389 lines
9.4 KiB
C
389 lines
9.4 KiB
C
/*
|
|
* User access functions based on page table walks for enhanced
|
|
* system layout without hardware support.
|
|
*
|
|
* Copyright IBM Corp. 2006, 2012
|
|
* Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
|
|
*/
|
|
|
|
#include <linux/errno.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <asm/uaccess.h>
|
|
#include <asm/futex.h>
|
|
#include "uaccess.h"
|
|
|
|
|
|
/*
|
|
* Returns kernel address for user virtual address. If the returned address is
|
|
* >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occured and the address
|
|
* contains the (negative) exception code.
|
|
*/
|
|
static __always_inline unsigned long follow_table(struct mm_struct *mm,
|
|
unsigned long addr, int write)
|
|
{
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
pte_t *ptep;
|
|
|
|
pgd = pgd_offset(mm, addr);
|
|
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
|
|
return -0x3aUL;
|
|
|
|
pud = pud_offset(pgd, addr);
|
|
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
|
|
return -0x3bUL;
|
|
|
|
pmd = pmd_offset(pud, addr);
|
|
if (pmd_none(*pmd))
|
|
return -0x10UL;
|
|
if (pmd_large(*pmd)) {
|
|
if (write && (pmd_val(*pmd) & _SEGMENT_ENTRY_RO))
|
|
return -0x04UL;
|
|
return (pmd_val(*pmd) & HPAGE_MASK) + (addr & ~HPAGE_MASK);
|
|
}
|
|
if (unlikely(pmd_bad(*pmd)))
|
|
return -0x10UL;
|
|
|
|
ptep = pte_offset_map(pmd, addr);
|
|
if (!pte_present(*ptep))
|
|
return -0x11UL;
|
|
if (write && !pte_write(*ptep))
|
|
return -0x04UL;
|
|
|
|
return (pte_val(*ptep) & PAGE_MASK) + (addr & ~PAGE_MASK);
|
|
}
|
|
|
|
static __always_inline 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, done, size, kaddr;
|
|
void *from, *to;
|
|
|
|
done = 0;
|
|
retry:
|
|
spin_lock(&mm->page_table_lock);
|
|
do {
|
|
kaddr = follow_table(mm, uaddr, write_user);
|
|
if (IS_ERR_VALUE(kaddr))
|
|
goto fault;
|
|
|
|
offset = uaddr & ~PAGE_MASK;
|
|
size = min(n - done, PAGE_SIZE - offset);
|
|
if (write_user) {
|
|
to = (void *) kaddr;
|
|
from = kptr + done;
|
|
} else {
|
|
from = (void *) kaddr;
|
|
to = kptr + done;
|
|
}
|
|
memcpy(to, from, size);
|
|
done += size;
|
|
uaddr += size;
|
|
} while (done < n);
|
|
spin_unlock(&mm->page_table_lock);
|
|
return n - done;
|
|
fault:
|
|
spin_unlock(&mm->page_table_lock);
|
|
if (__handle_fault(uaddr, -kaddr, 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 __always_inline unsigned long __dat_user_addr(unsigned long uaddr,
|
|
int write)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long kaddr;
|
|
int rc;
|
|
|
|
retry:
|
|
kaddr = follow_table(mm, uaddr, write);
|
|
if (IS_ERR_VALUE(kaddr))
|
|
goto fault;
|
|
|
|
return kaddr;
|
|
fault:
|
|
spin_unlock(&mm->page_table_lock);
|
|
rc = __handle_fault(uaddr, -kaddr, write);
|
|
spin_lock(&mm->page_table_lock);
|
|
if (!rc)
|
|
goto retry;
|
|
return 0;
|
|
}
|
|
|
|
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)
|
|
{
|
|
unsigned long uaddr = (unsigned long) src;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long offset, done, len, kaddr;
|
|
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 {
|
|
kaddr = follow_table(mm, uaddr, 0);
|
|
if (IS_ERR_VALUE(kaddr))
|
|
goto fault;
|
|
|
|
offset = uaddr & ~PAGE_MASK;
|
|
len = min(count - done, PAGE_SIZE - offset);
|
|
len_str = strnlen((char *) kaddr, len);
|
|
done += len_str;
|
|
uaddr += len_str;
|
|
} while ((len_str == len) && (done < count));
|
|
spin_unlock(&mm->page_table_lock);
|
|
return done + 1;
|
|
fault:
|
|
spin_unlock(&mm->page_table_lock);
|
|
if (__handle_fault(uaddr, -kaddr, 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_max, uaddr, done, size, error_code;
|
|
unsigned long uaddr_from = (unsigned long) from;
|
|
unsigned long uaddr_to = (unsigned long) to;
|
|
unsigned long kaddr_to, kaddr_from;
|
|
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 {
|
|
write_user = 0;
|
|
uaddr = uaddr_from;
|
|
kaddr_from = follow_table(mm, uaddr_from, 0);
|
|
error_code = kaddr_from;
|
|
if (IS_ERR_VALUE(error_code))
|
|
goto fault;
|
|
|
|
write_user = 1;
|
|
uaddr = uaddr_to;
|
|
kaddr_to = follow_table(mm, uaddr_to, 1);
|
|
error_code = (unsigned long) kaddr_to;
|
|
if (IS_ERR_VALUE(error_code))
|
|
goto fault;
|
|
|
|
offset_max = max(uaddr_from & ~PAGE_MASK,
|
|
uaddr_to & ~PAGE_MASK);
|
|
size = min(n - done, PAGE_SIZE - offset_max);
|
|
|
|
memcpy((void *) kaddr_to, (void *) kaddr_from, size);
|
|
done += size;
|
|
uaddr_from += size;
|
|
uaddr_to += size;
|
|
} while (done < n);
|
|
spin_unlock(&mm->page_table_lock);
|
|
return n - done;
|
|
fault:
|
|
spin_unlock(&mm->page_table_lock);
|
|
if (__handle_fault(uaddr, -error_code, 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, u32 __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, u32 __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(¤t->mm->page_table_lock);
|
|
uaddr = (u32 __force __user *)
|
|
__dat_user_addr((__force unsigned long) uaddr, 1);
|
|
if (!uaddr) {
|
|
spin_unlock(¤t->mm->page_table_lock);
|
|
return -EFAULT;
|
|
}
|
|
get_page(virt_to_page(uaddr));
|
|
spin_unlock(¤t->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(u32 *uval, u32 __user *uaddr,
|
|
u32 oldval, u32 newval)
|
|
{
|
|
int ret;
|
|
|
|
asm volatile("0: cs %1,%4,0(%5)\n"
|
|
"1: la %0,0\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" );
|
|
*uval = oldval;
|
|
return ret;
|
|
}
|
|
|
|
int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
|
|
u32 oldval, u32 newval)
|
|
{
|
|
int ret;
|
|
|
|
if (segment_eq(get_fs(), KERNEL_DS))
|
|
return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
|
|
spin_lock(¤t->mm->page_table_lock);
|
|
uaddr = (u32 __force __user *)
|
|
__dat_user_addr((__force unsigned long) uaddr, 1);
|
|
if (!uaddr) {
|
|
spin_unlock(¤t->mm->page_table_lock);
|
|
return -EFAULT;
|
|
}
|
|
get_page(virt_to_page(uaddr));
|
|
spin_unlock(¤t->mm->page_table_lock);
|
|
ret = __futex_atomic_cmpxchg_pt(uval, 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,
|
|
};
|