efi: Introduce EFI_NX_PE_DATA bit and set it from properties table

UEFI v2.5 introduces a runtime memory protection feature that splits
PE/COFF runtime images into separate code and data regions. Since this
may require special handling by the OS, allocate a EFI_xxx bit to
keep track of whether this feature is currently active or not.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

drivers/firmware/efi/efi.c

@@ -426,6 +426,24 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
 	}
 	pr_cont("\n");
 	set_bit(EFI_CONFIG_TABLES, &efi.flags);
+
+	/* Parse the EFI Properties table if it exists */
+	if (efi.properties_table != EFI_INVALID_TABLE_ADDR) {
+		efi_properties_table_t *tbl;
+
+		tbl = early_memremap(efi.properties_table, sizeof(*tbl));
+		if (tbl == NULL) {
+			pr_err("Could not map Properties table!\n");
+			return -ENOMEM;
+		}
+
+		if (tbl->memory_protection_attribute &
+		    EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA)
+			set_bit(EFI_NX_PE_DATA, &efi.flags);
+
+		early_memunmap(tbl, sizeof(*tbl));
+	}
+
 	return 0;
 }
 

include/linux/efi.h

@@ -973,6 +973,7 @@ extern int __init efi_setup_pcdp_console(char *);
 #define EFI_PARAVIRT		6	/* Access is via a paravirt interface */
 #define EFI_ARCH_1		7	/* First arch-specific bit */
 #define EFI_DBG			8	/* Print additional debug info at runtime */
+#define EFI_NX_PE_DATA		9	/* Can runtime data regions be mapped non-executable? */
 
 #ifdef CONFIG_EFI
 /*