Re: [XEN v1 3/4] xen/arm32: Split and move MMU-specific head.S to mmu/head.S

[Julien Grall <julien@xxxxxxx>]

Hi,

On 11/09/2023 14:59, Ayan Kumar Halder wrote:
> This is based on
> "[PATCH v6 03/13] xen/arm64: Split and move MMU-specific head.S to mmu/head.S"
>
> https://www.mail-archive.com/xen-devel@xxxxxxxxxxxxxxxxxxxx/msg151920.html
Same remark as patch #1. Please provide a proper commit message.

[...]

> diff --git a/xen/arch/arm/include/asm/arm32/macros.h 
> b/xen/arch/arm/include/asm/arm32/macros.h
> index a4e20aa520..64fbe4876a 100644
> --- a/xen/arch/arm/include/asm/arm32/macros.h
> +++ b/xen/arch/arm/include/asm/arm32/macros.h
> @@ -1,8 +1,70 @@
>   #ifndef __ASM_ARM_ARM32_MACROS_H
>   #define __ASM_ARM_ARM32_MACROS_H
>   
> +/* Offset between the early boot xen mapping and the runtime xen mapping */
> +#define XEN_TEMPORARY_OFFSET      (TEMPORARY_XEN_VIRT_START - XEN_VIRT_START)
> +
>       .macro ret
>           mov     pc, lr
>       .endm
>   
> +/*
> + * Move an immediate constant into a 32-bit register using movw/movt
> + * instructions.
> + */
> +.macro mov_w reg, word
> +        movw  \reg, #:lower16:\word
> +        movt  \reg, #:upper16:\word
> +.endm
> +
> +/*
> + * Pseudo-op for PC relative adr <reg>, <symbol> where <symbol> is
> + * within the range +/- 4GB of the PC.
> + *
> + * @dst: destination register
> + * @sym: name of the symbol
> + */
> +.macro adr_l, dst, sym
> +        mov_w \dst, \sym - .Lpc\@
> +        .set  .Lpc\@, .+ 8          /* PC bias */
> +        add   \dst, \dst, pc
> +.endm
> +
> +.macro load_paddr rb, sym
> +        mov_w \rb, \sym
> +        add   \rb, \rb, r10
> +.endm
I see that we are still using load_paddr in arm64/head.S. But I don't 
think it makes entirely sense as r10 (x20) would always be 0 for the MPU.
In fact all the use in arm{32, 64}/head.S after this patch could be 
easily replaced with adr_l because they are called when the MMU is off 
so the return address will be a physical address.
So can you add a prequisite patch for arm32 to replace the remaining 
some of the load_paddr? With that, load_paddr can be moved in mmu/head.S.
I will take care of the arm64 part.

Cheers,

--
Julien Grall