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[v7,07/12] x86/CPU: Adapt assembly for PIE support

Message ID 20190520231948.49693-8-thgarnie@chromium.org (mailing list archive)
State New, archived
Headers show
Series x86: PIE support to extend KASLR randomization | expand

Commit Message

Thomas Garnier May 20, 2019, 11:19 p.m. UTC 
From: Thomas Garnier <thgarnie@google.com>

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. Use the new _ASM_MOVABS macro instead of
the 'mov $symbol, %dst' construct.

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

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/processor.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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Patch

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c34a35c78618..5490a6ead17c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -710,11 +710,13 @@  static inline void sync_core(void)
 		"pushfq\n\t"
 		"mov %%cs, %0\n\t"
 		"pushq %q0\n\t"
-		"pushq $1f\n\t"
+		"movabsq $1f, %q0\n\t"
+		"pushq %q0\n\t"
 		"iretq\n\t"
 		UNWIND_HINT_RESTORE
 		"1:"
-		: "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
+		: "=&r" (tmp), ASM_CALL_CONSTRAINT
+		: : "cc", "memory");
 #endif
 }