[deliverable/linux.git] / arch / x86_64 / vdso / vma.c

/*
 * Set up the VMAs to tell the VM about the vDSO.
 * Copyright 2007 Andi Kleen, SUSE Labs.
 * Subject to the GPL, v.2
 */
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/random.h>
#include <asm/vsyscall.h>
#include <asm/vgtod.h>
#include <asm/proto.h>
#include "voffset.h"

int vdso_enabled = 1;

#define VEXTERN(x) extern typeof(__ ## x) *vdso_ ## x;
#include "vextern.h"
#undef VEXTERN

extern char vdso_kernel_start[], vdso_start[], vdso_end[];
extern unsigned short vdso_sync_cpuid;

struct page **vdso_pages;

static inline void *var_ref(void *vbase, char *var, char *name)
{
	unsigned offset = var - &vdso_kernel_start[0] + VDSO_TEXT_OFFSET;
	void *p = vbase + offset;
	if (*(void **)p != (void *)VMAGIC) {
		printk("VDSO: variable %s broken\n", name);
		vdso_enabled = 0;
	}
	return p;
}

static int __init init_vdso_vars(void)
{
	int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
	int i;
	char *vbase;

	vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL);
	if (!vdso_pages)
		goto oom;
	for (i = 0; i < npages; i++) {
		struct page *p;
		p = alloc_page(GFP_KERNEL);
		if (!p)
			goto oom;
		vdso_pages[i] = p;
		copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
	}

	vbase = vmap(vdso_pages, npages, 0, PAGE_KERNEL);
	if (!vbase)
		goto oom;

	if (memcmp(vbase, "\177ELF", 4)) {
		printk("VDSO: I'm broken; not ELF\n");
		vdso_enabled = 0;
	}

#define V(x) *(typeof(x) *) var_ref(vbase, (char *)RELOC_HIDE(&x, 0), #x)
#define VEXTERN(x) \
	V(vdso_ ## x) = &__ ## x;
#include "vextern.h"
#undef VEXTERN
	return 0;

 oom:
	printk("Cannot allocate vdso\n");
	vdso_enabled = 0;
	return -ENOMEM;
}
__initcall(init_vdso_vars);

struct linux_binprm;

/* Put the vdso above the (randomized) stack with another randomized offset.
   This way there is no hole in the middle of address space.
   To save memory make sure it is still in the same PTE as the stack top.
   This doesn't give that many random bits */
static unsigned long vdso_addr(unsigned long start, unsigned len)
{
	unsigned long addr, end;
	unsigned offset;
	end = (start + PMD_SIZE - 1) & PMD_MASK;
	if (end >= TASK_SIZE64)
		end = TASK_SIZE64;
	end -= len;
	/* This loses some more bits than a modulo, but is cheaper */
	offset = get_random_int() & (PTRS_PER_PTE - 1);
	addr = start + (offset << PAGE_SHIFT);
	if (addr >= end)
		addr = end;
	return addr;
}

/* Setup a VMA at program startup for the vsyscall page.
   Not called for compat tasks */
int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
{
	struct mm_struct *mm = current->mm;
	unsigned long addr;
	int ret;
	unsigned len = round_up(vdso_end - vdso_start, PAGE_SIZE);

	if (!vdso_enabled)
		return 0;

	down_write(&mm->mmap_sem);
	addr = vdso_addr(mm->start_stack, len);
	addr = get_unmapped_area(NULL, addr, len, 0, 0);
	if (IS_ERR_VALUE(addr)) {
		ret = addr;
		goto up_fail;
	}

	ret = install_special_mapping(mm, addr, len,
				      VM_READ|VM_EXEC|
				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
				      VM_ALWAYSDUMP,
				      vdso_pages);
	if (ret)
		goto up_fail;

	current->mm->context.vdso = (void *)addr;
up_fail:
	up_write(&mm->mmap_sem);
	return ret;
}

static __init int vdso_setup(char *s)
{
	vdso_enabled = simple_strtoul(s, NULL, 0);
	return 0;
}
__setup("vdso=", vdso_setup);
Commit	Line	Data
2aae950b AK	1	/*
	2	* Set up the VMAs to tell the VM about the vDSO.
	3	* Copyright 2007 Andi Kleen, SUSE Labs.
	4	* Subject to the GPL, v.2
	5	*/
	6	#include <linux/mm.h>
4e950f6f	7	#include <linux/err.h>
2aae950b AK	8	#include <linux/sched.h>
	9	#include <linux/init.h>
	10	#include <linux/random.h>
	11	#include <asm/vsyscall.h>
	12	#include <asm/vgtod.h>
	13	#include <asm/proto.h>
	14	#include "voffset.h"
	15
	16	int vdso_enabled = 1;
	17
	18	#define VEXTERN(x) extern typeof(__ ## x) *vdso_ ## x;
	19	#include "vextern.h"
	20	#undef VEXTERN
	21
	22	extern char vdso_kernel_start[], vdso_start[], vdso_end[];
	23	extern unsigned short vdso_sync_cpuid;
	24
	25	struct page **vdso_pages;
	26
	27	static inline void var_ref(void vbase, char var, char name)
	28	{
	29	unsigned offset = var - &vdso_kernel_start[0] + VDSO_TEXT_OFFSET;
	30	void *p = vbase + offset;
	31	if ((void )p != (void )VMAGIC) {
	32	printk("VDSO: variable %s broken\n", name);
	33	vdso_enabled = 0;
	34	}
	35	return p;
	36	}
	37
	38	static int __init init_vdso_vars(void)
	39	{
	40	int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
	41	int i;
	42	char *vbase;
	43
	44	vdso_pages = kmalloc(sizeof(struct page ) npages, GFP_KERNEL);
	45	if (!vdso_pages)
	46	goto oom;
	47	for (i = 0; i < npages; i++) {
	48	struct page *p;
	49	p = alloc_page(GFP_KERNEL);
	50	if (!p)
	51	goto oom;
	52	vdso_pages[i] = p;
	53	copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
	54	}
	55
	56	vbase = vmap(vdso_pages, npages, 0, PAGE_KERNEL);
	57	if (!vbase)
	58	goto oom;
	59
	60	if (memcmp(vbase, "\177ELF", 4)) {
	61	printk("VDSO: I'm broken; not ELF\n");
	62	vdso_enabled = 0;
	63	}
	64
	65	#define V(x) (typeof(x) ) var_ref(vbase, (char *)RELOC_HIDE(&x, 0), #x)
	66	#define VEXTERN(x) \
	67	V(vdso_ ## x) = &__ ## x;
	68	#include "vextern.h"
	69	#undef VEXTERN
	70	return 0;
	71
72	oom:
73	printk("Cannot allocate vdso\n");
74	vdso_enabled = 0;
75	return -ENOMEM;
76	}
77	__initcall(init_vdso_vars);
78
79	struct linux_binprm;
80
81	/* Put the vdso above the (randomized) stack with another randomized offset.
82	This way there is no hole in the middle of address space.
83	To save memory make sure it is still in the same PTE as the stack top.
84	This doesn't give that many random bits */
85	static unsigned long vdso_addr(unsigned long start, unsigned len)
86	{
87	unsigned long addr, end;
88	unsigned offset;
89	end = (start + PMD_SIZE - 1) & PMD_MASK;
90	if (end >= TASK_SIZE64)
91	end = TASK_SIZE64;
92	end -= len;
93	/* This loses some more bits than a modulo, but is cheaper */
94	offset = get_random_int() & (PTRS_PER_PTE - 1);
95	addr = start + (offset << PAGE_SHIFT);
96	if (addr >= end)
97	addr = end;
98	return addr;
99	}
100
101	/* Setup a VMA at program startup for the vsyscall page.
102	Not called for compat tasks */
103	int arch_setup_additional_pages(struct linux_binprm *bprm, int exstack)
104	{
105	struct mm_struct *mm = current->mm;
106	unsigned long addr;
107	int ret;
108	unsigned len = round_up(vdso_end - vdso_start, PAGE_SIZE);
109
110	if (!vdso_enabled)
111	return 0;
112
113	down_write(&mm->mmap_sem);
114	addr = vdso_addr(mm->start_stack, len);
115	addr = get_unmapped_area(NULL, addr, len, 0, 0);
116	if (IS_ERR_VALUE(addr)) {
117	ret = addr;
118	goto up_fail;
119	}
120
121	ret = install_special_mapping(mm, addr, len,
122	VM_READ\|VM_EXEC\|
123	VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC\|
124	VM_ALWAYSDUMP,
125	vdso_pages);
126	if (ret)
127	goto up_fail;
128
129	current->mm->context.vdso = (void *)addr;
130	up_fail:
131	up_write(&mm->mmap_sem);
132	return ret;
133	}
134
135	static __init int vdso_setup(char *s)
136	{
137	vdso_enabled = simple_strtoul(s, NULL, 0);
138	return 0;
139	}
140	__setup("vdso=", vdso_setup);