arch/x86/platform/efi/efi_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Extensible Firmware Interface
   4  *
   5  * Based on Extensible Firmware Interface Specification version 1.0
   6  *
   7  * Copyright (C) 1999 VA Linux Systems
   8  * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
   9  * Copyright (C) 1999-2002 Hewlett-Packard Co.
  10  *      David Mosberger-Tang <davidm@hpl.hp.com>
  11  *      Stephane Eranian <eranian@hpl.hp.com>
  12  *
  13  * All EFI Runtime Services are not implemented yet as EFI only
  14  * supports physical mode addressing on SoftSDV. This is to be fixed
  15  * in a future version.  --drummond 1999-07-20
  16  *
  17  * Implemented EFI runtime services and virtual mode calls.  --davidm
  18  *
  19  * Goutham Rao: <goutham.rao@intel.com>
  20  *      Skip non-WB memory and ignore empty memory ranges.
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/types.h>
  25 #include <linux/ioport.h>
  26 #include <linux/efi.h>
  27
  28 #include <asm/io.h>
  29 #include <asm/desc.h>
  30 #include <asm/page.h>
  31 #include <asm/pgtable.h>
  32 #include <asm/tlbflush.h>
  33 #include <asm/efi.h>
  34
  35 /*
  36  * To make EFI call EFI runtime service in physical addressing mode we need
  37  * prolog/epilog before/after the invocation to claim the EFI runtime service
  38  * handler exclusively and to duplicate a memory mapping in low memory space,
  39  * say 0 - 3G.
  40  */
  41
  42 int __init efi_alloc_page_tables(void)
  43 {
  44         return 0;
  45 }
  46
  47 void efi_sync_low_kernel_mappings(void) {}
  48
  49 void __init efi_dump_pagetable(void)
  50 {
  51 #ifdef CONFIG_EFI_PGT_DUMP
  52         ptdump_walk_pgd_level(NULL, swapper_pg_dir);
  53 #endif
  54 }
  55
  56 int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
  57 {
  58         return 0;
  59 }
  60
  61 void __init efi_map_region(efi_memory_desc_t *md)
  62 {
  63         old_map_region(md);
  64 }
  65
  66 void __init efi_map_region_fixed(efi_memory_desc_t *md) {}
  67 void __init parse_efi_setup(u64 phys_addr, u32 data_len) {}
  68
  69 pgd_t * __init efi_call_phys_prolog(void)
  70 {
  71         struct desc_ptr gdt_descr;
  72         pgd_t *save_pgd;
  73
  74         /* Current pgd is swapper_pg_dir, we'll restore it later: */
  75         save_pgd = swapper_pg_dir;
  76         load_cr3(initial_page_table);
  77         __flush_tlb_all();
  78
  79         gdt_descr.address = get_cpu_gdt_paddr(0);
  80         gdt_descr.size = GDT_SIZE - 1;
  81         load_gdt(&gdt_descr);
  82
  83         return save_pgd;
  84 }
  85
  86 void __init efi_call_phys_epilog(pgd_t *save_pgd)
  87 {
  88         struct desc_ptr gdt_descr;
  89
  90         gdt_descr.address = (unsigned long)get_cpu_gdt_rw(0);
  91         gdt_descr.size = GDT_SIZE - 1;
  92         load_gdt(&gdt_descr);
  93
  94         load_cr3(save_pgd);
  95         __flush_tlb_all();
  96 }
  97
  98 void __init efi_runtime_update_mappings(void)
  99 {
 100         if (__supported_pte_mask & _PAGE_NX)
 101                 runtime_code_page_mkexec();
 102 }