linux-kernel - [PATCH v8 03/11] x86: relocate_kernel

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Message-Id: <20190708174913.123308-4-thgarnie@chromium.org>
Date:   Mon,  8 Jul 2019 10:48:56 -0700
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>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Allison Randal <allison@...utok.net>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v8 03/11] 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>
Reviewed-by: Kees Cook <keescook@...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 c51ccff5cd01..c72889b09840 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -206,7 +206,7 @@ identity_mapped:
 	movq	%rax, %cr3
 	lea	PAGE_SIZE(%r8), %rsp
 	call	swap_pages
-	movq	$virtual_mapped, %rax
+	movabsq	$virtual_mapped, %rax
 	pushq	%rax
 	ret
 
-- 
2.22.0.410.gd8fdbe21b5-goog