LXR linux/arch/x86/kernel/efi

   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
  40static unsigned long efi_rt_eflags;
  41static pgd_t efi_bak_pg_dir_pointer[2];
  42
  43void 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
  85void 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