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[Xen-devel] [RFC v2 05/23] xen: 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>, Arnd Bergmann <arnd@xxxxxxxx>, Thomas Garnier <thgarnie@xxxxxxxxxx>, 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>, Tom Lendacky <thomas.lendacky@xxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxx>, Brian Gerst <brgerst@xxxxxxxxx>, "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>, "Rafael J . Wysocki" <rjw@xxxxxxxxxxxxx>, Len Brown <len.brown@xxxxxxxxx>, Pavel Machek <pavel@xxxxxx>, Tejun Heo <tj@xxxxxxxxxx>, Christoph Lameter <cl@xxxxxxxxx>, Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>, Chris Metcalf <cmetcalf@xxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, "Paul E . McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>, Christopher Li <sparse@xxxxxxxxxxx>, "Rafael J . Wysocki" <rafael.j.wysocki@xxxxxxxxx>, Lukas Wunner <lukas@xxxxxxxxx>, Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>, Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>, Daniel Borkmann <daniel@xxxxxxxxxxxxx>, Alexei Starovoitov <ast@xxxxxxxxxx>, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>, Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Kees Cook <keescook@xxxxxxxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>, David Howells <dhowells@xxxxxxxxxx>, Waiman Long <longman@xxxxxxxxxx>, Kyle Huey <me@xxxxxxxxxxxx>, Peter Foley <pefoley2@xxxxxxxxxxx>, Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>, Michal Hocko <mhocko@xxxxxxxx>, Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>, "H . J . Lu" <hjl.tools@xxxxxxxxx>, Paul Bolle <pebolle@xxxxxxxxxx>, Rob Landley <rob@xxxxxxxxxxx>, Baoquan He <bhe@xxxxxxxxxx>, Daniel Micay <danielmicay@xxxxxxxxx>
- From: Thomas Garnier <thgarnie@xxxxxxxxxx>
- Date: Thu, 10 Aug 2017 10:25:57 -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: Thu, 10 Aug 2017 17:26:56 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
Change the assembly code to use the new _ASM_GET_PTR macro which get a
symbol reference while being PIE compatible. Modify the RELOC macro that
was using an assignment generating a non-relative 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/xen/xen-asm.h | 3 ++-
arch/x86/xen/xen-head.S | 9 +++++----
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/x86/xen/xen-asm.h b/arch/x86/xen/xen-asm.h
index 465276467a47..3b1c8a2e77d8 100644
--- a/arch/x86/xen/xen-asm.h
+++ b/arch/x86/xen/xen-asm.h
@@ -2,8 +2,9 @@
#define _XEN_XEN_ASM_H
#include <linux/linkage.h>
+#include <asm/asm.h>
-#define RELOC(x, v) .globl x##_reloc; x##_reloc=v
+#define RELOC(x, v) .globl x##_reloc; x##_reloc: _ASM_PTR v
#define ENDPATCH(x) .globl x##_end; x##_end=.
/* Pseudo-flag used for virtual NMI, which we don't implement yet */
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index a7525e95d53f..a98cd42b9832 100644
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -23,14 +23,15 @@ ENTRY(startup_xen)
/* Clear .bss */
xor %eax,%eax
- mov $__bss_start, %_ASM_DI
- mov $__bss_stop, %_ASM_CX
+ _ASM_GET_PTR(__bss_start, %_ASM_DI)
+ _ASM_GET_PTR(__bss_stop, %_ASM_CX)
sub %_ASM_DI, %_ASM_CX
shr $__ASM_SEL(2, 3), %_ASM_CX
rep __ASM_SIZE(stos)
- mov %_ASM_SI, xen_start_info
- mov $init_thread_union+THREAD_SIZE, %_ASM_SP
+ _ASM_GET_PTR(xen_start_info, %_ASM_AX)
+ mov %_ASM_SI, (%_ASM_AX)
+ _ASM_GET_PTR(init_thread_union+THREAD_SIZE, %_ASM_SP)
jmp xen_start_kernel
--
2.14.0.434.g98096fd7a8-goog
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