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Commit fb45daa6 authored by Huang Ying's avatar Huang Ying Committed by Linus Torvalds
Browse files

kexec jump: check code size in control page 



Kexec/Kexec-jump require code size in control page is less than
PAGE_SIZE/2.  This patch add link-time checking for this.

ASSERT() of ld link script is used as the link-time checking mechanism.

[akpm@linux-foundation.org: build fix]
Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 163f6876

arch/x86/kernel/machine_kexec_32.c

+1 −1
Original line number Diff line number Diff line
@@ -138,7 +138,7 @@ void machine_kexec(struct kimage *image) 
	}



	control_page = page_address(image->control_code_page);

	memcpy(control_page, relocate_kernel, PAGE_SIZE/2);

	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);



	relocate_kernel_ptr = control_page;

	page_list[PA_CONTROL_PAGE] = __pa(control_page);

arch/x86/kernel/relocate_kernel_32.S

+7 −3
Original line number Diff line number Diff line
@@ -20,10 +20,11 @@ 
#define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)

#define PAE_PGD_ATTR (_PAGE_PRESENT)



/* control_page + PAGE_SIZE/2 ~ control_page + PAGE_SIZE * 3/4 are

 * used to save some data for jumping back

/* control_page + KEXEC_CONTROL_CODE_MAX_SIZE

 * ~ control_page + PAGE_SIZE are used as data storage and stack for

 * jumping back

 */

#define DATA(offset)		(PAGE_SIZE/2+(offset))

#define DATA(offset)		(KEXEC_CONTROL_CODE_MAX_SIZE+(offset))



/* Minimal CPU state */

#define ESP			DATA(0x0)
@@ -376,3 +377,6 @@ swap_pages: 
	popl	%ebx

	popl	%ebp

	ret



	.globl kexec_control_code_size

.set kexec_control_code_size, . - relocate_kernel

arch/x86/kernel/vmlinux_32.lds.S

+8 −0
Original line number Diff line number Diff line
@@ -209,3 +209,11 @@ SECTIONS 


  DWARF_DEBUG

}



#ifdef CONFIG_KEXEC

/* Link time checks */

#include <asm/kexec.h>



ASSERT(kexec_control_code_size <= KEXEC_CONTROL_CODE_MAX_SIZE,

       "kexec control code size is too big")

#endif

include/asm-x86/kexec.h

+4 −0
Original line number Diff line number Diff line
@@ -41,6 +41,10 @@ 
# define PAGES_NR		17

#endif



#ifdef CONFIG_X86_32

# define KEXEC_CONTROL_CODE_MAX_SIZE	2048

#endif



#ifndef __ASSEMBLY__



#include <linux/string.h>