Hi Ard,
On Fri, Jul 24, 2015 at 10:41:53AM +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>
> ---
> arch/arm64/kernel/efi-stub.c | 47 ++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 39 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
> index f5374065ad53..c8df74d14368 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,
Any reason for the _arg addition?
> unsigned long *image_addr,
> unsigned long *image_size,
> unsigned long *reserve_addr,
> @@ -23,21 +23,52 @@ 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;
>
> /* 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'.
> + //
/*
* Nit: please use the standard comment style
*/
> + *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) {
> + memcpy((void *)*reserve_addr, (void *)*image_addr,
> + kernel_size);
> + *image_addr = *reserve_addr;
> + *reserve_size = kernel_memsize;
> + } else {
> + status = efi_low_alloc(sys_table_arg,
> + kernel_memsize + TEXT_OFFSET,
> + SZ_2M, reserve_addr);
> +
> + if (status == EFI_SUCCESS) {
> + memcpy((void *)*reserve_addr + TEXT_OFFSET,
> + (void *)*image_addr,
> + kernel_size);
> + *image_addr = *reserve_addr + TEXT_OFFSET;
> + *reserve_size = kernel_memsize + TEXT_OFFSET;
> + }
> + }
> if (status != EFI_SUCCESS) {
> - pr_efi_err(sys_table, "Failed to relocate kernel\n");
> + pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
> return status;
> }
> - memcpy((void *)*reserve_addr + TEXT_OFFSET, (void *)*image_addr,
> - kernel_size);
Could we have a new_image_addr assigned in each case, and keep the
common memcpy here, followed by assignment to *image_addr? That would
save a couple of lines and guarantee the two cases stay in sync.
Otherwise this looks good to me.
Thanks,
Mark.
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