Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

eed2ef44 · Linus Torvalds <[email protected]> · 2020-10-01 11:49:01 -07:00

Pull arm64 fix from Catalin Marinas:
 "A previous commit to prevent AML memory opregions from accessing the
  kernel memory turned out to be too restrictive. Relax the permission
  check to permit the ACPI core to map kernel memory used for table
  overrides"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: permit ACPI core to map kernel memory used for table overrides

Commit: eed2ef4403de3d8937ccb624e15d3c5004e7dda5
Parents: fcadab74 · a509a66a

Merge commit. Changes below are compared with the first parent: fcadab74.

Changes

2 files changed · +21 −3

File	Status	Add	Del	Content
arch/arm64/kernel/acpi.c	modified	+20	−2	View file
include/linux/acpi.h	modified	+1	−1	View file

arch/arm64/kernel/acpi.c

View file

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index a85174d..cada0b8 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -298,8 +298,21 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
 		case EFI_BOOT_SERVICES_DATA:
 		case EFI_CONVENTIONAL_MEMORY:
 		case EFI_PERSISTENT_MEMORY:
-			pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys);
-			return NULL;
+			if (memblock_is_map_memory(phys) ||
+			    !memblock_is_region_memory(phys, size)) {
+				pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys);
+				return NULL;
+			}
+			/*
+			 * Mapping kernel memory is permitted if the region in
+			 * question is covered by a single memblock with the
+			 * NOMAP attribute set: this enables the use of ACPI
+			 * table overrides passed via initramfs, which are
+			 * reserved in memory using arch_reserve_mem_area()
+			 * below. As this particular use case only requires
+			 * read access, fall through to the R/O mapping case.
+			 */
+			fallthrough;
 
 		case EFI_RUNTIME_SERVICES_CODE:
 			/*
@@ -388,3 +401,8 @@ int apei_claim_sea(struct pt_regs *regs)
 
 	return err;
 }
+
+void arch_reserve_mem_area(acpi_physical_address addr, size_t size)
+{
+	memblock_mark_nomap(addr, size);
+}

include/linux/acpi.h

View file

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 1e4cdc6..64ae25c 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -958,7 +958,7 @@ void acpi_os_set_prepare_extended_sleep(int (*func)(u8 sleep_state,
 acpi_status acpi_os_prepare_extended_sleep(u8 sleep_state,
 					   u32 val_a, u32 val_b);
 
-#ifdef CONFIG_X86
+#ifndef CONFIG_IA64
 void arch_reserve_mem_area(acpi_physical_address addr, size_t size);
 #else
 static inline void arch_reserve_mem_area(acpi_physical_address addr,