lkml.org 
[lkml]   [2019]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v6 05/27] x86/entry/64: Adapt assembly for PIE support
Date
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.

Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
---
arch/x86/entry/entry_64.S | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1f0efdb7b629..16a93eb4c11f 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1269,7 +1269,8 @@ ENTRY(error_entry)
movl %ecx, %eax /* zero extend */
cmpq %rax, RIP+8(%rsp)
je .Lbstep_iret
- cmpq $.Lgs_change, RIP+8(%rsp)
+ leaq .Lgs_change(%rip), %rcx
+ cmpq %rcx, RIP+8(%rsp)
jne .Lerror_entry_done

/*
@@ -1466,10 +1467,10 @@ ENTRY(nmi)
* resume the outer NMI.
*/

- movq $repeat_nmi, %rdx
+ leaq repeat_nmi(%rip), %rdx
cmpq 8(%rsp), %rdx
ja 1f
- movq $end_repeat_nmi, %rdx
+ leaq end_repeat_nmi(%rip), %rdx
cmpq 8(%rsp), %rdx
ja nested_nmi_out
1:
@@ -1523,7 +1524,8 @@ nested_nmi:
pushq %rdx
pushfq
pushq $__KERNEL_CS
- pushq $repeat_nmi
+ leaq repeat_nmi(%rip), %rdx
+ pushq %rdx

/* Put stack back */
addq $(6*8), %rsp
@@ -1562,7 +1564,11 @@ first_nmi:
addq $8, (%rsp) /* Fix up RSP */
pushfq /* RFLAGS */
pushq $__KERNEL_CS /* CS */
- pushq $1f /* RIP */
+ pushq $0 /* Futur return address */
+ pushq %rax /* Save RAX */
+ leaq 1f(%rip), %rax /* RIP */
+ movq %rax, 8(%rsp) /* Put 1f on return address */
+ popq %rax /* Restore RAX */
iretq /* continues at repeat_nmi below */
UNWIND_HINT_IRET_REGS
1:
--
2.20.1.495.gaa96b0ce6b-goog
\
 
 \ /
  Last update: 2019-01-31 20:40    [W:0.030 / U:28.452 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site