[PATCH v2 3/8][Cosmic][SRU Bionic] efi/arm: preserve early mapping of UEFI memory map longer for BGRT

dann frazier dann.frazier at canonical.com
Tue Aug 28 20:47:34 UTC 2018


From: Ard Biesheuvel <ard.biesheuvel at linaro.org>

BugLink: https://bugs.launchpad.net/bugs/1786878

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 at linaro.org>
[will: fold in EFI_MEMMAP attribute check from Ard]
Signed-off-by: Will Deacon <will.deacon at arm.com>
(cherry picked from commit 3ea86495aef2f6de26b7cb1599ba350dd6a0c521)
Signed-off-by: dann frazier <dann.frazier at canonical.com>
---
 drivers/firmware/efi/arm-init.c    | 1 -
 drivers/firmware/efi/arm-runtime.c | 4 +++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index 80d1a885def5c..a7c522eac640f 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -259,7 +259,6 @@ void __init efi_init(void)
 
 	reserve_regions();
 	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 5889cbea60b84..4712445c32130 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -110,11 +110,13 @@ 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;
-- 
2.18.0





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