kernel/syscall.c

   1 /*
   2  *    Copyright (c) 2009 Joshua Phillips. All rights reserved.
   3  *
   4  *  Redistribution and use in source and binary forms, with or without
   5  *  modification, are permitted provided that the following conditions are
   6  *  met:
   7  *
   8  *    1. Redistributions of source code must retain the above copyright
   9  *       notice, this list of conditions and the following disclaimer.
  10  *    2. Redistributions in binary form must reproduce the above copyright
  11  *       notice, this list of conditions and the following disclaimer in
  12  *       the documentation and/or other materials provided with the
  13  *       distribution.
  14  *
  15  *  THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
  16  *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  18  *  DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
  19  *  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  21  *  GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  22  *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
  23  *  IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  *  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
  25  *  IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "syscall.h"
  29 #include "string.h"
  30 #include "interrupt.h"
  31 #include "trace.h"
  32 #include "exit.h"
  33
  34 static const syscall_t syscall_table[] = {
  35     NULL,
  36     sys_exit,
  37 };
  38
  39 static const int n_syscalls = sizeof syscall_table / sizeof *syscall_table;
  40
  41 static void syscall_handler(int vector, struct interrupt_stack *is)
  42 {
  43     int syscall_n = is->r.eax;
  44     struct syscall_args args;
  45     if (syscall_n < 0 || syscall_n >= n_syscalls
  46       || !syscall_table[syscall_n]){
  47         TRACE("Invalid syscall: %d", syscall_n);
  48         is->r.eax = -1;
  49         // TODO: set errno (HOW? Where?)
  50     } else {
  51         // get the system call arguments from the registers
  52         args.args[0].ui = is->r.ebx;
  53         args.args[1].ui = is->r.ecx;
  54         args.args[2].ui = is->r.edx;
  55         args.args[3].ui = is->r.esi;
  56         args.args[4].ui = is->r.edi;
  57         is->r.eax = syscall_table[syscall_n](&args);
  58         TRACE("Done syscall: returning to %.8X", is->eip);
  59     }
  60 }
  61
  62 void syscall_init(void)
  63 {
  64     set_interrupt(0x80, syscall_handler);
  65     interrupt_flags(0x80, INTR_USER);
  66 }