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[Xen-devel] [RFC 10/22] x86/CPU: Adapt assembly for PIE support
- To: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>, "David S . Miller" <davem@xxxxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, "H . Peter Anvin" <hpa@xxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Josh Poimboeuf <jpoimboe@xxxxxxxxxx>, Thomas Garnier <thgarnie@xxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, Matthias Kaehlcke <mka@xxxxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Radim Krčmář <rkrcmar@xxxxxxxxxx>, Joerg Roedel <joro@xxxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>, Brian Gerst <brgerst@xxxxxxxxx>, Borislav Petkov <bp@xxxxxxx>, Christian Borntraeger <borntraeger@xxxxxxxxxx>, "Rafael J . Wysocki" <rjw@xxxxxxxxxxxxx>, Len Brown <len.brown@xxxxxxxxx>, Pavel Machek <pavel@xxxxxx>, Tejun Heo <tj@xxxxxxxxxx>, Christoph Lameter <cl@xxxxxxxxx>, Kees Cook <keescook@xxxxxxxxxxxx>, Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>, Chris Metcalf <cmetcalf@xxxxxxxxxxxx>, "Paul E . McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Christopher Li <sparse@xxxxxxxxxxx>, Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>, Daniel Borkmann <daniel@xxxxxxxxxxxxx>, Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>, Peter Foley <pefoley2@xxxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>, Michal Hocko <mhocko@xxxxxxxx>, Rob Landley <rob@xxxxxxxxxxx>, Jiri Kosina <jkosina@xxxxxxx>, "H . J . Lu" <hjl.tools@xxxxxxxxx>, Paul Bolle <pebolle@xxxxxxxxxx>, Baoquan He <bhe@xxxxxxxxxx>, Daniel Micay <danielmicay@xxxxxxxxx>
- From: Thomas Garnier <thgarnie@xxxxxxxxxx>
- Date: Tue, 18 Jul 2017 15:33:21 -0700
- Cc: linux-arch@xxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, linux-pm@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-sparse@xxxxxxxxxxxxxxx, linux-crypto@xxxxxxxxxxxxxxx, kernel-hardening@xxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 18 Jul 2017 22:34:31 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible. Use the new _ASM_GET_PTR macro instead of
the 'mov $symbol, %dst' construct to not have an absolute reference.
Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.
Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx>
---
arch/x86/include/asm/processor.h | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 028245e1c42b..1adea8c4436e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -47,7 +47,7 @@ static inline void *current_text_addr(void)
{
void *pc;
- asm volatile("mov $1f, %0; 1:":"=r" (pc));
+ asm volatile(_ASM_GET_PTR(1f, %0) "; 1:":"=r" (pc));
return pc;
}
@@ -682,6 +682,7 @@ static inline void sync_core(void)
: "+r" (__sp) : : "memory");
#else
unsigned int tmp;
+ unsigned long tmp2;
asm volatile (
"mov %%ss, %0\n\t"
@@ -691,10 +692,11 @@ 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"
"1:"
- : "=&r" (tmp), "+r" (__sp) : : "cc", "memory");
+ : "=&r" (tmp), "=&r" (tmp2), "+r" (__sp) : : "cc", "memory");
#endif
}
--
2.13.2.932.g7449e964c-goog
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