MIT_6.s081_Lab2:Xv6 and Syscall

//trace.c
int main(int argc, char *argv[])
{
  int i;
  char *nargv[MAXARG];

  if(argc < 3 || (argv[1][0] < '0' || argv[1][0] > '9')){
    fprintf(2, "Usage: %s mask command\n", argv[0]);
    exit(1);
  }

  if (trace(atoi(argv[1])) < 0) {
    fprintf(2, "%s: trace failed\n", argv[0]);
    exit(1);
  }
  
  for(i = 2; i < argc && i < MAXARG; i++){
    nargv[i-2] = argv[i];
  }
  exec(nargv[0], nargv);
  exit(0);
}

#!/usr/bin/perl -w

# Generate usys.S, the stubs for syscalls.

print "# generated by usys.pl - do not edit\n";

print "#include \"kernel/syscall.h\"\n";

sub entry {
    my $name = shift;
    print ".global $name\n";
    print "${name}:\n";
    print " li a7, SYS_${name}\n";
    print " ecall\n";
    print " ret\n";
}
	
entry("fork");
entry("exit");
entry("wait");
entry("pipe");
entry("read");
entry("write");
entry("close");
entry("kill");
entry("exec");
entry("open");
entry("mknod");
entry("unlink");
entry("fstat");
entry("link");
entry("mkdir");
entry("chdir");
entry("dup");
entry("getpid");
entry("sbrk");
entry("sleep");
entry("uptime");
entry("trace");

// System call numbers
#define SYS_fork    1
#define SYS_exit    2
#define SYS_wait    3
#define SYS_pipe    4
#define SYS_read    5
#define SYS_kill    6
#define SYS_exec    7
#define SYS_fstat   8
#define SYS_chdir   9
#define SYS_dup    10
#define SYS_getpid 11
#define SYS_sbrk   12
#define SYS_sleep  13
#define SYS_uptime 14
#define SYS_open   15
#define SYS_write  16
#define SYS_mknod  17
#define SYS_unlink 18
#define SYS_link   19
#define SYS_mkdir  20
#define SYS_close  21
#define SYS_trace  22

uint64
sys_trace(void)
{
  int n;
  if (argint(0, &n) < 0) // get the number of argv[1].
    return -1;
  myproc()->mask = n;    // save in the mask.
  return 0;
}

//在syscall的函数数组中添加即可.
......
[SYS_close]   sys_close,
[SYS_trace]   sys_trace,
};
//添加函数声明.
extern uint64 sys_trace(void);

void
syscall(void)
{
  int num;
  struct proc *p = myproc();

  num = p->trapframe->a7;
  if(num > 0 && num < NELEM(syscalls) && syscalls[num]) {
    p->trapframe->a0 = syscalls[num]();
    if (p->mask & (1 << num))
    {
      printf("%d: syscall %s -> %d\n",p->pid, syscalls_name[num], p->trapframe->a0);
    }
  } else {
    printf("%d %s: unknown sys call %d\n",
            p->pid, p->name, num);
    p->trapframe->a0 = -1;
  }
}

//return: the proc that are occupied.
int
proc_size()
{
  int i;
  int n = 0;
  for (i = 0; i < NPROC; i++)
  {
    if (proc[i].state != UNUSED) n++;
  }
  return n;
}

uint64 
freememory()
{
  struct run* p = kmem.freelist;
  uint64 num = 0;
  while (p)
  {
    num ++;
    p = p->next;
  }
  return num * PGSIZE;
}

uint64
sys_sysinfo(void)
{
  struct sysinfo info;
  uint64 addr;
  // get the the address of the sysinfo structure.
  if (argaddr(0, &addr) < 0) 
    return -1;
  struct proc* p = myproc();
  //get freemem
  info.freemem = freememory();
  //get the proc
  info.nproc = proc_size();
  // copyto the structure.
  if (copyout(p->pagetable, addr, (char*)&info, sizeof(info)) < 0)
    return -1;
  return 0;
}