[PATCH v3 05/11] arm64/efi: adapt to relaxed FDT placement requirements

[Mark Rutland]

On Fri, Apr 10, 2015 at 02:53:49PM +0100, Ard Biesheuvel wrote:
> With the relaxed FDT placement requirements in place, we can change
> the allocation strategy used by the stub to put the FDT image higher
> up in memory. At the same time, reduce the minimal alignment to 8 bytes,
> and impose a 2 MB size limit, as per the new requirements.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  arch/arm64/include/asm/efi.h            |  8 +++-----
>  drivers/firmware/efi/libstub/arm-stub.c |  5 ++---
>  drivers/firmware/efi/libstub/efistub.h  |  1 -
>  drivers/firmware/efi/libstub/fdt.c      | 23 +++++++++++++----------
>  4 files changed, 18 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
> index ef572206f1c3..bd513dd663b9 100644
> --- a/arch/arm64/include/asm/efi.h
> +++ b/arch/arm64/include/asm/efi.h
> @@ -39,12 +39,10 @@ extern void efi_init(void);
>  /* arch specific definitions used by the stub code */
>  
>  /*
> - * AArch64 requires the DTB to be 8-byte aligned in the first 512MiB from
> - * start of kernel and may not cross a 2MiB boundary. We set alignment to
> - * 2MiB so we know it won't cross a 2MiB boundary.
> + * AArch64 requires the DTB to be 8-byte aligned and not exceed 2MiB in size.
>   */
> -#define EFI_FDT_ALIGN	SZ_2M   /* used by allocate_new_fdt_and_exit_boot() */
> -#define MAX_FDT_OFFSET	SZ_512M
> +#define EFI_FDT_ALIGN		8
> +#define EFI_FDT_MAX_SIZE	SZ_2M

Is there any way we can organise things so we can share the kernel's
MAX_FDT_SIZE definition, so as to keep the stub and kernel in sync?

Otherwise, the patch looks good to me.

Mark.

>  
>  #define efi_call_early(f, ...) sys_table_arg->boottime->f(__VA_ARGS__)
>  
> diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
> index dcae482a9a17..f54c76a4fd32 100644
> --- a/drivers/firmware/efi/libstub/arm-stub.c
> +++ b/drivers/firmware/efi/libstub/arm-stub.c
> @@ -269,9 +269,8 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
>  
>  	new_fdt_addr = fdt_addr;
>  	status = allocate_new_fdt_and_exit_boot(sys_table, handle,
> -				&new_fdt_addr, dram_base + MAX_FDT_OFFSET,
> -				initrd_addr, initrd_size, cmdline_ptr,
> -				fdt_addr, fdt_size);
> +				&new_fdt_addr, initrd_addr, initrd_size,
> +				cmdline_ptr, fdt_addr, fdt_size);
>  
>  	/*
>  	 * If all went well, we need to return the FDT address to the
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 47437b16b186..c8e096094ea9 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -35,7 +35,6 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
>  efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
>  					    void *handle,
>  					    unsigned long *new_fdt_addr,
> -					    unsigned long max_addr,
>  					    u64 initrd_addr, u64 initrd_size,
>  					    char *cmdline_ptr,
>  					    unsigned long fdt_addr,
> diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
> index 91da56c4fd54..ace5ed70a88e 100644
> --- a/drivers/firmware/efi/libstub/fdt.c
> +++ b/drivers/firmware/efi/libstub/fdt.c
> @@ -165,10 +165,6 @@ fdt_set_fail:
>  	return EFI_LOAD_ERROR;
>  }
>  
> -#ifndef EFI_FDT_ALIGN
> -#define EFI_FDT_ALIGN EFI_PAGE_SIZE
> -#endif
> -
>  /*
>   * Allocate memory for a new FDT, then add EFI, commandline, and
>   * initrd related fields to the FDT.  This routine increases the
> @@ -186,7 +182,6 @@ fdt_set_fail:
>  efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
>  					    void *handle,
>  					    unsigned long *new_fdt_addr,
> -					    unsigned long max_addr,
>  					    u64 initrd_addr, u64 initrd_size,
>  					    char *cmdline_ptr,
>  					    unsigned long fdt_addr,
> @@ -197,6 +192,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
>  	unsigned long mmap_key;
>  	efi_memory_desc_t *memory_map, *runtime_map;
>  	unsigned long new_fdt_size;
> +	void *fdt_alloc;
>  	efi_status_t status;
>  	int runtime_entry_count = 0;
>  
> @@ -221,14 +217,21 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
>  	 * will allocate a bigger buffer if this ends up being too
>  	 * small, so a rough guess is OK here.
>  	 */
> -	new_fdt_size = fdt_size + EFI_PAGE_SIZE;
> +	new_fdt_size = fdt_size + EFI_PAGE_SIZE + EFI_FDT_ALIGN;
>  	while (1) {
> -		status = efi_high_alloc(sys_table, new_fdt_size, EFI_FDT_ALIGN,
> -					new_fdt_addr, max_addr);
> +		if (new_fdt_size > EFI_FDT_MAX_SIZE) {
> +			pr_efi_err(sys_table, "FDT size exceeds EFI_FDT_MAX_SIZE.\n");
> +			goto fail;
> +		}
> +		status = sys_table->boottime->allocate_pool(EFI_LOADER_DATA,
> +							    new_fdt_size,
> +							    &fdt_alloc);
>  		if (status != EFI_SUCCESS) {
>  			pr_efi_err(sys_table, "Unable to allocate memory for new device tree.\n");
>  			goto fail;
>  		}
> +		*new_fdt_addr = round_up((unsigned long)fdt_alloc,
> +					 EFI_FDT_ALIGN);
>  
>  		/*
>  		 * Now that we have done our final memory allocation (and free)
> @@ -258,7 +261,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
>  			 * to get new one that reflects the free/alloc we do
>  			 * on the device tree buffer.
>  			 */
> -			efi_free(sys_table, new_fdt_size, *new_fdt_addr);
> +			sys_table->boottime->free_pool(&fdt_alloc);
>  			sys_table->boottime->free_pool(memory_map);
>  			new_fdt_size += EFI_PAGE_SIZE;
>  		} else {
> @@ -316,7 +319,7 @@ fail_free_mmap:
>  	sys_table->boottime->free_pool(memory_map);
>  
>  fail_free_new_fdt:
> -	efi_free(sys_table, new_fdt_size, *new_fdt_addr);
> +	sys_table->boottime->free_pool(&fdt_alloc);
>  
>  fail:
>  	sys_table->boottime->free_pool(runtime_map);
> -- 
> 1.8.3.2
>