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-rw-r--r--arch/arm64/kernel/acpi.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index a85174d05473..cada0b816c8a 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);
+}