blob: 7e8efaade2ea1196275dd294ec8b48d2748899d3 [file] [log] [blame]
/*
* 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;
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" );
int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
{
int oldval = 0, newval, ret;
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);
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;
}
put_page(virt_to_page(uaddr));
*old = oldval;
return ret;
}
int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
{
int ret;
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);
asm volatile(" cs %1,%4,0(%5)\n"
"0: lr %0,%1\n"
"1:\n"
EX_TABLE(0b,1b)
: "=d" (ret), "+d" (oldval), "=m" (*uaddr)
: "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
: "cc", "memory" );
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,
};