arch/mips/kernel/vdso.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 2009, 2010 Cavium Networks, Inc.
   7  */
   8
   9
  10 #include <linux/kernel.h>
  11 #include <linux/err.h>
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/init.h>
  15 #include <linux/binfmts.h>
  16 #include <linux/elf.h>
  17 #include <linux/vmalloc.h>
  18 #include <linux/unistd.h>
  19
  20 #include <asm/vdso.h>
  21 #include <asm/uasm.h>
  22
  23 /*
  24  * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
  25  */
  26 #define __NR_O32_sigreturn              4119
  27 #define __NR_O32_rt_sigreturn           4193
  28 #define __NR_N32_rt_sigreturn           6211
  29
  30 static struct page *vdso_page;
  31
  32 static void __init install_trampoline(u32 *tramp, unsigned int sigreturn)
  33 {
  34         uasm_i_addiu(&tramp, 2, 0, sigreturn);  /* li v0, sigreturn */
  35         uasm_i_syscall(&tramp, 0);
  36 }
  37
  38 static int __init init_vdso(void)
  39 {
  40         struct mips_vdso *vdso;
  41
  42         vdso_page = alloc_page(GFP_KERNEL);
  43         if (!vdso_page)
  44                 panic("Cannot allocate vdso");
  45
  46         vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
  47         if (!vdso)
  48                 panic("Cannot map vdso");
  49         clear_page(vdso);
  50
  51         install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn);
  52 #ifdef CONFIG_32BIT
  53         install_trampoline(vdso->signal_trampoline, __NR_sigreturn);
  54 #else
  55         install_trampoline(vdso->n32_rt_signal_trampoline,
  56                            __NR_N32_rt_sigreturn);
  57         install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn);
  58         install_trampoline(vdso->o32_rt_signal_trampoline,
  59                            __NR_O32_rt_sigreturn);
  60 #endif
  61
  62         vunmap(vdso);
  63
  64         pr_notice("init_vdso successfull\n");
  65
  66         return 0;
  67 }
  68 device_initcall(init_vdso);
  69
  70 static unsigned long vdso_addr(unsigned long start)
  71 {
  72         return STACK_TOP;
  73 }
  74
  75 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
  76 {
  77         int ret;
  78         unsigned long addr;
  79         struct mm_struct *mm = current->mm;
  80
  81         down_write(&mm->mmap_sem);
  82
  83         addr = vdso_addr(mm->start_stack);
  84
  85         addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
  86         if (IS_ERR_VALUE(addr)) {
  87                 ret = addr;
  88                 goto up_fail;
  89         }
  90
  91         ret = install_special_mapping(mm, addr, PAGE_SIZE,
  92                                       VM_READ|VM_EXEC|
  93                                       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
  94                                       VM_ALWAYSDUMP,
  95                                       &vdso_page);
  96
  97         if (ret)
  98                 goto up_fail;
  99
 100         mm->context.vdso = (void *)addr;
 101
 102 up_fail:
 103         up_write(&mm->mmap_sem);
 104         return ret;
 105 }
 106
 107 const char *arch_vma_name(struct vm_area_struct *vma)
 108 {
 109         if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
 110                 return "[vdso]";
 111         return NULL;
 112 }