1 #include <linux/io.h> 2 #include <linux/slab.h> 3 #include <linux/memblock.h> 4 5 #include <asm/set_memory.h> 6 #include <asm/pgtable.h> 7 #include <asm/realmode.h> 8 #include <asm/tlbflush.h> 9 10 struct real_mode_header *real_mode_header; 11 u32 *trampoline_cr4_features; 12 13 /* Hold the pgd entry used on booting additional CPUs */ 14 pgd_t trampoline_pgd_entry; 15 16 void __init set_real_mode_mem(phys_addr_t mem, size_t size) 17 { 18 void *base = __va(mem); 19 20 real_mode_header = (struct real_mode_header *) base; 21 printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n", 22 base, (unsigned long long)mem, size); 23 } 24 25 void __init reserve_real_mode(void) 26 { 27 phys_addr_t mem; 28 size_t size = real_mode_size_needed(); 29 30 if (!size) 31 return; 32 33 WARN_ON(slab_is_available()); 34 35 /* Has to be under 1M so we can execute real-mode AP code. */ 36 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE); 37 if (!mem) { 38 pr_info("No sub-1M memory is available for the trampoline\n"); 39 return; 40 } 41 42 memblock_reserve(mem, size); 43 set_real_mode_mem(mem, size); 44 } 45 46 static void __init setup_real_mode(void) 47 { 48 u16 real_mode_seg; 49 const u32 *rel; 50 u32 count; 51 unsigned char *base; 52 unsigned long phys_base; 53 struct trampoline_header *trampoline_header; 54 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 55 #ifdef CONFIG_X86_64 56 u64 *trampoline_pgd; 57 u64 efer; 58 #endif 59 60 base = (unsigned char *)real_mode_header; 61 62 memcpy(base, real_mode_blob, size); 63 64 phys_base = __pa(base); 65 real_mode_seg = phys_base >> 4; 66 67 rel = (u32 *) real_mode_relocs; 68 69 /* 16-bit segment relocations. */ 70 count = *rel++; 71 while (count--) { 72 u16 *seg = (u16 *) (base + *rel++); 73 *seg = real_mode_seg; 74 } 75 76 /* 32-bit linear relocations. */ 77 count = *rel++; 78 while (count--) { 79 u32 *ptr = (u32 *) (base + *rel++); 80 *ptr += phys_base; 81 } 82 83 /* Must be perfomed *after* relocation. */ 84 trampoline_header = (struct trampoline_header *) 85 __va(real_mode_header->trampoline_header); 86 87 #ifdef CONFIG_X86_32 88 trampoline_header->start = __pa_symbol(startup_32_smp); 89 trampoline_header->gdt_limit = __BOOT_DS + 7; 90 trampoline_header->gdt_base = __pa_symbol(boot_gdt); 91 #else 92 /* 93 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR 94 * so we need to mask it out. 95 */ 96 rdmsrl(MSR_EFER, efer); 97 trampoline_header->efer = efer & ~EFER_LMA; 98 99 trampoline_header->start = (u64) secondary_startup_64; 100 trampoline_cr4_features = &trampoline_header->cr4; 101 *trampoline_cr4_features = mmu_cr4_features; 102 103 trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); 104 trampoline_pgd[0] = trampoline_pgd_entry.pgd; 105 trampoline_pgd[511] = init_level4_pgt[511].pgd; 106 #endif 107 } 108 109 /* 110 * reserve_real_mode() gets called very early, to guarantee the 111 * availability of low memory. This is before the proper kernel page 112 * tables are set up, so we cannot set page permissions in that 113 * function. Also trampoline code will be executed by APs so we 114 * need to mark it executable at do_pre_smp_initcalls() at least, 115 * thus run it as a early_initcall(). 116 */ 117 static void __init set_real_mode_permissions(void) 118 { 119 unsigned char *base = (unsigned char *) real_mode_header; 120 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 121 122 size_t ro_size = 123 PAGE_ALIGN(real_mode_header->ro_end) - 124 __pa(base); 125 126 size_t text_size = 127 PAGE_ALIGN(real_mode_header->ro_end) - 128 real_mode_header->text_start; 129 130 unsigned long text_start = 131 (unsigned long) __va(real_mode_header->text_start); 132 133 set_memory_nx((unsigned long) base, size >> PAGE_SHIFT); 134 set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT); 135 set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT); 136 } 137 138 static int __init init_real_mode(void) 139 { 140 if (!real_mode_header) 141 panic("Real mode trampoline was not allocated"); 142 143 setup_real_mode(); 144 set_real_mode_permissions(); 145 146 return 0; 147 } 148 early_initcall(init_real_mode); 149