/*
 * Copryight 1997 Sean Eric Fagan
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Sean Eric Fagan
 * 4. Neither the name of the author may be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/usr.bin/truss/i386-fbsd.c,v 1.7.2.2 2001/10/29 20:12:56 des Exp $
 */

/*
 * FreeBSD/x86_64-specific system call handling.  This is probably the most
 * complex part of the entire truss program, although I've got lots of
 * it handled relatively cleanly now.  The system call names are generated
 * automatically, thanks to /usr/src/sys/kern/syscalls.master.  The
 * names used for the various structures are confusing, I sadly admit.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/pioctl.h>
#include <sys/syscall.h>

#include <machine/reg.h>
#include <machine/psl.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "truss.h"
#include "extern.h"
#include "syscall.h"

static int fd = -1;
static int cpid = -1;

#include "syscalls.h"

static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);

/*
 * This is what this particular file uses to keep track of a system call.
 * It is probably not quite sufficient -- I can probably use the same
 * structure for the various syscall personalities, and I also probably
 * need to nest system calls (for signal handlers).
 *
 * 'struct syscall' describes the system call; it may be NULL, however,
 * if we don't know about this particular system call yet.
 */
static struct freebsd_syscall {
        struct syscall *sc;
        const char *name;
        int number;
        unsigned long *args;
        int nargs;      /* number of arguments -- *not* number of words! */
        char **s_args;  /* the printable arguments */
} fsc;

/* Clear up and free parts of the fsc structure. */
static inline void
clear_fsc(void) {
  free(fsc.args);
  if (fsc.s_args) {
    int i;
    for (i = 0; i < fsc.nargs; i++)
      free(fsc.s_args[i]);
    free(fsc.s_args);
  }
  memset(&fsc, 0, sizeof(fsc));
}

/*
 * Called when a process has entered a system call.  nargs is the
 * number of words, not number of arguments (a necessary distinction
 * in some cases).  Note that if the STOPEVENT() code in i386/i386/trap.c
 * is ever changed these functions need to keep up.
 */

void
x86_64_syscall_entry(struct trussinfo *trussinfo, int nargs) {
  char *buf;
  struct reg regs = { .r_err = 0 };
  int syscall_num;
  int i, reg;
  int is_xsyscall;
  struct syscall *sc;

  if (fd == -1 || trussinfo->pid != cpid) {
    asprintf(&buf, "%s/%d/regs", procfs_path, trussinfo->pid);
    if (buf == NULL)
      err(1, "Out of memory");
    fd = open(buf, O_RDWR);
    free(buf);
    if (fd == -1) {
      fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
      return;
    }
    cpid = trussinfo->pid;
  }

  clear_fsc();
  i = pread(fd, &regs, sizeof(regs), 0L);

  /*
   * FreeBSD has two special kinds of system call redirctions --
   * SYS_syscall, and SYS___syscall.  The former is the old syscall()
   * routine, basicly; the latter is for quad-aligned arguments.
   */
  reg = 0;
  syscall_num = regs.r_rax;
  is_xsyscall = 0;
  switch (syscall_num) {
  case SYS_syscall:
  case SYS___syscall:
    is_xsyscall = 1;
    syscall_num = regs.r_rdi;
    reg++;
    break;
  }

  fsc.number = syscall_num;
  fsc.name =
    (syscall_num < 0 || syscall_num >= nsyscalls) ? NULL : syscallnames[syscall_num];
  if (!fsc.name) {
    fprintf(trussinfo->outfile, "-- UNKNOWN SYSCALL %d --\n", syscall_num);
  }

  sc = fsc.name ? get_syscall(fsc.name) : NULL;
  if (sc) {
    fsc.nargs = sc->nargs;
  } else {
#ifdef DEBUG
    fprintf(trussinfo->outfile, "unknown syscall %s -- setting args to %d\n",
           fsc.name, nargs);
#endif
    fsc.nargs = nargs;
  }

  if (is_xsyscall) {
    /* We need to figure out nargs ourselves in case of xsyscall() for now. */
    if (nargs == 0)
      nargs = fsc.nargs;
  }
  if (nargs == 0) {
    return;
  }

  fsc.args = malloc((1+nargs) * sizeof(unsigned long));
  for (i = 0; i < nargs && reg < 6; i++, reg++) {
    switch (reg) {
    case 0: fsc.args[i] = regs.r_rdi; break;
    case 1: fsc.args[i] = regs.r_rsi; break;
    case 2: fsc.args[i] = regs.r_rdx; break;
    case 3: fsc.args[i] = regs.r_rcx; break;
    case 4: fsc.args[i] = regs.r_r8; break;
    case 5: fsc.args[i] = regs.r_r9; break;
    }
  }
  if (nargs > i) {
    if (pread(Procfd, &fsc.args[i], (nargs-i) * sizeof(register_t),
              regs.r_rsp + 2*sizeof(register_t)) == -1) {
      free(fsc.args);
      return;
    }
  }

  fsc.s_args = calloc(1+fsc.nargs, sizeof(char*));
  fsc.sc = sc;

  /*
   * At this point, we set up the system call arguments.
   * We ignore any OUT ones, however -- those are arguments that
   * are set by the system call, and so are probably meaningless
   * now.  This doesn't currently support arguments that are
   * passed in *and* out, however.
   */

  if (fsc.name) {

#ifdef DEBUG
    fprintf(stderr, "syscall %s(", fsc.name);
#endif
    for (i = 0; i < fsc.nargs; i++) {
#ifdef DEBUG
      fprintf(stderr, "0x%lx%s",
             sc
             ? fsc.args[sc->args[i].offset]
             : fsc.args[i],
             i < (fsc.nargs -1) ? "," : "");
#endif
      if (sc && !(sc->args[i].type & OUT)) {
        fsc.s_args[i] = print_arg(Procfd, &sc->args[i], fsc.args);
      }
    }
#ifdef DEBUG
    fprintf(stderr, ")\n");
#endif
  }

#ifdef DEBUG
  fprintf(trussinfo->outfile, "\n");
#endif

  /*
   * Some system calls should be printed out before they are done --
   * execve() and exit(), for example, never return.  Possibly change
   * this to work for any system call that doesn't have an OUT
   * parameter?
   */

  if (fsc.name != NULL &&
      (!strcmp(fsc.name, "execve") || !strcmp(fsc.name, "exit"))) {
    print_syscall(trussinfo, fsc.name, fsc.nargs, fsc.s_args);
  }

  if (sc != NULL && sc->ret_type == 0)
    fprintf(trussinfo->outfile, "\n");

  return;
}

/*
 * And when the system call is done, we handle it here.
 * Currently, no attempt is made to ensure that the system calls
 * match -- this needs to be fixed (and is, in fact, why S_SCX includes
 * the sytem call number instead of, say, an error status).
 */

int
x86_64_syscall_exit(struct trussinfo *trussinfo, int syscall_num __unused) {
  char *buf;
  struct reg regs;
  int retval;
  int i;
  int errorp;
  struct syscall *sc;

  if (fsc.name == NULL)
    return 0;

  if (fd == -1 || trussinfo->pid != cpid) {
    asprintf(&buf, "%s/%d/regs", procfs_path, trussinfo->pid);
    if (buf == NULL)
      err(1, "Out of memory");
    fd = open(buf, O_RDONLY);
    free(buf);
    if (fd == -1) {
      fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
      return 0;
    }
    cpid = trussinfo->pid;
  }

  if (pread(fd, &regs, sizeof(regs), 0L) != sizeof(regs)) {
          fprintf(trussinfo->outfile, "\n");
          return 0;
  }
  retval = regs.r_rax;
  errorp = !!(regs.r_rflags & PSL_C);

  /*
   * This code, while simpler than the initial versions I used, could
   * stand some significant cleaning.
   */

  sc = fsc.sc;
  if (!sc) {
    for (i = 0; i < fsc.nargs; i++)
      asprintf(&fsc.s_args[i], "0x%lx", fsc.args[i]);
  } else {
    /*
     * Here, we only look for arguments that have OUT masked in --
     * otherwise, they were handled in the syscall_entry function.
     */
    for (i = 0; i < sc->nargs; i++) {
      char *temp;
      if (sc->args[i].type & OUT) {
        /*
         * If an error occurred, than don't bothe getting the data;
         * it may not be valid.
         */
        if (errorp) {
          asprintf(&temp, "0x%lx", fsc.args[sc->args[i].offset]);
        } else {
          temp = print_arg(Procfd, &sc->args[i], fsc.args);
        }
        fsc.s_args[i] = temp;
      }
    }
  }

  /*
   * It would probably be a good idea to merge the error handling,
   * but that complicates things considerably.
   */

  print_syscall_ret(trussinfo, fsc.name, fsc.nargs, fsc.s_args, errorp, retval);
  clear_fsc();

  return (retval);
}