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 static pgd_t efi_bak_pg_dir_pointer[2]; 43 44 void efi_call_phys_prelog(void) 45 { 46 unsigned long cr4; 47 unsigned long temp; 48 struct desc_ptr gdt_descr; 49 50 local_irq_save(efi_rt_eflags); 51 52 /* 53 * If I don't have PAE, I should just duplicate two entries in page 54 * directory. If I have PAE, I just need to duplicate one entry in 55 * page directory. 56 */ 57 cr4 = read_cr4_safe(); 58 59 if (cr4 & X86_CR4_PAE) { 60 efi_bak_pg_dir_pointer[0].pgd = 61 swapper_pg_dir[pgd_index(0)].pgd; 62 swapper_pg_dir[0].pgd = 63 swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd; 64 } else { 65 efi_bak_pg_dir_pointer[0].pgd = 66 swapper_pg_dir[pgd_index(0)].pgd; 67 efi_bak_pg_dir_pointer[1].pgd = 68 swapper_pg_dir[pgd_index(0x400000)].pgd; 69 swapper_pg_dir[pgd_index(0)].pgd = 70 swapper_pg_dir[pgd_index(PAGE_OFFSET)].pgd; 71 temp = PAGE_OFFSET + 0x400000; 72 swapper_pg_dir[pgd_index(0x400000)].pgd = 73 swapper_pg_dir[pgd_index(temp)].pgd; 74 } 75 76 /* 77 * After the lock is released, the original page table is restored. 78 */ 79 __flush_tlb_all(); 80 81 gdt_descr.address = __pa(get_cpu_gdt_table(0)); 82 gdt_descr.size = GDT_SIZE - 1; 83 load_gdt(&gdt_descr); 84 } 85 86 void efi_call_phys_epilog(void) 87 { 88 unsigned long cr4; 89 struct desc_ptr gdt_descr; 90 91 gdt_descr.address = (unsigned long)get_cpu_gdt_table(0); 92 gdt_descr.size = GDT_SIZE - 1; 93 load_gdt(&gdt_descr); 94 95 cr4 = read_cr4_safe(); 96 97 if (cr4 & X86_CR4_PAE) { 98 swapper_pg_dir[pgd_index(0)].pgd = 99 efi_bak_pg_dir_pointer[0].pgd; 100 } else { 101 swapper_pg_dir[pgd_index(0)].pgd = 102 efi_bak_pg_dir_pointer[0].pgd; 103 swapper_pg_dir[pgd_index(0x400000)].pgd = 104 efi_bak_pg_dir_pointer[1].pgd; 105 } 106 107 /* 108 * After the lock is released, the original page table is restored. 109 */ 110 __flush_tlb_all(); 111 112 local_irq_restore(efi_rt_eflags); 113 } 114