arch/x86/platform/efi/efi_32.c

   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/desc.h>
  29 #include <asm/page.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/tlbflush.h>
  32 #include <asm/efi.h>
  33
  34 /*
  35  * To make EFI call EFI runtime service in physical addressing mode we need
  36  * prelog/epilog before/after the invocation to disable interrupt, to
  37  * claim EFI runtime service handler exclusively and to duplicate a memory in
  38  * low memory space say 0 - 3G.
  39  */
  40
  41 static unsigned long efi_rt_eflags;
  42
  43 void efi_call_phys_prelog(void)
  44 {
  45         struct desc_ptr gdt_descr;
  46
  47         local_irq_save(efi_rt_eflags);
  48
  49         load_cr3(initial_page_table);
  50         __flush_tlb_all();
  51
  52         gdt_descr.address = __pa(get_cpu_gdt_table(0));
  53         gdt_descr.size = GDT_SIZE - 1;
  54         load_gdt(&gdt_descr);
  55 }
  56
  57 void efi_call_phys_epilog(void)
  58 {
  59         struct desc_ptr gdt_descr;
  60
  61         gdt_descr.address = (unsigned long)get_cpu_gdt_table(0);
  62         gdt_descr.size = GDT_SIZE - 1;
  63         load_gdt(&gdt_descr);
  64
  65         load_cr3(swapper_pg_dir);
  66         __flush_tlb_all();
  67
  68         local_irq_restore(efi_rt_eflags);
  69 }