dtr.c

#define HASH_TABLE_BITS 8
#define HASH_TABLE_SIZE (1<<HASH_TABLE_BITS)
#define BUCKETS 16 /* largest histogram width */
#include <linux/module.h>
#include <linux/interrupt.h>
#include <net/sock.h>
#include <linux/netlink.h>

#include "runtime.h"
#include "io.c"
#include "map.c"
#include "probes.c"
#include "stack.c"

MODULE_DESCRIPTION("SystemTap probe: test4");
MODULE_AUTHOR("Martin Hunt <hunt@redhat.com>");

static char tbuffer[2][50000];
static void stp_helper(void *);
static DECLARE_WORK(stp_work, stp_helper, tbuffer);

MAP opens, reads, writes, traces;
static int bufcount = 0;

/* netlink control channel */
static struct sock *control;
static int seq = 0;

int pid;
/*
 * send_reply - send reply to userspace over netlink control channel
 */
static int send_reply(int type, void *reply, int len, int pid)
{
        struct sk_buff *skb;
        struct nlmsghdr *nlh;
        void *data;
        int size;
        int err;
                
        size = NLMSG_SPACE(len);
        skb = alloc_skb(size, GFP_KERNEL);
        if (!skb)
                return -1;
        nlh = NLMSG_PUT(skb, pid, seq++, type, size - sizeof(*nlh));
        nlh->nlmsg_flags = 0;
        data = NLMSG_DATA(nlh);
        memcpy(data, reply, len);
        err = netlink_unicast(control, skb, pid, MSG_DONTWAIT);

        return 0;

nlmsg_failure:
        if (skb)
                kfree_skb(skb);
        
        return -1;
}

static char pbuff[1024];

void nlog  (const char *fmt, ...)
{
  int len;
  va_list args;
  va_start(args, fmt);
  len = vscnprintf (pbuff, sizeof(pbuff), fmt, args) + 1;
  va_end(args);
  send_reply (42, pbuff, len, pid);
}

/*
 * msg_rcv_skb - dispatch userspace requests from netlink control channel
 */
static void msg_rcv_skb(struct sk_buff *skb)
{
        struct nlmsghdr *nlh = NULL;
        int flags;
        int nlmsglen, skblen;
        void *data;
        
        skblen = skb->len;
        //      dlog ("skblen = %d %d\n", skblen, sizeof(*nlh));
        if (skblen < sizeof (*nlh))
                return; 

        nlh = (struct nlmsghdr *)skb->data;
        nlmsglen = nlh->nlmsg_len;
        
        //      dlog ("nlmsghlen=%d\n", nlmsglen);
        if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
                return;

        pid = nlh->nlmsg_pid;
        flags = nlh->nlmsg_flags;

        //      dlog ("pid=%d flags=%x %x %x %x\n", pid, flags, NLM_F_REQUEST, MSG_TRUNC, NLM_F_ACK);
        if (pid <= 0 || !(flags & NLM_F_REQUEST)) {
                netlink_ack(skb, nlh, -EINVAL);
                return;
        }

        if (flags & MSG_TRUNC) {
                netlink_ack(skb, nlh, -ECOMM);
                return;
        }
        
        data = NLMSG_DATA(nlh);

        //      dlog ("NETLINK: Got message \"%s\" of type %d from pid %d\n", data, nlh->nlmsg_type,pid);
        
        if (flags & NLM_F_ACK)
                netlink_ack(skb, nlh, 0);

        send_reply (42, "Howdy Partner", 14, pid);
}

static void msg_rcv(struct sock *sk, int len)
{
        struct sk_buff *skb;
        dlog ("netlink message received\n");
        while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
                msg_rcv_skb(skb);
                kfree_skb(skb);
        }
}

static void stp_helper (void *data)
{
  dlog ("HELPER\n");
}

asmlinkage long inst_sys_open (const char __user * filename, int flags, int mode)
{
  _stp_map_key_str (opens, current->comm);
  _stp_map_add_int64 (opens, 1);
  jprobe_return();
  return 0;
}

asmlinkage ssize_t inst_sys_read (unsigned int fd, char __user * buf, size_t count)
{
  _stp_map_key_str (reads, current->comm);
  _stp_map_stat_add (reads, count);
  jprobe_return();
  return 0;
}

asmlinkage ssize_t inst_sys_write (unsigned int fd, const char __user * buf, size_t count)
{
  _stp_map_key_str (writes, current->comm);
  _stp_map_stat_add (writes, count);
  jprobe_return();
  return 0;
}

int inst_show_cpuinfo(struct seq_file *m, void *v)
{
  _stp_stack_print (0,0);
  _stp_stack_print (1,0);

  _stp_scbuf_clear();
  _stp_list_add (traces, _stp_stack_sprint(0,0));
  if (bufcount++ == 0)
    schedule_work (&stp_work);

  jprobe_return();
  return 0;
}


static struct jprobe dtr_probes[] = {
  {
    .kp.addr = (kprobe_opcode_t *)"sys_open",
    .entry = (kprobe_opcode_t *) inst_sys_open
  },
  {
    .kp.addr = (kprobe_opcode_t *)"sys_read",
    .entry = (kprobe_opcode_t *) inst_sys_read
  },
  {
    .kp.addr = (kprobe_opcode_t *)"sys_write",
    .entry = (kprobe_opcode_t *) inst_sys_write
  },
  {
    .kp.addr = (kprobe_opcode_t *)"show_cpuinfo",
    .entry = (kprobe_opcode_t *) inst_show_cpuinfo,
  },
};

#define MAX_DTR_ROUTINE (sizeof(dtr_probes)/sizeof(struct jprobe))

static int init_dtr(void)
{
  int ret;
  
  control = netlink_kernel_create(31, msg_rcv);
  if (!control) {
    dlog ("Couldn't create netlink channel\n");
    return -1;
  }
  
  opens = _stp_map_new (1000, INT64);
  reads = _stp_map_new (1000, STAT);
  writes = _stp_map_new (1000, STAT);
  traces = _stp_list_new (1000, STRING);

  ret = _stp_register_jprobes (dtr_probes, MAX_DTR_ROUTINE);

  dlog("instrumentation is enabled...\n");
  return ret;

}

static void cleanup_dtr(void)
{
  struct map_node_stat *st;
  struct map_node_int64 *ptr;
  struct map_node_str *sptr;

  _stp_unregister_jprobes (dtr_probes, MAX_DTR_ROUTINE);

  foreach (traces, sptr)
    nlog ("trace: %s\n", sptr->str);

  foreach (opens, ptr)
    nlog ("opens[%s] = %lld\n", key1str(ptr), ptr->val); 
  nlog ("\n");

  foreach (reads, st)
    nlog ("reads[%s] = [count=%lld  sum=%lld   min=%lld   max=%lld]\n", key1str(st), 
          st->stats.count, st->stats.sum, st->stats.min, st->stats.max);
  nlog ("\n");
  
  foreach (writes, st)
    nlog ("writes[%s] = [count=%lld  sum=%lld   min=%lld   max=%lld]\n", key1str(st), 
          st->stats.count, st->stats.sum, st->stats.min, st->stats.max);
  nlog ("\n");

  _stp_map_del (opens);
  _stp_map_del (reads);
  _stp_map_del (writes);

  if (control)
    sock_release(control->sk_socket);

  dlog("EXIT\n");
}

module_init(init_dtr);
module_exit(cleanup_dtr);
MODULE_LICENSE("GPL");