diff mbox series

[v4,04/17] arm64: kernel: avoid x18 __cpu_soft_restart

Message ID 20191101221150.116536-5-samitolvanen@google.com
State Superseded
Headers show
Series None | expand

Commit Message

Sami Tolvanen Nov. 1, 2019, 10:11 p.m. UTC 
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>


The code in __cpu_soft_restart() uses x18 as an arbitrary temp register,
which will shortly be disallowed. So use x8 instead.

Link: https://patchwork.kernel.org/patch/9836877/
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

[Sami: updated commit message]
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Mark Rutland <mark.rutland@arm.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

---
 arch/arm64/kernel/cpu-reset.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.24.0.rc1.363.gb1bccd3e3d-goog

Comments

Mark Rutland Nov. 4, 2019, 11:39 a.m. UTC | #1 
On Fri, Nov 01, 2019 at 03:11:37PM -0700, Sami Tolvanen wrote:
> From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> 

> The code in __cpu_soft_restart() uses x18 as an arbitrary temp register,

> which will shortly be disallowed. So use x8 instead.

> 

> Link: https://patchwork.kernel.org/patch/9836877/

> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

> [Sami: updated commit message]

> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

> Reviewed-by: Mark Rutland <mark.rutland@arm.com>

> Reviewed-by: Kees Cook <keescook@chromium.org>


Trivial nit, but the commit title is missing "in" between x18 and
__cpu_soft_restart.

Mark.

> ---

>  arch/arm64/kernel/cpu-reset.S | 4 ++--

>  1 file changed, 2 insertions(+), 2 deletions(-)

> 

> diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S

> index 6ea337d464c4..32c7bf858dd9 100644

> --- a/arch/arm64/kernel/cpu-reset.S

> +++ b/arch/arm64/kernel/cpu-reset.S

> @@ -42,11 +42,11 @@ ENTRY(__cpu_soft_restart)

>  	mov	x0, #HVC_SOFT_RESTART

>  	hvc	#0				// no return

>  

> -1:	mov	x18, x1				// entry

> +1:	mov	x8, x1				// entry

>  	mov	x0, x2				// arg0

>  	mov	x1, x3				// arg1

>  	mov	x2, x4				// arg2

> -	br	x18

> +	br	x8

>  ENDPROC(__cpu_soft_restart)

>  

>  .popsection

> -- 

> 2.24.0.rc1.363.gb1bccd3e3d-goog

>
Sami Tolvanen Nov. 4, 2019, 4:44 p.m. UTC | #2 
On Mon, Nov 4, 2019 at 3:39 AM Mark Rutland <mark.rutland@arm.com> wrote:
> Trivial nit, but the commit title is missing "in" between x18 and

> __cpu_soft_restart.


Oops, thanks for pointing that out. I'll fix this in v5.

Sami
diff mbox series

Patch

diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 6ea337d464c4..32c7bf858dd9 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -42,11 +42,11 @@  ENTRY(__cpu_soft_restart)
 	mov	x0, #HVC_SOFT_RESTART
 	hvc	#0				// no return
 
-1:	mov	x18, x1				// entry
+1:	mov	x8, x1				// entry
 	mov	x0, x2				// arg0
 	mov	x1, x3				// arg1
 	mov	x2, x4				// arg2
-	br	x18
+	br	x8
 ENDPROC(__cpu_soft_restart)
 
 .popsection