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Commit 3c98e71b authored by Chao Fan's avatar Chao Fan Committed by Borislav Petkov
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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: default avatarChao Fan <fanc.fnst@cn.fujitsu.com>
Signed-off-by: default avatarBorislav 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 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 Diff line number Diff line
@@ -25,6 +25,9 @@ 
#include <asm/bootparam.h>

#include <asm/bootparam_utils.h>



#define BOOT_CTYPE_H

#include <linux/acpi.h>



#define BOOT_BOOT_H

#include "../ctype.h"