LXR linux/arch/arm64/include/asm/futex.h

   1/*
   2 * Copyright (C) 2012 ARM Ltd.
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public License
  14 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15 */
  16#ifndef __ASM_FUTEX_H
  17#define __ASM_FUTEX_H
  18
  19#ifdef __KERNEL__
  20
  21#include <linux/futex.h>
  22#include <linux/uaccess.h>
  23
  24#include <asm/alternative.h>
  25#include <asm/cpufeature.h>
  26#include <asm/errno.h>
  27#include <asm/sysreg.h>
  28
  29#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
  30        asm volatile(                                                   \
  31        ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,            \
  32                    CONFIG_ARM64_PAN)                                   \
  33"       prfm    pstl1strm, %2\n"                                        \
  34"1:     ldxr    %w1, %2\n"                                              \
  35        insn "\n"                                                       \
  36"2:     stlxr   %w3, %w0, %2\n"                                         \
  37"       cbnz    %w3, 1b\n"                                              \
  38"       dmb     ish\n"                                                  \
  39"3:\n"                                                                  \
  40"       .pushsection .fixup,\"ax\"\n"                                   \
  41"       .align  2\n"                                                    \
  42"4:     mov     %w0, %w5\n"                                             \
  43"       b       3b\n"                                                   \
  44"       .popsection\n"                                                  \
  45        _ASM_EXTABLE(1b, 4b)                                            \
  46        _ASM_EXTABLE(2b, 4b)                                            \
  47        ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,            \
  48                    CONFIG_ARM64_PAN)                                   \
  49        : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp)       \
  50        : "r" (oparg), "Ir" (-EFAULT)                                   \
  51        : "memory")
  52
  53static inline int
  54futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
  55{
  56        int op = (encoded_op >> 28) & 7;
  57        int cmp = (encoded_op >> 24) & 15;
  58        int oparg = (encoded_op << 8) >> 20;
  59        int cmparg = (encoded_op << 20) >> 20;
  60        int oldval = 0, ret, tmp;
  61
  62        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  63                oparg = 1 << oparg;
  64
  65        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  66                return -EFAULT;
  67
  68        pagefault_disable();
  69
  70        switch (op) {
  71        case FUTEX_OP_SET:
  72                __futex_atomic_op("mov  %w0, %w4",
  73                                  ret, oldval, uaddr, tmp, oparg);
  74                break;
  75        case FUTEX_OP_ADD:
  76                __futex_atomic_op("add  %w0, %w1, %w4",
  77                                  ret, oldval, uaddr, tmp, oparg);
  78                break;
  79        case FUTEX_OP_OR:
  80                __futex_atomic_op("orr  %w0, %w1, %w4",
  81                                  ret, oldval, uaddr, tmp, oparg);
  82                break;
  83        case FUTEX_OP_ANDN:
  84                __futex_atomic_op("and  %w0, %w1, %w4",
  85                                  ret, oldval, uaddr, tmp, ~oparg);
  86                break;
  87        case FUTEX_OP_XOR:
  88                __futex_atomic_op("eor  %w0, %w1, %w4",
  89                                  ret, oldval, uaddr, tmp, oparg);
  90                break;
  91        default:
  92                ret = -ENOSYS;
  93        }
  94
  95        pagefault_enable();
  96
  97        if (!ret) {
  98                switch (cmp) {
  99                case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 100                case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
 101                case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
 102                case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 103                case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 104                case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 105                default: ret = -ENOSYS;
 106                }
 107        }
 108        return ret;
 109}
 110
 111static inline int
 112futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 113                              u32 oldval, u32 newval)
 114{
 115        int ret = 0;
 116        u32 val, tmp;
 117
 118        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 119                return -EFAULT;
 120
 121        asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 122ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 123"       prfm    pstl1strm, %2\n"
 124"1:     ldxr    %w1, %2\n"
 125"       sub     %w3, %w1, %w4\n"
 126"       cbnz    %w3, 3f\n"
 127"2:     stlxr   %w3, %w5, %2\n"
 128"       cbnz    %w3, 1b\n"
 129"       dmb     ish\n"
 130"3:\n"
 131"       .pushsection .fixup,\"ax\"\n"
 132"4:     mov     %w0, %w6\n"
 133"       b       3b\n"
 134"       .popsection\n"
 135        _ASM_EXTABLE(1b, 4b)
 136        _ASM_EXTABLE(2b, 4b)
 137ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 138        : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 139        : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 140        : "memory");
 141
 142        *uval = val;
 143        return ret;
 144}
 145
 146#endif /* __KERNEL__ */
 147#endif /* __ASM_FUTEX_H */
 148