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SubjectRe: [PATCH v2] ARM: decompress: Use /memreserve/ DTS nodes when validating memory
On Tue, 7 Sept 2021 at 16:57, Bert Vermeulen <bert@biot.com> wrote:
>
> If the bootloader needs the start of memory to be preserved, for example
> because it dropped the Trusted Firmware blob there, this chunk of memory
> shouldn't be used by the kernel.
>
> To avoid adding yet another SoC-specific text offset to arch/arm/Makefile,
> this patch allows for a /memreserve/ entry in the DTS to mark off the
> memory chunk instead.
>
> Signed-off-by: Bert Vermeulen <bert@biot.com>

Thanks for working on this - I hope this will allow us to phase out at
least some of the existing text_offset hacks too.

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
> arch/arm/boot/compressed/fdt_check_mem_start.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/compressed/fdt_check_mem_start.c b/arch/arm/boot/compressed/fdt_check_mem_start.c
> index 62450d824c3c..1d47de1e860b 100644
> --- a/arch/arm/boot/compressed/fdt_check_mem_start.c
> +++ b/arch/arm/boot/compressed/fdt_check_mem_start.c
> @@ -64,7 +64,7 @@ uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
> uint32_t addr_cells, size_cells, base;
> uint32_t fdt_mem_start = 0xffffffff;
> const fdt32_t *reg, *endp;
> - uint64_t size, end;
> + uint64_t rsvaddr, size, end;
> const char *type;
> int offset, len;
>
> @@ -74,6 +74,19 @@ uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
> if (fdt_magic(fdt) != FDT_MAGIC)
> return mem_start;
>
> + for (offset = fdt_off_mem_rsvmap(fdt); ; offset += 16) {
> + rsvaddr = get_val(fdt + offset, 2);
> + size = get_val(fdt + offset + 8, 2);
> +
> + if (!rsvaddr && !size)
> + break;
> +
> + end = rsvaddr + size;
> + if (mem_start >= rsvaddr && mem_start <= end)
> + /* Relocate past reserved block */
> + mem_start = round_up(end, SZ_2M);
> + }
> +
> /* There may be multiple cells on LPAE platforms */
> addr_cells = get_cells(fdt, "#address-cells");
> size_cells = get_cells(fdt, "#size-cells");
> --
> 2.25.1
>

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