arch/riscv/include/asm/futex.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (c) 2006  Ralf Baechle (ralf@linux-mips.org)
   4  * Copyright (c) 2018  Jim Wilson (jimw@sifive.com)
   5  */
   6
   7 #ifndef _ASM_FUTEX_H
   8 #define _ASM_FUTEX_H
   9
  10 #ifndef CONFIG_RISCV_ISA_A
  11 /*
  12  * Use the generic interrupt disabling versions if the A extension
  13  * is not supported.
  14  */
  15 #ifdef CONFIG_SMP
  16 #error "Can't support generic futex calls without A extension on SMP"
  17 #endif
  18 #include <asm-generic/futex.h>
  19
  20 #else /* CONFIG_RISCV_ISA_A */
  21
  22 #include <linux/futex.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/errno.h>
  25 #include <asm/asm.h>
  26
  27 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)      \
  28 {                                                               \
  29         uintptr_t tmp;                                          \
  30         __enable_user_access();                                 \
  31         __asm__ __volatile__ (                                  \
  32         "1:     " insn "                                \n"     \
  33         "2:                                             \n"     \
  34         "       .section .fixup,\"ax\"                  \n"     \
  35         "       .balign 4                               \n"     \
  36         "3:     li %[r],%[e]                            \n"     \
  37         "       jump 2b,%[t]                            \n"     \
  38         "       .previous                               \n"     \
  39         "       .section __ex_table,\"a\"               \n"     \
  40         "       .balign " RISCV_SZPTR "                 \n"     \
  41         "       " RISCV_PTR " 1b, 3b                    \n"     \
  42         "       .previous                               \n"     \
  43         : [r] "+r" (ret), [ov] "=&r" (oldval),                  \
  44           [u] "+m" (*uaddr), [t] "=&r" (tmp)                    \
  45         : [op] "Jr" (oparg), [e] "i" (-EFAULT)                  \
  46         : "memory");                                            \
  47         __disable_user_access();                                \
  48 }
  49
  50 static inline int
  51 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
  52 {
  53         int oldval = 0, ret = 0;
  54
  55         pagefault_disable();
  56
  57         switch (op) {
  58         case FUTEX_OP_SET:
  59                 __futex_atomic_op("amoswap.w.aqrl %[ov],%z[op],%[u]",
  60                                   ret, oldval, uaddr, oparg);
  61                 break;
  62         case FUTEX_OP_ADD:
  63                 __futex_atomic_op("amoadd.w.aqrl %[ov],%z[op],%[u]",
  64                                   ret, oldval, uaddr, oparg);
  65                 break;
  66         case FUTEX_OP_OR:
  67                 __futex_atomic_op("amoor.w.aqrl %[ov],%z[op],%[u]",
  68                                   ret, oldval, uaddr, oparg);
  69                 break;
  70         case FUTEX_OP_ANDN:
  71                 __futex_atomic_op("amoand.w.aqrl %[ov],%z[op],%[u]",
  72                                   ret, oldval, uaddr, ~oparg);
  73                 break;
  74         case FUTEX_OP_XOR:
  75                 __futex_atomic_op("amoxor.w.aqrl %[ov],%z[op],%[u]",
  76                                   ret, oldval, uaddr, oparg);
  77                 break;
  78         default:
  79                 ret = -ENOSYS;
  80         }
  81
  82         pagefault_enable();
  83
  84         if (!ret)
  85                 *oval = oldval;
  86
  87         return ret;
  88 }
  89
  90 static inline int
  91 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  92                               u32 oldval, u32 newval)
  93 {
  94         int ret = 0;
  95         u32 val;
  96         uintptr_t tmp;
  97
  98         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  99                 return -EFAULT;
 100
 101         __enable_user_access();
 102         __asm__ __volatile__ (
 103         "1:     lr.w.aqrl %[v],%[u]                     \n"
 104         "       bne %[v],%z[ov],3f                      \n"
 105         "2:     sc.w.aqrl %[t],%z[nv],%[u]              \n"
 106         "       bnez %[t],1b                            \n"
 107         "3:                                             \n"
 108         "       .section .fixup,\"ax\"                  \n"
 109         "       .balign 4                               \n"
 110         "4:     li %[r],%[e]                            \n"
 111         "       jump 3b,%[t]                            \n"
 112         "       .previous                               \n"
 113         "       .section __ex_table,\"a\"               \n"
 114         "       .balign " RISCV_SZPTR "                 \n"
 115         "       " RISCV_PTR " 1b, 4b                    \n"
 116         "       " RISCV_PTR " 2b, 4b                    \n"
 117         "       .previous                               \n"
 118         : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
 119         : [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "i" (-EFAULT)
 120         : "memory");
 121         __disable_user_access();
 122
 123         *uval = val;
 124         return ret;
 125 }
 126
 127 #endif /* CONFIG_RISCV_ISA_A */
 128 #endif /* _ASM_FUTEX_H */