[linux-2.6-block.git] / arch / x86 / 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/slab.h>
#include <linux/init.h>
#include <linux/random.h>
#include <linux/elf.h>
#include <asm/vsyscall.h>
#include <asm/vgtod.h>
#include <asm/proto.h>
#include <asm/vdso.h>

#include "vextern.h"		/* Just for VMAGIC.  */
#undef VEXTERN

unsigned int __read_mostly vdso_enabled = 1;

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

static struct page **vdso_pages;
static unsigned vdso_size;

static inline void *var_ref(void *p, char *name)
{
	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_size = npages << PAGE_SHIFT;
	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 VEXTERN(x) \
	*(typeof(__ ## x) **) var_ref(VDSO64_SYMBOL(vbase, x), #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_SIZE_MAX)
		end = TASK_SIZE_MAX;
	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 uses_interp)
{
	struct mm_struct *mm = current->mm;
	unsigned long addr;
	int ret;

	if (!vdso_enabled)
		return 0;

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

	current->mm->context.vdso = (void *)addr;

	ret = install_special_mapping(mm, addr, vdso_size,
				      VM_READ|VM_EXEC|
				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
				      VM_ALWAYSDUMP,
				      vdso_pages);
	if (ret) {
		current->mm->context.vdso = NULL;
		goto up_fail;
	}

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	8	#include <linux/sched.h>
5a0e3ad6	9	#include <linux/slab.h>
2aae950b AK	10	#include <linux/init.h>
2aae950b AK	11	#include <linux/random.h>
3fa89ca7	12	#include <linux/elf.h>
2aae950b AK	13	#include <asm/vsyscall.h>
	14	#include <asm/vgtod.h>
	15	#include <asm/proto.h>
7f3646aa	16	#include <asm/vdso.h>
2aae950b	17
7f3646aa	18	#include "vextern.h" /* Just for VMAGIC. */
2aae950b AK	19	#undef VEXTERN
2aae950b AK	20
e6b0edef	21	unsigned int __read_mostly vdso_enabled = 1;
7f3646aa RM	22
7f3646aa RM	23	extern char vdso_start[], vdso_end[];
2aae950b AK	24	extern unsigned short vdso_sync_cpuid;
2aae950b AK	25
369c9920 JB	26	static struct page **vdso_pages;
369c9920 JB	27	static unsigned vdso_size;
2aae950b	28
7f3646aa	29	static inline void var_ref(void p, char *name)
2aae950b	30	{
2aae950b AK	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
369c9920	44	vdso_size = npages << PAGE_SHIFT;
2aae950b AK	45	vdso_pages = kmalloc(sizeof(struct page ) npages, GFP_KERNEL);
	46	if (!vdso_pages)
	47	goto oom;
	48	for (i = 0; i < npages; i++) {
	49	struct page *p;
	50	p = alloc_page(GFP_KERNEL);
	51	if (!p)
	52	goto oom;
	53	vdso_pages[i] = p;
	54	copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
	55	}
	56
	57	vbase = vmap(vdso_pages, npages, 0, PAGE_KERNEL);
	58	if (!vbase)
	59	goto oom;
	60
	61	if (memcmp(vbase, "\177ELF", 4)) {
	62	printk("VDSO: I'm broken; not ELF\n");
	63	vdso_enabled = 0;
	64	}
	65
2aae950b	66	#define VEXTERN(x) \
7f3646aa	67	(typeof(__ ## x) *) var_ref(VDSO64_SYMBOL(vbase, x), #x) = &__ ## x;
2aae950b AK	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;
d9517346 IM	90	if (end >= TASK_SIZE_MAX)
d9517346 IM	91	end = TASK_SIZE_MAX;
2aae950b AK	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 */
fc5243d9	103	int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
2aae950b AK	104	{
	105	struct mm_struct *mm = current->mm;
	106	unsigned long addr;
	107	int ret;
2aae950b AK	108
	109	if (!vdso_enabled)
	110	return 0;
	111
	112	down_write(&mm->mmap_sem);
369c9920 JB	113	addr = vdso_addr(mm->start_stack, vdso_size);
369c9920 JB	114	addr = get_unmapped_area(NULL, addr, vdso_size, 0, 0);
2aae950b AK	115	if (IS_ERR_VALUE(addr)) {
	116	ret = addr;
	117	goto up_fail;
	118	}
	119
f7b6eb3f PZ	120	current->mm->context.vdso = (void *)addr;
f7b6eb3f PZ	121
369c9920	122	ret = install_special_mapping(mm, addr, vdso_size,
2aae950b AK	123	VM_READ\|VM_EXEC\|
	124	VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC\|
	125	VM_ALWAYSDUMP,
	126	vdso_pages);
f7b6eb3f PZ	127	if (ret) {
f7b6eb3f PZ	128	current->mm->context.vdso = NULL;
2aae950b	129	goto up_fail;
f7b6eb3f	130	}
2aae950b	131
2aae950b AK	132	up_fail:
	133	up_write(&mm->mmap_sem);
	134	return ret;
	135	}
	136
	137	static __init int vdso_setup(char *s)
	138	{
	139	vdso_enabled = simple_strtoul(s, NULL, 0);
	140	return 0;
	141	}
	142	__setup("vdso=", vdso_setup);