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x86/kexec: Disable RET on kexec

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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: Edward Tran <edward.tran@oracle.com>
Reported-by: Awais Tanveer <awais.tanveer@oracle.com>
Suggested-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Konrad Rzeszutek Wilk 2022-07-08 19:10:11 +02:00 committed by Borislav Petkov
parent 2259da159f
commit 697977d841
2 changed files with 36 additions and 12 deletions
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25
arch/x86/kernel/relocate_kernel_32.S
View File

@ -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

23
arch/x86/kernel/relocate_kernel_64.S
View File

@ -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