linux-kernel - [PATCH v6 04/27] x86: relocate_kernel

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Date:   Thu, 31 Jan 2019 11:24:11 -0800
From:   Thomas Garnier <thgarnie@...omium.org>
To:     kernel-hardening@...ts.openwall.com
Cc:     kristen@...ux.intel.com, Thomas Garnier <thgarnie@...omium.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,
        Thomas Garnier <thgarnie@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 04/27] x86: relocate_kernel - Adapt assembly for PIE support

Change the assembly code to use only absolute 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@...omium.org>
---
 arch/x86/kernel/relocate_kernel_64.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 11eda21eb697..3320368b6ec9 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -208,7 +208,7 @@ identity_mapped:
 	movq	%rax, %cr3
 	lea	PAGE_SIZE(%r8), %rsp
 	call	swap_pages
-	movq	$virtual_mapped, %rax
+	movabsq	$virtual_mapped, %rax
 	pushq	%rax
 	ret
 
-- 
2.20.1.495.gaa96b0ce6b-goog