Re: [PATCH 4.4 072/101] arm64: assembler: make adr_l work in modules under KASLR

[Greg Kroah-Hartman]

On Tue, Jul 04, 2017 at 10:24:37AM +0100, Ard Biesheuvel wrote:
> On 3 July 2017 at 14:35, Greg Kroah-Hartman  
> wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> >
> > --
> >
> > From: Ard Biesheuvel 
> >
> >
> > [ Upstream commit 41c066f2c4d436c535616fe182331766c57838f0 ]
> >
> > When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded
> > modules and the core kernel may exceed 4 GB, putting symbols exported
> > by the core kernel out of the reach of the ordinary adrp/add instruction
> > pairs used to generate relative symbol references. So make the adr_l
> > macro emit a movz/movk sequence instead when executing in module context.
> >
> > While at it, remove the pointless special case for the stack pointer.
> >
> 
> As it turns out, this 'pointless special case' was not so pointless in
> v4.4, and removing it breaks the build.
> 
> Given that the only in-module user of adr_l is the new scalar AES
> code, which is not backported to v4.4, there is really no point in
> backporting this to v4.4.

Yes, I dropped it from the tree about 2 hours ago after the build-bots
reported it killed things :)

thanks,

greg k-h

Re: [PATCH 4.4 072/101] arm64: assembler: make adr_l work in modules under KASLR

[Greg Kroah-Hartman]

On Tue, Jul 04, 2017 at 10:24:37AM +0100, Ard Biesheuvel wrote:
> On 3 July 2017 at 14:35, Greg Kroah-Hartman  
> wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> >
> > --
> >
> > From: Ard Biesheuvel 
> >
> >
> > [ Upstream commit 41c066f2c4d436c535616fe182331766c57838f0 ]
> >
> > When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded
> > modules and the core kernel may exceed 4 GB, putting symbols exported
> > by the core kernel out of the reach of the ordinary adrp/add instruction
> > pairs used to generate relative symbol references. So make the adr_l
> > macro emit a movz/movk sequence instead when executing in module context.
> >
> > While at it, remove the pointless special case for the stack pointer.
> >
> 
> As it turns out, this 'pointless special case' was not so pointless in
> v4.4, and removing it breaks the build.
> 
> Given that the only in-module user of adr_l is the new scalar AES
> code, which is not backported to v4.4, there is really no point in
> backporting this to v4.4.

Yes, I dropped it from the tree about 2 hours ago after the build-bots
reported it killed things :)

thanks,

greg k-h

Re: [PATCH 4.4 072/101] arm64: assembler: make adr_l work in modules under KASLR

[Ard Biesheuvel]

On 3 July 2017 at 14:35, Greg Kroah-Hartman  wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
>
> --
>
> From: Ard Biesheuvel 
>
>
> [ Upstream commit 41c066f2c4d436c535616fe182331766c57838f0 ]
>
> When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded
> modules and the core kernel may exceed 4 GB, putting symbols exported
> by the core kernel out of the reach of the ordinary adrp/add instruction
> pairs used to generate relative symbol references. So make the adr_l
> macro emit a movz/movk sequence instead when executing in module context.
>
> While at it, remove the pointless special case for the stack pointer.
>

As it turns out, this 'pointless special case' was not so pointless in
v4.4, and removing it breaks the build.

Given that the only in-module user of adr_l is the new scalar AES
code, which is not backported to v4.4, there is really no point in
backporting this to v4.4.

-- 
Ard.


> Acked-by: Mark Rutland 
> Acked-by: Will Deacon 
> Signed-off-by: Ard Biesheuvel 
> Signed-off-by: Catalin Marinas 
> Signed-off-by: Sasha Levin 
> Signed-off-by: Greg Kroah-Hartman 
> ---
>  arch/arm64/include/asm/assembler.h |   36 
> +++-
>  1 file changed, 27 insertions(+), 9 deletions(-)
>
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -147,22 +147,25 @@ lr.reqx30 // link register
>
>  /*
>   * Pseudo-ops for PC-relative adr/ldr/str ,  where
> - *  is within the range +/- 4 GB of the PC.
> + *  is within the range +/- 4 GB of the PC when running
> + * in core kernel context. In module context, a movz/movk sequence
> + * is used, since modules may be loaded far away from the kernel
> + * when KASLR is in effect.
>   */
> /*
>  * @dst: destination register (64 bit wide)
>  * @sym: name of the symbol
> -* @tmp: optional scratch register to be used if  == sp, which
> -*   is not allowed in an adrp instruction
>  */
> -   .macro  adr_l, dst, sym, tmp=
> -   .ifb\tmp
> +   .macro  adr_l, dst, sym
> +#ifndef MODULE
> adrp\dst, \sym
> add \dst, \dst, :lo12:\sym
> -   .else
> -   adrp\tmp, \sym
> -   add \dst, \tmp, :lo12:\sym
> -   .endif
> +#else
> +   movz\dst, #:abs_g3:\sym
> +   movk\dst, #:abs_g2_nc:\sym
> +   movk\dst, #:abs_g1_nc:\sym
> +   movk\dst, #:abs_g0_nc:\sym
> +#endif
> .endm
>
> /*
> @@ -173,6 +176,7 @@ lr  .reqx30 // link register
>  *   the address
>  */
> .macro  ldr_l, dst, sym, tmp=
> +#ifndef MODULE
> .ifb\tmp
> adrp\dst, \sym
> ldr \dst, [\dst, :lo12:\sym]
> @@ -180,6 +184,15 @@ lr .reqx30 // link register
> adrp\tmp, \sym
> ldr \dst, [\tmp, :lo12:\sym]
> .endif
> +#else
> +   .ifb\tmp
> +   adr_l   \dst, \sym
> +   ldr \dst, [\dst]
> +   .else
> +   adr_l   \tmp, \sym
> +   ldr \dst, [\tmp]
> +   .endif
> +#endif
> .endm
>
> /*
> @@ -189,8 +202,13 @@ lr .reqx30 // link register
>  *   while  needs to be preserved.
>  */
> .macro  str_l, src, sym, tmp
> +#ifndef MODULE
> adrp\tmp, \sym
> str \src, [\tmp, :lo12:\sym]
> +#else
> +   adr_l   \tmp, \sym
> +   str \src, [\tmp]
> +#endif
> .endm
>
>  /*
>
>

Re: [PATCH 4.4 072/101] arm64: assembler: make adr_l work in modules under KASLR

[Ard Biesheuvel]

On 3 July 2017 at 14:35, Greg Kroah-Hartman  wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
>
> --
>
> From: Ard Biesheuvel 
>
>
> [ Upstream commit 41c066f2c4d436c535616fe182331766c57838f0 ]
>
> When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded
> modules and the core kernel may exceed 4 GB, putting symbols exported
> by the core kernel out of the reach of the ordinary adrp/add instruction
> pairs used to generate relative symbol references. So make the adr_l
> macro emit a movz/movk sequence instead when executing in module context.
>
> While at it, remove the pointless special case for the stack pointer.
>

As it turns out, this 'pointless special case' was not so pointless in
v4.4, and removing it breaks the build.

Given that the only in-module user of adr_l is the new scalar AES
code, which is not backported to v4.4, there is really no point in
backporting this to v4.4.

-- 
Ard.


> Acked-by: Mark Rutland 
> Acked-by: Will Deacon 
> Signed-off-by: Ard Biesheuvel 
> Signed-off-by: Catalin Marinas 
> Signed-off-by: Sasha Levin 
> Signed-off-by: Greg Kroah-Hartman 
> ---
>  arch/arm64/include/asm/assembler.h |   36 
> +++-
>  1 file changed, 27 insertions(+), 9 deletions(-)
>
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -147,22 +147,25 @@ lr.reqx30 // link register
>
>  /*
>   * Pseudo-ops for PC-relative adr/ldr/str ,  where
> - *  is within the range +/- 4 GB of the PC.
> + *  is within the range +/- 4 GB of the PC when running
> + * in core kernel context. In module context, a movz/movk sequence
> + * is used, since modules may be loaded far away from the kernel
> + * when KASLR is in effect.
>   */
> /*
>  * @dst: destination register (64 bit wide)
>  * @sym: name of the symbol
> -* @tmp: optional scratch register to be used if  == sp, which
> -*   is not allowed in an adrp instruction
>  */
> -   .macro  adr_l, dst, sym, tmp=
> -   .ifb\tmp
> +   .macro  adr_l, dst, sym
> +#ifndef MODULE
> adrp\dst, \sym
> add \dst, \dst, :lo12:\sym
> -   .else
> -   adrp\tmp, \sym
> -   add \dst, \tmp, :lo12:\sym
> -   .endif
> +#else
> +   movz\dst, #:abs_g3:\sym
> +   movk\dst, #:abs_g2_nc:\sym
> +   movk\dst, #:abs_g1_nc:\sym
> +   movk\dst, #:abs_g0_nc:\sym
> +#endif
> .endm
>
> /*
> @@ -173,6 +176,7 @@ lr  .reqx30 // link register
>  *   the address
>  */
> .macro  ldr_l, dst, sym, tmp=
> +#ifndef MODULE
> .ifb\tmp
> adrp\dst, \sym
> ldr \dst, [\dst, :lo12:\sym]
> @@ -180,6 +184,15 @@ lr .reqx30 // link register
> adrp\tmp, \sym
> ldr \dst, [\tmp, :lo12:\sym]
> .endif
> +#else
> +   .ifb\tmp
> +   adr_l   \dst, \sym
> +   ldr \dst, [\dst]
> +   .else
> +   adr_l   \tmp, \sym
> +   ldr \dst, [\tmp]
> +   .endif
> +#endif
> .endm
>
> /*
> @@ -189,8 +202,13 @@ lr .reqx30 // link register
>  *   while  needs to be preserved.
>  */
> .macro  str_l, src, sym, tmp
> +#ifndef MODULE
> adrp\tmp, \sym
> str \src, [\tmp, :lo12:\sym]
> +#else
> +   adr_l   \tmp, \sym
> +   str \src, [\tmp]
> +#endif
> .endm
>
>  /*
>
>

[PATCH 4.4 072/101] arm64: assembler: make adr_l work in modules under KASLR

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Ard Biesheuvel 


[ Upstream commit 41c066f2c4d436c535616fe182331766c57838f0 ]

When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded
modules and the core kernel may exceed 4 GB, putting symbols exported
by the core kernel out of the reach of the ordinary adrp/add instruction
pairs used to generate relative symbol references. So make the adr_l
macro emit a movz/movk sequence instead when executing in module context.

While at it, remove the pointless special case for the stack pointer.

Acked-by: Mark Rutland 
Acked-by: Will Deacon 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Catalin Marinas 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman 
---
 arch/arm64/include/asm/assembler.h |   36 +++-
 1 file changed, 27 insertions(+), 9 deletions(-)

--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -147,22 +147,25 @@ lr.reqx30 // link register
 
 /*
  * Pseudo-ops for PC-relative adr/ldr/str ,  where
- *  is within the range +/- 4 GB of the PC.
+ *  is within the range +/- 4 GB of the PC when running
+ * in core kernel context. In module context, a movz/movk sequence
+ * is used, since modules may be loaded far away from the kernel
+ * when KASLR is in effect.
  */
/*
 * @dst: destination register (64 bit wide)
 * @sym: name of the symbol
-* @tmp: optional scratch register to be used if  == sp, which
-*   is not allowed in an adrp instruction
 */
-   .macro  adr_l, dst, sym, tmp=
-   .ifb\tmp
+   .macro  adr_l, dst, sym
+#ifndef MODULE
adrp\dst, \sym
add \dst, \dst, :lo12:\sym
-   .else
-   adrp\tmp, \sym
-   add \dst, \tmp, :lo12:\sym
-   .endif
+#else
+   movz\dst, #:abs_g3:\sym
+   movk\dst, #:abs_g2_nc:\sym
+   movk\dst, #:abs_g1_nc:\sym
+   movk\dst, #:abs_g0_nc:\sym
+#endif
.endm
 
/*
@@ -173,6 +176,7 @@ lr  .reqx30 // link register
 *   the address
 */
.macro  ldr_l, dst, sym, tmp=
+#ifndef MODULE
.ifb\tmp
adrp\dst, \sym
ldr \dst, [\dst, :lo12:\sym]
@@ -180,6 +184,15 @@ lr .reqx30 // link register
adrp\tmp, \sym
ldr \dst, [\tmp, :lo12:\sym]
.endif
+#else
+   .ifb\tmp
+   adr_l   \dst, \sym
+   ldr \dst, [\dst]
+   .else
+   adr_l   \tmp, \sym
+   ldr \dst, [\tmp]
+   .endif
+#endif
.endm
 
/*
@@ -189,8 +202,13 @@ lr .reqx30 // link register
 *   while  needs to be preserved.
 */
.macro  str_l, src, sym, tmp
+#ifndef MODULE
adrp\tmp, \sym
str \src, [\tmp, :lo12:\sym]
+#else
+   adr_l   \tmp, \sym
+   str \src, [\tmp]
+#endif
.endm
 
 /*

[PATCH 4.4 072/101] arm64: assembler: make adr_l work in modules under KASLR

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Ard Biesheuvel 


[ Upstream commit 41c066f2c4d436c535616fe182331766c57838f0 ]

When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded
modules and the core kernel may exceed 4 GB, putting symbols exported
by the core kernel out of the reach of the ordinary adrp/add instruction
pairs used to generate relative symbol references. So make the adr_l
macro emit a movz/movk sequence instead when executing in module context.

While at it, remove the pointless special case for the stack pointer.

Acked-by: Mark Rutland 
Acked-by: Will Deacon 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Catalin Marinas 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman 
---
 arch/arm64/include/asm/assembler.h |   36 +++-
 1 file changed, 27 insertions(+), 9 deletions(-)

--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -147,22 +147,25 @@ lr.reqx30 // link register
 
 /*
  * Pseudo-ops for PC-relative adr/ldr/str ,  where
- *  is within the range +/- 4 GB of the PC.
+ *  is within the range +/- 4 GB of the PC when running
+ * in core kernel context. In module context, a movz/movk sequence
+ * is used, since modules may be loaded far away from the kernel
+ * when KASLR is in effect.
  */
/*
 * @dst: destination register (64 bit wide)
 * @sym: name of the symbol
-* @tmp: optional scratch register to be used if  == sp, which
-*   is not allowed in an adrp instruction
 */
-   .macro  adr_l, dst, sym, tmp=
-   .ifb\tmp
+   .macro  adr_l, dst, sym
+#ifndef MODULE
adrp\dst, \sym
add \dst, \dst, :lo12:\sym
-   .else
-   adrp\tmp, \sym
-   add \dst, \tmp, :lo12:\sym
-   .endif
+#else
+   movz\dst, #:abs_g3:\sym
+   movk\dst, #:abs_g2_nc:\sym
+   movk\dst, #:abs_g1_nc:\sym
+   movk\dst, #:abs_g0_nc:\sym
+#endif
.endm
 
/*
@@ -173,6 +176,7 @@ lr  .reqx30 // link register
 *   the address
 */
.macro  ldr_l, dst, sym, tmp=
+#ifndef MODULE
.ifb\tmp
adrp\dst, \sym
ldr \dst, [\dst, :lo12:\sym]
@@ -180,6 +184,15 @@ lr .reqx30 // link register
adrp\tmp, \sym
ldr \dst, [\tmp, :lo12:\sym]
.endif
+#else
+   .ifb\tmp
+   adr_l   \dst, \sym
+   ldr \dst, [\dst]
+   .else
+   adr_l   \tmp, \sym
+   ldr \dst, [\tmp]
+   .endif
+#endif
.endm
 
/*
@@ -189,8 +202,13 @@ lr .reqx30 // link register
 *   while  needs to be preserved.
 */
.macro  str_l, src, sym, tmp
+#ifndef MODULE
adrp\tmp, \sym
str \src, [\tmp, :lo12:\sym]
+#else
+   adr_l   \tmp, \sym
+   str \src, [\tmp]
+#endif
.endm
 
 /*