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From:   Thomas Garnier <thgarnie@chromium.org>
To:     kernel-hardening@lists.openwall.com
Cc:     kristen@linux.intel.com, Thomas Garnier <thgarnie@chromium.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Garnier <thgarnie@google.com>,
        linux-kernel@vger.kernel.org
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>
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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@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 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