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Message-Id: <20180529221625.33541-9-thgarnie@google.com>
Date: Tue, 29 May 2018 15:15:09 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: kernel-hardening@...ts.openwall.com
Cc: Thomas Garnier <thgarnie@...gle.com>,
"Skip Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Skip Vitaly Kuznetsov <vkuznets@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
x86@...nel.org,
Borislav Petkov <bp@...e.de>,
Andy Lutomirski <luto@...nel.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH v4 08/27] x86/CPU: Adapt assembly for PIE support
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 0xffffffff80000000.
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
arch/x86/include/asm/processor.h | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index e28add6b791f..7ae9fb91f7b5 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -50,7 +50,7 @@ static inline void *current_text_addr(void)
{
void *pc;
- asm volatile("mov $1f, %0; 1:":"=r" (pc));
+ asm volatile(_ASM_MOVABS " $1f, %0; 1:":"=r" (pc));
return pc;
}
@@ -711,6 +711,7 @@ static inline void sync_core(void)
: ASM_CALL_CONSTRAINT : : "memory");
#else
unsigned int tmp;
+ unsigned long tmp2;
asm volatile (
UNWIND_HINT_SAVE
@@ -721,11 +722,13 @@ 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), %1\n\t"
+ "pushq %1\n\t"
"iretq\n\t"
UNWIND_HINT_RESTORE
"1:"
- : "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
+ : "=&r" (tmp), "=&r" (tmp2), ASM_CALL_CONSTRAINT
+ : : "cc", "memory");
#endif
}
--
2.17.0.921.gf22659ad46-goog
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