arch/x86/kernel/efi_64.c

   1 /*
   2  * x86_64 specific EFI support functions
   3  * Based on Extensible Firmware Interface Specification version 1.0
   4  *
   5  * Copyright (C) 2005-2008 Intel Co.
   6  *      Fenghua Yu <fenghua.yu@intel.com>
   7  *      Bibo Mao <bibo.mao@intel.com>
   8  *      Chandramouli Narayanan <mouli@linux.intel.com>
   9  *      Huang Ying <ying.huang@intel.com>
  10  *
  11  * Code to convert EFI to E820 map has been implemented in elilo bootloader
  12  * based on a EFI patch by Edgar Hucek. Based on the E820 map, the page table
  13  * is setup appropriately for EFI runtime code.
  14  * - mouli 06/14/2007.
  15  *
  16  */
  17
  18 #include <linux/kernel.h>
  19 #include <linux/init.h>
  20 #include <linux/mm.h>
  21 #include <linux/types.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/bootmem.h>
  24 #include <linux/ioport.h>
  25 #include <linux/module.h>
  26 #include <linux/efi.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/io.h>
  29 #include <linux/reboot.h>
  30
  31 #include <asm/setup.h>
  32 #include <asm/page.h>
  33 #include <asm/e820.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/tlbflush.h>
  36 #include <asm/proto.h>
  37 #include <asm/efi.h>
  38
  39 static pgd_t save_pgd __initdata;
  40 static unsigned long efi_flags __initdata;
  41
  42 static void __init early_mapping_set_exec(unsigned long start,
  43                                           unsigned long end,
  44                                           int executable)
  45 {
  46         pte_t *kpte;
  47         unsigned int level;
  48
  49         while (start < end) {
  50                 kpte = lookup_address((unsigned long)__va(start), &level);
  51                 BUG_ON(!kpte);
  52                 if (executable)
  53                         set_pte(kpte, pte_mkexec(*kpte));
  54                 else
  55                         set_pte(kpte, __pte((pte_val(*kpte) | _PAGE_NX) & \
  56                                             __supported_pte_mask));
  57                 if (level == PG_LEVEL_4K)
  58                         start = (start + PAGE_SIZE) & PAGE_MASK;
  59                 else
  60                         start = (start + PMD_SIZE) & PMD_MASK;
  61         }
  62 }
  63
  64 static void __init early_runtime_code_mapping_set_exec(int executable)
  65 {
  66         efi_memory_desc_t *md;
  67         void *p;
  68
  69         if (!(__supported_pte_mask & _PAGE_NX))
  70                 return;
  71
  72         /* Make EFI runtime service code area executable */
  73         for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
  74                 md = p;
  75                 if (md->type == EFI_RUNTIME_SERVICES_CODE) {
  76                         unsigned long end;
  77                         end = md->phys_addr + (md->num_pages << PAGE_SHIFT);
  78                         early_mapping_set_exec(md->phys_addr, end, executable);
  79                 }
  80         }
  81 }
  82
  83 void __init efi_call_phys_prelog(void)
  84 {
  85         unsigned long vaddress;
  86
  87         local_irq_save(efi_flags);
  88         early_runtime_code_mapping_set_exec(1);
  89         vaddress = (unsigned long)__va(0x0UL);
  90         save_pgd = *pgd_offset_k(0x0UL);
  91         set_pgd(pgd_offset_k(0x0UL), *pgd_offset_k(vaddress));
  92         __flush_tlb_all();
  93 }
  94
  95 void __init efi_call_phys_epilog(void)
  96 {
  97         /*
  98          * After the lock is released, the original page table is restored.
  99          */
 100         set_pgd(pgd_offset_k(0x0UL), save_pgd);
 101         early_runtime_code_mapping_set_exec(0);
 102         __flush_tlb_all();
 103         local_irq_restore(efi_flags);
 104 }
 105
 106 void __init efi_reserve_bootmem(void)
 107 {
 108         reserve_bootmem_generic((unsigned long)memmap.phys_map,
 109                                 memmap.nr_map * memmap.desc_size);
 110 }
 111
 112 void __iomem * __init efi_ioremap(unsigned long phys_addr, unsigned long size)
 113 {
 114         static unsigned pages_mapped;
 115         unsigned i, pages;
 116
 117         /* phys_addr and size must be page aligned */
 118         if ((phys_addr & ~PAGE_MASK) || (size & ~PAGE_MASK))
 119                 return NULL;
 120
 121         pages = size >> PAGE_SHIFT;
 122         if (pages_mapped + pages > MAX_EFI_IO_PAGES)
 123                 return NULL;
 124
 125         for (i = 0; i < pages; i++) {
 126                 __set_fixmap(FIX_EFI_IO_MAP_FIRST_PAGE - pages_mapped,
 127                              phys_addr, PAGE_KERNEL);
 128                 phys_addr += PAGE_SIZE;
 129                 pages_mapped++;
 130         }
 131
 132         return (void __iomem *)__fix_to_virt(FIX_EFI_IO_MAP_FIRST_PAGE - \
 133                                              (pages_mapped - pages));
 134 }