arch/x86/kernel/trampoline.c

   1 #include <linux/io.h>
   2 #include <linux/memblock.h>
   3
   4 #include <asm/trampoline.h>
   5 #include <asm/cacheflush.h>
   6 #include <asm/pgtable.h>
   7
   8 unsigned char *x86_trampoline_base;
   9
  10 void __init setup_trampolines(void)
  11 {
  12         phys_addr_t mem;
  13         size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
  14
  15         /* Has to be in very low memory so we can execute real-mode AP code. */
  16         mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
  17         if (mem == MEMBLOCK_ERROR)
  18                 panic("Cannot allocate trampoline\n");
  19
  20         x86_trampoline_base = __va(mem);
  21         memblock_x86_reserve_range(mem, mem + size, "TRAMPOLINE");
  22
  23         printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
  24                x86_trampoline_base, (unsigned long long)mem, size);
  25
  26         memcpy(x86_trampoline_base, x86_trampoline_start, size);
  27 }
  28
  29 /*
  30  * setup_trampolines() gets called very early, to guarantee the
  31  * availability of low memory.  This is before the proper kernel page
  32  * tables are set up, so we cannot set page permissions in that
  33  * function.  Thus, we use an arch_initcall instead.
  34  */
  35 static int __init configure_trampolines(void)
  36 {
  37         size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
  38
  39         set_memory_x((unsigned long)x86_trampoline_base, size >> PAGE_SHIFT);
  40         return 0;
  41 }
  42 arch_initcall(configure_trampolines);