From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier Subject: [PATCH v6 07/27] x86/CPU: Adapt assembly for PIE support Date: Thu, 31 Jan 2019 11:24:14 -0800 Message-Id: <20190131192533.34130-8-thgarnie@chromium.org> In-Reply-To: <20190131192533.34130-1-thgarnie@chromium.org> References: <20190131192533.34130-1-thgarnie@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: kernel-hardening@lists.openwall.com Cc: kristen@linux.intel.com, Thomas Garnier , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Andrew Morton , Thomas Garnier , linux-kernel@vger.kernel.org List-ID: 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 --- 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 33051436c864..ce9851bf6778 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -723,11 +723,13 @@ 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 } -- 2.20.1.495.gaa96b0ce6b-goog