arch/blackfin/include/asm/syscall.h

   1 /*
   2  * Magic syscall break down functions
   3  *
   4  * Copyright 2010 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #ifndef __ASM_BLACKFIN_SYSCALL_H__
  10 #define __ASM_BLACKFIN_SYSCALL_H__
  11
  12 /*
  13  * Blackfin syscalls are simple:
  14  *      enter:
  15  *              p0: syscall number
  16  *              r{0,1,2,3,4,5}: syscall args 0,1,2,3,4,5
  17  *      exit:
  18  *              r0: return/error value
  19  */
  20
  21 #include <linux/err.h>
  22 #include <linux/sched.h>
  23 #include <asm/ptrace.h>
  24
  25 static inline long
  26 syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
  27 {
  28         return regs->p0;
  29 }
  30
  31 static inline void
  32 syscall_rollback(struct task_struct *task, struct pt_regs *regs)
  33 {
  34         regs->p0 = regs->orig_p0;
  35 }
  36
  37 static inline long
  38 syscall_get_error(struct task_struct *task, struct pt_regs *regs)
  39 {
  40         return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
  41 }
  42
  43 static inline long
  44 syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
  45 {
  46         return regs->r0;
  47 }
  48
  49 static inline void
  50 syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
  51                          int error, long val)
  52 {
  53         regs->r0 = error ? -error : val;
  54 }
  55
  56 /**
  57  *      syscall_get_arguments()
  58  *      @task:   unused
  59  *      @regs:   the register layout to extract syscall arguments from
  60  *      @i:      first syscall argument to extract
  61  *      @n:      number of syscall arguments to extract
  62  *      @args:   array to return the syscall arguments in
  63  *
  64  * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
  65  */
  66 static inline void
  67 syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
  68                       unsigned int i, unsigned int n, unsigned long *args)
  69 {
  70         /*
  71          * Assume the ptrace layout doesn't change -- r5 is first in memory,
  72          * then r4, ..., then r0.  So we simply reverse the ptrace register
  73          * array in memory to store into the args array.
  74          */
  75         long *aregs = &regs->r0 - i;
  76
  77         BUG_ON(i > 5 || i + n > 6);
  78
  79         while (n--)
  80                 *args++ = *aregs--;
  81 }
  82
  83 /* See syscall_get_arguments() comments */
  84 static inline void
  85 syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
  86                       unsigned int i, unsigned int n, const unsigned long *args)
  87 {
  88         long *aregs = &regs->r0 - i;
  89
  90         BUG_ON(i > 5 || i + n > 6);
  91
  92         while (n--)
  93                 *aregs-- = *args++;
  94 }
  95
  96 #endif