1#include <linux/io.h>
  2#include <linux/memblock.h>
  3
  4#include <asm/cacheflush.h>
  5#include <asm/pgtable.h>
  6#include <asm/realmode.h>
  7
  8struct real_mode_header *real_mode_header;
  9u32 *trampoline_cr4_features;
 10
 11void __init setup_real_mode(void)
 12{
 13	phys_addr_t mem;
 14	u16 real_mode_seg;
 15	u32 *rel;
 16	u32 count;
 17	u32 *ptr;
 18	u16 *seg;
 19	int i;
 20	unsigned char *base;
 21	struct trampoline_header *trampoline_header;
 22	size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 23#ifdef CONFIG_X86_64
 24	u64 *trampoline_pgd;
 25	u64 efer;
 26#endif
 27
 28	/* Has to be in very low memory so we can execute real-mode AP code. */
 29	mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
 30	if (!mem)
 31		panic("Cannot allocate trampoline\n");
 32
 33	base = __va(mem);
 34	memblock_reserve(mem, size);
 35	real_mode_header = (struct real_mode_header *) base;
 36	printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
 37	       base, (unsigned long long)mem, size);
 38
 39	memcpy(base, real_mode_blob, size);
 40
 41	real_mode_seg = __pa(base) >> 4;
 42	rel = (u32 *) real_mode_relocs;
 43
 44	/* 16-bit segment relocations. */
 45	count = rel[0];
 46	rel = &rel[1];
 47	for (i = 0; i < count; i++) {
 48		seg = (u16 *) (base + rel[i]);
 49		*seg = real_mode_seg;
 50	}
 51
 52	/* 32-bit linear relocations. */
 53	count = rel[i];
 54	rel =  &rel[i + 1];
 55	for (i = 0; i < count; i++) {
 56		ptr = (u32 *) (base + rel[i]);
 57		*ptr += __pa(base);
 58	}
 59
 60	/* Must be perfomed *after* relocation. */
 61	trampoline_header = (struct trampoline_header *)
 62		__va(real_mode_header->trampoline_header);
 63
 64#ifdef CONFIG_X86_32
 65	trampoline_header->start = __pa(startup_32_smp);
 66	trampoline_header->gdt_limit = __BOOT_DS + 7;
 67	trampoline_header->gdt_base = __pa(boot_gdt);
 68#else
 69	/*
 70	 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
 71	 * so we need to mask it out.
 72	 */
 73	rdmsrl(MSR_EFER, efer);
 74	trampoline_header->efer = efer & ~EFER_LMA;
 75
 76	trampoline_header->start = (u64) secondary_startup_64;
 77	trampoline_cr4_features = &trampoline_header->cr4;
 78	*trampoline_cr4_features = read_cr4();
 79
 80	trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
 81	trampoline_pgd[0] = __pa(level3_ident_pgt) + _KERNPG_TABLE;
 82	trampoline_pgd[511] = __pa(level3_kernel_pgt) + _KERNPG_TABLE;
 83#endif
 84}
 85
 86/*
 87 * set_real_mode_permissions() gets called very early, to guarantee the
 88 * availability of low memory.  This is before the proper kernel page
 89 * tables are set up, so we cannot set page permissions in that
 90 * function.  Thus, we use an arch_initcall instead.
 91 */
 92static int __init set_real_mode_permissions(void)
 93{
 94	unsigned char *base = (unsigned char *) real_mode_header;
 95	size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
 96
 97	size_t ro_size =
 98		PAGE_ALIGN(real_mode_header->ro_end) -
 99		__pa(base);
100
101	size_t text_size =
102		PAGE_ALIGN(real_mode_header->ro_end) -
103		real_mode_header->text_start;
104
105	unsigned long text_start =
106		(unsigned long) __va(real_mode_header->text_start);
107
108	set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
109	set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
110	set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
111
112	return 0;
113}
114
115arch_initcall(set_real_mode_permissions);