path: root/tapsets.cxx

// tapset resolution
// Copyright (C) 2005 Red Hat Inc.
//
// This file is part of systemtap, and is free software.  You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.

#include "config.h"
#include "staptree.h"
#include "elaborate.h"
#include "tapsets.h"
#include "translate.h"

#include <deque>
#include <iostream>
#include <map>
#include <set>
#include <sstream>
#include <stdexcept>
#include <vector>

extern "C" {
#include <elfutils/libdwfl.h>
#include <elfutils/libdw.h>
#include <dwarf.h>
#include <elf.h>
#include <obstack.h>
#include "loc2c.h"
}

#include <fnmatch.h>

using namespace std;

// ------------------------------------------------------------------------
// begin/end probes are run right during registration / deregistration
// ------------------------------------------------------------------------

struct be_derived_probe: public derived_probe
{
  bool begin;
  be_derived_probe (probe* p, bool b): derived_probe (p), begin (b) {}
  be_derived_probe (probe* p, probe_point* l, bool b):
    derived_probe (p, l), begin (b) {}

  void emit_registrations (translator_output* o, unsigned i);
  void emit_deregistrations (translator_output* o, unsigned i);
  void emit_probe_entries (translator_output* o, unsigned i);
};

struct
be_builder
  : public derived_probe_builder
{
  bool begin;
  be_builder(bool b) : begin(b) {}
  virtual void build(systemtap_session & sess,
		     probe * base,
		     probe_point * location,
		     std::map<std::string, literal *> const & parameters,
		     vector<probe *> & results_to_expand_further,
		     vector<derived_probe *> & finished_results)
  {
    finished_results.push_back(new be_derived_probe(base, location, begin));
  }
  virtual ~be_builder() {}
};


void
be_derived_probe::emit_registrations (translator_output* o, unsigned j)
{
  if (begin)
    for (unsigned i=0; i<locations.size(); i++)
      o->newline() << "enter_" << j << "_" << i << " ();";
}


void
be_derived_probe::emit_deregistrations (translator_output* o, unsigned j)
{
  if (!begin)
    for (unsigned i=0; i<locations.size(); i++)
      o->newline() << "enter_" << j << "_" << i << " ();";
}


void
be_derived_probe::emit_probe_entries (translator_output* o, unsigned j)
{
  for (unsigned i=0; i<locations.size(); i++)
    {
      probe_point *l = locations[i];
      o->newline() << "/* location " << i << ": " << *l << " */";
      o->newline() << "static void enter_" << j << "_" << i << " (void);";
      o->newline() << "void enter_" << j << "_" << i << " () {";

      // While begin/end probes are executed single-threaded, we
      // still code defensively and use a per-cpu context.
      o->newline(1) << "struct context* c = & contexts [smp_processor_id()];";

      // A precondition for running a probe handler is that we're in STARTING
      // or STOPPING state (not ERROR), and that no one else is already using
      // this context.
      o->newline() << "if (atomic_read (&session_state) != ";
      if (begin) o->line() << "STAP_SESSION_STARTING)";
      else o->line() << "STAP_SESSION_STOPPING)";
      o->newline(1) << "return;";
      o->newline(-1) << "if (c->busy) {";
      o->newline(1) << "printk (KERN_ERR \"probe reentrancy\");";
      o->newline() << "atomic_set (& session_state, STAP_SESSION_ERROR);";
      o->newline() << "return;";
      o->newline(-1) << "}";
      o->newline();

      o->newline() << "c->busy ++;";
      o->newline() << "mb ();"; // for smp
      o->newline() << "c->errorcount = 0;";
      o->newline() << "c->actioncount = 0;";
      o->newline() << "c->nesting = 0;";
      o->newline() << "c->regs = 0;";

      // NB: locals are initialized by probe function itself
      o->newline() << "probe_" << j << " (c);";

      // see translate.cxx: visit_functioncall and elsewhere to see all the
      // possible context indications that a probe exited prematurely
      o->newline() << "if (c->errorcount || c->actioncount > MAXACTION"
                   << " || c->nesting+2 >= MAXNESTING) {";
      o->newline(1) << "printk (KERN_ERR \"probe execution failure (e%d,n%d,a%d)\",";
      o->newline(1) << "c->errorcount, c->nesting, c->actioncount);";
      o->newline(-1) << "atomic_set (& session_state, STAP_SESSION_ERROR);";
      o->newline(-1) << "}";

      o->newline() << "c->busy --;";
      o->newline() << "mb ();";
      o->newline(-1) << "}" << endl;
    }
}


// ------------------------------------------------------------------------
//  Dwarf derived probes.
// ------------------------------------------------------------------------

template <typename OUT, typename IN> inline OUT
lex_cast(IN const & in)
{
  stringstream ss;
  OUT out;
  if (!(ss << in && ss >> out))
    throw runtime_error("bad lexical cast");
  return out;
}

// Helper for dealing with selected portions of libdwfl in a more readable
// fashion, and with specific cleanup / checking / logging options.

struct
dwflpp
{
  systemtap_session & sess;
  Dwfl * dwfl;

  // These are "current" values we focus on.
  Dwfl_Module * module;
  Dwarf * module_dwarf;
  Dwarf_Addr module_bias;
  Dwarf_Die * cu;
  Dwarf_Func * function;

  string module_name;
  string cu_name;
  string function_name;

  string const default_name(char const * in,
			    char const * type)
  {
    if (in)
      return in;
    if (false && sess.verbose)
      clog << "WARNING: no name found for " << type << endl;
    return string("");
  }

  void get_module_dwarf()
  {
    if (!module_dwarf)
      module_dwarf = dwfl_module_getdwarf(module, &module_bias);
    if (module_dwarf == NULL && sess.verbose)
      clog << "WARNING: dwfl_module_getdwarf() : " 
	   << dwfl_errmsg (dwfl_errno ()) << endl;
  }

  void focus_on_module(Dwfl_Module * m)
  {
    assert(m);
    module = m;
    module_dwarf = NULL;
    module_name = default_name(dwfl_module_info(module, NULL,
						NULL, NULL,
						NULL, NULL,
						NULL, NULL),
			       "module");
    cu_name.clear();
    function_name.clear();

    if (false && sess.verbose)
      clog << "focused on module " << module_name << endl;
  }

  void focus_on_cu(Dwarf_Die * c)
  {
    assert(c);
    cu = c;
    cu_name = default_name(dwarf_diename(c), "cu");
    function_name.clear();

    if (false && sess.verbose)
      clog << "focused on CU " << cu_name
	   << ", in module " << module_name << endl;
  }

  void focus_on_function(Dwarf_Func * f)
  {
    assert(f);
    function = f;
    function_name = default_name(dwarf_func_name(function),
				 "function");
    if (false && sess.verbose)
      clog << "focused on function " << function_name
	   << ", in CU " << cu_name
	   << ", module " << module_name << endl;
  }

  void focus_on_module_containing_global_address(Dwarf_Addr a)
  {
    assert(dwfl);
    if (false && sess.verbose)
      clog << "focusing on module containing global addr " << a << endl;
    focus_on_module(dwfl_addrmodule(dwfl, a));
  }

  void focus_on_cu_containing_module_address(Dwarf_Addr a)
  {
    assert(dwfl);
    assert(module);
    Dwarf_Addr bias;
    get_module_dwarf();
    if (sess.verbose)
      clog << "focusing on cu containing module addr " << a << endl;
    focus_on_cu(dwfl_module_addrdie(module, a, &bias));
    assert(bias == module_bias);
  }

  void focus_on_cu_containing_global_address(Dwarf_Addr a)
  {
    assert(dwfl);
    get_module_dwarf();
    if (sess.verbose)
      clog << "focusing on cu containing global addr " << a << endl;
    focus_on_module_containing_global_address(a);
    assert(a > module_bias);
    a = global_address_to_module(a);
    focus_on_cu_containing_module_address(a);
  }

  Dwarf_Addr module_address_to_global(Dwarf_Addr a)
  {
    assert(module);
    get_module_dwarf();
    if (sess.verbose)
      clog << "module addr " << a
	   << " + bias " << module_bias
	   << " -> global addr " << a + module_bias << endl;
    return a + module_bias;
  }

  Dwarf_Addr global_address_to_module(Dwarf_Addr a)
  {
    assert(module);
    get_module_dwarf();
    if (sess.verbose)
      clog << "global addr " << a
	   << " - bias " << module_bias
	   << " -> module addr " << a - module_bias << endl;
    return a - module_bias;
  }


  bool module_name_matches(string pattern)
  {
    assert(module);
    bool t = (fnmatch(pattern.c_str(), module_name.c_str(), 0) == 0);
    if (t && sess.verbose)
      clog << "pattern '" << pattern << "' "
	   << "matches "
	   << "module '" << module_name << "'" << endl;
    return t;
  }

  bool function_name_matches(string pattern)
  {
    assert(function);
    bool t = (fnmatch(pattern.c_str(), function_name.c_str(), 0) == 0);
    if (t && sess.verbose)
      clog << "pattern '" << pattern << "' "
	   << "matches "
	   << "function '" << function_name << "'" << endl;
    return t;
  }

  bool cu_name_matches(string pattern)
  {
    assert(cu);
    bool t = (fnmatch(pattern.c_str(), cu_name.c_str(), 0) == 0);
    if (t && sess.verbose)
      clog << "pattern '" << pattern << "' "
	   << "matches "
	   << "CU '" << cu_name << "'" << endl;
    return t;
  }

  void dwflpp_assert(string desc, int rc) // NB: "rc == 0" means OK in this case
  {
    string msg = "dwfl failure (" + desc + "): ";
    if (rc < 0) msg += dwfl_errmsg (rc);
    else if (rc > 0) msg += strerror (rc);
    if (rc != 0)
      throw semantic_error (msg);
  }

  dwflpp(systemtap_session & sess)
    :
    sess(sess),
    dwfl(NULL),
    module(NULL),
    module_dwarf(NULL),
    module_bias(0),
    cu(NULL),
    function(NULL)
  {}

  void setup(bool kernel)
  {
    static const Dwfl_Callbacks proc_callbacks =
      {
	dwfl_linux_proc_find_elf,
	dwfl_standard_find_debuginfo,
	NULL,
	NULL
      };

    static const Dwfl_Callbacks kernel_callbacks =
      {
	dwfl_linux_kernel_find_elf,
	dwfl_standard_find_debuginfo,
	dwfl_linux_kernel_module_section_address,
	NULL
      };

    if (kernel)
      {
	dwfl = dwfl_begin(&kernel_callbacks);
	if (!dwfl)
	  throw semantic_error("cannot open dwfl");
	dwfl_report_begin(dwfl);
        // XXX: if we have only kernel.* probe points, we shouldn't waste time
        // looking for module debug-info (and vice versa).
	dwflpp_assert("find kernel debug-info", dwfl_linux_kernel_report_kernel(dwfl));
	dwflpp_assert("find modules debug-info", dwfl_linux_kernel_report_modules(dwfl));
      }
    else
      {
	dwfl = dwfl_begin(&proc_callbacks);
	dwfl_report_begin(dwfl);
	if (!dwfl)
	  throw semantic_error("cannot open dwfl");
	// XXX: Find pids or processes, do userspace stuff.
      }

    dwflpp_assert("report_end", dwfl_report_end(dwfl, NULL, NULL));
  }

  void iterate_over_modules(int (* callback)(Dwfl_Module *, void **,
					     const char *, Dwarf_Addr,
					     void *),
			    void * data)
  {
    if (false && sess.verbose)
      clog << "iterating over modules" << endl;
    ptrdiff_t off = 0;
    do
      {
	off = dwfl_getmodules (dwfl, callback, data, off);
      }
    while (off > 0);
    if (false && sess.verbose)
      clog << "finished iterating over modules" << endl;
    dwflpp_assert("getdwarf", off);
  }

  void iterate_over_cus (int (*callback)(Dwarf_Die * die, void * arg),
			 void * data)
  {
    get_module_dwarf();

    if (!module_dwarf)
      {
	cerr << "WARNING: no dwarf info found for module " << module_name << endl;
	return;
      }

    if (false && sess.verbose)
      clog << "iterating over CUs in module " << module_name << endl;

    Dwarf *dw = module_dwarf;
    Dwarf_Off off = 0;
    size_t cuhl;
    Dwarf_Off noff;
    while (dwarf_nextcu(dw, off, &noff, &cuhl, NULL, NULL, NULL) == 0)
      {
	Dwarf_Die die_mem;
	Dwarf_Die *die;
	die = dwarf_offdie(dw, off + cuhl, &die_mem);
	if (callback(die, data) != DWARF_CB_OK)
	  break;
	off = noff;
      }
  }

  void iterate_over_functions(int (* callback)(Dwarf_Func * func, void * arg),
			      void * data)
  {
    assert(module);
    assert(cu);
    if (false && sess.verbose)
      clog << "iterating over functions in CU " << cu_name << endl;
    dwarf_getfuncs(cu, callback, data, 0);
  }

  bool function_entrypc(Dwarf_Addr * addr)
  {
    return (dwarf_func_entrypc(function, addr) == 0);
  }

  bool function_includes_global_addr(Dwarf_Addr addr)
  {
    assert(module_dwarf);
    assert(cu);
    assert(function);
    Dwarf_Addr lo, hi;
    if (dwarf_func_lowpc(function, &lo) != 0)
      {
	if (sess.verbose)
	  clog << "WARNING: cannot find low PC value for function " << function_name << endl;
	return false;
      }

    if (dwarf_func_highpc(function, &hi) != 0)
    {
      if (sess.verbose)
	clog << "WARNING: cannot find high PC value for function " << function_name << endl;
      return false;
    }

    bool t = lo <= addr && addr <= hi;
    if (sess.verbose)
      clog << "function " << function_name << " = [" << lo << "," << hi << "] "
	   << (t ? "contains " : "does not contain ")
	   << " global addr " << addr << endl;
    return t;
  }

  bool function_includes_module_addr(Dwarf_Addr addr)
  {
    return function_includes_global_addr(module_address_to_global(addr));
  }

  Dwarf_Addr global_addr_of_line_in_cu(int line)
  {
    Dwarf_Lines * lines;
    size_t nlines;
    Dwarf_Addr addr;
    Dwarf_Line * linep;

    assert(module);
    assert(cu);
    dwflpp_assert("getsrclines", dwarf_getsrclines(cu, &lines, &nlines));
    linep = dwarf_onesrcline(lines, line);
    dwflpp_assert("lineaddr", dwarf_lineaddr(linep, &addr));
    if (sess.verbose)
      clog << "line " << line
	   << " of cu " << cu_name
	   << " has module address " << addr
	   << " in " << module_name << endl;
    return module_address_to_global(addr);
  }


  string literal_stmt_for_local(Dwarf_Addr pc,
				string const & local)
  {
    assert (cu);

    Dwarf_Die *scopes;
    Dwarf_Die vardie;

    int nscopes = dwarf_getscopes (cu, pc, &scopes);
    if (nscopes == 0)
      {
	throw semantic_error ("unable to find any scopes containing "
			      + lex_cast<string>(pc)
			      + " while searching for local '" + local + "'");
      }

    int declaring_scope = dwarf_getscopevar (scopes, nscopes,
					     local.c_str(),
					     0, NULL, 0, 0,
					     &vardie);
    if (declaring_scope < 0)
      {
	throw semantic_error ("unable to find local '" + local + "'"
			      + " near pc " + lex_cast<string>(pc));
      }

    Dwarf_Attribute fb_attr_mem, *fb_attr = NULL;
    for (int inner = 0; inner < nscopes; ++inner)
      {
	switch (dwarf_tag (&scopes[inner]))
	  {
	  default:
	    continue;
	  case DW_TAG_subprogram:
	  case DW_TAG_entry_point:
	  case DW_TAG_inlined_subroutine:  /* XXX */
	    if (inner >= declaring_scope)
	      fb_attr = dwarf_attr_integrate (&scopes[inner],
					      DW_AT_frame_base,
					      &fb_attr_mem);
	    break;
	  }
      }

    if (sess.verbose)
      clog << "finding location for local '" << local
	   << "' near address " << hex << "0x" << pc
	   << ", module bias " << hex << "0x" << module_bias
	   << endl;

    Dwarf_Attribute attr_mem;
    if (dwarf_attr_integrate (&vardie, DW_AT_location, &attr_mem) == NULL)
      throw semantic_error("failed to retrieve location "
			   "attribute for local '" + local + "'");

#define obstack_chunk_alloc malloc
#define obstack_chunk_free free

    struct obstack pool;
    obstack_init (&pool);
    struct location *tail = NULL;
    struct location *head = c_translate_location (&pool, 1, module_bias,
						  &attr_mem, pc,
						  &tail, fb_attr);

  if (dwarf_attr_integrate (&vardie, DW_AT_type, &attr_mem) == NULL)
      throw semantic_error("failed to retrieve type "
			   "attribute for local '" + local + "'");

    c_translate_fetch (&pool, 1, module_bias, &vardie,
		       &attr_mem, &tail,
		       "THIS->__retvalue");


    size_t bufsz = 1024;
    char *buf = static_cast<char*>(malloc(bufsz));
    assert(buf);

    FILE *memstream = open_memstream (&buf, &bufsz);
    assert(memstream);

    bool deref = c_emit_location (memstream, head, 1);
    fprintf(memstream, "  goto out;\n");

    // dummy use of deref_fault label, to disable warning if deref() not used
    fprintf(memstream, "if (0) goto deref_fault;\n");

    // XXX: deref flag not reliable; emit fault label unconditionally
    if (deref) ;
    fprintf(memstream,
            "deref_fault:\n"
            "  c->errorcount++; \n"
            "  goto out;\n");

    fclose (memstream);
    string result(buf);
    free (buf);
    return result;
  }



  ~dwflpp()
  {
    if (dwfl)
      dwfl_end(dwfl);
  }
};

static string TOK_PROCESS("process");
static string TOK_KERNEL("kernel");
static string TOK_MODULE("module");

static string TOK_FUNCTION("function");
static string TOK_RETURN("return");
static string TOK_CALLEES("callees");

static string TOK_STATEMENT("statement");
static string TOK_LABEL("label");
static string TOK_RELATIVE("relative");


enum
function_spec_type
  {
    function_alone,
    function_and_file,
    function_file_and_line
  };


struct dwarf_builder;
struct dwarf_query;

struct dwarf_derived_probe : public derived_probe
{
  dwarf_derived_probe (dwarf_query & q,
		       Dwarf_Addr addr);
  
  string module_name;
  string function_name;
  bool has_statement;
  Dwarf_Addr addr;
  Dwarf_Addr module_bias;
  bool has_return;

  // Pattern registration helpers.
  static void register_relative_variants(match_node * root,
					 dwarf_builder * dw);
  static void register_statement_variants(match_node * root,
					  dwarf_builder * dw);
  static void register_function_variants(match_node * root,
					  dwarf_builder * dw);
  static void register_function_and_statement_variants(match_node * root,
						       dwarf_builder * dw);
  static void register_patterns(match_node * root);

  virtual void emit_registrations (translator_output * o, unsigned i);
  virtual void emit_deregistrations (translator_output * o, unsigned i);
  virtual void emit_probe_entries (translator_output * o, unsigned i);
  virtual ~dwarf_derived_probe() {}
};

// Helper struct to thread through the dwfl callbacks.
struct
dwarf_query
{
  dwarf_query(systemtap_session & sess,
	      probe * base_probe,
	      probe_point * base_loc,
	      dwflpp & dw,
	      map<string, literal *> const & params,
	      vector<derived_probe *> & results);

  systemtap_session & sess;

  // Parameter extractors.
  static bool has_null_param(map<string, literal *> const & params,
			     string const & k);
  static bool get_string_param(map<string, literal *> const & params,
			       string const & k, string & v);
  static bool get_number_param(map<string, literal *> const & params,
			       string const & k, long & v);

  string pt_regs_member_for_regnum(uint8_t dwarf_regnum);

  vector<derived_probe *> & results;

  bool has_kernel;
  bool has_process;
  bool has_module;
  string process_val;
  string module_val;
  string function_val;

  bool has_function_str;
  bool has_statement_str;
  bool has_function_num;
  bool has_statement_num;
  string statement_str_val;
  string function_str_val;
  long statement_num_val;
  long function_num_val;

  bool has_callees;
  long callee_val;

  bool has_return;

  bool has_label;
  string label_val;

  bool has_relative;
  long relative_val;

  function_spec_type parse_function_spec(string & spec);
  function_spec_type spec_type;
  string function;
  string file;
  int line;

  probe * base_probe;
  probe_point * base_loc;
  dwflpp & dw;
};

struct
dwarf_builder
  : public derived_probe_builder
{
  dwarf_builder() {}
  virtual void build(systemtap_session & sess,
		     probe * base,
		     probe_point * location,
		     std::map<std::string, literal *> const & parameters,
		     vector<probe *> & results_to_expand_further,
		     vector<derived_probe *> & finished_results);
  virtual ~dwarf_builder() {}
};

bool
dwarf_query::has_null_param(map<string, literal *> const & params,
			    string const & k)
{
  map<string, literal *>::const_iterator i = params.find(k);
  if (i != params.end() && i->second == NULL)
    return true;
  return false;
}

bool
dwarf_query::get_string_param(map<string, literal *> const & params,
			      string const & k, string & v)
{
  map<string, literal *>::const_iterator i = params.find(k);
  if (i == params.end())
    return false;
  literal_string * ls = dynamic_cast<literal_string *>(i->second);
  if (!ls)
    return false;
  v = ls->value;
  return true;
}

bool
dwarf_query::get_number_param(map<string, literal *> const & params,
			      string const & k, long & v)
{
  map<string, literal *>::const_iterator i = params.find(k);
  if (i == params.end())
    return false;
  if (i->second == NULL)
    return false;
  literal_number * ln = dynamic_cast<literal_number *>(i->second);
  if (!ln)
    return false;
  v = ln->value;
  return true;
}


dwarf_query::dwarf_query(systemtap_session & sess,
			 probe * base_probe,
			 probe_point * base_loc,
			 dwflpp & dw,
			 map<string, literal *> const & params,
			 vector<derived_probe *> & results)
  : sess(sess),
    results(results),
    base_probe(base_probe),
    base_loc(base_loc),
    dw(dw)
{

  // Reduce the query to more reasonable semantic values (booleans,
  // extracted strings, numbers, etc).

  has_kernel = has_null_param(params, TOK_KERNEL);
  has_module = get_string_param(params, TOK_MODULE, module_val);
  has_process = get_string_param(params, TOK_PROCESS, process_val);

  has_function_str = get_string_param(params, TOK_FUNCTION, function_str_val);
  has_function_num = get_number_param(params, TOK_FUNCTION, function_num_val);

  has_statement_str = get_string_param(params, TOK_STATEMENT, statement_str_val);
  has_statement_num = get_number_param(params, TOK_STATEMENT, statement_num_val);

  callee_val = 1;
  has_callees = (has_null_param(params, TOK_CALLEES) ||
		 get_number_param(params, TOK_CALLEES, callee_val));

  has_return = has_null_param(params, TOK_RETURN);

  has_label = get_string_param(params, TOK_LABEL, label_val);
  has_relative = get_number_param(params, TOK_RELATIVE, relative_val);

  if (has_function_str)
    spec_type = parse_function_spec(function_str_val);
  else if (has_statement_str)
    spec_type = parse_function_spec(statement_str_val);
}


function_spec_type
dwarf_query::parse_function_spec(string & spec)
{
  string::const_iterator i = spec.begin(), e = spec.end();

  function.clear();
  file.clear();
  line = 0;

  while (i != e && *i != '@')
    {
      if (*i == ':')
	goto bad;
      function += *i++;
    }

  if (i == e)
    {
      if (sess.verbose)
	clog << "parsed '" << spec
	     << "' -> func '" << function
	     << "'" << endl;
      return function_alone;
    }

  if (i++ == e)
    goto bad;

  while (i != e && *i != ':')
    file += *i++;

  if (i == e)
    {
      if (sess.verbose)
	clog << "parsed '" << spec
	     << "' -> func '"<< function
	     << "', file '" << file
	     << "'" << endl;
      return function_and_file;
    }

  if (i++ == e)
    goto bad;

  try
    {
      line = lex_cast<int>(string(i, e));
      if (sess.verbose)
	clog << "parsed '" << spec
	     << "' -> func '"<< function
	     << "', file '" << file
	     << "', line " << line << endl;
      return function_file_and_line;
    }
  catch (runtime_error & exn)
    {
      goto bad;
    }

 bad:
    throw semantic_error("malformed specification '" + spec + "'",
			 base_probe->tok);
}


static void
query_statement(Dwarf_Addr stmt_addr, dwarf_query * q)
{
  // XXX: implement
  if (q->has_relative)
    throw semantic_error("incomplete: do not know how to interpret .relative",
			 q->base_probe->tok);

  q->results.push_back(new dwarf_derived_probe(*q, stmt_addr));
}

static int
query_function(Dwarf_Func * func, void * arg)
{

  dwarf_query * q = static_cast<dwarf_query *>(arg);

  // XXX: implement
  if (q->has_callees)
    throw semantic_error("incomplete: do not know how to interpret .callees",
			 q->base_probe->tok);

  if (q->has_label)
    throw semantic_error("incomplete: do not know how to interpret .label",
			 q->base_probe->tok);

  q->dw.focus_on_function(func);

  if (q->has_statement_str || q->has_function_str)
    {
      if (q->dw.function_name_matches(q->function))
	{
	  // XXX: We assume addr is a global address here. Is it?
	  // XXX: This code is duplicated below, but it's important
	  // for performance reasons to test things in this order.

	  Dwarf_Addr addr;
	  if (!q->dw.function_entrypc(&addr))
	    {
	      if (q->sess.verbose)
		clog << "WARNING: cannot find entry PC for function "
		     << q->dw.function_name << endl;
	      return DWARF_CB_OK;
	    }

	  // If this function's name matches a function or statement
	  // pattern, we use its entry pc, but we do not abort iteration
	  // since there might be other functions matching the pattern.
	  query_statement(addr, q);
	}
    }
  else
    {
      // XXX: We assume addr is a global address here. Is it?
      Dwarf_Addr addr;
      if (!q->dw.function_entrypc(&addr))
	{
	  if (false && q->sess.verbose)
	    clog << "WARNING: cannot find entry PC for function "
		 << q->dw.function_name << endl;
	  return DWARF_CB_OK;
	}

      if (q->has_kernel
	  && q->has_function_num
	  && q->dw.function_includes_global_addr(q->function_num_val))
	{
	  // If this function's address range matches a kernel-relative
	  // function address, we use its entry pc and break out of the
	  // iteration, since there can only be one such function.
	  query_statement(addr, q);
	  return DWARF_CB_ABORT;
	}
      else if (q->has_module
	       && q->has_function_num
	       && q->dw.function_includes_module_addr(q->function_num_val))
	{
	  // If this function's address range matches a module-relative
	  // function address, we use its entry pc and break out of the
	  // iteration, since there can only be one such function.
	  query_statement(addr, q);
	  return DWARF_CB_ABORT;
	}
    }

  return DWARF_CB_OK;
}

static int
query_cu (Dwarf_Die * cudie, void * arg)
{
  dwarf_query * q = static_cast<dwarf_query *>(arg);

  q->dw.focus_on_cu(cudie);

  // If we have enough information in the pattern to skip a CU
  // and the CU does not match that information, return early.
  if ((q->has_statement_str || q->has_function_str)
      && (q->spec_type == function_file_and_line ||
	  q->spec_type == function_and_file)
      && (!q->dw.cu_name_matches(q->file)))
    return DWARF_CB_OK;

  if (q->has_statement_str
      && (q->spec_type == function_file_and_line)
      && q->dw.cu_name_matches(q->file))
    {
      // If we have a complete file:line statement
      // functor (not function functor) landing on
      // this CU, we can look up a specific address
      // for the statement, and skip scanning
      // the remaining functions within the CU.
      query_statement(q->dw.global_addr_of_line_in_cu(q->line), q);
    }
  else
    {
      // Otherwise we need to scan all the functions in this CU.
      q->dw.iterate_over_functions(&query_function, q);
    }
  return DWARF_CB_OK;
}

static int
query_module (Dwfl_Module *mod __attribute__ ((unused)),
	      void **userdata __attribute__ ((unused)),
	      const char *name, Dwarf_Addr base,
	      void *arg __attribute__ ((unused)))
{

  dwarf_query * q = static_cast<dwarf_query *>(arg);

  q->dw.focus_on_module(mod);

  // If we have enough information in the pattern to skip a module and
  // the module does not match that information, return early.

  if (q->has_kernel && !q->dw.module_name_matches("kernel"))
    return DWARF_CB_OK;

  if (q->has_module && !q->dw.module_name_matches(q->module_val))
    return DWARF_CB_OK;

  if (q->has_function_num || q->has_statement_num)
    {
      // If we have module("foo").function(0xbeef) or
      // module("foo").statement(0xbeef), the address is relative
      // to the start of the module, so we seek the function
      // number plus the module's bias.
      Dwarf_Addr addr;
      if (q->has_function_num)
	addr = q->function_num_val;
      else
	addr = q->function_num_val;

      q->dw.focus_on_cu_containing_module_address(addr);
      q->dw.iterate_over_functions(&query_function, q);
    }
  else
    {
      // Otherwise if we have a function("foo") or statement("foo")
      // specifier, we have to scan over all the CUs looking for
      // the function in question
      assert(q->has_function_str || q->has_statement_str);
      q->dw.iterate_over_cus(&query_cu, q);
    }

  // If we just processed the module "kernel", and the user asked for
  // the kernel patterh, there's no need to iterate over any further
  // modules

  if (q->has_kernel && q->dw.module_name_matches("kernel"))
    return DWARF_CB_ABORT;

  return DWARF_CB_OK;
}

struct
var_expanding_copy_visitor
  : public deep_copy_visitor
{
  // Alas, we cannot easily mixin lvalue_aware_traversing_visitor.
  // But behold the *awesome power* of copy and paste.

  static unsigned tick;

  dwarf_query & q;
  unsigned lval_depth;
  Dwarf_Addr addr;

  var_expanding_copy_visitor(dwarf_query & q, Dwarf_Addr a)
    : q(q), lval_depth(0), addr(a)
  {}

  bool is_in_lvalue()
  {
    return lval_depth > 0;
  }

  void visit_pre_crement (pre_crement* e)
  {
    ++lval_depth;
    deep_copy_visitor::visit_pre_crement (e);
    --lval_depth;
  }

  void visit_post_crement (post_crement* e)
  {
    ++lval_depth;
    deep_copy_visitor::visit_post_crement (e);
    --lval_depth;
  }

  void visit_assignment (assignment* e)
  {
    assignment* n = new assignment;
    n->op = e->op;
    n->tok = e->tok;
    ++lval_depth;
    require <expression*> (this, &(n->left), e->left);
    --lval_depth;
    require <expression*> (this, &(n->right), e->right);
    provide <assignment*> (this, n);
  }

  void visit_delete_statement (delete_statement* s)
  {
    ++lval_depth;
    deep_copy_visitor::visit_delete_statement (s);
    --lval_depth;
  }

  void visit_symbol (symbol* e);
};


unsigned var_expanding_copy_visitor::tick = 0;


void
var_expanding_copy_visitor::visit_symbol (symbol *e)
{
  if (e->name.size() > 0 &&
      e->name[0] == '$')
    {
      if (is_in_lvalue())
	{
	  throw semantic_error("read-only special variable "
			       + e->name + " used in lvalue", e->tok);
	}

      string fname = "get_" + e->name.substr(1) + "_" + lex_cast<string>(tick++);

      // synthesize a function
      functiondecl *fdecl = new functiondecl;
      embeddedcode *ec = new embeddedcode;
      ec->code = q.dw.literal_stmt_for_local(addr, e->name.substr(1));
      fdecl->name = fname;
      fdecl->body = ec;
      fdecl->type = pe_long;
      q.sess.functions.push_back(fdecl);

      // synthesize a call
      functioncall* n = new functioncall;
      n->tok = e->tok;
      n->function = fname;
      n->referent = NULL;
      provide <functioncall*> (this, n);

    }
  else
    {
      deep_copy_visitor::visit_symbol (e);
    }
}


dwarf_derived_probe::dwarf_derived_probe (dwarf_query & q,
					  Dwarf_Addr addr)
  : derived_probe (NULL),
    module_name(q.dw.module_name),
    function_name(q.dw.function_name),
    has_statement(q.has_statement_str || q.has_statement_num),
    addr(addr),
    module_bias(q.dw.module_bias),
    has_return (q.has_return)
{
  // first synthesize an "expanded" location
  vector<probe_point::component*> comps;
  comps.push_back
    (module_name == TOK_KERNEL
     ? new probe_point::component(TOK_KERNEL)
     : new probe_point::component
     (TOK_MODULE, new literal_string(module_name)));
  
  if (!function_name.empty())
    {
      comps.push_back
	(new probe_point::component
	 (TOK_FUNCTION, new literal_string(function_name)));
      // XXX: add "@filename:linenumber" when able

      if (has_return)
	comps.push_back
	  (new probe_point::component(TOK_RETURN));
    }

  if (has_statement)
    comps.push_back
      (new probe_point::component
       (TOK_STATEMENT, new literal_number(addr)));
  
  
  assert(q.base_probe->locations.size() > 0);
  locations.push_back(new probe_point(comps, q.base_probe->locations[0]->tok));

  // Now make a local-variable-expanded copy of the probe body
  var_expanding_copy_visitor v (q, addr);
  require <block*> (&v, &(this->body), q.base_probe->body);
  this->tok = q.base_probe->tok;
}

void
dwarf_derived_probe::register_relative_variants(match_node * root,
						dwarf_builder * dw)
{
  // Here we match 2 forms:
  //
  // .
  // .relative(NN)

  root->bind(dw);
  root->bind_num(TOK_RELATIVE)->bind(dw);
}

void
dwarf_derived_probe::register_statement_variants(match_node * root,
						 dwarf_builder * dw)
{
  // Here we match 3 forms:
  //
  // .
  // .return
  // .label("foo")

  register_relative_variants(root, dw);
  register_relative_variants(root->bind_str(TOK_LABEL), dw);
}

void
dwarf_derived_probe::register_function_variants(match_node * root,
					      dwarf_builder * dw)
{
  // Here we match 4 forms:
  //
  // .
  // .return
  // .callees
  // .callees(N)
  //
  // The last form permits N-level callee resolving without any
  // recursive .callees.callees.callees... pattern-matching on our part.

  root->bind(dw);
  root->bind(TOK_RETURN)->bind(dw);
  root->bind(TOK_CALLEES)->bind(dw);
  root->bind_num(TOK_CALLEES)->bind(dw);
}

void
dwarf_derived_probe::register_function_and_statement_variants(match_node * root,
							      dwarf_builder * dw)
{
  // Here we match 4 forms:
  //
  // .function("foo")
  // .function(0xdeadbeef)
  // .statement("foo")
  // .statement(0xdeadbeef)

  register_function_variants(root->bind_str(TOK_FUNCTION), dw);
  register_function_variants(root->bind_num(TOK_FUNCTION), dw);
  register_statement_variants(root->bind_str(TOK_STATEMENT), dw);
  register_statement_variants(root->bind_num(TOK_STATEMENT), dw);
}

void
dwarf_derived_probe::register_patterns(match_node * root)
{
  dwarf_builder *dw = new dwarf_builder();

  // Here we match 3 forms:
  //
  // .kernel
  // .module("foo")
  // .process("foo")

  register_function_and_statement_variants(root->bind(TOK_KERNEL), dw);
  // XXX: may need to disable these for 2005-08 release
  register_function_and_statement_variants(root->bind_str(TOK_MODULE), dw);
  register_function_and_statement_variants(root->bind_str(TOK_PROCESS), dw);
}

static string
probe_entry_function_name(unsigned probenum)
{
  return "dwarf_kprobe_" + lex_cast<string>(probenum) + "_enter";
}

static string
probe_entry_struct_kprobe_name(unsigned probenum)
{
  return "dwarf_kprobe_" + lex_cast<string>(probenum);
}

void
dwarf_derived_probe::emit_registrations (translator_output* o, unsigned probenum)
{
  if (module_name.empty() || module_name == "kernel")
    {
      if (has_return)
        {
          o->newline() << probe_entry_struct_kprobe_name(probenum)
                       << ".kp.addr = (void *) 0x" << hex << addr << ";";
          o->newline() << "rc = register_kretprobe (&"
                       << probe_entry_struct_kprobe_name(probenum)
                       << ");";
        }
      else
        {
          o->newline() << probe_entry_struct_kprobe_name(probenum)
                       << ".addr = (void *) 0x" << hex << addr << ";";
          o->newline() << "rc = register_kprobe (&"
                       << probe_entry_struct_kprobe_name(probenum)
                       << ");";
        }
    }
  else
    {
      o->newline() << "{";
      o->indent(1);
      o->newline() << "struct module *mod = get_module(\"" << module_name << "\");";
      o->newline() << "if (!mod)";
      o->newline(1) << "rc++;";
      o->newline(-1) << "else {";
      o->newline(1) << probe_entry_struct_kprobe_name(probenum)
		   << ".addr = (void *) (mod->module_core + 0x" << hex << addr << ");";
      o->newline() << "rc = register_kprobe (&"
		   << probe_entry_struct_kprobe_name(probenum)
		   << ");";
      o->newline(-1) << "}";
      o->newline(-1) << "}";
    }
}

void
dwarf_derived_probe::emit_deregistrations (translator_output* o, unsigned probenum)
{
  if (has_return)
    o->newline() << "unregister_kretprobe (& "
                 << probe_entry_struct_kprobe_name(probenum)
                 << ");";
  else
    o->newline() << "unregister_kprobe (& "
                 << probe_entry_struct_kprobe_name(probenum)
                 << ");";
}

void
dwarf_derived_probe::emit_probe_entries (translator_output* o, unsigned probenum)
{

  // Construct a single entry function, and a struct kprobe pointing into
  // the entry function. The entry function will call the probe function.
  o->newline();
  o->newline() << "static int ";
  o->newline() << probe_entry_function_name(probenum) << " (";
  if (has_return)
    o->line() << "struct kretprobe_instance *_ignored";
  else
    o->line() << "struct kprobe *_ignored";
  o->line() << ", struct pt_regs *regs) {";
  o->newline(1) << "struct context *c = & contexts [smp_processor_id()];";
  o->newline();

  // A precondition for running a probe handler is that we're in RUNNING
  // state (not ERROR), and that no one else is already using this context.
  o->newline() << "if (atomic_read (&session_state) != STAP_SESSION_RUNNING)";
  o->newline(1) << "return 0;";
  o->newline(-1) << "if (c->busy) {";
  o->newline(1) << "printk (KERN_ERR \"probe reentrancy\");";
  o->newline() << "atomic_set (& session_state, STAP_SESSION_ERROR);";
  o->newline() << "return 0;";
  o->newline(-1) << "}";
  o->newline();

  o->newline() << "c->busy ++;";
  o->newline() << "mb ();"; // for smp
  o->newline() << "c->errorcount = 0;";
  o->newline() << "c->actioncount = 0;";
  o->newline() << "c->nesting = 0;";
  o->newline() << "c->regs = regs;";
  // NB: locals are initialized by probe function itself
  o->newline() << "probe_" << probenum << " (c);";

  // see translate.cxx: visit_functioncall and elsewhere to see all the
  // possible context indications that a probe exited prematurely
  o->newline() << "if (c->errorcount || c->actioncount > MAXACTION"
               << " || c->nesting+2 >= MAXNESTING) {";
  o->newline(1) << "printk (KERN_ERR \"probe execution failure (e%d,n%d,a%d)\",";
  o->newline(1) << "c->errorcount, c->nesting, c->actioncount);";
  o->newline(-1) << "atomic_set (& session_state, STAP_SESSION_ERROR);";
  o->newline(-1) << "}";

  o->newline() << "c->busy --;";
  o->newline() << "mb ();";

  o->newline() << "return 0;";
  o->newline(-1) << "}" << endl;

  o->newline();
  if (has_return)
    {
      o->newline() << "static struct kretprobe "
                   << probe_entry_struct_kprobe_name(probenum)
                   << "= {";
      o->newline(1) << ".kp.addr = 0x0," ;
      o->newline() << ".handler = &" << probe_entry_function_name(probenum);
      o->newline(-1) << "};";
    }
  else
    {
      o->newline() << "static struct kprobe "
                   << probe_entry_struct_kprobe_name(probenum)
                   << "= {";
      o->newline(1) << ".addr       = 0x0," ;
      o->newline() << ".pre_handler = &" << probe_entry_function_name(probenum);
      o->newline(-1) << "};";
    }
  o->newline();
}


void
dwarf_builder::build(systemtap_session & sess,
		     probe * base,
		     probe_point * location,
		     std::map<std::string, literal *> const & parameters,
		     vector<probe *> & results_to_expand_further,
		     vector<derived_probe *> & finished_results)
{

  dwflpp dw(sess);
  dwarf_query q(sess, base, location, dw, parameters, finished_results);

  dw.setup(q.has_kernel || q.has_module);

  if (q.has_kernel && q.has_statement_num)
    {
      // If we have kernel.statement(0xbeef), the address is global
      // (relative to the kernel) and we can seek directly to the
      // statement in question.
      query_statement(q.statement_num_val, &q);
    }
  else if (q.has_kernel && q.has_function_num)
    {
      // If we have kernel.function(0xbeef), the address is global
      // (relative to the kernel) and we can seek directly to the
      // cudie in question.
      dw.focus_on_cu_containing_global_address(q.function_num_val);
      dw.iterate_over_functions(&query_function, &q);
    }
  else
    {
      // Otherwise we have module("foo"), kernel.statement("foo"), or
      // kernel.function("foo"); in these cases we need to scan all
      // the modules.
      assert((q.has_kernel && q.has_function_str) ||
	     (q.has_kernel && q.has_statement_str) ||
	     (q.has_module));
      dw.iterate_over_modules(&query_module, &q);
    }
}


// ------------------------------------------------------------------------
//  Standard tapset registry.
// ------------------------------------------------------------------------

void
register_standard_tapsets(systemtap_session & s)
{
  // Rudimentary binders for begin and end targets
  s.pattern_root->bind("begin")->bind(new be_builder(true));
  s.pattern_root->bind("end")->bind(new be_builder(false));

  // kernel/module parts
  dwarf_derived_probe::register_patterns(s.pattern_root);
}