From: Patrick Rudolph <patrick.rudo...@9elements.com> Expose coreboot's binary FMAP[1] to /sys/firmware/fmap.
coreboot copies the FMAP to a CBMEM buffer at boot since CB:35377[2], allowing an architecture independ way of exposing the FMAP to userspace. Will be used by fwupd[3] to determine the current firmware layout. [1]: https://doc.coreboot.org/lib/flashmap.html [2]: https://review.coreboot.org/c/coreboot/+/35377 [3]: https://fwupd.org/ Signed-off-by: Patrick Rudolph <patrick.rudo...@9elements.com> --- drivers/firmware/google/Kconfig | 8 ++ drivers/firmware/google/Makefile | 1 + drivers/firmware/google/fmap-coreboot.c | 156 ++++++++++++++++++++++ drivers/firmware/google/fmap-coreboot.h | 13 ++ drivers/firmware/google/fmap_serialized.h | 59 ++++++++ 5 files changed, 237 insertions(+) create mode 100644 drivers/firmware/google/fmap-coreboot.c create mode 100644 drivers/firmware/google/fmap-coreboot.h create mode 100644 drivers/firmware/google/fmap_serialized.h diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig index a3a6ca659ffa..5fbbd7b8fef6 100644 --- a/drivers/firmware/google/Kconfig +++ b/drivers/firmware/google/Kconfig @@ -74,4 +74,12 @@ config GOOGLE_VPD This option enables the kernel to expose the content of Google VPD under /sys/firmware/vpd. +config GOOGLE_FMAP + tristate "Coreboot FMAP access" + depends on GOOGLE_COREBOOT_TABLE + help + This option enables the kernel to search for a Google FMAP in + the coreboot table. If found, this binary file is exported to userland + in the file /sys/firmware/fmap. + endif # GOOGLE_FIRMWARE diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile index d17caded5d88..6d31fe167700 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -6,6 +6,7 @@ obj-$(CONFIG_GOOGLE_FRAMEBUFFER_COREBOOT) += framebuffer-coreboot.o obj-$(CONFIG_GOOGLE_MEMCONSOLE) += memconsole.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_COREBOOT) += memconsole-coreboot.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_X86_LEGACY) += memconsole-x86-legacy.o +obj-$(CONFIG_GOOGLE_FMAP) += fmap-coreboot.o vpd-sysfs-y := vpd.o vpd_decode.o obj-$(CONFIG_GOOGLE_VPD) += vpd-sysfs.o diff --git a/drivers/firmware/google/fmap-coreboot.c b/drivers/firmware/google/fmap-coreboot.c new file mode 100644 index 000000000000..14050030ebc6 --- /dev/null +++ b/drivers/firmware/google/fmap-coreboot.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * fmap-coreboot.c + * + * Exports the binary FMAP through coreboot table. + * + * Copyright 2012-2013 David Herrmann <dh.herrm...@gmail.com> + * Copyright 2017 Google Inc. + * Copyright 2019 9elements Agency GmbH <patrick.rudo...@9elements.com> + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/string.h> +#include <linux/io.h> + +#include "coreboot_table.h" +#include "fmap_serialized.h" + +#define CB_TAG_FMAP 0x37 + +static void *fmap; +static u32 fmap_size; + +/* + * Convert FMAP region to name. + * The caller has to free the string. + * Return NULL if no containing region was found. + */ +const char *coreboot_fmap_region_to_name(const u32 start, const u32 size) +{ + const char *name = NULL; + struct fmap *iter; + u32 size_old = ~0; + int i; + + iter = fmap; + /* Find smallest containing region */ + for (i = 0; i < iter->nareas && fmap; i++) { + if (iter->areas[i].offset <= start && + iter->areas[i].size >= size && + iter->areas[i].size <= size_old) { + size_old = iter->areas[i].size; + name = iter->areas[i].name; + } + } + + if (name) + return kstrdup(name, GFP_KERNEL); + return NULL; +} +EXPORT_SYMBOL(coreboot_fmap_region_to_name); + +static ssize_t fmap_read(struct file *filp, struct kobject *kobp, + struct bin_attribute *bin_attr, char *buf, + loff_t pos, size_t count) +{ + if (!fmap) + return -ENODEV; + + return memory_read_from_buffer(buf, count, &pos, fmap, fmap_size); +} + +static int fmap_probe(struct coreboot_device *dev) +{ + struct lb_cbmem_ref *cbmem_ref = &dev->cbmem_ref; + struct fmap *header; + + if (!cbmem_ref) + return -ENODEV; + + header = memremap(cbmem_ref->cbmem_addr, sizeof(*header), MEMREMAP_WB); + if (!header) { + pr_warn("coreboot: Failed to remap FMAP\n"); + return -ENOMEM; + } + + /* Validate FMAP signature */ + if (memcmp(header->signature, FMAP_SIGNATURE, + sizeof(header->signature))) { + pr_warn("coreboot: FMAP signature mismatch\n"); + memunmap(header); + return -ENODEV; + } + + /* Validate FMAP version */ + if (header->ver_major != FMAP_VER_MAJOR) { + pr_warn("coreboot: FMAP version not supported\n"); + memunmap(header); + return -ENODEV; + } + + pr_info("coreboot: Got valid FMAP v%u.%u for 0x%x byte ROM\n", + header->ver_major, header->ver_minor, header->size); + + fmap_size = sizeof(*header) + header->nareas * sizeof(struct fmap_area); + memunmap(header); + + fmap = devm_memremap(&dev->dev, cbmem_ref->cbmem_addr, fmap_size, + MEMREMAP_WB); + if (!fmap) { + pr_warn("coreboot: Failed to remap FMAP\n"); + return -ENOMEM; + } + + return 0; +} + +static int fmap_remove(struct coreboot_device *dev) +{ + struct platform_device *pdev = dev_get_drvdata(&dev->dev); + + platform_device_unregister(pdev); + + return 0; +} + +static struct coreboot_driver fmap_driver = { + .probe = fmap_probe, + .remove = fmap_remove, + .drv = { + .name = "fmap", + }, + .tag = CB_TAG_FMAP, +}; + +static struct bin_attribute fmap_bin_attr = { + .attr = {.name = "fmap", .mode = 0444}, + .read = fmap_read, +}; + +static int __init coreboot_fmap_init(void) +{ + int err; + + err = sysfs_create_bin_file(firmware_kobj, &fmap_bin_attr); + if (err) + return err; + + return coreboot_driver_register(&fmap_driver); +} + +static void coreboot_fmap_exit(void) +{ + coreboot_driver_unregister(&fmap_driver); + sysfs_remove_bin_file(firmware_kobj, &fmap_bin_attr); +} + +module_init(coreboot_fmap_init); +module_exit(coreboot_fmap_exit); + +MODULE_AUTHOR("9elements Agency GmbH"); +MODULE_LICENSE("GPL"); diff --git a/drivers/firmware/google/fmap-coreboot.h b/drivers/firmware/google/fmap-coreboot.h new file mode 100644 index 000000000000..7107a01af0e3 --- /dev/null +++ b/drivers/firmware/google/fmap-coreboot.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * bootmedia-coreboot.h + * + * Copyright 2019 9elements Agency GmbH <patrick.rudo...@9elements.com> + */ + +#ifndef __FMAP_COREBOOT_H +#define __FMAP_COREBOOT_H + +const char *coreboot_fmap_region_to_name(const u32 start, const u32 size); + +#endif /* __FMAP_COREBOOT_H */ diff --git a/drivers/firmware/google/fmap_serialized.h b/drivers/firmware/google/fmap_serialized.h new file mode 100644 index 000000000000..a001e47fa244 --- /dev/null +++ b/drivers/firmware/google/fmap_serialized.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright 2010, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + */ + +#ifndef FLASHMAP_SERIALIZED_H__ +#define FLASHMAP_SERIALIZED_H__ + +#define FMAP_SIGNATURE "__FMAP__" +#define FMAP_VER_MAJOR 1 /* this header's FMAP major version */ +#define FMAP_VER_MINOR 1 /* this header's FMAP minor version */ +#define FMAP_STRLEN 32 /* maximum length for strings, + * including null-terminator + */ + +enum fmap_flags { + FMAP_AREA_STATIC = 1 << 0, + FMAP_AREA_COMPRESSED = 1 << 1, + FMAP_AREA_RO = 1 << 2, + FMAP_AREA_PRESERVE = 1 << 3, +}; + +/* Mapping of volatile and static regions in firmware binary */ +struct fmap_area { + u32 offset; /* offset relative to base */ + u32 size; /* size in bytes */ + u8 name[FMAP_STRLEN]; /* descriptive name */ + u16 flags; /* flags for this area */ +} __packed; + +struct fmap { + u8 signature[8]; /* "__FMAP__" (0x5F5F464D41505F5F) */ + u8 ver_major; /* major version */ + u8 ver_minor; /* minor version */ + u64 base; /* address of the firmware binary */ + u32 size; /* size of firmware binary in bytes */ + u8 name[FMAP_STRLEN]; /* name of this firmware binary */ + u16 nareas; /* number of areas described by + * fmap_areas[] below + */ + struct fmap_area areas[]; +} __packed; + +#endif /* FLASHMAP_SERIALIZED_H__ */ -- 2.21.0
