usually from finding CBFS). */
                if (!verify_fmap(fmap))
                        goto register_cache;
 
                printk(BIOS_ERR, "FMAP cache corrupted?!\n");
                if (CONFIG(TOCTOU_SAFETY))
                        die("TOCTOU safety relies on FMAP cache");
        }
 
        /* In case we fail below, make sure the cache is invalid. */
        memset(fmap->signature, 0, sizeof(fmap->signature));
 
        boot_device_init();
        const struct region_device *boot_rdev = boot_device_ro();
        if (!boot_rdev)
                return;
 
        /* memlayout statically guarantees that the FMAP_CACHE is big enough. */
        if (rdev_readat(boot_rdev, fmap, FMAP_OFFSET, FMAP_SIZE) != FMAP_SIZE)
                return;
        if (verify_fmap(fmap))
                return;
        report(fmap);
 
register_cache:
        rdev_chain_mem(cache_rdev, fmap, FMAP_SIZE);
}
 
static int find_fmap_directory(struct region_device *fmrd)
{
        const struct region_device *boot;
        struct fmap *fmap;
        size_t offset = FMAP_OFFSET;
 
        /* Try FMAP cache first */
        if (!region_device_sz(&fmap_cache))
                setup_preram_cache(&fmap_cache);
        if (region_device_sz(&fmap_cache))
                return rdev_chain_full(fmrd, &fmap_cache);
 
        boot_device_init();
        boot = boot_device_ro();
 
        if (boot == NULL)
                return -1;
 
        fmap = rdev_mmap(boot, offset, sizeof(struct fmap));
 
        if (fmap == NULL)
                return -1;
 
        if (verify_fmap(fmap)) {
                printk(BIOS_ERR, "FMAP missing or corrupted at offset 0x%zx!\n",
                       offset);
                rdev_munmap(boot, fmap);
                return -1;
        }
 
        report(fmap);
 
        rdev_munmap(boot, fmap);
 
        return rdev_chain(fmrd, boot, offset, FMAP_SIZE);
}
 
int fmap_locate_area_as_rdev(const char *name, struct region_device *area)
{
        struct region ar;
 
        if (fmap_locate_area(name, &ar))
                return -1;
 
        return boot_device_ro_subregion(&ar, area);
}
 
int fmap_locate_area_as_rdev_rw(const char *name, struct region_device *area)
{
        struct region ar;
 
        if (fmap_locate_area(name, &ar))
                return -1;
 
        return boot_device_rw_subregion(&ar, area);
}
 
int fmap_locate_area(const char *name, struct region *ar)
{
        struct region_device fmrd;
        size_t offset;
 
        if (name == NULL || ar == NULL)
                return -1;
 
        if (find_fmap_directory(&fmrd))
                return -1;
 
        /* Start reading the areas just after fmap header. */
        offset = sizeof(struct fmap);
 
        while (1) {
                struct fmap_area *area;
 
                area = rdev_mmap(&fmrd, offset, sizeof(*area));
 
                if (area == NULL)
                        return -1;
 
                if (strcmp((const char *)area->name, name)) {
                        rdev_munmap(&fmrd, area);
                        offset += sizeof(struct fmap_area);
                        continue;
                }
 
                printk(BIOS_DEBUG, "FMAP: area %s found @ %x (%d bytes)\n",
                       name, le32toh(area->offset), le32toh(area->size));
 
                ar->offset = le32toh(area->offset);
                ar->size = le32toh(area->size);
 
                rdev_munmap(&fmrd, area);
 
                return 0;
        }
 
        printk(BIOS_DEBUG, "FMAP: area %s not found\n", name);
 
        return -1;
}
 
int fmap_find_region_name(const struct region * const ar,
        char name[FMAP_STRLEN])
{
        struct region_device fmrd;
        size_t offset;
 
        if (name == NULL || ar == NULL)
                return -1;
 
        if (find_fmap_directory(&fmrd))
                return -1;
 
        /* Start reading the areas just after fmap header. */
        offset = sizeof(struct fmap);
 
        while (1) {
                struct fmap_area *area;
 
                area = rdev_mmap(&fmrd, offset, sizeof(*area));
 
                if (area == NULL)
                        return -1;
 
                if ((ar->offset != le32toh(area->offset)) ||
                    (ar->size != le32toh(area->size))) {
                        rdev_munmap(&fmrd, area);
                        offset += sizeof(struct fmap_area);
                        continue;
                }
 
                printk(BIOS_DEBUG, "FMAP: area (%zx, %zx) found, named %s\n",
                        ar->offset, ar->size, area->name);
 
                memcpy(name, area->name, FMAP_STRLEN);
 
                rdev_munmap(&fmrd, area);
 
                return 0;
        }
 
        printk(BIOS_DEBUG, "FMAP: area (%zx, %zx) not found\n",
                ar->offset, ar->size);
 
        return -1;
}
 
ssize_t fmap_read_area(const char *name, void *buffer, size_t size)
{
        struct region_device rdev;
        if (fmap_locate_area_as_rdev(name, &rdev))
                return -1;
        return rdev_readat(&rdev, buffer, 0,
                        MIN(size, region_device_sz(&rdev)));
}
 
ssize_t fmap_overwrite_area(const char *name, const void *buffer, size_t size)
{
        struct region_device rdev;
 
        if (fmap_locate_area_as_rdev_rw(name, &rdev))
                return -1;
        if (size > region_device_sz(&rdev))
                return -1;
        if (rdev_eraseat(&rdev, 0, region_device_sz(&rdev)) < 0)
                return -1;
        return rdev_writeat(&rdev, buffer, 0, size);
}
 
static void fmap_register_cbmem_cache(void)
{
        const struct cbmem_entry *e;
 
        /* Find the FMAP cache installed by previous stage */
        e = cbmem_entry_find(CBMEM_ID_FMAP);
        /* Don't set fmap_cache so that find_fmap_directory will use regular path */
        if (!e)
                return;
 
        rdev_chain_mem(&fmap_cache, cbmem_entry_start(e), cbmem_entry_size(e));
}
 
/*
 * The main reason to copy the FMAP into CBMEM is to make it available to the
 * OS on every architecture. As side effect use the CBMEM copy as cache.
 */
static void fmap_add_cbmem_cache(void)
{
        struct region_device fmrd;
 
        if (find_fmap_directory(&fmrd))
                return;
 
        /* Reloads the FMAP even on ACPI S3 resume */
        const size_t s = region_device_sz(&fmrd);
        struct fmap *fmap = cbmem_add(CBMEM_ID_FMAP, s);
        if (!fmap) {
                printk(BIOS_ERR, "Failed to allocate CBMEM\n");
                return;
        }
 
        const ssize_t ret = rdev_readat(&fmrd, fmap, 0, s);
        if (ret != s) {
                printk(BIOS_ERR, "Failed to read FMAP into CBMEM\n");
                cbmem_entry_remove(cbmem_entry_find(CBMEM_ID_FMAP));
                return;
        }
}
 
static void fmap_setup_cbmem_cache(int unused)
{
        if (ENV_ROMSTAGE)
                fmap_add_cbmem_cache();
 
        /* Finally advertise the cache for the current stage */
        fmap_register_cbmem_cache();
}
 
ROMSTAGE_CBMEM_INIT_HOOK(fmap_setup_cbmem_cache)
RAMSTAGE_CBMEM_INIT_HOOK(fmap_setup_cbmem_cache)
POSTCAR_CBMEM_INIT_HOOK(fmap_setup_cbmem_cache)