arch/x86/realmode/init.c

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