tracefile.c

/* Trace file support in GDB.

   Copyright (C) 1997-2015 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "tracefile.h"
#include "ctf.h"
#include "exec.h"
#include "regcache.h"

/* Helper macros.  */

#define TRACE_WRITE_R_BLOCK(writer, buf, size)	\
  writer->ops->frame_ops->write_r_block ((writer), (buf), (size))
#define TRACE_WRITE_M_BLOCK_HEADER(writer, addr, size)		  \
  writer->ops->frame_ops->write_m_block_header ((writer), (addr), \
						(size))
#define TRACE_WRITE_M_BLOCK_MEMORY(writer, buf, size)	  \
  writer->ops->frame_ops->write_m_block_memory ((writer), (buf), \
						(size))
#define TRACE_WRITE_V_BLOCK(writer, num, val)	\
  writer->ops->frame_ops->write_v_block ((writer), (num), (val))

/* Free trace file writer.  */

static void
trace_file_writer_xfree (void *arg)
{
  struct trace_file_writer *writer = arg;

  writer->ops->dtor (writer);
  xfree (writer);
}

/* Save tracepoint data to file named FILENAME through WRITER.  WRITER
   determines the trace file format.  If TARGET_DOES_SAVE is non-zero,
   the save is performed on the target, otherwise GDB obtains all trace
   data and saves it locally.  */

static void
trace_save (const char *filename, struct trace_file_writer *writer,
	    int target_does_save)
{
  struct trace_status *ts = current_trace_status ();
  int status;
  struct uploaded_tp *uploaded_tps = NULL, *utp;
  struct uploaded_tsv *uploaded_tsvs = NULL, *utsv;

  ULONGEST offset = 0;
#define MAX_TRACE_UPLOAD 2000
  gdb_byte buf[MAX_TRACE_UPLOAD];
  int written;
  enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());

  /* If the target is to save the data to a file on its own, then just
     send the command and be done with it.  */
  if (target_does_save)
    {
      if (!writer->ops->target_save (writer, filename))
	error (_("Target failed to save trace data to '%s'."),
	       filename);
      return;
    }

  /* Get the trace status first before opening the file, so if the
     target is losing, we can get out without touching files.  */
  status = target_get_trace_status (ts);

  writer->ops->start (writer, filename);

  writer->ops->write_header (writer);

  /* Write descriptive info.  */

  /* Write out the size of a register block.  */
  writer->ops->write_regblock_type (writer, trace_regblock_size);

  /* Write out status of the tracing run (aka "tstatus" info).  */
  writer->ops->write_status (writer, ts);

  /* Note that we want to upload tracepoints and save those, rather
     than simply writing out the local ones, because the user may have
     changed tracepoints in GDB in preparation for a future tracing
     run, or maybe just mass-deleted all types of breakpoints as part
     of cleaning up.  So as not to contaminate the session, leave the
     data in its uploaded form, don't make into real tracepoints.  */

  /* Get trace state variables first, they may be checked when parsing
     uploaded commands.  */

  target_upload_trace_state_variables (&uploaded_tsvs);

  for (utsv = uploaded_tsvs; utsv; utsv = utsv->next)
    writer->ops->write_uploaded_tsv (writer, utsv);

  free_uploaded_tsvs (&uploaded_tsvs);

  target_upload_tracepoints (&uploaded_tps);

  for (utp = uploaded_tps; utp; utp = utp->next)
    target_get_tracepoint_status (NULL, utp);

  for (utp = uploaded_tps; utp; utp = utp->next)
    writer->ops->write_uploaded_tp (writer, utp);

  free_uploaded_tps (&uploaded_tps);

  /* Mark the end of the definition section.  */
  writer->ops->write_definition_end (writer);

  /* Get and write the trace data proper.  */
  while (1)
    {
      LONGEST gotten = 0;

      /* The writer supports writing the contents of trace buffer
	  directly to trace file.  Don't parse the contents of trace
	  buffer.  */
      if (writer->ops->write_trace_buffer != NULL)
	{
	  /* We ask for big blocks, in the hopes of efficiency, but
	     will take less if the target has packet size limitations
	     or some such.  */
	  gotten = target_get_raw_trace_data (buf, offset,
					      MAX_TRACE_UPLOAD);
	  if (gotten < 0)
	    error (_("Failure to get requested trace buffer data"));
	  /* No more data is forthcoming, we're done.  */
	  if (gotten == 0)
	    break;

	  writer->ops->write_trace_buffer (writer, buf, gotten);

	  offset += gotten;
	}
      else
	{
	  uint16_t tp_num;
	  uint32_t tf_size;
	  /* Parse the trace buffers according to how data are stored
	     in trace buffer in GDBserver.  */

	  gotten = target_get_raw_trace_data (buf, offset, 6);

	  if (gotten == 0)
	    break;

	  /* Read the first six bytes in, which is the tracepoint
	     number and trace frame size.  */
	  tp_num = (uint16_t)
	    extract_unsigned_integer (&buf[0], 2, byte_order);

	  tf_size = (uint32_t)
	    extract_unsigned_integer (&buf[2], 4, byte_order);

	  writer->ops->frame_ops->start (writer, tp_num);
	  gotten = 6;

	  if (tf_size > 0)
	    {
	      unsigned int block;

	      offset += 6;

	      for (block = 0; block < tf_size; )
		{
		  gdb_byte block_type;

		  /* We'll fetch one block each time, in order to
		     handle the extremely large 'M' block.  We first
		     fetch one byte to get the type of the block.  */
		  gotten = target_get_raw_trace_data (buf, offset, 1);
		  if (gotten < 1)
		    error (_("Failure to get requested trace buffer data"));

		  gotten = 1;
		  block += 1;
		  offset += 1;

		  block_type = buf[0];
		  switch (block_type)
		    {
		    case 'R':
		      gotten
			= target_get_raw_trace_data (buf, offset,
						     trace_regblock_size);
		      if (gotten < trace_regblock_size)
			error (_("Failure to get requested trace"
				 " buffer data"));

		      TRACE_WRITE_R_BLOCK (writer, buf,
					   trace_regblock_size);
		      break;
		    case 'M':
		      {
			unsigned short mlen;
			ULONGEST addr;
			LONGEST t;
			int j;

			t = target_get_raw_trace_data (buf,offset, 10);
			if (t < 10)
			  error (_("Failure to get requested trace"
				   " buffer data"));

			offset += 10;
			block += 10;

			gotten = 0;
			addr = (ULONGEST)
			  extract_unsigned_integer (buf, 8,
						    byte_order);
			mlen = (unsigned short)
			  extract_unsigned_integer (&buf[8], 2,
						    byte_order);

			TRACE_WRITE_M_BLOCK_HEADER (writer, addr,
						    mlen);

			/* The memory contents in 'M' block may be
			   very large.  Fetch the data from the target
			   and write them into file one by one.  */
			for (j = 0; j < mlen; )
			  {
			    unsigned int read_length;

			    if (mlen - j > MAX_TRACE_UPLOAD)
			      read_length = MAX_TRACE_UPLOAD;
			    else
			      read_length = mlen - j;

			    t = target_get_raw_trace_data (buf,
							   offset + j,
							   read_length);
			    if (t < read_length)
			      error (_("Failure to get requested"
				       " trace buffer data"));

			    TRACE_WRITE_M_BLOCK_MEMORY (writer, buf,
							read_length);

			    j += read_length;
			    gotten += read_length;
			  }

			break;
		      }
		    case 'V':
		      {
			int vnum;
			LONGEST val;

			gotten
			  = target_get_raw_trace_data (buf, offset,
						       12);
			if (gotten < 12)
			  error (_("Failure to get requested"
				   " trace buffer data"));

			vnum  = (int) extract_signed_integer (buf,
							      4,
							      byte_order);
			val
			  = extract_signed_integer (&buf[4], 8,
						    byte_order);

			TRACE_WRITE_V_BLOCK (writer, vnum, val);
		      }
		      break;
		    default:
		      error (_("Unknown block type '%c' (0x%x) in"
			       " trace frame"),
			     block_type, block_type);
		    }

		  block += gotten;
		  offset += gotten;
		}
	    }
	  else
	    offset += gotten;

	  writer->ops->frame_ops->end (writer);
	}
    }

  writer->ops->end (writer);
}

static void
trace_save_command (char *args, int from_tty)
{
  int target_does_save = 0;
  char **argv;
  char *filename = NULL;
  struct cleanup *back_to;
  int generate_ctf = 0;
  struct trace_file_writer *writer = NULL;

  if (args == NULL)
    error_no_arg (_("file in which to save trace data"));

  argv = gdb_buildargv (args);
  back_to = make_cleanup_freeargv (argv);

  for (; *argv; ++argv)
    {
      if (strcmp (*argv, "-r") == 0)
	target_does_save = 1;
      if (strcmp (*argv, "-ctf") == 0)
	generate_ctf = 1;
      else if (**argv == '-')
	error (_("unknown option `%s'"), *argv);
      else
	filename = *argv;
    }

  if (!filename)
    error_no_arg (_("file in which to save trace data"));

  if (generate_ctf)
    writer = ctf_trace_file_writer_new ();
  else
    writer = tfile_trace_file_writer_new ();

  make_cleanup (trace_file_writer_xfree, writer);

  trace_save (filename, writer, target_does_save);

  if (from_tty)
    printf_filtered (_("Trace data saved to %s '%s'.\n"),
		     generate_ctf ? "directory" : "file", filename);

  do_cleanups (back_to);
}

/* Save the trace data to file FILENAME of tfile format.  */

void
trace_save_tfile (const char *filename, int target_does_save)
{
  struct trace_file_writer *writer;
  struct cleanup *back_to;

  writer = tfile_trace_file_writer_new ();
  back_to = make_cleanup (trace_file_writer_xfree, writer);
  trace_save (filename, writer, target_does_save);
  do_cleanups (back_to);
}

/* Save the trace data to dir DIRNAME of ctf format.  */

void
trace_save_ctf (const char *dirname, int target_does_save)
{
  struct trace_file_writer *writer;
  struct cleanup *back_to;

  writer = ctf_trace_file_writer_new ();
  back_to = make_cleanup (trace_file_writer_xfree, writer);

  trace_save (dirname, writer, target_does_save);
  do_cleanups (back_to);
}

/* Fetch register data from tracefile, shared for both tfile and
   ctf.  */

void
tracefile_fetch_registers (struct regcache *regcache, int regno)
{
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  int regn, pc_regno;

  /* We get here if no register data has been found.  Mark registers
     as unavailable.  */
  for (regn = 0; regn < gdbarch_num_regs (gdbarch); regn++)
    regcache_raw_supply (regcache, regn, NULL);

  /* We can often usefully guess that the PC is going to be the same
     as the address of the tracepoint.  */
  pc_regno = gdbarch_pc_regnum (gdbarch);

  /* XXX This guessing code below only works if the PC register isn't
     a pseudo-register.  The value of a pseudo-register isn't stored
     in the (non-readonly) regcache -- instead it's recomputed
     (probably from some other cached raw register) whenever the
     register is read.  This guesswork should probably move to some
     higher layer.  */
  if (pc_regno < 0 || pc_regno >= gdbarch_num_regs (gdbarch))
    return;

  if (regno == -1 || regno == pc_regno)
    {
      struct tracepoint *tp = get_tracepoint (get_tracepoint_number ());
      gdb_byte *regs;

      if (tp && tp->base.loc)
	{
	  /* But don't try to guess if tracepoint is multi-location...  */
	  if (tp->base.loc->next)
	    {
	      warning (_("Tracepoint %d has multiple "
			 "locations, cannot infer $pc"),
		       tp->base.number);
	      return;
	    }
	  /* ... or does while-stepping.  */
	  if (tp->step_count > 0)
	    {
	      warning (_("Tracepoint %d does while-stepping, "
			 "cannot infer $pc"),
		       tp->base.number);
	      return;
	    }

	  regs = alloca (register_size (gdbarch, pc_regno));
	  store_unsigned_integer (regs, register_size (gdbarch, pc_regno),
				  gdbarch_byte_order (gdbarch),
				  tp->base.loc->address);
	  regcache_raw_supply (regcache, pc_regno, regs);
	}
    }
}

/* This is the implementation of target_ops method to_has_all_memory.  */

static int
tracefile_has_all_memory (struct target_ops *ops)
{
  return 1;
}

/* This is the implementation of target_ops method to_has_memory.  */

static int
tracefile_has_memory (struct target_ops *ops)
{
  return 1;
}

/* This is the implementation of target_ops method to_has_stack.
   The target has a stack when GDB has already selected one trace
   frame.  */

static int
tracefile_has_stack (struct target_ops *ops)
{
  return get_traceframe_number () != -1;
}

/* This is the implementation of target_ops method to_has_registers.
   The target has registers when GDB has already selected one trace
   frame.  */

static int
tracefile_has_registers (struct target_ops *ops)
{
  return get_traceframe_number () != -1;
}

/* This is the implementation of target_ops method to_thread_alive.
   tracefile has one thread faked by GDB.  */

static int
tracefile_thread_alive (struct target_ops *ops, ptid_t ptid)
{
  return 1;
}

/* This is the implementation of target_ops method to_get_trace_status.
   The trace status for a file is that tracing can never be run.  */

static int
tracefile_get_trace_status (struct target_ops *self, struct trace_status *ts)
{
  /* Other bits of trace status were collected as part of opening the
     trace files, so nothing to do here.  */

  return -1;
}

/* Initialize OPS for tracefile related targets.  */

void
init_tracefile_ops (struct target_ops *ops)
{
  ops->to_stratum = process_stratum;
  ops->to_get_trace_status = tracefile_get_trace_status;
  ops->to_has_all_memory = tracefile_has_all_memory;
  ops->to_has_memory = tracefile_has_memory;
  ops->to_has_stack = tracefile_has_stack;
  ops->to_has_registers = tracefile_has_registers;
  ops->to_thread_alive = tracefile_thread_alive;
  ops->to_magic = OPS_MAGIC;
}

extern initialize_file_ftype _initialize_tracefile;

void
_initialize_tracefile (void)
{
  add_com ("tsave", class_trace, trace_save_command, _("\
Save the trace data to a file.\n\
Use the '-ctf' option to save the data to CTF format.\n\
Use the '-r' option to direct the target to save directly to the file,\n\
using its own filesystem."));
}