cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

efi-bgrt.c (2199B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright 2012 Intel Corporation
      4 * Author: Josh Triplett <josh@joshtriplett.org>
      5 *
      6 * Based on the bgrt driver:
      7 * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
      8 * Author: Matthew Garrett
      9 */
     10
     11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     12
     13#include <linux/kernel.h>
     14#include <linux/init.h>
     15#include <linux/acpi.h>
     16#include <linux/efi.h>
     17#include <linux/efi-bgrt.h>
     18
     19struct acpi_table_bgrt bgrt_tab;
     20size_t bgrt_image_size;
     21
     22struct bmp_header {
     23	u16 id;
     24	u32 size;
     25} __packed;
     26
     27void __init efi_bgrt_init(struct acpi_table_header *table)
     28{
     29	void *image;
     30	struct bmp_header bmp_header;
     31	struct acpi_table_bgrt *bgrt = &bgrt_tab;
     32
     33	if (acpi_disabled)
     34		return;
     35
     36	if (!efi_enabled(EFI_MEMMAP))
     37		return;
     38
     39	if (table->length < sizeof(bgrt_tab)) {
     40		pr_notice("Ignoring BGRT: invalid length %u (expected %zu)\n",
     41		       table->length, sizeof(bgrt_tab));
     42		return;
     43	}
     44	*bgrt = *(struct acpi_table_bgrt *)table;
     45	/*
     46	 * Only version 1 is defined but some older laptops (seen on Lenovo
     47	 * Ivy Bridge models) have a correct version 1 BGRT table with the
     48	 * version set to 0, so we accept version 0 and 1.
     49	 */
     50	if (bgrt->version > 1) {
     51		pr_notice("Ignoring BGRT: invalid version %u (expected 1)\n",
     52		       bgrt->version);
     53		goto out;
     54	}
     55	if (bgrt->image_type != 0) {
     56		pr_notice("Ignoring BGRT: invalid image type %u (expected 0)\n",
     57		       bgrt->image_type);
     58		goto out;
     59	}
     60	if (!bgrt->image_address) {
     61		pr_notice("Ignoring BGRT: null image address\n");
     62		goto out;
     63	}
     64
     65	if (efi_mem_type(bgrt->image_address) != EFI_BOOT_SERVICES_DATA) {
     66		pr_notice("Ignoring BGRT: invalid image address\n");
     67		goto out;
     68	}
     69	image = early_memremap(bgrt->image_address, sizeof(bmp_header));
     70	if (!image) {
     71		pr_notice("Ignoring BGRT: failed to map image header memory\n");
     72		goto out;
     73	}
     74
     75	memcpy(&bmp_header, image, sizeof(bmp_header));
     76	early_memunmap(image, sizeof(bmp_header));
     77	if (bmp_header.id != 0x4d42) {
     78		pr_notice("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
     79			bmp_header.id);
     80		goto out;
     81	}
     82	bgrt_image_size = bmp_header.size;
     83	efi_mem_reserve(bgrt->image_address, bgrt_image_size);
     84
     85	return;
     86out:
     87	memset(bgrt, 0, sizeof(bgrt_tab));
     88}