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Message-Id: <20200228000105.165012-5-thgarnie@chromium.org>
Date: Thu, 27 Feb 2020 16:00:49 -0800
From: Thomas Garnier <thgarnie@...omium.org>
To: kernel-hardening@...ts.openwall.com
Cc: kristen@...ux.intel.com,
keescook@...omium.org,
Thomas Garnier <thgarnie@...omium.org>,
Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v11 04/11] x86/entry/64: Adapt assembly for PIE support
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.
Signed-off-by: Thomas Garnier <thgarnie@...omium.org>
Reviewed-by: Kees Cook <keescook@...omium.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 f2bb91e87877..2c8200d35797 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1329,7 +1329,8 @@ SYM_CODE_START_LOCAL(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_lfence
/*
@@ -1529,10 +1530,10 @@ SYM_CODE_START(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:
@@ -1586,7 +1587,8 @@ 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
@@ -1625,7 +1627,11 @@ first_nmi:
addq $8, (%rsp) /* Fix up RSP */
pushfq /* RFLAGS */
pushq $__KERNEL_CS /* CS */
- pushq $1f /* RIP */
+ pushq $0 /* Space for RIP */
+ pushq %rdx /* Save RDX */
+ leaq 1f(%rip), %rdx /* Put the address of 1f label into RDX */
+ movq %rdx, 8(%rsp) /* Store it in RIP field */
+ popq %rdx /* Restore RDX */
iretq /* continues at repeat_nmi below */
UNWIND_HINT_IRET_REGS
1:
--
2.25.1.481.gfbce0eb801-goog
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