Re: [PATCH 5/8] kern/ieee1275/init: ppc64: Add support for alignment requirements

[Stefan Berger]

On 10/27/23 10:14, Stefan Berger wrote:
> Add support for memory alignment requirements and adjust a candidate
> address to it before checking whether the block is large enough since
> the alignment adjustment can make a block smaller than what was
> requested.
>
> Signed-off-by: stefan Berger <stefanb@linux.ibm.com>
> Cc: Hari Bathini <hbathini@linux.ibm.com>
> Cc: Pavithra Prakash <pavrampu@in.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Carolyn Scherrer <cpscherr@us.ibm.com>
> Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
> ---
>   grub-core/kern/ieee1275/init.c        | 10 ++++++++++
>   include/grub/powerpc/ieee1275/alloc.h |  1 +
>   2 files changed, 11 insertions(+)
>
> diff --git a/grub-core/kern/ieee1275/init.c b/grub-core/kern/ieee1275/init.c
> index a0ce9d55e..5414f659c 100644
> --- a/grub-core/kern/ieee1275/init.c
> +++ b/grub-core/kern/ieee1275/init.c
> @@ -506,6 +506,16 @@ regions_claim (grub_uint64_t addr, grub_uint64_t len, 
> grub_memory_type_t type,
>               }
>           }
>       }
> +
> +  /* Honor alignment restrictions on candidate addr */
> +  if (rcr->align)
> +    {
> +      grub_uint64_t align_addr = ALIGN_UP (addr, rcr->align);
> +
> +      len = len - (align_addr - addr);

In v2 this will look like this:

      grub_uint64_t align_addr = ALIGN_UP (addr, rcr->align);
      grub_uint64_t d = align_addr - addr;

      if (d > len)
        return 0;

      len -= d;

> +      addr = align_addr;
> +    }
> +
>     if (rcr->flags & GRUB_MM_ADD_REGION_CONSECUTIVE && len < rcr->total)
>       return 0;
>   
> diff --git a/include/grub/powerpc/ieee1275/alloc.h b/include/grub/powerpc/ieee1275/alloc.h
> index 136e1df0b..b3d14f095 100644
> --- a/include/grub/powerpc/ieee1275/alloc.h
> +++ b/include/grub/powerpc/ieee1275/alloc.h
> @@ -11,6 +11,7 @@ struct regions_claim_request {
>     bool init_region;       /* whether to init the region */
>     grub_uint64_t addr;     /* result address */
>     grub_uint64_t len;      /* number of bytes allocated */
> +  grub_size_t align;      /* alignment restrictions */
>   };
>   
>   #endif /* GRUB_POWERPC_IEEE1275_ALLOC_HEADER */