From 8e4bff4cab0ddac6060645b0715210484d02ff40 Mon Sep 17 00:00:00 2001
From: Yuval Adam <_@yuv.al>
Date: Wed, 30 Aug 2017 08:25:59 +0000
Subject: Initial file dump from open source release

---
 arch/x86/platform/efi/efi_32.c | 69 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 arch/x86/platform/efi/efi_32.c

(limited to 'arch/x86/platform/efi/efi_32.c')

diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
new file mode 100644
index 00000000..40e44694
--- /dev/null
+++ b/arch/x86/platform/efi/efi_32.c
@@ -0,0 +1,69 @@
+/*
+ * Extensible Firmware Interface
+ *
+ * Based on Extensible Firmware Interface Specification version 1.0
+ *
+ * Copyright (C) 1999 VA Linux Systems
+ * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
+ * Copyright (C) 1999-2002 Hewlett-Packard Co.
+ *	David Mosberger-Tang <davidm@hpl.hp.com>
+ *	Stephane Eranian <eranian@hpl.hp.com>
+ *
+ * All EFI Runtime Services are not implemented yet as EFI only
+ * supports physical mode addressing on SoftSDV. This is to be fixed
+ * in a future version.  --drummond 1999-07-20
+ *
+ * Implemented EFI runtime services and virtual mode calls.  --davidm
+ *
+ * Goutham Rao: <goutham.rao@intel.com>
+ *	Skip non-WB memory and ignore empty memory ranges.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/ioport.h>
+#include <linux/efi.h>
+
+#include <asm/io.h>
+#include <asm/desc.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/efi.h>
+
+/*
+ * To make EFI call EFI runtime service in physical addressing mode we need
+ * prelog/epilog before/after the invocation to disable interrupt, to
+ * claim EFI runtime service handler exclusively and to duplicate a memory in
+ * low memory space say 0 - 3G.
+ */
+
+static unsigned long efi_rt_eflags;
+
+void efi_call_phys_prelog(void)
+{
+	struct desc_ptr gdt_descr;
+
+	local_irq_save(efi_rt_eflags);
+
+	load_cr3(initial_page_table);
+	__flush_tlb_all();
+
+	gdt_descr.address = __pa(get_cpu_gdt_table(0));
+	gdt_descr.size = GDT_SIZE - 1;
+	load_gdt(&gdt_descr);
+}
+
+void efi_call_phys_epilog(void)
+{
+	struct desc_ptr gdt_descr;
+
+	gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);
+	gdt_descr.size = GDT_SIZE - 1;
+	load_gdt(&gdt_descr);
+
+	load_cr3(swapper_pg_dir);
+	__flush_tlb_all();
+
+	local_irq_restore(efi_rt_eflags);
+}
-- 
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