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Star64_linux/arch/s390/lib/uaccess_pt.c
Heiko Carstens 4f41c2b456 s390/uaccess: get rid of indirect function calls 
There are only two uaccess variants on s390 left: the version that is used
if the mvcos instruction is available, and the page table walk variant.
So there is no need for expensive indirect function calls.

By default the mvcos variant will be called. If the mvcos instruction is not
available it will call the page table walk variant.

For minimal performance impact the "if (mvcos_is_available)" is implemented
with a jump label, which will be a six byte nop on machines with mvcos.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-02-21 08:50:14 +01:00

471 lines
12 KiB
C
Raw Blame History

/*
* 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"
#ifndef CONFIG_64BIT
#define AHI "ahi"
#define SLR "slr"
#else
#define AHI "aghi"
#define SLR "slgr"
#endif
static size_t strnlen_kernel(const char __user *src, size_t count)
{
register unsigned long reg0 asm("0") = 0UL;
unsigned long tmp1, tmp2;
asm volatile(
" la %2,0(%1)\n"
" la %3,0(%0,%1)\n"
" "SLR" %0,%0\n"
"0: srst %3,%2\n"
" jo 0b\n"
" la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
" "SLR" %0,%1\n"
"1:\n"
EX_TABLE(0b,1b)
: "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
: "d" (reg0) : "cc", "memory");
return count;
}
static size_t copy_in_kernel(void __user *to, const void __user *from,
size_t count)
{
unsigned long tmp1;
asm volatile(
" "AHI" %0,-1\n"
" jo 5f\n"
" bras %3,3f\n"
"0:"AHI" %0,257\n"
"1: mvc 0(1,%1),0(%2)\n"
" la %1,1(%1)\n"
" la %2,1(%2)\n"
" "AHI" %0,-1\n"
" jnz 1b\n"
" j 5f\n"
"2: mvc 0(256,%1),0(%2)\n"
" la %1,256(%1)\n"
" la %2,256(%2)\n"
"3:"AHI" %0,-256\n"
" jnm 2b\n"
"4: ex %0,1b-0b(%3)\n"
"5:"SLR" %0,%0\n"
"6:\n"
EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
: "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
: : "cc", "memory");
return count;
}
/*
* Returns kernel address for user virtual address. If the returned address is
* >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occurred and the
* address contains the (negative) exception code.
*/
#ifdef CONFIG_64BIT
static unsigned long follow_table(struct mm_struct *mm,
unsigned long address, int write)
{
unsigned long *table = (unsigned long *)__pa(mm->pgd);
if (unlikely(address > mm->context.asce_limit - 1))
return -0x38UL;
switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
case _ASCE_TYPE_REGION1:
table = table + ((address >> 53) & 0x7ff);
if (unlikely(*table & _REGION_ENTRY_INVALID))
return -0x39UL;
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
/* fallthrough */
case _ASCE_TYPE_REGION2:
table = table + ((address >> 42) & 0x7ff);
if (unlikely(*table & _REGION_ENTRY_INVALID))
return -0x3aUL;
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
/* fallthrough */
case _ASCE_TYPE_REGION3:
table = table + ((address >> 31) & 0x7ff);
if (unlikely(*table & _REGION_ENTRY_INVALID))
return -0x3bUL;
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
/* fallthrough */
case _ASCE_TYPE_SEGMENT:
table = table + ((address >> 20) & 0x7ff);
if (unlikely(*table & _SEGMENT_ENTRY_INVALID))
return -0x10UL;
if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
if (write && (*table & _SEGMENT_ENTRY_PROTECT))
return -0x04UL;
return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
(address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
}
table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
}
table = table + ((address >> 12) & 0xff);
if (unlikely(*table & _PAGE_INVALID))
return -0x11UL;
if (write && (*table & _PAGE_PROTECT))
return -0x04UL;
return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
}
#else /* CONFIG_64BIT */
static unsigned long follow_table(struct mm_struct *mm,
unsigned long address, int write)
{
unsigned long *table = (unsigned long *)__pa(mm->pgd);
table = table + ((address >> 20) & 0x7ff);
if (unlikely(*table & _SEGMENT_ENTRY_INVALID))
return -0x10UL;
table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
table = table + ((address >> 12) & 0xff);
if (unlikely(*table & _PAGE_INVALID))
return -0x11UL;
if (write && (*table & _PAGE_PROTECT))
return -0x04UL;
return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
}
#endif /* CONFIG_64BIT */
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;
if (!mm)
return n;
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(void *to, const void __user *from, size_t n)
{
size_t rc;
if (segment_eq(get_fs(), KERNEL_DS))
return copy_in_kernel((void __user *) to, from, n);
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(void __user *to, const void *from, size_t n)
{
if (segment_eq(get_fs(), KERNEL_DS))
return copy_in_kernel(to, (void __user *) from, n);
return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
}
size_t clear_user_pt(void __user *to, size_t n)
{
void *zpage = (void *) empty_zero_page;
long done, size, ret;
done = 0;
do {
if (n - done > PAGE_SIZE)
size = PAGE_SIZE;
else
size = n - done;
if (segment_eq(get_fs(), KERNEL_DS))
ret = copy_in_kernel(to, (void __user *) zpage, n);
else
ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
done += size;
to += size;
if (ret)
return ret + n - done;
} while (done < n);
return 0;
}
size_t strnlen_user_pt(const char __user *src, size_t count)
{
unsigned long uaddr = (unsigned long) src;
struct mm_struct *mm = current->mm;
unsigned long offset, done, len, kaddr;
size_t len_str;
if (unlikely(!count))
return 0;
if (segment_eq(get_fs(), KERNEL_DS))
return strnlen_kernel(src, count);
if (!mm)
return 0;
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;
}
size_t strncpy_from_user_pt(char *dst, const char __user *src, size_t count)
{
size_t done, len, offset, len_str;
if (unlikely(!count))
return 0;
done = 0;
do {
offset = (size_t)src & ~PAGE_MASK;
len = min(count - done, PAGE_SIZE - offset);
if (segment_eq(get_fs(), KERNEL_DS)) {
if (copy_in_kernel((void __user *) dst, src, len))
return -EFAULT;
} else {
if (__user_copy_pt((unsigned long) src, dst, len, 0))
return -EFAULT;
}
len_str = strnlen(dst, len);
done += len_str;
src += len_str;
dst += len_str;
} while ((len_str == len) && (done < count));
return done;
}
size_t copy_in_user_pt(void __user *to, const void __user *from, size_t n)
{
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))
return copy_in_kernel(to, from, n);
if (!mm)
return n;
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_inuser(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);
if (unlikely(!current->mm))
return -EFAULT;
spin_lock(&current->mm->page_table_lock);
uaddr = (u32 __force __user *)
__dat_user_addr((__force unsigned long) uaddr, 1);
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(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_inatomic(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);
if (unlikely(!current->mm))
return -EFAULT;
spin_lock(&current->mm->page_table_lock);
uaddr = (u32 __force __user *)
__dat_user_addr((__force unsigned long) uaddr, 1);
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(uval, uaddr, oldval, newval);
put_page(virt_to_page(uaddr));
return ret;
}
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