1 /*
2 * Extensible Firmware Interface
3 *
4 * Based on Extensible Firmware Interface Specification version 1.0
5 *
6 * Copyright (C) 1999 VA Linux Systems
7 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
8 * Copyright (C) 1999-2002 Hewlett-Packard Co.
9 * David Mosberger-Tang <davidm@hpl.hp.com>
10 * Stephane Eranian <eranian@hpl.hp.com>
11 *
12 * All EFI Runtime Services are not implemented yet as EFI only
13 * supports physical mode addressing on SoftSDV. This is to be fixed
14 * in a future version. --drummond 1999-07-20
15 *
16 * Implemented EFI runtime services and virtual mode calls. --davidm
17 *
18 * Goutham Rao: <goutham.rao@intel.com>
19 * Skip non-WB memory and ignore empty memory ranges.
20 */
21
22 #include <linux/kernel.h>
23 #include <linux/types.h>
24 #include <linux/ioport.h>
25 #include <linux/efi.h>
26
27 #include <asm/io.h>
28 #include <asm/page.h>
29 #include <asm/pgtable.h>
30 #include <asm/tlbflush.h>
31 #include <asm/efi.h>
32
33 /*
34 * To make EFI call EFI runtime service in physical addressing mode we need
35 * prelog/epilog before/after the invocation to disable interrupt, to
36 * claim EFI runtime service handler exclusively and to duplicate a memory in
37 * low memory space say 0 - 3G.
38 */
39
40 static unsigned long efi_rt_eflags;
41 static pgd_t efi_bak_pg_dir_pointer[2];
42
43 void efi_call_phys_prelog(void)
44 {
45 unsigned long cr4;
46 unsigned long temp;
47 struct desc_ptr gdt_descr;
48
49 local_irq_save(efi_rt_eflags);
50
51 /*
52 * If I don't have PAE, I should just duplicate two entries in page
53 * directory. If I have PAE, I just need to duplicate one entry in
54 * page directory.
55 */
56 cr4 = read_cr4_safe();
57
58 if (cr4 & X86_CR4_PAE) {
59 efi_bak_pg_dir_pointer[0].pgd =
60 swapper_pg_dir[pgd_index(0)].pgd;
61 swapper_pg_dir[0].pgd =
62 swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd;
63 } else {
64 efi_bak_pg_dir_pointer[0].pgd =
65 swapper_pg_dir[pgd_index(0)].pgd;
66 efi_bak_pg_dir_pointer[1].pgd =
67 swapper_pg_dir[pgd_index(0x400000)].pgd;
68 swapper_pg_dir[pgd_index(0)].pgd =
69 swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd;
70 temp = PAGE_OFFSET + 0x400000;
71 swapper_pg_dir[pgd_index(0x400000)].pgd =
72 swapper_pg_dir[pgd_index(temp)].pgd;
73 }
74
75 /*
76 * After the lock is released, the original page table is restored.
77 */
78 __flush_tlb_all();
79
80 gdt_descr.address = __pa(get_cpu_gdt_table(0));
81 gdt_descr.size = GDT_SIZE - 1;
82 load_gdt(&gdt_descr);
83 }
84
85 void efi_call_phys_epilog(void)
86 {
87 unsigned long cr4;
88 struct desc_ptr gdt_descr;
89
90 gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);
91 gdt_descr.size = GDT_SIZE - 1;
92 load_gdt(&gdt_descr);
93
94 cr4 = read_cr4_safe();
95
96 if (cr4 & X86_CR4_PAE) {
97 swapper_pg_dir[pgd_index(0)].pgd =
98 efi_bak_pg_dir_pointer[0].pgd;
99 } else {
100 swapper_pg_dir[pgd_index(0)].pgd =
101 efi_bak_pg_dir_pointer[0].pgd;
102 swapper_pg_dir[pgd_index(0x400000)].pgd =
103 efi_bak_pg_dir_pointer[1].pgd;
104 }
105
106 /*
107 * After the lock is released, the original page table is restored.
108 */
109 __flush_tlb_all();
110
111 local_irq_restore(efi_rt_eflags);
112 }
113
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