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#include <linux/random.h>
20
21#include <asm/vdso.h>
22#include <asm/uasm.h>
23#include <asm/processor.h>
24
25/*
26 * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
27 */
28#define __NR_O32_sigreturn		4119
29#define __NR_O32_rt_sigreturn		4193
30#define __NR_N32_rt_sigreturn		6211
31
32static struct page *vdso_page;
33
34static void __init install_trampoline(u32 *tramp, unsigned int sigreturn)
35{
36	uasm_i_addiu(&tramp, 2, 0, sigreturn);	/* li v0, sigreturn */
37	uasm_i_syscall(&tramp, 0);
38}
39
40static int __init init_vdso(void)
41{
42	struct mips_vdso *vdso;
43
44	vdso_page = alloc_page(GFP_KERNEL);
45	if (!vdso_page)
46		panic("Cannot allocate vdso");
47
48	vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
49	if (!vdso)
50		panic("Cannot map vdso");
51	clear_page(vdso);
52
53	install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn);
54#ifdef CONFIG_32BIT
55	install_trampoline(vdso->signal_trampoline, __NR_sigreturn);
56#else
57	install_trampoline(vdso->n32_rt_signal_trampoline,
58			   __NR_N32_rt_sigreturn);
59	install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn);
60	install_trampoline(vdso->o32_rt_signal_trampoline,
61			   __NR_O32_rt_sigreturn);
62#endif
63
64	vunmap(vdso);
65
66	return 0;
67}
68subsys_initcall(init_vdso);
69
70static unsigned long vdso_addr(unsigned long start)
71{
72	unsigned long offset = 0UL;
73
74	if (current->flags & PF_RANDOMIZE) {
75		offset = get_random_int();
76		offset <<= PAGE_SHIFT;
77		if (TASK_IS_32BIT_ADDR)
78			offset &= 0xfffffful;
79		else
80			offset &= 0xffffffful;
81	}
82
83	return STACK_TOP + offset;
84}
85
86int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
87{
88	int ret;
89	unsigned long addr;
90	struct mm_struct *mm = current->mm;
91
92	down_write(&mm->mmap_sem);
93
94	addr = vdso_addr(mm->start_stack);
95
96	addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0);
97	if (IS_ERR_VALUE(addr)) {
98		ret = addr;
99		goto up_fail;
100	}
101
102	ret = install_special_mapping(mm, addr, PAGE_SIZE,
103				      VM_READ|VM_EXEC|
104				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
105				      &vdso_page);
106
107	if (ret)
108		goto up_fail;
109
110	mm->context.vdso = (void *)addr;
111
112up_fail:
113	up_write(&mm->mmap_sem);
114	return ret;
115}
116
117const char *arch_vma_name(struct vm_area_struct *vma)
118{
119	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
120		return "[vdso]";
121	return NULL;
122}
123