1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/io.h> 3 #include <linux/slab.h> 4 #include <linux/memblock.h> 5 #include <linux/mem_encrypt.h> 6 7 #include <asm/set_memory.h> 8 #include <asm/pgtable.h> 9 #include <asm/realmode.h> 10 #include <asm/tlbflush.h> 11 12 struct real_mode_header *real_mode_header; 13 u32 *trampoline_cr4_features; 14 15 /* Hold the pgd entry used on booting additional CPUs */ 16 pgd_t trampoline_pgd_entry; 17 18 void __init set_real_mode_mem(phys_addr_t mem, size_t size) 19 { 20 void *base = __va(mem); 21 22 real_mode_header = (struct real_mode_header *) base; 23 printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n", 24 base, (unsigned long long)mem, size); 25 } 26 27 void __init reserve_real_mode(void) 28 { 29 phys_addr_t mem; 30 size_t size = real_mode_size_needed(); 31 32 if (!size) 33 return; 34 35 WARN_ON(slab_is_available()); 36 37 /* Has to be under 1M so we can execute real-mode AP code. */ 38 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE); 39 if (!mem) { 40 pr_info("No sub-1M memory is available for the trampoline\n"); 41 return; 42 } 43 44 memblock_reserve(mem, size); 45 set_real_mode_mem(mem, size); 46 } 47 48 static void __init setup_real_mode(void) 49 { 50 u16 real_mode_seg; 51 const u32 *rel; 52 u32 count; 53 unsigned char *base; 54 unsigned long phys_base; 55 struct trampoline_header *trampoline_header; 56 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 57 #ifdef CONFIG_X86_64 58 u64 *trampoline_pgd; 59 u64 efer; 60 #endif 61 62 base = (unsigned char *)real_mode_header; 63 64 /* 65 * If SME is active, the trampoline area will need to be in 66 * decrypted memory in order to bring up other processors 67 * successfully. 68 */ 69 set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT); 70 71 memcpy(base, real_mode_blob, size); 72 73 phys_base = __pa(base); 74 real_mode_seg = phys_base >> 4; 75 76 rel = (u32 *) real_mode_relocs; 77 78 /* 16-bit segment relocations. */ 79 count = *rel++; 80 while (count--) { 81 u16 *seg = (u16 *) (base + *rel++); 82 *seg = real_mode_seg; 83 } 84 85 /* 32-bit linear relocations. */ 86 count = *rel++; 87 while (count--) { 88 u32 *ptr = (u32 *) (base + *rel++); 89 *ptr += phys_base; 90 } 91 92 /* Must be perfomed *after* relocation. */ 93 trampoline_header = (struct trampoline_header *) 94 __va(real_mode_header->trampoline_header); 95 96 #ifdef CONFIG_X86_32 97 trampoline_header->start = __pa_symbol(startup_32_smp); 98 trampoline_header->gdt_limit = __BOOT_DS + 7; 99 trampoline_header->gdt_base = __pa_symbol(boot_gdt); 100 #else 101 /* 102 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR 103 * so we need to mask it out. 104 */ 105 rdmsrl(MSR_EFER, efer); 106 trampoline_header->efer = efer & ~EFER_LMA; 107 108 trampoline_header->start = (u64) secondary_startup_64; 109 trampoline_cr4_features = &trampoline_header->cr4; 110 *trampoline_cr4_features = mmu_cr4_features; 111 112 trampoline_header->flags = 0; 113 if (sme_active()) 114 trampoline_header->flags |= TH_FLAGS_SME_ACTIVE; 115 116 trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); 117 trampoline_pgd[0] = trampoline_pgd_entry.pgd; 118 trampoline_pgd[511] = init_top_pgt[511].pgd; 119 #endif 120 } 121 122 /* 123 * reserve_real_mode() gets called very early, to guarantee the 124 * availability of low memory. This is before the proper kernel page 125 * tables are set up, so we cannot set page permissions in that 126 * function. Also trampoline code will be executed by APs so we 127 * need to mark it executable at do_pre_smp_initcalls() at least, 128 * thus run it as a early_initcall(). 129 */ 130 static void __init set_real_mode_permissions(void) 131 { 132 unsigned char *base = (unsigned char *) real_mode_header; 133 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 134 135 size_t ro_size = 136 PAGE_ALIGN(real_mode_header->ro_end) - 137 __pa(base); 138 139 size_t text_size = 140 PAGE_ALIGN(real_mode_header->ro_end) - 141 real_mode_header->text_start; 142 143 unsigned long text_start = 144 (unsigned long) __va(real_mode_header->text_start); 145 146 set_memory_nx((unsigned long) base, size >> PAGE_SHIFT); 147 set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT); 148 set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT); 149 } 150 151 static int __init init_real_mode(void) 152 { 153 if (!real_mode_header) 154 panic("Real mode trampoline was not allocated"); 155 156 setup_real_mode(); 157 set_real_mode_permissions(); 158 159 return 0; 160 } 161 early_initcall(init_real_mode); 162