arch/x86/include/asm/syscall.h

   1 /*
   2  * Access to user system call parameters and results
   3  *
   4  * Copyright (C) 2008-2009 Red Hat, Inc.  All rights reserved.
   5  *
   6  * This copyrighted material is made available to anyone wishing to use,
   7  * modify, copy, or redistribute it subject to the terms and conditions
   8  * of the GNU General Public License v.2.
   9  *
  10  * See asm-generic/syscall.h for descriptions of what we must do here.
  11  */
  12
  13 #ifndef _ASM_X86_SYSCALL_H
  14 #define _ASM_X86_SYSCALL_H
  15
  16 #include <linux/sched.h>
  17 #include <linux/err.h>
  18
  19 /*
  20  * Only the low 32 bits of orig_ax are meaningful, so we return int.
  21  * This importantly ignores the high bits on 64-bit, so comparisons
  22  * sign-extend the low 32 bits.
  23  */
  24 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
  25 {
  26         return regs->orig_ax;
  27 }
  28
  29 static inline void syscall_rollback(struct task_struct *task,
  30                                     struct pt_regs *regs)
  31 {
  32         regs->ax = regs->orig_ax;
  33 }
  34
  35 static inline long syscall_get_error(struct task_struct *task,
  36                                      struct pt_regs *regs)
  37 {
  38         unsigned long error = regs->ax;
  39 #ifdef CONFIG_IA32_EMULATION
  40         /*
  41          * TS_COMPAT is set for 32-bit syscall entries and then
  42          * remains set until we return to user mode.
  43          */
  44         if (task_thread_info(task)->status & TS_COMPAT)
  45                 /*
  46                  * Sign-extend the value so (int)-EFOO becomes (long)-EFOO
  47                  * and will match correctly in comparisons.
  48                  */
  49                 error = (long) (int) error;
  50 #endif
  51         return IS_ERR_VALUE(error) ? error : 0;
  52 }
  53
  54 static inline long syscall_get_return_value(struct task_struct *task,
  55                                             struct pt_regs *regs)
  56 {
  57         return regs->ax;
  58 }
  59
  60 static inline void syscall_set_return_value(struct task_struct *task,
  61                                             struct pt_regs *regs,
  62                                             int error, long val)
  63 {
  64         regs->ax = (long) error ?: val;
  65 }
  66
  67 #ifdef CONFIG_X86_32
  68
  69 static inline void syscall_get_arguments(struct task_struct *task,
  70                                          struct pt_regs *regs,
  71                                          unsigned int i, unsigned int n,
  72                                          unsigned long *args)
  73 {
  74         BUG_ON(i + n > 6);
  75         memcpy(args, &regs->bx + i, n * sizeof(args[0]));
  76 }
  77
  78 static inline void syscall_set_arguments(struct task_struct *task,
  79                                          struct pt_regs *regs,
  80                                          unsigned int i, unsigned int n,
  81                                          const unsigned long *args)
  82 {
  83         BUG_ON(i + n > 6);
  84         memcpy(&regs->bx + i, args, n * sizeof(args[0]));
  85 }
  86
  87 #else    /* CONFIG_X86_64 */
  88
  89 static inline void syscall_get_arguments(struct task_struct *task,
  90                                          struct pt_regs *regs,
  91                                          unsigned int i, unsigned int n,
  92                                          unsigned long *args)
  93 {
  94 # ifdef CONFIG_IA32_EMULATION
  95         if (task_thread_info(task)->status & TS_COMPAT)
  96                 switch (i) {
  97                 case 0:
  98                         if (!n--) break;
  99                         *args++ = regs->bx;
 100                 case 1:
 101                         if (!n--) break;
 102                         *args++ = regs->cx;
 103                 case 2:
 104                         if (!n--) break;
 105                         *args++ = regs->dx;
 106                 case 3:
 107                         if (!n--) break;
 108                         *args++ = regs->si;
 109                 case 4:
 110                         if (!n--) break;
 111                         *args++ = regs->di;
 112                 case 5:
 113                         if (!n--) break;
 114                         *args++ = regs->bp;
 115                 case 6:
 116                         if (!n--) break;
 117                 default:
 118                         BUG();
 119                         break;
 120                 }
 121         else
 122 # endif
 123                 switch (i) {
 124                 case 0:
 125                         if (!n--) break;
 126                         *args++ = regs->di;
 127                 case 1:
 128                         if (!n--) break;
 129                         *args++ = regs->si;
 130                 case 2:
 131                         if (!n--) break;
 132                         *args++ = regs->dx;
 133                 case 3:
 134                         if (!n--) break;
 135                         *args++ = regs->r10;
 136                 case 4:
 137                         if (!n--) break;
 138                         *args++ = regs->r8;
 139                 case 5:
 140                         if (!n--) break;
 141                         *args++ = regs->r9;
 142                 case 6:
 143                         if (!n--) break;
 144                 default:
 145                         BUG();
 146                         break;
 147                 }
 148 }
 149
 150 static inline void syscall_set_arguments(struct task_struct *task,
 151                                          struct pt_regs *regs,
 152                                          unsigned int i, unsigned int n,
 153                                          const unsigned long *args)
 154 {
 155 # ifdef CONFIG_IA32_EMULATION
 156         if (task_thread_info(task)->status & TS_COMPAT)
 157                 switch (i) {
 158                 case 0:
 159                         if (!n--) break;
 160                         regs->bx = *args++;
 161                 case 1:
 162                         if (!n--) break;
 163                         regs->cx = *args++;
 164                 case 2:
 165                         if (!n--) break;
 166                         regs->dx = *args++;
 167                 case 3:
 168                         if (!n--) break;
 169                         regs->si = *args++;
 170                 case 4:
 171                         if (!n--) break;
 172                         regs->di = *args++;
 173                 case 5:
 174                         if (!n--) break;
 175                         regs->bp = *args++;
 176                 case 6:
 177                         if (!n--) break;
 178                 default:
 179                         BUG();
 180                         break;
 181                 }
 182         else
 183 # endif
 184                 switch (i) {
 185                 case 0:
 186                         if (!n--) break;
 187                         regs->di = *args++;
 188                 case 1:
 189                         if (!n--) break;
 190                         regs->si = *args++;
 191                 case 2:
 192                         if (!n--) break;
 193                         regs->dx = *args++;
 194                 case 3:
 195                         if (!n--) break;
 196                         regs->r10 = *args++;
 197                 case 4:
 198                         if (!n--) break;
 199                         regs->r8 = *args++;
 200                 case 5:
 201                         if (!n--) break;
 202                         regs->r9 = *args++;
 203                 case 6:
 204                         if (!n--) break;
 205                 default:
 206                         BUG();
 207                         break;
 208                 }
 209 }
 210
 211 #endif  /* CONFIG_X86_32 */
 212
 213 #endif  /* _ASM_X86_SYSCALL_H */