369c99205f
Even though it's only the difference of the two __initdata symbols that's being calculated, modpost still doesn't like this. So rather calculate the size once in an __init function and store it for later use. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
138 lines
3.1 KiB
C
138 lines
3.1 KiB
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 <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_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;
|
|
|
|
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;
|
|
}
|
|
|
|
ret = install_special_mapping(mm, addr, vdso_size,
|
|
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);
|