linux/arch/s390/lib/uaccess_pt.c
Heiko Carstens 3f12ebce6a [S390] uaccess: Always access the correct address space.
The current uaccess page table walk code assumes at a few places that
any access is a user space access. This is not correct if somebody
has issued a set_fs(KERNEL_DS) in advance.
Add code which checks which address space we are in and with this make
sure we access the correct address space. This way we get also rid of
the dirty
if (!currrent-mm)
	return -EFAULT;
hack in futex_atomic_cmpxchg_pt.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2008-04-17 07:47:06 +02:00

465 lines
11 KiB
C

/*
* arch/s390/lib/uaccess_pt.c
*
* User access functions based on page table walks for enhanced
* system layout without hardware support.
*
* Copyright IBM Corp. 2006
* Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
*/
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#include <asm/futex.h>
#include "uaccess.h"
static inline pte_t *follow_table(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pgd = pgd_offset(mm, addr);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
return NULL;
pud = pud_offset(pgd, addr);
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
return NULL;
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
return NULL;
return pte_offset_map(pmd, addr);
}
static int __handle_fault(struct mm_struct *mm, unsigned long address,
int write_access)
{
struct vm_area_struct *vma;
int ret = -EFAULT;
int fault;
if (in_atomic())
return ret;
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
if (unlikely(!vma))
goto out;
if (unlikely(vma->vm_start > address)) {
if (!(vma->vm_flags & VM_GROWSDOWN))
goto out;
if (expand_stack(vma, address))
goto out;
}
if (!write_access) {
/* page not present, check vm flags */
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto out;
} else {
if (!(vma->vm_flags & VM_WRITE))
goto out;
}
survive:
fault = handle_mm_fault(mm, vma, address, write_access);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGBUS)
goto out_sigbus;
BUG();
}
if (fault & VM_FAULT_MAJOR)
current->maj_flt++;
else
current->min_flt++;
ret = 0;
out:
up_read(&mm->mmap_sem);
return ret;
out_of_memory:
up_read(&mm->mmap_sem);
if (is_global_init(current)) {
yield();
down_read(&mm->mmap_sem);
goto survive;
}
printk("VM: killing process %s\n", current->comm);
return ret;
out_sigbus:
up_read(&mm->mmap_sem);
current->thread.prot_addr = address;
current->thread.trap_no = 0x11;
force_sig(SIGBUS, current);
return ret;
}
static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
size_t n, int write_user)
{
struct mm_struct *mm = current->mm;
unsigned long offset, pfn, done, size;
pte_t *pte;
void *from, *to;
done = 0;
retry:
spin_lock(&mm->page_table_lock);
do {
pte = follow_table(mm, uaddr);
if (!pte || !pte_present(*pte) ||
(write_user && !pte_write(*pte)))
goto fault;
pfn = pte_pfn(*pte);
if (!pfn_valid(pfn))
goto out;
offset = uaddr & (PAGE_SIZE - 1);
size = min(n - done, PAGE_SIZE - offset);
if (write_user) {
to = (void *)((pfn << PAGE_SHIFT) + offset);
from = kptr + done;
} else {
from = (void *)((pfn << PAGE_SHIFT) + offset);
to = kptr + done;
}
memcpy(to, from, size);
done += size;
uaddr += size;
} while (done < n);
out:
spin_unlock(&mm->page_table_lock);
return n - done;
fault:
spin_unlock(&mm->page_table_lock);
if (__handle_fault(mm, uaddr, write_user))
return n - done;
goto retry;
}
/*
* Do DAT for user address by page table walk, return kernel address.
* This function needs to be called with current->mm->page_table_lock held.
*/
static unsigned long __dat_user_addr(unsigned long uaddr)
{
struct mm_struct *mm = current->mm;
unsigned long pfn, ret;
pte_t *pte;
int rc;
ret = 0;
retry:
pte = follow_table(mm, uaddr);
if (!pte || !pte_present(*pte))
goto fault;
pfn = pte_pfn(*pte);
if (!pfn_valid(pfn))
goto out;
ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
out:
return ret;
fault:
spin_unlock(&mm->page_table_lock);
rc = __handle_fault(mm, uaddr, 0);
spin_lock(&mm->page_table_lock);
if (rc)
goto out;
goto retry;
}
size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
{
size_t rc;
if (segment_eq(get_fs(), KERNEL_DS)) {
memcpy(to, (void __kernel __force *) from, n);
return 0;
}
rc = __user_copy_pt((unsigned long) from, to, n, 0);
if (unlikely(rc))
memset(to + n - rc, 0, rc);
return rc;
}
size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
{
if (segment_eq(get_fs(), KERNEL_DS)) {
memcpy((void __kernel __force *) to, from, n);
return 0;
}
return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
}
static size_t clear_user_pt(size_t n, void __user *to)
{
long done, size, ret;
if (segment_eq(get_fs(), KERNEL_DS)) {
memset((void __kernel __force *) to, 0, n);
return 0;
}
done = 0;
do {
if (n - done > PAGE_SIZE)
size = PAGE_SIZE;
else
size = n - done;
ret = __user_copy_pt((unsigned long) to + done,
&empty_zero_page, size, 1);
done += size;
if (ret)
return ret + n - done;
} while (done < n);
return 0;
}
static size_t strnlen_user_pt(size_t count, const char __user *src)
{
char *addr;
unsigned long uaddr = (unsigned long) src;
struct mm_struct *mm = current->mm;
unsigned long offset, pfn, done, len;
pte_t *pte;
size_t len_str;
if (segment_eq(get_fs(), KERNEL_DS))
return strnlen((const char __kernel __force *) src, count) + 1;
done = 0;
retry:
spin_lock(&mm->page_table_lock);
do {
pte = follow_table(mm, uaddr);
if (!pte || !pte_present(*pte))
goto fault;
pfn = pte_pfn(*pte);
if (!pfn_valid(pfn)) {
done = -1;
goto out;
}
offset = uaddr & (PAGE_SIZE-1);
addr = (char *)(pfn << PAGE_SHIFT) + offset;
len = min(count - done, PAGE_SIZE - offset);
len_str = strnlen(addr, len);
done += len_str;
uaddr += len_str;
} while ((len_str == len) && (done < count));
out:
spin_unlock(&mm->page_table_lock);
return done + 1;
fault:
spin_unlock(&mm->page_table_lock);
if (__handle_fault(mm, uaddr, 0)) {
return 0;
}
goto retry;
}
static size_t strncpy_from_user_pt(size_t count, const char __user *src,
char *dst)
{
size_t n = strnlen_user_pt(count, src);
if (!n)
return -EFAULT;
if (n > count)
n = count;
if (segment_eq(get_fs(), KERNEL_DS)) {
memcpy(dst, (const char __kernel __force *) src, n);
if (dst[n-1] == '\0')
return n-1;
else
return n;
}
if (__user_copy_pt((unsigned long) src, dst, n, 0))
return -EFAULT;
if (dst[n-1] == '\0')
return n-1;
else
return n;
}
static size_t copy_in_user_pt(size_t n, void __user *to,
const void __user *from)
{
struct mm_struct *mm = current->mm;
unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
uaddr, done, size;
unsigned long uaddr_from = (unsigned long) from;
unsigned long uaddr_to = (unsigned long) to;
pte_t *pte_from, *pte_to;
int write_user;
if (segment_eq(get_fs(), KERNEL_DS)) {
memcpy((void __force *) to, (void __force *) from, n);
return 0;
}
done = 0;
retry:
spin_lock(&mm->page_table_lock);
do {
pte_from = follow_table(mm, uaddr_from);
if (!pte_from || !pte_present(*pte_from)) {
uaddr = uaddr_from;
write_user = 0;
goto fault;
}
pte_to = follow_table(mm, uaddr_to);
if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
uaddr = uaddr_to;
write_user = 1;
goto fault;
}
pfn_from = pte_pfn(*pte_from);
if (!pfn_valid(pfn_from))
goto out;
pfn_to = pte_pfn(*pte_to);
if (!pfn_valid(pfn_to))
goto out;
offset_from = uaddr_from & (PAGE_SIZE-1);
offset_to = uaddr_from & (PAGE_SIZE-1);
offset_max = max(offset_from, offset_to);
size = min(n - done, PAGE_SIZE - offset_max);
memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
(void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
done += size;
uaddr_from += size;
uaddr_to += size;
} while (done < n);
out:
spin_unlock(&mm->page_table_lock);
return n - done;
fault:
spin_unlock(&mm->page_table_lock);
if (__handle_fault(mm, uaddr, write_user))
return n - done;
goto retry;
}
#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
asm volatile("0: l %1,0(%6)\n" \
"1: " insn \
"2: cs %1,%2,0(%6)\n" \
"3: jl 1b\n" \
" lhi %0,0\n" \
"4:\n" \
EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
: "=d" (ret), "=&d" (oldval), "=&d" (newval), \
"=m" (*uaddr) \
: "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
"m" (*uaddr) : "cc" );
static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
{
int oldval = 0, newval, ret;
switch (op) {
case FUTEX_OP_SET:
__futex_atomic_op("lr %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
__futex_atomic_op("lr %2,%1\nar %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_OR:
__futex_atomic_op("lr %2,%1\nor %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_ANDN:
__futex_atomic_op("lr %2,%1\nnr %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
case FUTEX_OP_XOR:
__futex_atomic_op("lr %2,%1\nxr %2,%5\n",
ret, oldval, newval, uaddr, oparg);
break;
default:
ret = -ENOSYS;
}
if (ret == 0)
*old = oldval;
return ret;
}
int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
{
int ret;
if (segment_eq(get_fs(), KERNEL_DS))
return __futex_atomic_op_pt(op, uaddr, oparg, old);
spin_lock(&current->mm->page_table_lock);
uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
if (!uaddr) {
spin_unlock(&current->mm->page_table_lock);
return -EFAULT;
}
get_page(virt_to_page(uaddr));
spin_unlock(&current->mm->page_table_lock);
ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
put_page(virt_to_page(uaddr));
return ret;
}
static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
{
int ret;
asm volatile("0: cs %1,%4,0(%5)\n"
"1: lr %0,%1\n"
"2:\n"
EX_TABLE(0b,2b) EX_TABLE(1b,2b)
: "=d" (ret), "+d" (oldval), "=m" (*uaddr)
: "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
: "cc", "memory" );
return ret;
}
int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
{
int ret;
if (segment_eq(get_fs(), KERNEL_DS))
return __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
spin_lock(&current->mm->page_table_lock);
uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
if (!uaddr) {
spin_unlock(&current->mm->page_table_lock);
return -EFAULT;
}
get_page(virt_to_page(uaddr));
spin_unlock(&current->mm->page_table_lock);
ret = __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
put_page(virt_to_page(uaddr));
return ret;
}
struct uaccess_ops uaccess_pt = {
.copy_from_user = copy_from_user_pt,
.copy_from_user_small = copy_from_user_pt,
.copy_to_user = copy_to_user_pt,
.copy_to_user_small = copy_to_user_pt,
.copy_in_user = copy_in_user_pt,
.clear_user = clear_user_pt,
.strnlen_user = strnlen_user_pt,
.strncpy_from_user = strncpy_from_user_pt,
.futex_atomic_op = futex_atomic_op_pt,
.futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
};