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kernel/linux-rt-4.4.41/arch/blackfin/include/asm/syscall.h 2.15 KB
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  /*
   * Magic syscall break down functions
   *
   * Copyright 2010 Analog Devices Inc.
   *
   * Licensed under the GPL-2 or later.
   */
  
  #ifndef __ASM_BLACKFIN_SYSCALL_H__
  #define __ASM_BLACKFIN_SYSCALL_H__
  
  /*
   * Blackfin syscalls are simple:
   *	enter:
   *		p0: syscall number
   *		r{0,1,2,3,4,5}: syscall args 0,1,2,3,4,5
   *	exit:
   *		r0: return/error value
   */
  
  #include <linux/err.h>
  #include <linux/sched.h>
  #include <asm/ptrace.h>
  
  static inline long
  syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
  {
  	return regs->p0;
  }
  
  static inline void
  syscall_rollback(struct task_struct *task, struct pt_regs *regs)
  {
  	regs->p0 = regs->orig_p0;
  }
  
  static inline long
  syscall_get_error(struct task_struct *task, struct pt_regs *regs)
  {
  	return IS_ERR_VALUE(regs->r0) ? regs->r0 : 0;
  }
  
  static inline long
  syscall_get_return_value(struct task_struct *task, struct pt_regs *regs)
  {
  	return regs->r0;
  }
  
  static inline void
  syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
                           int error, long val)
  {
  	regs->r0 = error ? -error : val;
  }
  
  /**
   *	syscall_get_arguments()
   *	@task:   unused
   *	@regs:   the register layout to extract syscall arguments from
   *	@i:      first syscall argument to extract
   *	@n:      number of syscall arguments to extract
   *	@args:   array to return the syscall arguments in
   *
   * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
   */
  static inline void
  syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
                        unsigned int i, unsigned int n, unsigned long *args)
  {
  	/*
  	 * Assume the ptrace layout doesn't change -- r5 is first in memory,
  	 * then r4, ..., then r0.  So we simply reverse the ptrace register
  	 * array in memory to store into the args array.
  	 */
  	long *aregs = &regs->r0 - i;
  
  	BUG_ON(i > 5 || i + n > 6);
  
  	while (n--)
  		*args++ = *aregs--;
  }
  
  /* See syscall_get_arguments() comments */
  static inline void
  syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
                        unsigned int i, unsigned int n, const unsigned long *args)
  {
  	long *aregs = &regs->r0 - i;
  
  	BUG_ON(i > 5 || i + n > 6);
  
  	while (n--)
  		*aregs-- = *args++;
  }
  
  #endif