Re: [PATCH 1/3] xen/arm64: head: Move earlyprintk 'hex' string to .rodata.str

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 21/11/2023 09:45, Michal Orzel wrote:
> At the moment, the 'hex' string is placed right after the 'putn'
> function in the .text section. This is because of the limited range
> (+/- 1MB) of PC relative 'adr' instruction 'putn' uses. Modify it to use
> 'adr_l' instead (range extended to +/- 4GB) and move the string to
> .rodata.str. This way all the earlyprintk messages will be part of .rodata
> and the behavior will be consistent with what we already do on arm32.
This will be correct today, but I am actually thinking to move 'hex' to 
.rodata.idmap so it can be used while we are on the 1:1 mapping and/or 
temporary mapping.
So I would consider to drop this patch for now.

Cheers,

> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> ---
>   xen/arch/arm/arm64/head.S | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index 8dbd3300d89f..b6111399e766 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -498,7 +498,7 @@ ENDPROC(asm_puts)
>    * Clobbers x0-x3
>    */
>   putn:
> -        adr   x1, hex
> +        adr_l x1, hex
>           mov   x3, #16
>   1:
>           early_uart_ready x23, 2
> @@ -512,8 +512,7 @@ putn:
>           ret
>   ENDPROC(putn)
>   
> -hex:    .ascii "0123456789abcdef"
> -        .align 2
> +RODATA_STR(hex, "0123456789abcdef")
>   
>   #else  /* CONFIG_EARLY_PRINTK */
>   
[1] https://lore.kernel.org/20231101233011.83098-3-julien@xxxxxxx

--
Julien Grall