[v7,11/12] x86/paravirt: Adapt assembly for PIE support
diff mbox series

Message ID 20190520231948.49693-12-thgarnie@chromium.org
State New
Headers show
Series
  • x86: PIE support to extend KASLR randomization
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Commit Message

Thomas Garnier May 20, 2019, 11:19 p.m. UTC
From: Thomas Garnier <thgarnie@google.com>

if PIE is enabled, switch the paravirt assembly constraints to be
compatible. The %c/i constrains generate smaller code so is kept by
default.

Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/paravirt_types.h | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Comments

Jürgen Groß May 27, 2019, 5:47 a.m. UTC | #1
On 21/05/2019 01:19, Thomas Garnier wrote:
> From: Thomas Garnier <thgarnie@google.com>
> 
> if PIE is enabled, switch the paravirt assembly constraints to be
> compatible. The %c/i constrains generate smaller code so is kept by
> default.
> 
> Position Independent Executable (PIE) support will allow to extend the
> KASLR randomization range below 0xffffffff80000000.
> 
> Signed-off-by: Thomas Garnier <thgarnie@google.com>

Acked-by: Juergen Gross <jgross@suse.com>


Juergen
Thomas Garnier May 29, 2019, 3:48 p.m. UTC | #2
On Sun, May 26, 2019 at 10:47 PM Juergen Gross <jgross@suse.com> wrote:
>
> On 21/05/2019 01:19, Thomas Garnier wrote:
> > From: Thomas Garnier <thgarnie@google.com>
> >
> > if PIE is enabled, switch the paravirt assembly constraints to be
> > compatible. The %c/i constrains generate smaller code so is kept by
> > default.
> >
> > Position Independent Executable (PIE) support will allow to extend the
> > KASLR randomization range below 0xffffffff80000000.
> >
> > Signed-off-by: Thomas Garnier <thgarnie@google.com>
>
> Acked-by: Juergen Gross <jgross@suse.com>

Thanks Juergen.

>
>
> Juergen

Patch
diff mbox series

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 2474e434a6f7..93be18bdb63e 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -343,9 +343,17 @@  extern struct paravirt_patch_template pv_ops;
 #define PARAVIRT_PATCH(x)					\
 	(offsetof(struct paravirt_patch_template, x) / sizeof(void *))
 
+#ifdef CONFIG_X86_PIE
+#define paravirt_opptr_call "a"
+#define paravirt_opptr_type "p"
+#else
+#define paravirt_opptr_call "c"
+#define paravirt_opptr_type "i"
+#endif
+
 #define paravirt_type(op)				\
 	[paravirt_typenum] "i" (PARAVIRT_PATCH(op)),	\
-	[paravirt_opptr] "i" (&(pv_ops.op))
+	[paravirt_opptr] paravirt_opptr_type (&(pv_ops.op))
 #define paravirt_clobber(clobber)		\
 	[paravirt_clobber] "i" (clobber)
 
@@ -393,7 +401,7 @@  int paravirt_disable_iospace(void);
  */
 #define PARAVIRT_CALL					\
 	ANNOTATE_RETPOLINE_SAFE				\
-	"call *%c[paravirt_opptr];"
+	"call *%" paravirt_opptr_call "[paravirt_opptr];"
 
 /*
  * These macros are intended to wrap calls through one of the paravirt