Commit 3c98e71b authored Jan 23, 2019 by Chao Fan Committed by Borislav Petkov Feb 01, 2019

x86/boot: Add "acpi_rsdp=" early parsing



KASLR may randomly choose offsets which are located in movable memory
regions resulting in the movable memory becoming immovable.

The ACPI SRAT (System/Static Resource Affinity Table) describes memory
ranges including ranges of memory provided by hot-added memory devices.
In order to access SRAT, one needs the Root System Description Pointer
(RSDP) with which to find the Root/Extended System Description Table
(R/XSDT) which then contains the system description tables of which SRAT
is one of.

In case the RSDP address has been passed on the command line (kexec-ing
a second kernel) parse it from there.

 [ bp: Rewrite the commit message and cleanup the code. ]

Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: bhe@redhat.com
Cc: caoj.fnst@cn.fujitsu.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: indou.takao@jp.fujitsu.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kasong@redhat.com
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: msys.mizuma@gmail.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190123110850.12433-3-fanc.fnst@cn.fujitsu.com

parent de50ce20

arch/x86/boot/compressed/acpi.c

0 → 100644

+32 −0

Original line number	Original line	Diff line number	Diff line
			// SPDX-License-Identifier: GPL-2.0
			#define BOOT_CTYPE_H
			#include "misc.h"
			#include "error.h"
			#include "../string.h"

			#ifdef CONFIG_ACPI

			/*
			* Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex
			* digits, and '\0' for termination.
			*/
			#define MAX_ADDR_LEN 19

			static acpi_physical_address get_acpi_rsdp(void)
			{
			acpi_physical_address addr = 0;

			#ifdef CONFIG_KEXEC
			char val[MAX_ADDR_LEN] = { };
			int ret;

			ret = cmdline_find_option("acpi_rsdp", val, MAX_ADDR_LEN);
			if (ret < 0)
			return 0;

			if (kstrtoull(val, 16, &addr))
			return 0;
			#endif
			return addr;
			}
			#endif /* CONFIG_ACPI */

arch/x86/boot/compressed/misc.h

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -25,6 +25,9 @@
	#include <asm/bootparam.h>		#include <asm/bootparam.h>
	#include <asm/bootparam_utils.h>		#include <asm/bootparam_utils.h>

			#define BOOT_CTYPE_H
			#include <linux/acpi.h>

	#define BOOT_BOOT_H		#define BOOT_BOOT_H
	#include "../ctype.h"		#include "../ctype.h"

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