1 files changed, 60 insertions, 0 deletions
diff --git a/arch/x86/include/asm/bios_ebda.h b/arch/x86/include/asm/bios_ebda.h
new file mode 100644
index 000000000..aa6a3170a
--- /dev/null
+++ b/arch/x86/include/asm/bios_ebda.h
@@ -0,0 +1,60 @@
+#ifndef _ASM_X86_BIOS_EBDA_H
+#define _ASM_X86_BIOS_EBDA_H
+
+#include <asm/io.h>
+
+/*
+ * Returns physical address of EBDA.  Returns 0 if there is no EBDA.
+ */
+static inline unsigned int get_bios_ebda(void)
+{
+	/*
+	 * There is a real-mode segmented pointer pointing to the
+	 * 4K EBDA area at 0x40E.
+	 */
+	unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
+	address <<= 4;
+	return address;	/* 0 means none */
+}
+
+/*
+ * Return the sanitized length of the EBDA in bytes, if it exists.
+ */
+static inline unsigned int get_bios_ebda_length(void)
+{
+	unsigned int address;
+	unsigned int length;
+
+	address = get_bios_ebda();
+	if (!address)
+		return 0;
+
+	/* EBDA length is byte 0 of the EBDA (stored in KiB) */
+	length = *(unsigned char *)phys_to_virt(address);
+	length <<= 10;
+
+	/* Trim the length if it extends beyond 640KiB */
+	length = min_t(unsigned int, (640 * 1024) - address, length);
+	return length;
+}
+
+void reserve_ebda_region(void);
+
+#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
+/*
+ * This is obviously not a great place for this, but we want to be
+ * able to scatter it around anywhere in the kernel.
+ */
+void check_for_bios_corruption(void);
+void start_periodic_check_for_corruption(void);
+#else
+static inline void check_for_bios_corruption(void)
+{
+}
+
+static inline void start_periodic_check_for_corruption(void)
+{
+}
+#endif
+
+#endif /* _ASM_X86_BIOS_EBDA_H */