Commit 697977d8 authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk Committed by Borislav Petkov
Browse files

x86/kexec: Disable RET on kexec 



All the invocations unroll to __x86_return_thunk and this file
must be PIC independent.

This fixes kexec on 64-bit AMD boxes.

  [ bp: Fix 32-bit build. ]

Reported-by: default avatarEdward Tran <edward.tran@oracle.com>
Reported-by: default avatarAwais Tanveer <awais.tanveer@oracle.com>
Suggested-by: default avatarAnkur Arora <ankur.a.arora@oracle.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
parent 2259da15

arch/x86/kernel/relocate_kernel_32.S

+19 −6
Original line number Diff line number Diff line
@@ -7,10 +7,12 @@ 
#include <linux/linkage.h>

#include <asm/page_types.h>

#include <asm/kexec.h>

#include <asm/nospec-branch.h>

#include <asm/processor-flags.h>



/*

 * Must be relocatable PIC code callable as a C function

 * Must be relocatable PIC code callable as a C function, in particular

 * there must be a plain RET and not jump to return thunk.

 */



#define PTR(x) (x << 2)
@@ -91,7 +93,9 @@ SYM_CODE_START_NOALIGN(relocate_kernel) 
	movl    %edi, %eax

	addl    $(identity_mapped - relocate_kernel), %eax

	pushl   %eax

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(relocate_kernel)



SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
@@ -159,12 +163,15 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	xorl    %edx, %edx

	xorl    %esi, %esi

	xorl    %ebp, %ebp

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

1:

	popl	%edx

	movl	CP_PA_SWAP_PAGE(%edi), %esp

	addl	$PAGE_SIZE, %esp

2:

	ANNOTATE_RETPOLINE_SAFE

	call	*%edx



	/* get the re-entry point of the peer system */
@@ -190,7 +197,9 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	movl	%edi, %eax

	addl	$(virtual_mapped - relocate_kernel), %eax

	pushl	%eax

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(identity_mapped)



SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
@@ -208,7 +217,9 @@ SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped) 
	popl	%edi

	popl	%esi

	popl	%ebx

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(virtual_mapped)



	/* Do the copies */
@@ -271,7 +282,9 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages) 
	popl	%edi

	popl	%ebx

	popl	%ebp

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(swap_pages)



	.globl kexec_control_code_size

arch/x86/kernel/relocate_kernel_64.S

+17 −6
Original line number Diff line number Diff line
@@ -13,7 +13,8 @@ 
#include <asm/unwind_hints.h>



/*

 * Must be relocatable PIC code callable as a C function

 * Must be relocatable PIC code callable as a C function, in particular

 * there must be a plain RET and not jump to return thunk.

 */



#define PTR(x) (x << 3)
@@ -105,7 +106,9 @@ SYM_CODE_START_NOALIGN(relocate_kernel) 
	/* jump to identity mapped page */

	addq	$(identity_mapped - relocate_kernel), %r8

	pushq	%r8

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(relocate_kernel)



SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
@@ -200,7 +203,9 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	xorl	%r14d, %r14d

	xorl	%r15d, %r15d



	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3



1:

	popq	%rdx
@@ -219,7 +224,9 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) 
	call	swap_pages

	movq	$virtual_mapped, %rax

	pushq	%rax

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(identity_mapped)



SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
@@ -241,7 +248,9 @@ SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped) 
	popq	%r12

	popq	%rbp

	popq	%rbx

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(virtual_mapped)



	/* Do the copies */
@@ -298,7 +307,9 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages) 
	lea	PAGE_SIZE(%rax), %rsi

	jmp	0b

3:

	RET

	ANNOTATE_UNRET_SAFE

	ret

	int3

SYM_CODE_END(swap_pages)



	.globl kexec_control_code_size