efi/arm: Revert deferred unmap of early memmap mapping

Ard Biesheuvel · Ingo Molnar · commit 33412b867313 · 2018-11-15T10:04:46.000+01:00
Commit: 3ea8649 ("efi/arm: preserve early mapping of UEFI memory map longer for BGRT") deferred the unmap of the early mapping of the UEFI memory map to accommodate the ACPI BGRT code, which looks up the memory type that backs the BGRT table to validate it against the requirements of the UEFI spec. Unfortunately, this causes problems on ARM, which does not permit early mappings to persist after paging_init() is called, resulting in a WARN() splat. Since we don't support the BGRT table on ARM anway, let's revert ARM to the old behaviour, which is to take down the early mapping at the end of efi_init(). Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Fixes: 3ea8649 ("efi/arm: preserve early mapping of UEFI memory ...") Link: http://lkml.kernel.org/r/20181114175544.12860-3-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
@@ -265,6 +265,10 @@ void __init efi_init(void)
 				    (params.mmap & ~PAGE_MASK)));
 
 	init_screen_info();
+
+	/* ARM does not permit early mappings to persist across paging_init() */
+	if (IS_ENABLED(CONFIG_ARM))
+		efi_memmap_unmap();
 }
 
 static int __init register_gop_device(void)
diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
@@ -110,7 +110,7 @@ static int __init arm_enable_runtime_services(void)
 {
 	u64 mapsize;
 
-	if (!efi_enabled(EFI_BOOT) || !efi_enabled(EFI_MEMMAP)) {
+	if (!efi_enabled(EFI_BOOT)) {
 		pr_info("EFI services will not be available.\n");
 		return 0;
 	}
diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
@@ -118,6 +118,9 @@ int __init efi_memmap_init_early(struct efi_memory_map_data *data)
 
 void __init efi_memmap_unmap(void)
 {
+	if (!efi_enabled(EFI_MEMMAP))
+		return;
+
 	if (!efi.memmap.late) {
 		unsigned long size;
 

Original file line number	Diff line number	Diff line change
`@@ -265,6 +265,10 @@ void __init efi_init(void)`
`265`	`265`	`(params.mmap & ~PAGE_MASK)));`
`266`	`266`
`267`	`267`	`init_screen_info();`
	`268`	`+`
	`269`	`+ /* ARM does not permit early mappings to persist across paging_init() */`
	`270`	`+ if (IS_ENABLED(CONFIG_ARM))`
	`271`	`+ efi_memmap_unmap();`
`268`	`272`	`}`
`269`	`273`
`270`	`274`	`static int __init register_gop_device(void)`
Original file line number	Diff line number	Diff line change
`@@ -110,7 +110,7 @@ static int __init arm_enable_runtime_services(void)`
`110`	`110`	`{`
`111`	`111`	`u64 mapsize;`
`112`	`112`
`113`		`- if (!efi_enabled(EFI_BOOT) \|\| !efi_enabled(EFI_MEMMAP)) {`
	`113`	`+ if (!efi_enabled(EFI_BOOT)) {`
`114`	`114`	`pr_info("EFI services will not be available.\n");`
`115`	`115`	`return 0;`
`116`	`116`	`}`
Original file line number	Diff line number	Diff line change
`@@ -118,6 +118,9 @@ int __init efi_memmap_init_early(struct efi_memory_map_data *data)`
`118`	`118`
`119`	`119`	`void __init efi_memmap_unmap(void)`
`120`	`120`	`{`
	`121`	`+ if (!efi_enabled(EFI_MEMMAP))`
	`122`	`+ return;`
	`123`	`+`
`121`	`124`	`if (!efi.memmap.late) {`
`122`	`125`	`unsigned long size;`
`123`	`126`