diff mbox series

[1/7] xen/arm64: head: Don't set x22 and update the documentation

Message ID 20220812192448.43016-2-julien@xen.org (mailing list archive)
State New, archived
Headers show
Series xen/arm: More clean-ups and improvement | expand

Commit Message

Julien Grall Aug. 12, 2022, 7:24 p.m. UTC 
From: Julien Grall <jgrall@amazon.com>

Since commit 7e14a47e7c73 ("xen/arm64: head Rework and document
launch()"), the boot code is setting x22 but not read it.

So remove the two instructions setting x22 and update the documentation
to show x22 has no specific purpose.

Signed-off-by: Julien Grall <jgrall@amazon.com>
---
 xen/arch/arm/arm64/head.S | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

Comments

Wei Chen Aug. 15, 2022, 1:36 a.m. UTC | #1 
Hi Julien,

> -----Original Message-----
> From: Xen-devel <xen-devel-bounces@lists.xenproject.org> On Behalf Of
> Julien Grall
> Sent: 2022年8月13日 3:25
> To: xen-devel@lists.xenproject.org
> Cc: julien@xen.org; Julien Grall <jgrall@amazon.com>; Stefano Stabellini
> <sstabellini@kernel.org>; Bertrand Marquis <Bertrand.Marquis@arm.com>;
> Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
> Subject: [PATCH 1/7] xen/arm64: head: Don't set x22 and update the
> documentation
> 
> From: Julien Grall <jgrall@amazon.com>
> 
> Since commit 7e14a47e7c73 ("xen/arm64: head Rework and document
> launch()"), the boot code is setting x22 but not read it.
> 
> So remove the two instructions setting x22 and update the documentation
> to show x22 has no specific purpose.
> 
> Signed-off-by: Julien Grall <jgrall@amazon.com>
> ---
>  xen/arch/arm/arm64/head.S | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index 1babcc65d7c9..26cc7705f556 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -71,7 +71,7 @@
>   *  x19 - paddr(start)
>   *  x20 - phys offset
>   *  x21 - DTB address (boot cpu only)
> - *  x22 - is_secondary_cpu
> + *  x22 -
>   *  x23 - UART address
>   *  x24 -
>   *  x25 -
> @@ -305,8 +305,6 @@ real_start_efi:
>  #endif
>          PRINT("- Boot CPU booting -\r\n")
> 
> -        mov   x22, #0                /* x22 := is_secondary_cpu */
> -
>          bl    check_cpu_mode
>          bl    cpu_init
>          bl    create_page_tables
> @@ -345,8 +343,6 @@ GLOBAL(init_secondary)
>          adr   x19, start             /* x19 := paddr (start) */
>          sub   x20, x19, x0           /* x20 := phys-offset */
> 
> -        mov   x22, #1                /* x22 := is_secondary_cpu */
> -
>          mrs   x0, mpidr_el1
>          ldr   x13, =(~MPIDR_HWID_MASK)
>          bic   x24, x0, x13           /* Mask out flags to get CPU ID */
> --
> 2.37.1
> 

Reviewed-by: Wei Chen <Wei.Chen@arm.com>
Bertrand Marquis Aug. 15, 2022, 1:43 p.m. UTC | #2 
Hi Julien,

> On 12 Aug 2022, at 20:24, Julien Grall <julien@xen.org> wrote:
> 
> From: Julien Grall <jgrall@amazon.com>
> 
> Since commit 7e14a47e7c73 ("xen/arm64: head Rework and document
> launch()"), the boot code is setting x22 but not read it.
> 
> So remove the two instructions setting x22 and update the documentation
> to show x22 has no specific purpose.
> 
> Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

Cheers
Bertrand
> ---
> xen/arch/arm/arm64/head.S | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index 1babcc65d7c9..26cc7705f556 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -71,7 +71,7 @@
>  *  x19 - paddr(start)
>  *  x20 - phys offset
>  *  x21 - DTB address (boot cpu only)
> - *  x22 - is_secondary_cpu
> + *  x22 -
>  *  x23 - UART address
>  *  x24 -
>  *  x25 -
> @@ -305,8 +305,6 @@ real_start_efi:
> #endif
>         PRINT("- Boot CPU booting -\r\n")
> 
> -        mov   x22, #0                /* x22 := is_secondary_cpu */
> -
>         bl    check_cpu_mode
>         bl    cpu_init
>         bl    create_page_tables
> @@ -345,8 +343,6 @@ GLOBAL(init_secondary)
>         adr   x19, start             /* x19 := paddr (start) */
>         sub   x20, x19, x0           /* x20 := phys-offset */
> 
> -        mov   x22, #1                /* x22 := is_secondary_cpu */
> -
>         mrs   x0, mpidr_el1
>         ldr   x13, =(~MPIDR_HWID_MASK)
>         bic   x24, x0, x13           /* Mask out flags to get CPU ID */
> -- 
> 2.37.1
>
diff mbox series

Patch

diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 1babcc65d7c9..26cc7705f556 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -71,7 +71,7 @@ 
  *  x19 - paddr(start)
  *  x20 - phys offset
  *  x21 - DTB address (boot cpu only)
- *  x22 - is_secondary_cpu
+ *  x22 -
  *  x23 - UART address
  *  x24 -
  *  x25 -
@@ -305,8 +305,6 @@  real_start_efi:
 #endif
         PRINT("- Boot CPU booting -\r\n")
 
-        mov   x22, #0                /* x22 := is_secondary_cpu */
-
         bl    check_cpu_mode
         bl    cpu_init
         bl    create_page_tables
@@ -345,8 +343,6 @@  GLOBAL(init_secondary)
         adr   x19, start             /* x19 := paddr (start) */
         sub   x20, x19, x0           /* x20 := phys-offset */
 
-        mov   x22, #1                /* x22 := is_secondary_cpu */
-
         mrs   x0, mpidr_el1
         ldr   x13, =(~MPIDR_HWID_MASK)
         bic   x24, x0, x13           /* Mask out flags to get CPU ID */