summaryrefslogtreecommitdiffstats
path: root/buildrun.cxx
blob: 3091c51105172f3dd5da191e33c863daec468b0f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
// build/run probes
// Copyright (C) 2005-2009 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 "buildrun.h"
#include "session.h"
#include "util.h"

#include <cstdlib>
#include <fstream>
#include <sstream>

extern "C" {
#include <signal.h>
#include <sys/wait.h>
#include <pwd.h>
#include <grp.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
}


using namespace std;

static int uprobes_pass (systemtap_session& s);

/* Adjust and run make_cmd to build a kernel module. */
static int
run_make_cmd(systemtap_session& s, string& make_cmd)
{
  // Before running make, fix up the environment a bit.  PATH should
  // already be overridden.  Clean out a few variables that
  // s.kernel_build_tree/Makefile uses.
  int rc = unsetenv("ARCH") || unsetenv("KBUILD_EXTMOD")
      || unsetenv("CROSS_COMPILE") || unsetenv("KBUILD_IMAGE")
      || unsetenv("KCONFIG_CONFIG") || unsetenv("INSTALL_PATH");
  if (rc)
    {
      const char* e = strerror (errno);
      cerr << "unsetenv failed: " << e << endl;
    }

  // Disable ccache to avoid saving files that will never be reused.
  // (ccache is useless to us, because our compiler commands always
  // include the randomized tmpdir path.)
  // It's not critical if this fails, so the return is ignored.
  (void) setenv("CCACHE_DISABLE", "1", 0);

  if (s.verbose > 2)
    make_cmd += " V=1";
  else if (s.verbose > 1)
    make_cmd += " --no-print-directory";
  else
    make_cmd += " -s --no-print-directory";

  if (strverscmp (s.kernel_base_release.c_str(), "2.6.29") < 0)
    {
      // Older kernels, before linux commit #fd54f502841c1, include
      // gratuitous "echo"s in their Makefile.  We need to suppress
      // that with this bluntness.
      make_cmd += " >/dev/null";
    }

  return stap_system (s.verbose, make_cmd);
}

static void
output_autoconf(systemtap_session& s, ofstream& o, const char *autoconf_c,
                const char *deftrue, const char *deffalse)
{
  o << "\t";
  if (s.verbose < 4)
    o << "@";
  o << "if $(CHECK_BUILD) $(SYSTEMTAP_RUNTIME)/" << autoconf_c;
  if (s.verbose < 5)
    o << " > /dev/null 2>&1";
  o << "; then ";
  if (deftrue)
    o << "echo \"#define " << deftrue << " 1\"";
  if (deffalse)
    o << "; else echo \"#define " << deffalse << " 1\"";
  o << "; fi >> $@" << endl;
}

void output_cpu_khz (systemtap_session& s, ofstream& o)
{
  // PR10493: search cpu_khz in Module.symvers
  string kernel_export_file = s.kernel_build_tree + "/Module.symvers";
  char *line = NULL, *name = NULL, *module = NULL, *type = NULL;
  size_t len = 0;
  unsigned long address;
  int ret;
  FILE *sym = fopen(kernel_export_file.c_str(),"r");
  
  if (sym == NULL)
    return;
  while (!feof(sym))
    {
      if (getline(&line, &len, sym) < 0)
         break;
      ret = sscanf(line, "%lx %as %as %as", &address, &name, &module, &type);
      if (name == NULL || module == NULL || type == NULL) 
         continue;
      if (ret == 4) {
         // cpu_khz is kernel EXPORT_SYMBOL'd
         if (!strcmp(name, "cpu_khz") && !strcmp(module, "vmlinux")
             && strstr(type, "EXPORT_SYMBOL")) // match all to avoid corrupt file
          {
            o << "\t";
            if (s.verbose < 4)
               o << "@";
            o << "echo \"#define STAPCONF_CPU_KHZ 1\"";
            o << ">> $@" << endl;
            break;
          }
      }
    }
  if (sym)
    fclose(sym);
}

int
compile_pass (systemtap_session& s)
{
  int rc = uprobes_pass (s);
  if (rc)
    return rc;

  // fill in a quick Makefile
  string makefile_nm = s.tmpdir + "/Makefile";
  ofstream o (makefile_nm.c_str());

  // Create makefile

  // Clever hacks copied from vmware modules
  string superverbose;
  if (s.verbose > 3)
    superverbose = "set -x;";

  string redirecterrors = "> /dev/null 2>&1";
  if (s.verbose > 6)
    redirecterrors = "";

  // Support O= (or KBUILD_OUTPUT) option
  o << "_KBUILD_CFLAGS := $(call flags,KBUILD_CFLAGS)" << endl;

  o << "stap_check_gcc = $(shell " << superverbose << " if $(CC) $(1) -S -o /dev/null -xc /dev/null > /dev/null 2>&1; then echo \"$(1)\"; else echo \"$(2)\"; fi)" << endl;
  o << "CHECK_BUILD := $(CC) $(KBUILD_CPPFLAGS) $(CPPFLAGS) $(LINUXINCLUDE) $(_KBUILD_CFLAGS) $(CFLAGS_KERNEL) $(EXTRA_CFLAGS) $(CFLAGS) -DKBUILD_BASENAME=\\\"" << s.module_name << "\\\" -Werror -S -o /dev/null -xc " << endl;
  o << "stap_check_build = $(shell " << superverbose << " if $(CHECK_BUILD) $(1) " << redirecterrors << " ; then echo \"$(2)\"; else echo \"$(3)\"; fi)" << endl;

  o << "SYSTEMTAP_RUNTIME = \"" << s.runtime_path << "\"" << endl;

  // "autoconf" options go here

  // RHBZ 543529: early rhel6 kernels' module-signing kbuild logic breaks out-of-tree modules
  o << "CONFIG_MODULE_SIG := n" << endl;

  string module_cflags = "EXTRA_CFLAGS";
  o << module_cflags << " :=" << endl;

  // XXX: This gruesome hack is needed on some kernels built with separate O=directory,
  // where files like 2.6.27 x86's asm/mach-*/mach_mpspec.h are not found on the cpp path.
  // This could be a bug in arch/x86/Makefile that names
  //      mflags-y += -Iinclude/asm-x86/mach-default
  // but that path does not exist in an O= build tree.
  o << module_cflags << " += -Iinclude2/asm/mach-default" << endl;

  // NB: don't try
  // o << module_cflags << " += -Iusr/include" << endl;
  // since such headers are cleansed of _KERNEL_ pieces that we need

  o << "STAPCONF_HEADER := " << s.tmpdir << "/" << s.stapconf_name << endl;
  o << s.translated_source << ": $(STAPCONF_HEADER)" << endl;
  o << "$(STAPCONF_HEADER):" << endl;
  o << "\t@echo -n > $@" << endl;
  output_autoconf(s, o, "autoconf-hrtimer-rel.c", "STAPCONF_HRTIMER_REL", NULL);
  output_autoconf(s, o, "autoconf-hrtimer-getset-expires.c", "STAPCONF_HRTIMER_GETSET_EXPIRES", NULL);
  output_autoconf(s, o, "autoconf-inode-private.c", "STAPCONF_INODE_PRIVATE", NULL);
  output_autoconf(s, o, "autoconf-constant-tsc.c", "STAPCONF_CONSTANT_TSC", NULL);
  output_autoconf(s, o, "autoconf-tsc-khz.c", "STAPCONF_TSC_KHZ", NULL);
  output_autoconf(s, o, "autoconf-ktime-get-real.c", "STAPCONF_KTIME_GET_REAL", NULL);
  output_autoconf(s, o, "autoconf-x86-uniregs.c", "STAPCONF_X86_UNIREGS", NULL);
  output_autoconf(s, o, "autoconf-nameidata.c", "STAPCONF_NAMEIDATA_CLEANUP", NULL);
  output_autoconf(s, o, "autoconf-unregister-kprobes.c", "STAPCONF_UNREGISTER_KPROBES", NULL);
  output_autoconf(s, o, "autoconf-real-parent.c", "STAPCONF_REAL_PARENT", NULL);
  output_autoconf(s, o, "autoconf-uaccess.c", "STAPCONF_LINUX_UACCESS_H", NULL);
  output_autoconf(s, o, "autoconf-oneachcpu-retry.c", "STAPCONF_ONEACHCPU_RETRY", NULL);
  output_autoconf(s, o, "autoconf-dpath-path.c", "STAPCONF_DPATH_PATH", NULL);
  output_autoconf(s, o, "autoconf-synchronize-sched.c", "STAPCONF_SYNCHRONIZE_SCHED", NULL);
  output_autoconf(s, o, "autoconf-task-uid.c", "STAPCONF_TASK_UID", NULL);
  output_autoconf(s, o, "autoconf-vm-area.c", "STAPCONF_VM_AREA", NULL);
  output_autoconf(s, o, "autoconf-procfs-owner.c", "STAPCONF_PROCFS_OWNER", NULL);
  output_autoconf(s, o, "autoconf-alloc-percpu-align.c", "STAPCONF_ALLOC_PERCPU_ALIGN", NULL);
  output_autoconf(s, o, "autoconf-x86-gs.c", "STAPCONF_X86_GS", NULL);
  output_autoconf(s, o, "autoconf-grsecurity.c", "STAPCONF_GRSECURITY", NULL);
  output_autoconf(s, o, "autoconf-trace-printk.c", "STAPCONF_TRACE_PRINTK", NULL);
  output_autoconf(s, o, "autoconf-regset.c", "STAPCONF_REGSET", NULL);
  output_autoconf(s, o, "autoconf-utrace-regset.c", "STAPCONF_UTRACE_REGSET", NULL);
  output_cpu_khz(s, o);

#if 0
  /* NB: For now, the performance hit of probe_kernel_read/write (vs. our
   * homegrown safe-access functions) is deemed undesireable, so we'll skip
   * this autoconf. */
  output_autoconf(s, o, "autoconf-probe-kernel.c", "STAPCONF_PROBE_KERNEL", NULL);
#endif
  output_autoconf(s, o, "autoconf-save-stack-trace.c",
                  "STAPCONF_KERNEL_STACKTRACE", NULL);
  output_autoconf(s, o, "autoconf-asm-syscall.c",
		  "STAPCONF_ASM_SYSCALL_H", NULL);
  output_autoconf(s, o, "autoconf-ring_buffer-flags.c", "STAPCONF_RING_BUFFER_FLAGS", NULL);

  o << module_cflags << " += -include $(STAPCONF_HEADER)" << endl;

  for (unsigned i=0; i<s.macros.size(); i++)
    o << "EXTRA_CFLAGS += -D " << lex_cast_qstring(s.macros[i]) << endl;

  if (s.verbose > 3)
    o << "EXTRA_CFLAGS += -ftime-report -Q" << endl;

  // XXX: unfortunately, -save-temps can't work since linux kbuild cwd
  // is not writeable.
  //
  // if (s.keep_tmpdir)
  // o << "CFLAGS += -fverbose-asm -save-temps" << endl;

  // Kernels can be compiled with CONFIG_CC_OPTIMIZE_FOR_SIZE to select
  // -Os, otherwise -O2 is the default.
  o << "EXTRA_CFLAGS += -freorder-blocks" << endl; // improve on -Os

  // We used to allow the user to override default optimization when so
  // requested by adding a -O[0123s] so they could determine the
  // time/space/speed tradeoffs themselves, but we cannot guantantee that
  // the (un)optimized code actually compiles and/or generates functional
  // code, so we had to remove it.
  // o << "EXTRA_CFLAGS += " << s.gcc_flags << endl; // Add -O[0123s]

  // o << "CFLAGS += -fno-unit-at-a-time" << endl;

  // 512 bytes should be enough for anybody
  // XXX but it's not enough for unwind_frame -- PR10821
  // XXX temporarily bumping to 600 bytes
  o << "EXTRA_CFLAGS += $(call cc-option,-Wframe-larger-than=600)" << endl;

  // Assumes linux 2.6 kbuild
  o << "EXTRA_CFLAGS += -Wno-unused -Werror" << endl;
  #if CHECK_POINTER_ARITH_PR5947
  o << "EXTRA_CFLAGS += -Wpointer-arith" << endl;
  #endif
  o << "EXTRA_CFLAGS += -I\"" << s.runtime_path << "\"" << endl;
  // XXX: this may help ppc toc overflow
  // o << "CFLAGS := $(subst -Os,-O2,$(CFLAGS)) -fminimal-toc" << endl;
  o << "obj-m := " << s.module_name << ".o" << endl;

  o.close ();

  // Generate module directory pathname and make sure it exists.
  string module_dir = s.kernel_build_tree;
  string module_dir_makefile = module_dir + "/Makefile";
  struct stat st;
  rc = stat(module_dir_makefile.c_str(), &st);
  if (rc != 0)
    {
	clog << "Checking \"" << module_dir_makefile << "\" failed: " << strerror(errno) << endl
	     << "Ensure kernel development headers & makefiles are installed." << endl;
	return rc;
    }

  // Run make
  string make_cmd = string("make")
    + string (" -C \"") + module_dir + string("\""); // XXX: lex_cast_qstring?
  make_cmd += string(" M=\"") + s.tmpdir + string("\"");

  // Add architecture
  make_cmd += string(" ARCH=") + lex_cast_qstring(s.architecture);

  // Add any custom kbuild flags
  for (unsigned k=0; k<s.kbuildflags.size(); k++)
    make_cmd += string(" ") + lex_cast_qstring(s.kbuildflags[k]);

  make_cmd += string (" modules");

  rc = run_make_cmd(s, make_cmd);

  return rc;
}

/*
 * If uprobes was built as part of the kernel build (either built-in
 * or as a module), the uprobes exports should show up in either
 * s.kernel_build_tree / Module.symvers.  Return true if so.
 */
static bool
kernel_built_uprobes (systemtap_session& s)
{
  string grep_cmd = string ("/bin/grep -q unregister_uprobe ") + 
    s.kernel_build_tree + string ("/Module.symvers");

  return (stap_system (s.verbose, grep_cmd) == 0);
}

/*
 * We only want root, the owner of the uprobes build directory
 * and members of the group owning the uprobes build directory
 * modifying uprobes.
 */
static bool
may_build_uprobes (const systemtap_session& s)
{
  // root may build uprobes.
  uid_t euid = geteuid ();
  if (euid == 0)
    return true;

  // Get information on the build directory.
  string uprobes_home = s.runtime_path + "/uprobes";
  struct stat file_info;
  if (stat(uprobes_home.c_str(), &file_info) != 0) {
    clog << "Unable to obtain information on " << uprobes_home << '.' << endl;
    return false;
  }

  // The owner of the build directory may build uprobes.
  if (euid == file_info.st_uid)
    return true;

  // Members of the group owner of the build directory may build uprobes.
  if (in_group_id (file_info.st_gid))
    return true;

  return false;
}

/*
 * Use "make -q" with a fake target to
 * verify that uprobes doesn't need to be rebuilt.
 */
static bool
verify_uprobes_uptodate (systemtap_session& s)
{
  if (s.verbose)
    clog << "Pass 4, preamble: "
	 << "verifying that SystemTap's version of uprobes is up to date."
	 << endl;

  string uprobes_home = s.runtime_path + "/uprobes";
  string make_cmd = string("make -q -C ") + uprobes_home
    + string(" uprobes.ko");
  int rc = run_make_cmd(s, make_cmd);
  if (rc) {
    clog << "SystemTap's version of uprobes is out of date." << endl;

    struct stat file_info;
    if (stat(uprobes_home.c_str(), &file_info) != 0) {
      clog << "Unable to obtain information on " << uprobes_home << '.' << endl;
    }
    else {
      struct passwd *owner = getpwuid (file_info.st_uid);
      string owner_name = owner == NULL ? "The owner of " + uprobes_home :
	                                  owner->pw_name;
      if (owner_name == "root")
	owner_name = "";
      struct group *owner_group = getgrgid (file_info.st_gid);
      string owner_group_name = owner_group == NULL ? "The owner group of " + uprobes_home :
	                                              owner_group->gr_name;
      clog << "As root, " << owner_name << (owner_name.empty () ? "" : ", ")
	   << "or a member of the '" << owner_group_name << "' group, run" << endl;
      clog << "\"make -C " << uprobes_home << "\"." << endl;
    }
  }

  return rc;
}

static int
make_uprobes (systemtap_session& s)
{
  if (s.verbose)
    clog << "Pass 4, preamble: "
	 << "(re)building SystemTap's version of uprobes."
	 << endl;

  string uprobes_home = s.runtime_path + "/uprobes";
  string make_cmd = string("make -C ") + uprobes_home;
  int rc = run_make_cmd(s, make_cmd);
  if (s.verbose > 1)
    clog << "uprobes rebuild rc=" << rc << endl;

  return rc;
}

/*
 * Copy uprobes' exports (in Module.symvers) into the temporary directory
 * so the script-module build can find them.
 */
static int
copy_uprobes_symbols (const systemtap_session& s)
{
  string uprobes_home = s.runtime_path + "/uprobes";
  string cp_cmd = string("/bin/cp ") + uprobes_home +
    string("/Module.symvers ") + s.tmpdir;

  return stap_system (s.verbose, cp_cmd);
}

static int
uprobes_pass (systemtap_session& s)
{
  if (!s.need_uprobes || kernel_built_uprobes(s))
    return 0;
  /*
   * We need to use the version of uprobes that comes with SystemTap, so
   * we may need to rebuild uprobes.ko there.  Unfortunately, this is
   * never a no-op; e.g., the modpost step gets run every time.  Only
   * certain users can build uprobes, so we keep the uprobes directory
   * writable only by those users.  But that means that other users
   * can't run the make even if everything's up to date.
   *
   * So for the other users, we just verify that uprobes doesn't need
   * to be rebuilt.  If that's not so, stap must fail.
   */
  int rc;
  if (may_build_uprobes (s))
    rc = make_uprobes(s);
  else
    rc = verify_uprobes_uptodate(s);
  if (rc == 0)
    rc = copy_uprobes_symbols(s);
  return rc;
}

int
run_pass (systemtap_session& s)
{
  // for now, just spawn staprun
  string staprun_cmd = string(getenv("SYSTEMTAP_STAPRUN") ?: BINDIR "/staprun")
    + " "
    + (s.verbose>1 ? "-v " : "")
    + (s.verbose>2 ? "-v " : "")
    + (s.output_file.empty() ? "" : "-o " + s.output_file + " ");

  if (s.cmd != "")
    staprun_cmd += "-c " + cmdstr_quoted(s.cmd) + " ";

  if (s.target_pid)
    staprun_cmd += "-t " + lex_cast(s.target_pid) + " ";

  if (s.buffer_size)
    staprun_cmd += "-b " + lex_cast(s.buffer_size) + " ";

  if (s.need_uprobes)
    staprun_cmd += "-u ";

  if (s.load_only)
    staprun_cmd += (s.output_file.empty() ? "-L " : "-D ");

  if (!s.size_option.empty())
    staprun_cmd += "-S " + s.size_option + " ";

  staprun_cmd += s.tmpdir + "/" + s.module_name + ".ko";

  return stap_system (s.verbose, staprun_cmd);
}


// Build a tiny kernel module to query tracepoints
int
make_tracequery(systemtap_session& s, string& name,
                const vector<string>& headers)
{
  static unsigned tick = 0;
  string basename("tracequery_kmod_" + lex_cast(++tick));

  // create a subdirectory for the module
  string dir(s.tmpdir + "/" + basename);
  if (create_dir(dir.c_str()) != 0)
    {
      if (! s.suppress_warnings)
        cerr << "Warning: failed to create directory for querying tracepoints." << endl;
      return 1;
    }

  name = dir + "/" + basename + ".ko";

  // create a simple Makefile
  string makefile(dir + "/Makefile");
  ofstream omf(makefile.c_str());
  // force debuginfo generation, and relax implicit functions
  omf << "EXTRA_CFLAGS := -g -Wno-implicit-function-declaration -Werror" << endl;
  omf << "obj-m := " + basename + ".o" << endl;
  omf.close();

  // create our source file
  string source(dir + "/" + basename + ".c");
  ofstream osrc(source.c_str());
  osrc << "#ifdef CONFIG_TRACEPOINTS" << endl;
  osrc << "#include <linux/tracepoint.h>" << endl;

  // override DECLARE_TRACE to synthesize probe functions for us
  osrc << "#undef DECLARE_TRACE" << endl;
  osrc << "#define DECLARE_TRACE(name, proto, args) \\" << endl;
  osrc << "  void stapprobe_##name(proto) {}" << endl;

  // older tracepoints used DEFINE_TRACE, so redirect that too
  osrc << "#undef DEFINE_TRACE" << endl;
  osrc << "#define DEFINE_TRACE(name, proto, args) \\" << endl;
  osrc << "  DECLARE_TRACE(name, TPPROTO(proto), TPARGS(args))" << endl;

  // add the specified headers
  for (unsigned z=0; z<headers.size(); z++)
    osrc << "#include <" << headers[z] << ">\n";

  // finish up the module source
  osrc << "#endif /* CONFIG_TRACEPOINTS */" << endl;
  osrc.close();

  // make the module
  string make_cmd = "make -C '" + s.kernel_build_tree + "'"
    + " M='" + dir + "' modules";

  // Add architecture
  make_cmd += string(" ARCH=") + lex_cast_qstring(s.architecture);

  // Add any custom kbuild flags
  for (unsigned k=0; k<s.kbuildflags.size(); k++)
    make_cmd += string(" ") + lex_cast_qstring(s.kbuildflags[k]);

  if (s.verbose < 4)
    make_cmd += " >/dev/null 2>&1";
  return run_make_cmd(s, make_cmd);
}


// Build a tiny kernel module to query type information
static int
make_typequery_kmod(systemtap_session& s, const string& header, string& name)
{
  static unsigned tick = 0;
  string basename("typequery_kmod_" + lex_cast(++tick));

  // create a subdirectory for the module
  string dir(s.tmpdir + "/" + basename);
  if (create_dir(dir.c_str()) != 0)
    {
      if (! s.suppress_warnings)
        cerr << "Warning: failed to create directory for querying types." << endl;
      return 1;
    }

  name = dir + "/" + basename + ".ko";

  // create a simple Makefile
  string makefile(dir + "/Makefile");
  ofstream omf(makefile.c_str());
  omf << "EXTRA_CFLAGS := -g -fno-eliminate-unused-debug-types" << endl;

  // NB: We use -include instead of #include because that gives us more power.
  // Using #include searches relative to the source's path, which in this case
  // is /tmp/..., so that's not helpful.  Using -include will search relative
  // to the cwd, which will be the kernel build root.  This means if you have a
  // full kernel build tree, it's possible to get at types that aren't in the
  // normal include path, e.g.:
  //    @cast(foo, "bsd_acct_struct", "kernel<kernel/acct.c>")->...
  omf << "CFLAGS_" << basename << ".o := -include " << header << endl;

  omf << "obj-m := " + basename + ".o" << endl;
  omf.close();

  // create our empty source file
  string source(dir + "/" + basename + ".c");
  ofstream osrc(source.c_str());
  osrc.close();

  // make the module
  string make_cmd = "make -C '" + s.kernel_build_tree + "'"
    + " M='" + dir + "' modules";

  // Add architecture
  make_cmd += string(" ARCH=") + lex_cast_qstring(s.architecture);

  // Add any custom kbuild flags
  for (unsigned k=0; k<s.kbuildflags.size(); k++)
    make_cmd += string(" ") + lex_cast_qstring(s.kbuildflags[k]);

  if (s.verbose < 4)
    make_cmd += " >/dev/null 2>&1";
  return run_make_cmd(s, make_cmd);
}


// Build a tiny user module to query type information
static int
make_typequery_umod(systemtap_session& s, const string& header, string& name)
{
  static unsigned tick = 0;

  name = s.tmpdir + "/typequery_umod_" + lex_cast(++tick) + ".so";

  // make the module
  //
  // NB: As with kmod, using -include makes relative paths more useful.  The
  // cwd in this case will be the cwd of stap itself though, which may be
  // trickier to deal with.  It might be better to "cd `dirname $script`"
  // first...
  string cmd = "gcc -shared -g -fno-eliminate-unused-debug-types -o "
     + name + " -xc /dev/null -include " + header;
  if (s.verbose < 4)
    cmd += " >/dev/null 2>&1";
  return stap_system (s.verbose, cmd);
}


int
make_typequery(systemtap_session& s, string& module)
{
  int rc;
  string new_module;

  if (module[module.size() - 1] != '>')
    return -1;

  if (module[0] == '<')
    {
      string header = module.substr(1, module.size() - 2);
      rc = make_typequery_umod(s, header, new_module);
    }
  else if (module.compare(0, 7, "kernel<") == 0)
    {
      string header = module.substr(7, module.size() - 8);
      rc = make_typequery_kmod(s, header, new_module);
    }
  else
    return -1;

  if (!rc)
    module = new_module;

  return rc;
}

/* vim: set sw=2 ts=8 cino=>4,n-2,{2,^-2,t0,(0,u0,w1,M1 : */