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
 30static struct page *vdso_page;
 31
 32static 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
 38static 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	return 0;
 65}
 66subsys_initcall(init_vdso);
 67
 68static unsigned long vdso_addr(unsigned long start)
 69{
 70	return STACK_TOP;
 71}
 72
 73int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 74{
 75	int ret;
 76	unsigned long addr;
 77	struct mm_struct *mm = current->mm;
 78
 79	down_write(&mm->mmap_sem);
 80
 81	addr = vdso_addr(mm->start_stack);
 82
 83	addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
 84	if (IS_ERR_VALUE(addr)) {
 85		ret = addr;
 86		goto up_fail;
 87	}
 88
 89	ret = install_special_mapping(mm, addr, PAGE_SIZE,
 90				      VM_READ|VM_EXEC|
 91				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 92				      &vdso_page);
 93
 94	if (ret)
 95		goto up_fail;
 96
 97	mm->context.vdso = (void *)addr;
 98
 99up_fail:
100	up_write(&mm->mmap_sem);
101	return ret;
102}
103
104const char *arch_vma_name(struct vm_area_struct *vma)
105{
106	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
107		return "[vdso]";
108	return NULL;
109}