efi/arm: preserve early mapping of UEFI memory map longer for BGRT

[ Upstream commit 3ea86495aef2f6de26b7cb1599ba350dd6a0c521 ]

The BGRT code validates the contents of the table against the UEFI
memory map, and so it expects it to be mapped when the code runs.

On ARM, this is currently not the case, since we tear down the early
mapping after efi_init() completes, and only create the permanent
mapping in arm_enable_runtime_services(), which executes as an early
initcall, but still leaves a window where the UEFI memory map is not
mapped.

So move the call to efi_memmap_unmap() from efi_init() to
arm_enable_runtime_services().

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[will: fold in EFI_MEMMAP attribute check from Ard]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index 8efe13075c922e6b79131af4af2d897245b94a42..1d1c9693ebfbb255c63d00381548ac79d2c5d8bc 100644 (file)
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -250,7 +250,6 @@ void __init efi_init(void)
        reserve_regions();
        efi_memattr_init();
        efi_esrt_init();
-       efi_memmap_unmap();
 
        memblock_reserve(params.mmap & PAGE_MASK,
                         PAGE_ALIGN(params.mmap_size +

diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
index 6bdf39e1e3857a549dafbeb903a2c49c7e9d3850..4d788e0debfedb471a120416d5e01b473b2f57c6 100644 (file)
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -118,11 +118,13 @@ static int __init arm_enable_runtime_services(void)
 {
        u64 mapsize;
 
-       if (!efi_enabled(EFI_BOOT)) {
+       if (!efi_enabled(EFI_BOOT) || !efi_enabled(EFI_MEMMAP)) {
                pr_info("EFI services will not be available.\n");
                return 0;
        }
 
+       efi_memmap_unmap();
+
        if (efi_runtime_disabled()) {
                pr_info("EFI runtime services will be disabled.\n");
                return 0;