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uaccess_std.c

/*
 *  arch/s390/lib/uaccess_std.c
 *
 *  Standard user space access functions based on mvcp/mvcs and doing
 *  interesting things in the secondary space mode.
 *
 *    Copyright (C) IBM Corp. 2006
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *           Gerald Schaefer (gerald.schaefer@de.ibm.com)
 */

#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <asm/futex.h>
#include "uaccess.h"

#ifndef __s390x__
#define AHI "ahi"
#define ALR "alr"
#define CLR "clr"
#define LHI "lhi"
#define SLR "slr"
#else
#define AHI "aghi"
#define ALR "algr"
#define CLR "clgr"
#define LHI "lghi"
#define SLR "slgr"
#endif

size_t copy_from_user_std(size_t size, const void __user *ptr, void *x)
{
      unsigned long tmp1, tmp2;

      tmp1 = -256UL;
      asm volatile(
            "0: mvcp  0(%0,%2),0(%1),%3\n"
            "   jz    8f\n"
            "1:"ALR"  %0,%3\n"
            "   la    %1,256(%1)\n"
            "   la    %2,256(%2)\n"
            "2: mvcp  0(%0,%2),0(%1),%3\n"
            "   jnz   1b\n"
            "   j     8f\n"
            "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
            "  "LHI"  %3,-4096\n"
            "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
            "  "SLR"  %4,%1\n"
            "  "CLR"  %0,%4\n"      /* copy crosses next page boundary? */
            "   jnh   5f\n"
            "4: mvcp  0(%4,%2),0(%1),%3\n"
            "  "SLR"  %0,%4\n"
            "  "ALR"  %2,%4\n"
            "5:"LHI"  %4,-1\n"
            "  "ALR"  %4,%0\n"      /* copy remaining size, subtract 1 */
            "   bras  %3,7f\n"      /* memset loop */
            "   xc    0(1,%2),0(%2)\n"
            "6: xc    0(256,%2),0(%2)\n"
            "   la    %2,256(%2)\n"
            "7:"AHI"  %4,-256\n"
            "   jnm   6b\n"
            "   ex    %4,0(%3)\n"
            "   j     9f\n"
            "8:"SLR"  %0,%0\n"
            "9: \n"
            EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b)
            : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
            : : "cc", "memory");
      return size;
}

static size_t copy_from_user_std_check(size_t size, const void __user *ptr,
                               void *x)
{
      if (size <= 1024)
            return copy_from_user_std(size, ptr, x);
      return copy_from_user_pt(size, ptr, x);
}

size_t copy_to_user_std(size_t size, void __user *ptr, const void *x)
{
      unsigned long tmp1, tmp2;

      tmp1 = -256UL;
      asm volatile(
            "0: mvcs  0(%0,%1),0(%2),%3\n"
            "   jz    5f\n"
            "1:"ALR"  %0,%3\n"
            "   la    %1,256(%1)\n"
            "   la    %2,256(%2)\n"
            "2: mvcs  0(%0,%1),0(%2),%3\n"
            "   jnz   1b\n"
            "   j     5f\n"
            "3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
            "  "LHI"  %3,-4096\n"
            "   nr    %4,%3\n"      /* %4 = (ptr + 255) & -4096 */
            "  "SLR"  %4,%1\n"
            "  "CLR"  %0,%4\n"      /* copy crosses next page boundary? */
            "   jnh   6f\n"
            "4: mvcs  0(%4,%1),0(%2),%3\n"
            "  "SLR"  %0,%4\n"
            "   j     6f\n"
            "5:"SLR"  %0,%0\n"
            "6: \n"
            EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
            : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
            : : "cc", "memory");
      return size;
}

static size_t copy_to_user_std_check(size_t size, void __user *ptr,
                             const void *x)
{
      if (size <= 1024)
            return copy_to_user_std(size, ptr, x);
      return copy_to_user_pt(size, ptr, x);
}

static size_t copy_in_user_std(size_t size, void __user *to,
                         const void __user *from)
{
      unsigned long tmp1;

      asm volatile(
            "  "AHI"  %0,-1\n"
            "   jo    5f\n"
            "   sacf  256\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"
            "   sacf  0\n"
            "5: "SLR"  %0,%0\n"
            "6:\n"
            EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
            : "+a" (size), "+a" (to), "+a" (from), "=a" (tmp1)
            : : "cc", "memory");
      return size;
}

static size_t clear_user_std(size_t size, void __user *to)
{
      unsigned long tmp1, tmp2;

      asm volatile(
            "  "AHI"  %0,-1\n"
            "   jo    5f\n"
            "   sacf  256\n"
            "   bras  %3,3f\n"
            "   xc    0(1,%1),0(%1)\n"
            "0:"AHI"  %0,257\n"
            "   la    %2,255(%1)\n" /* %2 = ptr + 255 */
            "   srl   %2,12\n"
            "   sll   %2,12\n"      /* %2 = (ptr + 255) & -4096 */
            "  "SLR"  %2,%1\n"
            "  "CLR"  %0,%2\n"      /* clear crosses next page boundary? */
            "   jnh   5f\n"
            "  "AHI"  %2,-1\n"
            "1: ex    %2,0(%3)\n"
            "  "AHI"  %2,1\n"
            "  "SLR"  %0,%2\n"
            "   j     5f\n"
            "2: xc    0(256,%1),0(%1)\n"
            "   la    %1,256(%1)\n"
            "3:"AHI"  %0,-256\n"
            "   jnm   2b\n"
            "4: ex    %0,0(%3)\n"
            "   sacf  0\n"
            "5: "SLR"  %0,%0\n"
            "6:\n"
            EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
            : "+a" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
            : : "cc", "memory");
      return size;
}

size_t strnlen_user_std(size_t size, const char __user *src)
{
      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"
            "   sacf  256\n"
            "0: srst  %3,%2\n"
            "   jo    0b\n"
            "   la    %0,1(%3)\n"   /* strnlen_user results includes \0 */
            "  "SLR"  %0,%1\n"
            "1: sacf  0\n"
            EX_TABLE(0b,1b)
            : "+a" (size), "+a" (src), "=a" (tmp1), "=a" (tmp2)
            : "d" (reg0) : "cc", "memory");
      return size;
}

size_t strncpy_from_user_std(size_t size, const char __user *src, char *dst)
{
      register unsigned long reg0 asm("0") = 0UL;
      unsigned long tmp1, tmp2;

      asm volatile(
            "   la    %3,0(%1)\n"
            "   la    %4,0(%0,%1)\n"
            "   sacf  256\n"
            "0: srst  %4,%3\n"
            "   jo    0b\n"
            "   sacf  0\n"
            "   la    %0,0(%4)\n"
            "   jh    1f\n"         /* found \0 in string ? */
            "  "AHI"  %4,1\n" /* include \0 in copy */
            "1:"SLR"  %0,%1\n"      /* %0 = return length (without \0) */
            "  "SLR"  %4,%1\n"      /* %4 = copy length (including \0) */
            "2: mvcp  0(%4,%2),0(%1),%5\n"
            "   jz    9f\n"
            "3:"AHI"  %4,-256\n"
            "   la    %1,256(%1)\n"
            "   la    %2,256(%2)\n"
            "4: mvcp  0(%4,%2),0(%1),%5\n"
            "   jnz   3b\n"
            "   j     9f\n"
            "7: sacf  0\n"
            "8:"LHI"  %0,%6\n"
            "9:\n"
            EX_TABLE(0b,7b) EX_TABLE(2b,8b) EX_TABLE(4b,8b)
            : "+a" (size), "+a" (src), "+d" (dst), "=a" (tmp1), "=a" (tmp2)
            : "d" (reg0), "K" (-EFAULT) : "cc", "memory");
      return size;
}

#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)      \
      asm volatile(                                         \
            "   sacf  256\n"                          \
            "0: l     %1,0(%6)\n"                           \
            "1:"insn                                  \
            "2: cs    %1,%2,0(%6)\n"                        \
            "3: jl    1b\n"                                 \
            "   lhi   %0,0\n"                         \
            "4: sacf  0\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_std(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;
      }
      *old = oldval;
      return ret;
}

int futex_atomic_cmpxchg_std(int __user *uaddr, int oldval, int newval)
{
      int ret;

      asm volatile(
            "   sacf 256\n"
            "0: cs   %1,%4,0(%5)\n"
            "1: lr   %0,%1\n"
            "2: sacf 0\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;
}

struct uaccess_ops uaccess_std = {
      .copy_from_user = copy_from_user_std_check,
      .copy_from_user_small = copy_from_user_std,
      .copy_to_user = copy_to_user_std_check,
      .copy_to_user_small = copy_to_user_std,
      .copy_in_user = copy_in_user_std,
      .clear_user = clear_user_std,
      .strnlen_user = strnlen_user_std,
      .strncpy_from_user = strncpy_from_user_std,
      .futex_atomic_op = futex_atomic_op_std,
      .futex_atomic_cmpxchg = futex_atomic_cmpxchg_std,
};

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