text: /*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2009, 2010 Cavium Networks, Inc.
   */
  
  
  #include <linux/kernel.h>
  #include <linux/err.h>
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/init.h>
  #include <linux/binfmts.h>
  #include <linux/elf.h>
  #include <linux/vmalloc.h>
  #include <linux/unistd.h>
  
  #include <asm/vdso.h>
  #include <asm/uasm.h>
  
  /*
   * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
   */
  #define __NR_O32_sigreturn		4119
  #define __NR_O32_rt_sigreturn		4193
  #define __NR_N32_rt_sigreturn		6211
  
  static struct page *vdso_page;
  
  static void __init install_trampoline(u32 *tramp, unsigned int sigreturn)
  {
  	uasm_i_addiu(&tramp, 2, 0, sigreturn);	/* li v0, sigreturn */
  	uasm_i_syscall(&tramp, 0);
  }
  
  static int __init init_vdso(void)
  {
  	struct mips_vdso *vdso;
  
  	vdso_page = alloc_page(GFP_KERNEL);
  	if (!vdso_page)
  		panic("Cannot allocate vdso");
  
  	vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
  	if (!vdso)
  		panic("Cannot map vdso");
  	clear_page(vdso);
  
  	install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn);
  #ifdef CONFIG_32BIT
  	install_trampoline(vdso->signal_trampoline, __NR_sigreturn);
  #else
  	install_trampoline(vdso->n32_rt_signal_trampoline,
  			   __NR_N32_rt_sigreturn);
  	install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn);
  	install_trampoline(vdso->o32_rt_signal_trampoline,
  			   __NR_O32_rt_sigreturn);
  #endif
  
  	vunmap(vdso);
  
  	pr_notice("init_vdso successfull\n");
  
  	return 0;
  }
  device_initcall(init_vdso);
  
  static unsigned long vdso_addr(unsigned long start)
  {
  	return STACK_TOP;
  }
  
  int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
  {
  	int ret;
  	unsigned long addr;
  	struct mm_struct *mm = current->mm;
  
  	down_write(&mm->mmap_sem);
  
  	addr = vdso_addr(mm->start_stack);
  
  	addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
  	if (IS_ERR_VALUE(addr)) {
  		ret = addr;
  		goto up_fail;
  	}
  
  	ret = install_special_mapping(mm, addr, PAGE_SIZE,
  				      VM_READ|VM_EXEC|
  				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
  				      VM_ALWAYSDUMP,
  				      &vdso_page);
  
  	if (ret)
  		goto up_fail;
  
  	mm->context.vdso = (void *)addr;
  
  up_fail:
  	up_write(&mm->mmap_sem);
  	return ret;
  }
  
  const char *arch_vma_name(struct vm_area_struct *vma)
  {
  	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
  		return "[vdso]";
  	return NULL;
  }
  