On Fri, Jul 24, 2015 at 12:38:27PM +0100, Ard Biesheuvel wrote:
> When allocating memory for the kernel image, try the AllocatePages()
> boot service to obtain memory at the preferred offset of
> 'dram_base + TEXT_OFFSET', and only revert to efi_low_alloc() if that
> fails. This is the only way to allocate at the base of DRAM if DRAM
> starts at 0x0, since efi_low_alloc() refuses to allocate at 0x0.
>
> Tested-by: Haojian Zhuang <haojian.zhuang@xxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
Mark.
> ---
> v2:
> - reshuffle code flow to make it more logical, and have only a single
> memcpy() invocation at the end of the function
> ---
> arch/arm64/kernel/efi-stub.c | 41 ++++++++++++++++++++++++++++++++---------
> 1 file changed, 32 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
> index f5374065ad53..816120ece6bc 100644
> --- a/arch/arm64/kernel/efi-stub.c
> +++ b/arch/arm64/kernel/efi-stub.c
> @@ -13,7 +13,7 @@
> #include <asm/efi.h>
> #include <asm/sections.h>
>
> -efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
> +efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
> unsigned long *image_addr,
> unsigned long *image_size,
> unsigned long *reserve_addr,
> @@ -23,21 +23,44 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
> {
> efi_status_t status;
> unsigned long kernel_size, kernel_memsize = 0;
> + unsigned long nr_pages;
> + void *old_image_addr = (void *)*image_addr;
>
> /* Relocate the image, if required. */
> kernel_size = _edata - _text;
> if (*image_addr != (dram_base + TEXT_OFFSET)) {
> kernel_memsize = kernel_size + (_end - _edata);
> - status = efi_low_alloc(sys_table, kernel_memsize + TEXT_OFFSET,
> - SZ_2M, reserve_addr);
> +
> + /*
> + * First, try a straight allocation at the preferred offset.
> + * This will work around the issue where, if dram_base == 0x0,
> + * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
> + * address of the allocation to be mistaken for a FAIL return
> + * value or a NULL pointer). It will also ensure that, on
> + * platforms where the [dram_base, dram_base + TEXT_OFFSET)
> + * interval is partially occupied by the firmware (like on APM
> + * Mustang), we can still place the kernel at the address
> + * 'dram_base + TEXT_OFFSET'.
> + */
> + *image_addr = *reserve_addr = dram_base + TEXT_OFFSET;
> + nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
> + EFI_PAGE_SIZE;
> + status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
> + EFI_LOADER_DATA, nr_pages,
> + (efi_physical_addr_t *)reserve_addr);
> if (status != EFI_SUCCESS) {
> - pr_efi_err(sys_table, "Failed to relocate kernel\n");
> - return status;
> + kernel_memsize += TEXT_OFFSET;
> + status = efi_low_alloc(sys_table_arg, kernel_memsize,
> + SZ_2M, reserve_addr);
> +
> + if (status != EFI_SUCCESS) {
> + pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
> + return status;
> + }
> + *image_addr = *reserve_addr + TEXT_OFFSET;
> }
> - memcpy((void *)*reserve_addr + TEXT_OFFSET, (void *)*image_addr,
> - kernel_size);
> - *image_addr = *reserve_addr + TEXT_OFFSET;
> - *reserve_size = kernel_memsize + TEXT_OFFSET;
> + memcpy((void *)*image_addr, old_image_addr, kernel_size);
> + *reserve_size = kernel_memsize;
> }
>
>
> --
> 1.9.1
>
--
To unsubscribe from this list: send the line "unsubscribe linux-efi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
