Re: [PATCH 4/6 v2] efi_loader: Replace config option for initrd loading

On 3/13/21 10:47 PM, Ilias Apalodimas wrote:

Up to now we install EFI_LOAD_FILE2_PROTOCOL to load an initrd unconditionally. Although we correctly return various EFI exit codes depending on the file status (i.e EFI_NO_MEDIA, EFI_NOT_FOUND etc), the kernel loader, only falls back to the cmdline interpreted initrd if the protocol is not installed.

This creates a problem for EFI installers, since they won't be able to load their own initrd and continue the installation. It also makes the feature hard to use, since we can either have a single initrd or we have to recompile u-boot if the filename changes.

So let's introduce a different logic that will decouple the initrd path from the config option we currently have. When defining a UEFI BootXXXX we can use the filepathlist and store a file path pointing to our initrd. Specifically the EFI spec describes:

"The first element of the array is a device path that describes the device and location of the Image for this load option. Other device paths may optionally exist in the FilePathList, but their usage is OSV specific". That means we can install a device path to our initrd(s) after the loaded image looking like this: VenMedia - initrd1 - end node (0x01) initrd2 - end node (0xff)

When the EFI application is launched through the bootmgr, we'll try to interpret the extra device path. If that points to a file that exists on our disk, we'll now install the load_file2 and the efi-stub will be able to use it.

This opens up another path using U-Boot and defines a new boot flow. A user will be able to control the kernel/initrd pairs without explicit cmdline args or GRUB.

Signed-off-by: Ilias Apalodimas ilias.apalodimas@linaro.org

cmd/bootefi.c | 3 + include/efi_loader.h | 1 + lib/efi_loader/Kconfig | 15 +-- lib/efi_loader/efi_bootmgr.c | 19 +++- lib/efi_loader/efi_load_initrd.c | 189 ++++++++++++++++++------------- 5 files changed, 136 insertions(+), 91 deletions(-)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c index 271b385edea6..cba81ffe75e4 100644 --- a/cmd/bootefi.c +++ b/cmd/bootefi.c @@ -358,6 +358,9 @@ static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)

free(load_options);

• if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD))

• efi_initrd_deregister();
  

• return ret; }

diff --git a/include/efi_loader.h b/include/efi_loader.h index aa812a9a3052..9e57eb37ff28 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -431,6 +431,7 @@ efi_status_t efi_net_register(void); /* Called by bootefi to make the watchdog available */ efi_status_t efi_watchdog_register(void); efi_status_t efi_initrd_register(void); +void efi_initrd_deregister(void); /* Called by bootefi to make SMBIOS tables available */ /**

• efi_acpi_register() - write out ACPI tables

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig index e729f727df11..029f0e515f57 100644 --- a/lib/efi_loader/Kconfig +++ b/lib/efi_loader/Kconfig @@ -317,16 +317,11 @@ config EFI_LOAD_FILE2_INITRD bool "EFI_FILE_LOAD2_PROTOCOL for Linux initial ramdisk" default n help

•  Expose a EFI_FILE_LOAD2_PROTOCOL that the Linux UEFI stub can
  

•  use to load the initial ramdisk. Once this is enabled using
  

•  initrd=<ramdisk> will stop working.
  

-config EFI_INITRD_FILESPEC

• string "initramfs path"
• default "host 0:1 initrd"
• depends on EFI_LOAD_FILE2_INITRD
• help

•  Full path of the initramfs file, e.g. mmc 0:2 initramfs.cpio.gz.
  

• Linux v5.7 and later can make use of this option. If the boot option
  

• selected by the UEFI boot manager specifies an existing file to be used
  

• as initial RAM disk, a Linux specific Load File2 protocol will be
  

• installed and Linux 5.7+ will ignore any initrd=<ramdisk> command line
  

• argument.
  
  

  config EFI_SECURE_BOOT bool "Enable EFI secure boot support"

diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c index 25f5cebfdb67..46c8011344b9 100644 --- a/lib/efi_loader/efi_bootmgr.c +++ b/lib/efi_loader/efi_bootmgr.c @@ -118,11 +118,13 @@ static efi_status_t try_load_entry(u16 n, efi_handle_t *handle, ret = efi_set_variable_int(L"BootCurrent", &efi_global_variable_guid, attributes, sizeof(n), &n, false);

• if (ret != EFI_SUCCESS) {
  

• 	if (EFI_CALL(efi_unload_image(*handle))
  

• 	    != EFI_SUCCESS)
  

• 		log_err("Unloading image failed\n");
  

• 	goto error;
  

• if (ret != EFI_SUCCESS)
  

• 	goto unload;
  

• /* try to register load file2 for initrd's */
  

• if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD)) {
  

• 	ret = efi_initrd_register();
  

• 	if (ret != EFI_SUCCESS)
  

• 		goto unload;
  

  }

  log_info("Booting: %ls\n", lo.label);

@@ -146,6 +148,13 @@ static efi_status_t try_load_entry(u16 n, efi_handle_t *handle, error: free(load_option);

• return ret;

+unload:

• if (EFI_CALL(efi_unload_image(*handle)) != EFI_SUCCESS)

• log_err("Unloading image failed\n");
  

• free(load_option);
• return ret; }

diff --git a/lib/efi_loader/efi_load_initrd.c b/lib/efi_loader/efi_load_initrd.c index b9ee8839054f..e76de30808e3 100644 --- a/lib/efi_loader/efi_load_initrd.c +++ b/lib/efi_loader/efi_load_initrd.c @@ -5,7 +5,9 @@

#include <common.h> #include <efi_loader.h> +#include <efi_helper.h> #include <efi_load_initrd.h> +#include <efi_variable.h> #include <fs.h> #include <malloc.h> #include <mapmem.h> @@ -39,41 +41,40 @@ static const struct efi_initrd_dp dp = { } };

+static efi_handle_t efi_initrd_handle;

• /**

• • get_file_size() - retrieve the size of initramfs, set efi status on error

• • get_initrd_fp() - Get initrd device path from a FilePathList device path

• • @dev: device to read from, e.g. "mmc"
• • @part: device partition, e.g. "0:1"
• • @file: name of file
• • @status: EFI exit code in case of failure

• • @initrd_fp: the final initrd filepath

• • Return: size of file

• • Return: status code. Caller must free initrd_fp
  */

-static loff_t get_file_size(const char *dev, const char *part, const char *file,

• 	    efi_status_t *status)
  

+static efi_status_t get_initrd_fp(struct efi_device_path **initrd_fp) {

• loff_t sz = 0;
• int ret;
• ret = fs_set_blk_dev(dev, part, FS_TYPE_ANY);
• if (ret) {

• *status = EFI_NO_MEDIA;
  

• goto out;
  

• }

• const efi_guid_t lf2_initrd_guid = EFI_INITRD_MEDIA_GUID;
• struct efi_device_path *dp = NULL;

This variable name shadows the variable defined in line 28. I think we should give the global variable a better name then simply dp. How about dp_lf2_handle?

Best regards

Heinrich