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efi_loader: re-enable GRUB workaround on 32bit ARM

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GRUB on ARM 32bit prior to version 2.04 lacks proper handling of caches.
In U-Boot v2019.04 a workaround for this was inadvertently removed.

The workaround is currently also needed for booting on systems with caches
that cannot be managed via CP15 (e.g. with an i.MX6 CPU).

Re-enable the workaround and make it customizable.

Fixes: f69d63fae2 ("efi_loader: use efi_start_image() for bootefi")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
This commit is contained in:
Heinrich Schuchardt 2019-07-22 22:04:36 +02:00
parent d0d07ba86a
commit 6f3badb67d
2 changed files with 21 additions and 15 deletions
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8
lib/efi_loader/Kconfig
View File

@ -107,4 +107,12 @@ config EFI_HAVE_RUNTIME_RESET
default y
depends on ARCH_BCM283X || FSL_LAYERSCAPE || PSCI_RESET || SYSRESET_X86
config EFI_GRUB_ARM32_WORKAROUND
bool "Workaround for GRUB on 32bit ARM"
default y
depends on ARM && !ARM64
help
GRUB prior to version 2.04 requires U-Boot to disable caches. This
workaround currently is also needed on systems with caches that
cannot be managed via CP15.
endif

28
lib/efi_loader/efi_boottime.c
View File

@ -39,14 +39,6 @@ LIST_HEAD(efi_register_notify_events);
/* Handle of the currently executing image */
static efi_handle_t current_image;
/*
* If we're running on nasty systems (32bit ARM booting into non-EFI Linux)
* we need to do trickery with caches. Since we don't want to break the EFI
* aware boot path, only apply hacks when loading exiting directly (breaking
* direct Linux EFI booting along the way - oh well).
*/
static bool efi_is_direct_boot = true;
#ifdef CONFIG_ARM
/*
* The "gd" pointer lives in a register on ARM and AArch64 that we declare
@ -1911,13 +1903,21 @@ error:
*/
static void efi_exit_caches(void)
{
#if defined(CONFIG_ARM) && !defined(CONFIG_ARM64)
#if defined(CONFIG_EFI_GRUB_ARM32_WORKAROUND)
/*
* Grub on 32bit ARM needs to have caches disabled before jumping into
* a zImage, but does not know of all cache layers. Give it a hand.
* Boooting Linux via GRUB prior to version 2.04 fails on 32bit ARM if
* caches are enabled.
*
* TODO:
* According to the UEFI spec caches that can be managed via CP15
* operations should be enabled. Caches requiring platform information
* to manage should be disabled. This should not happen in
* ExitBootServices() but before invoking any UEFI binary is invoked.
*
* We want to keep the current workaround while GRUB prior to version
* 2.04 is still in use.
*/
if (efi_is_direct_boot)
cleanup_before_linux();
cleanup_before_linux();
#endif
}
@ -2893,8 +2893,6 @@ efi_status_t EFIAPI efi_start_image(efi_handle_t image_handle,
if (ret != EFI_SUCCESS)
return EFI_EXIT(EFI_INVALID_PARAMETER);
efi_is_direct_boot = false;
image_obj->exit_data_size = exit_data_size;
image_obj->exit_data = exit_data;