[PATCH v9 06/11] x86/CPU: Adapt assembly for PIE support

Thomas Garnier
2019-07-30T19:13:27Z

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/include/asm/processor.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6e0a3b43d027..bf333d62889e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -713,11 +713,13 @@ static inline void sync_core(void)
"pushfq\n\t"
"mov %%cs, %0\n\t"
"pushq %q0\n\t"
- "pushq $1f\n\t"
+ "leaq 1f(%%rip), %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
}

--
2.22.0.770.g0f2c4a37fd-goog