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-rw-r--r--arch/x86/platform/efi/efi_64.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 319148bd4b05..2f25a363068c 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -269,6 +269,22 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
efi_scratch.use_pgd = true;
/*
+ * Certain firmware versions are way too sentimential and still believe
+ * they are exclusive and unquestionable owners of the first physical page,
+ * even though they explicitly mark it as EFI_CONVENTIONAL_MEMORY
+ * (but then write-access it later during SetVirtualAddressMap()).
+ *
+ * Create a 1:1 mapping for this page, to avoid triple faults during early
+ * boot with such firmware. We are free to hand this page to the BIOS,
+ * as trim_bios_range() will reserve the first page and isolate it away
+ * from memory allocators anyway.
+ */
+ if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
+ pr_err("Failed to create 1:1 mapping for the first page!\n");
+ return 1;
+ }
+
+ /*
* When making calls to the firmware everything needs to be 1:1
* mapped and addressable with 32-bit pointers. Map the kernel
* text and allocate a new stack because we can't rely on the