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