diff mbox series

efi_loader: update the timing of enabling and disabling EFI watchdog

Message ID 20220222005830.5996-1-masahisa.kojima@linaro.org
State Accepted
Commit 3fa9ed9ae3b30dd6e7f5e887c76d183ad72a44a2
Headers show
Series efi_loader: update the timing of enabling and disabling EFI watchdog | expand

Commit Message

Masahisa Kojima Feb. 22, 2022, 12:58 a.m. UTC 
UEFI specification requires that 5 minutes watchdog timer is
armed before the firmware's boot manager invokes an EFI boot option.
This watchdog timer is updated as follows, according to the
UEFI specification.

 1) The EFI Image may reset or disable the watchdog timer as needed.
 2) If control is returned to the firmware's boot manager,
    the watchdog timer must be disabled.
 3) On successful completion of EFI_BOOT_SERVICES.ExitBootServices()
    the watchdog timer is disabled.

1) is up to the EFI image, and 3) is already implemented in U-Boot.
This patch implements 2), the watchdog is disabled when control is
returned to U-Boot.

In addition, current implementation arms the EFI watchdog at only
the first "bootefi" invocation. The EFI watchdog must be armed
in every EFI boot option invocation.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
---
 cmd/bootefi.c                 | 17 +++++++++++++++++
 lib/efi_loader/efi_watchdog.c | 13 +------------
 2 files changed, 18 insertions(+), 12 deletions(-)

Comments

Heinrich Schuchardt Feb. 22, 2022, 7:34 a.m. UTC | #1 
On 2/22/22 01:58, Masahisa Kojima wrote:
> UEFI specification requires that 5 minutes watchdog timer is
> armed before the firmware's boot manager invokes an EFI boot option.
> This watchdog timer is updated as follows, according to the
> UEFI specification.
>
>   1) The EFI Image may reset or disable the watchdog timer as needed.
>   2) If control is returned to the firmware's boot manager,
>      the watchdog timer must be disabled.
>   3) On successful completion of EFI_BOOT_SERVICES.ExitBootServices()
>      the watchdog timer is disabled.
>
> 1) is up to the EFI image, and 3) is already implemented in U-Boot.
> This patch implements 2), the watchdog is disabled when control is
> returned to U-Boot.
>
> In addition, current implementation arms the EFI watchdog at only
> the first "bootefi" invocation. The EFI watchdog must be armed
> in every EFI boot option invocation.
>
> Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>

Thanks for fixing this.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

> ---
>   cmd/bootefi.c                 | 17 +++++++++++++++++
>   lib/efi_loader/efi_watchdog.c | 13 +------------
>   2 files changed, 18 insertions(+), 12 deletions(-)
>
> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> index 94d18ca73f..46eebd5ee2 100644
> --- a/cmd/bootefi.c
> +++ b/cmd/bootefi.c
> @@ -353,6 +353,19 @@ static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)
>   	/* On ARM switch from EL3 or secure mode to EL2 or non-secure mode */
>   	switch_to_non_secure_mode();
>
> +	/*
> +	 * The UEFI standard requires that the watchdog timer is set to five
> +	 * minutes when invoking an EFI boot option.
> +	 *
> +	 * Unified Extensible Firmware Interface (UEFI), version 2.7 Errata A
> +	 * 7.5. Miscellaneous Boot Services - EFI_BOOT_SERVICES.SetWatchdogTimer
> +	 */
> +	ret = efi_set_watchdog(300);
> +	if (ret != EFI_SUCCESS) {
> +		log_err("ERROR: Failed to set watchdog timer\n");
> +		goto out;
> +	}
> +
>   	/* Call our payload! */
>   	ret = EFI_CALL(efi_start_image(handle, &exit_data_size, &exit_data));
>   	if (ret != EFI_SUCCESS) {
> @@ -366,11 +379,15 @@ static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)
>
>   	efi_restore_gd();
>
> +out:
>   	free(load_options);
>
>   	if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD))
>   		efi_initrd_deregister();
>
> +	/* Control is returned to U-Boot, disable EFI watchdog */
> +	efi_set_watchdog(0);
> +
>   	return ret;
>   }
>
> diff --git a/lib/efi_loader/efi_watchdog.c b/lib/efi_loader/efi_watchdog.c
> index 87ca6c5b0b..d741076dcd 100644
> --- a/lib/efi_loader/efi_watchdog.c
> +++ b/lib/efi_loader/efi_watchdog.c
> @@ -75,17 +75,6 @@ efi_status_t efi_watchdog_register(void)
>   		printf("ERROR: Failed to register watchdog event\n");
>   		return r;
>   	}
> -	/*
> -	 * The UEFI standard requires that the watchdog timer is set to five
> -	 * minutes when invoking an EFI boot option.
> -	 *
> -	 * Unified Extensible Firmware Interface (UEFI), version 2.7 Errata A
> -	 * 7.5. Miscellaneous Boot Services - EFI_BOOT_SERVICES.SetWatchdogTimer
> -	 */
> -	r = efi_set_watchdog(300);
> -	if (r != EFI_SUCCESS) {
> -		printf("ERROR: Failed to set watchdog timer\n");
> -		return r;
> -	}
> +
>   	return EFI_SUCCESS;
>   }
diff mbox series

Patch

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 94d18ca73f..46eebd5ee2 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -353,6 +353,19 @@  static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)
 	/* On ARM switch from EL3 or secure mode to EL2 or non-secure mode */
 	switch_to_non_secure_mode();
 
+	/*
+	 * The UEFI standard requires that the watchdog timer is set to five
+	 * minutes when invoking an EFI boot option.
+	 *
+	 * Unified Extensible Firmware Interface (UEFI), version 2.7 Errata A
+	 * 7.5. Miscellaneous Boot Services - EFI_BOOT_SERVICES.SetWatchdogTimer
+	 */
+	ret = efi_set_watchdog(300);
+	if (ret != EFI_SUCCESS) {
+		log_err("ERROR: Failed to set watchdog timer\n");
+		goto out;
+	}
+
 	/* Call our payload! */
 	ret = EFI_CALL(efi_start_image(handle, &exit_data_size, &exit_data));
 	if (ret != EFI_SUCCESS) {
@@ -366,11 +379,15 @@  static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)
 
 	efi_restore_gd();
 
+out:
 	free(load_options);
 
 	if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD))
 		efi_initrd_deregister();
 
+	/* Control is returned to U-Boot, disable EFI watchdog */
+	efi_set_watchdog(0);
+
 	return ret;
 }
 
diff --git a/lib/efi_loader/efi_watchdog.c b/lib/efi_loader/efi_watchdog.c
index 87ca6c5b0b..d741076dcd 100644
--- a/lib/efi_loader/efi_watchdog.c
+++ b/lib/efi_loader/efi_watchdog.c
@@ -75,17 +75,6 @@  efi_status_t efi_watchdog_register(void)
 		printf("ERROR: Failed to register watchdog event\n");
 		return r;
 	}
-	/*
-	 * The UEFI standard requires that the watchdog timer is set to five
-	 * minutes when invoking an EFI boot option.
-	 *
-	 * Unified Extensible Firmware Interface (UEFI), version 2.7 Errata A
-	 * 7.5. Miscellaneous Boot Services - EFI_BOOT_SERVICES.SetWatchdogTimer
-	 */
-	r = efi_set_watchdog(300);
-	if (r != EFI_SUCCESS) {
-		printf("ERROR: Failed to set watchdog timer\n");
-		return r;
-	}
+
 	return EFI_SUCCESS;
 }