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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: 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
This commit is contained in:
Chao Fan 2019-01-23 19:08:45 +08:00 committed by Borislav Petkov
parent de50ce20cd
commit 3c98e71b42
2 changed files with 35 additions and 0 deletions
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32
arch/x86/boot/compressed/acpi.c Normal file
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@ -0,0 +1,32 @@
// 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 */

3
arch/x86/boot/compressed/misc.h
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@ -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"