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1#!/usr/bin/perl -w
2# (c) 2008, Steven Rostedt <srostedt@redhat.com>
3# Licensed under the terms of the GNU GPL License version 2
4#
5# recordmcount.pl - makes a section called __mcount_loc that holds
6# all the offsets to the calls to mcount.
7#
8#
9# What we want to end up with this is that each object file will have a
10# section called __mcount_loc that will hold the list of pointers to mcount
11# callers. After final linking, the vmlinux will have within .init.data the
12# list of all callers to mcount between __start_mcount_loc and __stop_mcount_loc.
13# Later on boot up, the kernel will read this list, save the locations and turn
14# them into nops. When tracing or profiling is later enabled, these locations
15# will then be converted back to pointers to some function.
16#
17# This is no easy feat. This script is called just after the original
18# object is compiled and before it is linked.
19#
20# When parse this object file using 'objdump', the references to the call
21# sites are offsets from the section that the call site is in. Hence, all
22# functions in a section that has a call site to mcount, will have the
23# offset from the beginning of the section and not the beginning of the
24# function.
25#
26# But where this section will reside finally in vmlinx is undetermined at
27# this point. So we can't use this kind of offsets to record the final
28# address of this call site.
29#
30# The trick is to change the call offset referring the start of a section to
31# referring a function symbol in this section. During the link step, 'ld' will
32# compute the final address according to the information we record.
33#
34# e.g.
35#
36# .section ".sched.text", "ax"
37# [...]
38# func1:
39# [...]
40# call mcount (offset: 0x10)
41# [...]
42# ret
43# .globl fun2
44# func2: (offset: 0x20)
45# [...]
46# [...]
47# ret
48# func3:
49# [...]
50# call mcount (offset: 0x30)
51# [...]
52#
53# Both relocation offsets for the mcounts in the above example will be
54# offset from .sched.text. If we choose global symbol func2 as a reference and
55# make another file called tmp.s with the new offsets:
56#
57# .section __mcount_loc
58# .quad func2 - 0x10
59# .quad func2 + 0x10
60#
61# We can then compile this tmp.s into tmp.o, and link it back to the original
62# object.
63#
64# In our algorithm, we will choose the first global function we meet in this
65# section as the reference. But this gets hard if there is no global functions
66# in this section. In such a case we have to select a local one. E.g. func1:
67#
68# .section ".sched.text", "ax"
69# func1:
70# [...]
71# call mcount (offset: 0x10)
72# [...]
73# ret
74# func2:
75# [...]
76# call mcount (offset: 0x20)
77# [...]
78# .section "other.section"
79#
80# If we make the tmp.s the same as above, when we link together with
81# the original object, we will end up with two symbols for func1:
82# one local, one global. After final compile, we will end up with
83# an undefined reference to func1 or a wrong reference to another global
84# func1 in other files.
85#
86# Since local objects can reference local variables, we need to find
87# a way to make tmp.o reference the local objects of the original object
88# file after it is linked together. To do this, we convert func1
89# into a global symbol before linking tmp.o. Then after we link tmp.o
90# we will only have a single symbol for func1 that is global.
91# We can convert func1 back into a local symbol and we are done.
92#
93# Here are the steps we take:
94#
95# 1) Record all the local and weak symbols by using 'nm'
96# 2) Use objdump to find all the call site offsets and sections for
97# mcount.
98# 3) Compile the list into its own object.
99# 4) Do we have to deal with local functions? If not, go to step 8.
100# 5) Make an object that converts these local functions to global symbols
101# with objcopy.
102# 6) Link together this new object with the list object.
103# 7) Convert the local functions back to local symbols and rename
104# the result as the original object.
105# 8) Link the object with the list object.
106# 9) Move the result back to the original object.
107#
108
109use strict;
110
111my $P = $0;
112$P =~ s@.*/@@g;
113
114my $V = '0.1';
115
116if ($#ARGV != 11) {
117 print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
118 print "version: $V\n";
119 exit(1);
120}
121
122my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
123 $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
124
125# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
126if ($inputfile =~ m,kernel/trace/ftrace\.o$,) {
127 exit(0);
128}
129
130# Acceptable sections to record.
131my %text_sections = (
132 ".text" => 1,
133 ".ref.text" => 1,
134 ".sched.text" => 1,
135 ".spinlock.text" => 1,
136 ".irqentry.text" => 1,
137 ".softirqentry.text" => 1,
138 ".kprobes.text" => 1,
139 ".cpuidle.text" => 1,
140 ".text.unlikely" => 1,
141);
142
143# Note: we are nice to C-programmers here, thus we skip the '||='-idiom.
144$objdump = 'objdump' if (!$objdump);
145$objcopy = 'objcopy' if (!$objcopy);
146$cc = 'gcc' if (!$cc);
147$ld = 'ld' if (!$ld);
148$nm = 'nm' if (!$nm);
149$rm = 'rm' if (!$rm);
150$mv = 'mv' if (!$mv);
151
152#print STDERR "running: $P '$arch' '$objdump' '$objcopy' '$cc' '$ld' " .
153# "'$nm' '$rm' '$mv' '$inputfile'\n";
154
155my %locals; # List of local (static) functions
156my %weak; # List of weak functions
157my %convert; # List of local functions used that needs conversion
158
159my $type;
160my $local_regex; # Match a local function (return function)
161my $weak_regex; # Match a weak function (return function)
162my $section_regex; # Find the start of a section
163my $function_regex; # Find the name of a function
164 # (return offset and func name)
165my $mcount_regex; # Find the call site to mcount (return offset)
166my $mcount_adjust; # Address adjustment to mcount offset
167my $alignment; # The .align value to use for $mcount_section
168my $section_type; # Section header plus possible alignment command
169my $can_use_local = 0; # If we can use local function references
170
171# Shut up recordmcount if user has older objcopy
172my $quiet_recordmcount = ".tmp_quiet_recordmcount";
173my $print_warning = 1;
174$print_warning = 0 if ( -f $quiet_recordmcount);
175
176##
177# check_objcopy - whether objcopy supports --globalize-symbols
178#
179# --globalize-symbols came out in 2.17, we must test the version
180# of objcopy, and if it is less than 2.17, then we can not
181# record local functions.
182sub check_objcopy
183{
184 open (IN, "$objcopy --version |") or die "error running $objcopy";
185 while (<IN>) {
186 if (/objcopy.*\s(\d+)\.(\d+)/) {
187 $can_use_local = 1 if ($1 > 2 || ($1 == 2 && $2 >= 17));
188 last;
189 }
190 }
191 close (IN);
192
193 if (!$can_use_local && $print_warning) {
194 print STDERR "WARNING: could not find objcopy version or version " .
195 "is less than 2.17.\n" .
196 "\tLocal function references are disabled.\n";
197 open (QUIET, ">$quiet_recordmcount");
198 printf QUIET "Disables the warning from recordmcount.pl\n";
199 close QUIET;
200 }
201}
202
203if ($arch =~ /(x86(_64)?)|(i386)/) {
204 if ($bits == 64) {
205 $arch = "x86_64";
206 } else {
207 $arch = "i386";
208 }
209}
210
211#
212# We base the defaults off of i386, the other archs may
213# feel free to change them in the below if statements.
214#
215$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
216$weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)";
217$section_regex = "Disassembly of section\\s+(\\S+):";
218$function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
219$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s(mcount|__fentry__)\$";
220$section_type = '@progbits';
221$mcount_adjust = 0;
222$type = ".long";
223
224if ($arch eq "x86_64") {
225 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s(mcount|__fentry__)([+-]0x[0-9a-zA-Z]+)?\$";
226 $type = ".quad";
227 $alignment = 8;
228 $mcount_adjust = -1;
229
230 # force flags for this arch
231 $ld .= " -m elf_x86_64";
232 $objdump .= " -M x86-64";
233 $objcopy .= " -O elf64-x86-64";
234 $cc .= " -m64";
235
236} elsif ($arch eq "i386") {
237 $alignment = 4;
238 $mcount_adjust = -1;
239
240 # force flags for this arch
241 $ld .= " -m elf_i386";
242 $objdump .= " -M i386";
243 $objcopy .= " -O elf32-i386";
244 $cc .= " -m32";
245
246} elsif ($arch eq "s390" && $bits == 64) {
247 if ($cc =~ /-DCC_USING_HOTPATCH/) {
248 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*brcl\\s*0,[0-9a-f]+ <([^\+]*)>\$";
249 $mcount_adjust = 0;
250 } else {
251 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$";
252 $mcount_adjust = -14;
253 }
254 $alignment = 8;
255 $type = ".quad";
256 $ld .= " -m elf64_s390";
257 $cc .= " -m64";
258
259} elsif ($arch eq "sh") {
260 $alignment = 2;
261
262 # force flags for this arch
263 $ld .= " -m shlelf_linux";
264 $objcopy .= " -O elf32-sh-linux";
265
266} elsif ($arch eq "powerpc") {
267 $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
268 # See comment in the sparc64 section for why we use '\w'.
269 $function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?\\w*?)>:";
270 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
271
272 if ($bits == 64) {
273 $type = ".quad";
274 }
275
276} elsif ($arch eq "arm") {
277 $alignment = 2;
278 $section_type = '%progbits';
279 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24|THM_CALL)" .
280 "\\s+(__gnu_mcount_nc|mcount)\$";
281
282} elsif ($arch eq "arm64") {
283 $alignment = 3;
284 $section_type = '%progbits';
285 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_AARCH64_CALL26\\s+_mcount\$";
286 $type = ".quad";
287} elsif ($arch eq "ia64") {
288 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
289 $type = "data8";
290
291 if ($is_module eq "0") {
292 $cc .= " -mconstant-gp";
293 }
294} elsif ($arch eq "sparc64") {
295 # In the objdump output there are giblets like:
296 # 0000000000000000 <igmp_net_exit-0x18>:
297 # As there's some data blobs that get emitted into the
298 # text section before the first instructions and the first
299 # real symbols. We don't want to match that, so to combat
300 # this we use '\w' so we'll match just plain symbol names,
301 # and not those that also include hex offsets inside of the
302 # '<>' brackets. Actually the generic function_regex setting
303 # could safely use this too.
304 $function_regex = "^([0-9a-fA-F]+)\\s+<(\\w*?)>:";
305
306 # Sparc64 calls '_mcount' instead of plain 'mcount'.
307 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
308
309 $alignment = 8;
310 $type = ".xword";
311 $ld .= " -m elf64_sparc";
312 $cc .= " -m64";
313 $objcopy .= " -O elf64-sparc";
314} elsif ($arch eq "mips") {
315 # To enable module support, we need to enable the -mlong-calls option
316 # of gcc for module, after using this option, we can not get the real
317 # offset of the calling to _mcount, but the offset of the lui
318 # instruction or the addiu one. herein, we record the address of the
319 # first one, and then we can replace this instruction by a branch
320 # instruction to jump over the profiling function to filter the
321 # indicated functions, or swith back to the lui instruction to trace
322 # them, which means dynamic tracing.
323 #
324 # c: 3c030000 lui v1,0x0
325 # c: R_MIPS_HI16 _mcount
326 # c: R_MIPS_NONE *ABS*
327 # c: R_MIPS_NONE *ABS*
328 # 10: 64630000 daddiu v1,v1,0
329 # 10: R_MIPS_LO16 _mcount
330 # 10: R_MIPS_NONE *ABS*
331 # 10: R_MIPS_NONE *ABS*
332 # 14: 03e0082d move at,ra
333 # 18: 0060f809 jalr v1
334 #
335 # for the kernel:
336 #
337 # 10: 03e0082d move at,ra
338 # 14: 0c000000 jal 0 <loongson_halt>
339 # 14: R_MIPS_26 _mcount
340 # 14: R_MIPS_NONE *ABS*
341 # 14: R_MIPS_NONE *ABS*
342 # 18: 00020021 nop
343 if ($is_module eq "0") {
344 $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_26\\s+_mcount\$";
345 } else {
346 $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_HI16\\s+_mcount\$";
347 }
348 $objdump .= " -Melf-trad".$endian."mips ";
349
350 if ($endian eq "big") {
351 $endian = " -EB ";
352 $ld .= " -melf".$bits."btsmip";
353 } else {
354 $endian = " -EL ";
355 $ld .= " -melf".$bits."ltsmip";
356 }
357
358 $cc .= " -mno-abicalls -fno-pic -mabi=" . $bits . $endian;
359 $ld .= $endian;
360
361 if ($bits == 64) {
362 $function_regex =
363 "^([0-9a-fA-F]+)\\s+<(.|[^\$]L.*?|\$[^L].*?|[^\$][^L].*?)>:";
364 $type = ".dword";
365 }
366} elsif ($arch eq "microblaze") {
367 # Microblaze calls '_mcount' instead of plain 'mcount'.
368 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
369} elsif ($arch eq "blackfin") {
370 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
371 $mcount_adjust = -4;
372} elsif ($arch eq "tilegx" || $arch eq "tile") {
373 # Default to the newer TILE-Gx architecture if only "tile" is given.
374 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
375 $type = ".quad";
376 $alignment = 8;
377} else {
378 die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
379}
380
381my $text_found = 0;
382my $read_function = 0;
383my $opened = 0;
384my $mcount_section = "__mcount_loc";
385
386my $dirname;
387my $filename;
388my $prefix;
389my $ext;
390
391if ($inputfile =~ m,^(.*)/([^/]*)$,) {
392 $dirname = $1;
393 $filename = $2;
394} else {
395 $dirname = ".";
396 $filename = $inputfile;
397}
398
399if ($filename =~ m,^(.*)(\.\S),) {
400 $prefix = $1;
401 $ext = $2;
402} else {
403 $prefix = $filename;
404 $ext = "";
405}
406
407my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
408my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
409
410check_objcopy();
411
412#
413# Step 1: find all the local (static functions) and weak symbols.
414# 't' is local, 'w/W' is weak
415#
416open (IN, "$nm $inputfile|") || die "error running $nm";
417while (<IN>) {
418 if (/$local_regex/) {
419 $locals{$1} = 1;
420 } elsif (/$weak_regex/) {
421 $weak{$2} = $1;
422 }
423}
424close(IN);
425
426my @offsets; # Array of offsets of mcount callers
427my $ref_func; # reference function to use for offsets
428my $offset = 0; # offset of ref_func to section beginning
429
430##
431# update_funcs - print out the current mcount callers
432#
433# Go through the list of offsets to callers and write them to
434# the output file in a format that can be read by an assembler.
435#
436sub update_funcs
437{
438 return unless ($ref_func and @offsets);
439
440 # Sanity check on weak function. A weak function may be overwritten by
441 # another function of the same name, making all these offsets incorrect.
442 if (defined $weak{$ref_func}) {
443 die "$inputfile: ERROR: referencing weak function" .
444 " $ref_func for mcount\n";
445 }
446
447 # is this function static? If so, note this fact.
448 if (defined $locals{$ref_func}) {
449
450 # only use locals if objcopy supports globalize-symbols
451 if (!$can_use_local) {
452 return;
453 }
454 $convert{$ref_func} = 1;
455 }
456
457 # Loop through all the mcount caller offsets and print a reference
458 # to the caller based from the ref_func.
459 if (!$opened) {
460 open(FILE, ">$mcount_s") || die "can't create $mcount_s\n";
461 $opened = 1;
462 print FILE "\t.section $mcount_section,\"a\",$section_type\n";
463 print FILE "\t.align $alignment\n" if (defined($alignment));
464 }
465 foreach my $cur_offset (@offsets) {
466 printf FILE "\t%s %s + %d\n", $type, $ref_func, $cur_offset - $offset;
467 }
468}
469
470#
471# Step 2: find the sections and mcount call sites
472#
473open(IN, "$objdump -hdr $inputfile|") || die "error running $objdump";
474
475my $text;
476
477
478# read headers first
479my $read_headers = 1;
480
481while (<IN>) {
482
483 if ($read_headers && /$mcount_section/) {
484 #
485 # Somehow the make process can execute this script on an
486 # object twice. If it does, we would duplicate the mcount
487 # section and it will cause the function tracer self test
488 # to fail. Check if the mcount section exists, and if it does,
489 # warn and exit.
490 #
491 print STDERR "ERROR: $mcount_section already in $inputfile\n" .
492 "\tThis may be an indication that your build is corrupted.\n" .
493 "\tDelete $inputfile and try again. If the same object file\n" .
494 "\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n";
495 exit(-1);
496 }
497
498 # is it a section?
499 if (/$section_regex/) {
500 $read_headers = 0;
501
502 # Only record text sections that we know are safe
503 $read_function = defined($text_sections{$1});
504 # print out any recorded offsets
505 update_funcs();
506
507 # reset all markers and arrays
508 $text_found = 0;
509 undef($ref_func);
510 undef(@offsets);
511
512 # section found, now is this a start of a function?
513 } elsif ($read_function && /$function_regex/) {
514 $text_found = 1;
515 $text = $2;
516
517 # if this is either a local function or a weak function
518 # keep looking for functions that are global that
519 # we can use safely.
520 if (!defined($locals{$text}) && !defined($weak{$text})) {
521 $ref_func = $text;
522 $read_function = 0;
523 $offset = hex $1;
524 } else {
525 # if we already have a function, and this is weak, skip it
526 if (!defined($ref_func) && !defined($weak{$text}) &&
527 # PPC64 can have symbols that start with .L and
528 # gcc considers these special. Don't use them!
529 $text !~ /^\.L/) {
530 $ref_func = $text;
531 $offset = hex $1;
532 }
533 }
534 }
535 # is this a call site to mcount? If so, record it to print later
536 if ($text_found && /$mcount_regex/) {
537 push(@offsets, (hex $1) + $mcount_adjust);
538 }
539}
540
541# dump out anymore offsets that may have been found
542update_funcs();
543
544# If we did not find any mcount callers, we are done (do nothing).
545if (!$opened) {
546 exit(0);
547}
548
549close(FILE);
550
551#
552# Step 3: Compile the file that holds the list of call sites to mcount.
553#
554`$cc -o $mcount_o -c $mcount_s`;
555
556my @converts = keys %convert;
557
558#
559# Step 4: Do we have sections that started with local functions?
560#
561if ($#converts >= 0) {
562 my $globallist = "";
563 my $locallist = "";
564
565 foreach my $con (@converts) {
566 $globallist .= " --globalize-symbol $con";
567 $locallist .= " --localize-symbol $con";
568 }
569
570 my $globalobj = $dirname . "/.tmp_gl_" . $filename;
571 my $globalmix = $dirname . "/.tmp_mx_" . $filename;
572
573 #
574 # Step 5: set up each local function as a global
575 #
576 `$objcopy $globallist $inputfile $globalobj`;
577
578 #
579 # Step 6: Link the global version to our list.
580 #
581 `$ld -r $globalobj $mcount_o -o $globalmix`;
582
583 #
584 # Step 7: Convert the local functions back into local symbols
585 #
586 `$objcopy $locallist $globalmix $inputfile`;
587
588 # Remove the temp files
589 `$rm $globalobj $globalmix`;
590
591} else {
592
593 my $mix = $dirname . "/.tmp_mx_" . $filename;
594
595 #
596 # Step 8: Link the object with our list of call sites object.
597 #
598 `$ld -r $inputfile $mcount_o -o $mix`;
599
600 #
601 # Step 9: Move the result back to the original object.
602 #
603 `$mv $mix $inputfile`;
604}
605
606# Clean up the temp files
607`$rm $mcount_o $mcount_s`;
608
609exit(0);
1#!/usr/bin/env perl
2# SPDX-License-Identifier: GPL-2.0-only
3# (c) 2008, Steven Rostedt <srostedt@redhat.com>
4#
5# recordmcount.pl - makes a section called __mcount_loc that holds
6# all the offsets to the calls to mcount.
7#
8#
9# What we want to end up with this is that each object file will have a
10# section called __mcount_loc that will hold the list of pointers to mcount
11# callers. After final linking, the vmlinux will have within .init.data the
12# list of all callers to mcount between __start_mcount_loc and __stop_mcount_loc.
13# Later on boot up, the kernel will read this list, save the locations and turn
14# them into nops. When tracing or profiling is later enabled, these locations
15# will then be converted back to pointers to some function.
16#
17# This is no easy feat. This script is called just after the original
18# object is compiled and before it is linked.
19#
20# When parse this object file using 'objdump', the references to the call
21# sites are offsets from the section that the call site is in. Hence, all
22# functions in a section that has a call site to mcount, will have the
23# offset from the beginning of the section and not the beginning of the
24# function.
25#
26# But where this section will reside finally in vmlinx is undetermined at
27# this point. So we can't use this kind of offsets to record the final
28# address of this call site.
29#
30# The trick is to change the call offset referring the start of a section to
31# referring a function symbol in this section. During the link step, 'ld' will
32# compute the final address according to the information we record.
33#
34# e.g.
35#
36# .section ".sched.text", "ax"
37# [...]
38# func1:
39# [...]
40# call mcount (offset: 0x10)
41# [...]
42# ret
43# .globl fun2
44# func2: (offset: 0x20)
45# [...]
46# [...]
47# ret
48# func3:
49# [...]
50# call mcount (offset: 0x30)
51# [...]
52#
53# Both relocation offsets for the mcounts in the above example will be
54# offset from .sched.text. If we choose global symbol func2 as a reference and
55# make another file called tmp.s with the new offsets:
56#
57# .section __mcount_loc
58# .quad func2 - 0x10
59# .quad func2 + 0x10
60#
61# We can then compile this tmp.s into tmp.o, and link it back to the original
62# object.
63#
64# In our algorithm, we will choose the first global function we meet in this
65# section as the reference. But this gets hard if there is no global functions
66# in this section. In such a case we have to select a local one. E.g. func1:
67#
68# .section ".sched.text", "ax"
69# func1:
70# [...]
71# call mcount (offset: 0x10)
72# [...]
73# ret
74# func2:
75# [...]
76# call mcount (offset: 0x20)
77# [...]
78# .section "other.section"
79#
80# If we make the tmp.s the same as above, when we link together with
81# the original object, we will end up with two symbols for func1:
82# one local, one global. After final compile, we will end up with
83# an undefined reference to func1 or a wrong reference to another global
84# func1 in other files.
85#
86# Since local objects can reference local variables, we need to find
87# a way to make tmp.o reference the local objects of the original object
88# file after it is linked together. To do this, we convert func1
89# into a global symbol before linking tmp.o. Then after we link tmp.o
90# we will only have a single symbol for func1 that is global.
91# We can convert func1 back into a local symbol and we are done.
92#
93# Here are the steps we take:
94#
95# 1) Record all the local and weak symbols by using 'nm'
96# 2) Use objdump to find all the call site offsets and sections for
97# mcount.
98# 3) Compile the list into its own object.
99# 4) Do we have to deal with local functions? If not, go to step 8.
100# 5) Make an object that converts these local functions to global symbols
101# with objcopy.
102# 6) Link together this new object with the list object.
103# 7) Convert the local functions back to local symbols and rename
104# the result as the original object.
105# 8) Link the object with the list object.
106# 9) Move the result back to the original object.
107#
108
109use warnings;
110use strict;
111
112my $P = $0;
113$P =~ s@.*/@@g;
114
115my $V = '0.1';
116
117if ($#ARGV != 11) {
118 print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
119 print "version: $V\n";
120 exit(1);
121}
122
123my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
124 $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
125
126# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
127if ($inputfile =~ m,kernel/trace/ftrace\.o$,) {
128 exit(0);
129}
130
131# Acceptable sections to record.
132my %text_sections = (
133 ".text" => 1,
134 ".init.text" => 1,
135 ".ref.text" => 1,
136 ".sched.text" => 1,
137 ".spinlock.text" => 1,
138 ".irqentry.text" => 1,
139 ".softirqentry.text" => 1,
140 ".kprobes.text" => 1,
141 ".cpuidle.text" => 1,
142 ".text.unlikely" => 1,
143);
144
145# Acceptable section-prefixes to record.
146my %text_section_prefixes = (
147 ".text." => 1,
148);
149
150# Note: we are nice to C-programmers here, thus we skip the '||='-idiom.
151$objdump = 'objdump' if (!$objdump);
152$objcopy = 'objcopy' if (!$objcopy);
153$cc = 'gcc' if (!$cc);
154$ld = 'ld' if (!$ld);
155$nm = 'nm' if (!$nm);
156$rm = 'rm' if (!$rm);
157$mv = 'mv' if (!$mv);
158
159#print STDERR "running: $P '$arch' '$objdump' '$objcopy' '$cc' '$ld' " .
160# "'$nm' '$rm' '$mv' '$inputfile'\n";
161
162my %locals; # List of local (static) functions
163my %weak; # List of weak functions
164my %convert; # List of local functions used that needs conversion
165
166my $type;
167my $local_regex; # Match a local function (return function)
168my $weak_regex; # Match a weak function (return function)
169my $section_regex; # Find the start of a section
170my $function_regex; # Find the name of a function
171 # (return offset and func name)
172my $mcount_regex; # Find the call site to mcount (return offset)
173my $mcount_adjust; # Address adjustment to mcount offset
174my $alignment; # The .align value to use for $mcount_section
175my $section_type; # Section header plus possible alignment command
176my $can_use_local = 0; # If we can use local function references
177
178# Shut up recordmcount if user has older objcopy
179my $quiet_recordmcount = ".tmp_quiet_recordmcount";
180my $print_warning = 1;
181$print_warning = 0 if ( -f $quiet_recordmcount);
182
183##
184# check_objcopy - whether objcopy supports --globalize-symbols
185#
186# --globalize-symbols came out in 2.17, we must test the version
187# of objcopy, and if it is less than 2.17, then we can not
188# record local functions.
189sub check_objcopy
190{
191 open (IN, "$objcopy --version |") or die "error running $objcopy";
192 while (<IN>) {
193 if (/objcopy.*\s(\d+)\.(\d+)/) {
194 $can_use_local = 1 if ($1 > 2 || ($1 == 2 && $2 >= 17));
195 last;
196 }
197 }
198 close (IN);
199
200 if (!$can_use_local && $print_warning) {
201 print STDERR "WARNING: could not find objcopy version or version " .
202 "is less than 2.17.\n" .
203 "\tLocal function references are disabled.\n";
204 open (QUIET, ">$quiet_recordmcount");
205 printf QUIET "Disables the warning from recordmcount.pl\n";
206 close QUIET;
207 }
208}
209
210if ($arch =~ /(x86(_64)?)|(i386)/) {
211 if ($bits == 64) {
212 $arch = "x86_64";
213 } else {
214 $arch = "i386";
215 }
216}
217
218#
219# We base the defaults off of i386, the other archs may
220# feel free to change them in the below if statements.
221#
222$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
223$weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)";
224$section_regex = "Disassembly of section\\s+(\\S+):";
225$function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
226$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s(mcount|__fentry__)\$";
227$section_type = '@progbits';
228$mcount_adjust = 0;
229$type = ".long";
230
231if ($arch eq "x86_64") {
232 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s(mcount|__fentry__)([+-]0x[0-9a-zA-Z]+)?\$";
233 $type = ".quad";
234 $alignment = 8;
235 $mcount_adjust = -1;
236
237 # force flags for this arch
238 $ld .= " -m elf_x86_64";
239 $objdump .= " -M x86-64";
240 $objcopy .= " -O elf64-x86-64";
241 $cc .= " -m64";
242
243} elsif ($arch eq "i386") {
244 $alignment = 4;
245 $mcount_adjust = -1;
246
247 # force flags for this arch
248 $ld .= " -m elf_i386";
249 $objdump .= " -M i386";
250 $objcopy .= " -O elf32-i386";
251 $cc .= " -m32";
252
253} elsif ($arch eq "s390" && $bits == 64) {
254 if ($cc =~ /-DCC_USING_HOTPATCH/) {
255 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*c0 04 00 00 00 00\\s*brcl\\s*0,[0-9a-f]+ <([^\+]*)>\$";
256 $mcount_adjust = 0;
257 } else {
258 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$";
259 $mcount_adjust = -14;
260 }
261 $alignment = 8;
262 $type = ".quad";
263 $ld .= " -m elf64_s390";
264 $cc .= " -m64";
265
266} elsif ($arch eq "sh") {
267 $alignment = 2;
268
269 # force flags for this arch
270 $ld .= " -m shlelf_linux";
271 $objcopy .= " -O elf32-sh-linux";
272
273} elsif ($arch eq "powerpc") {
274 my $ldemulation;
275
276 $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
277 # See comment in the sparc64 section for why we use '\w'.
278 $function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?\\w*?)>:";
279 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
280
281 if ($endian eq "big") {
282 $cc .= " -mbig-endian ";
283 $ld .= " -EB ";
284 $ldemulation = "ppc"
285 } else {
286 $cc .= " -mlittle-endian ";
287 $ld .= " -EL ";
288 $ldemulation = "lppc"
289 }
290 if ($bits == 64) {
291 $type = ".quad";
292 $cc .= " -m64 ";
293 $ld .= " -m elf64".$ldemulation." ";
294 } else {
295 $cc .= " -m32 ";
296 $ld .= " -m elf32".$ldemulation." ";
297 }
298
299} elsif ($arch eq "arm") {
300 $alignment = 2;
301 $section_type = '%progbits';
302 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24|THM_CALL)" .
303 "\\s+(__gnu_mcount_nc|mcount)\$";
304
305} elsif ($arch eq "arm64") {
306 $alignment = 3;
307 $section_type = '%progbits';
308 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_AARCH64_CALL26\\s+_mcount\$";
309 $type = ".quad";
310} elsif ($arch eq "ia64") {
311 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
312 $type = "data8";
313
314 if ($is_module eq "0") {
315 $cc .= " -mconstant-gp";
316 }
317} elsif ($arch eq "sparc64") {
318 # In the objdump output there are giblets like:
319 # 0000000000000000 <igmp_net_exit-0x18>:
320 # As there's some data blobs that get emitted into the
321 # text section before the first instructions and the first
322 # real symbols. We don't want to match that, so to combat
323 # this we use '\w' so we'll match just plain symbol names,
324 # and not those that also include hex offsets inside of the
325 # '<>' brackets. Actually the generic function_regex setting
326 # could safely use this too.
327 $function_regex = "^([0-9a-fA-F]+)\\s+<(\\w*?)>:";
328
329 # Sparc64 calls '_mcount' instead of plain 'mcount'.
330 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
331
332 $alignment = 8;
333 $type = ".xword";
334 $ld .= " -m elf64_sparc";
335 $cc .= " -m64";
336 $objcopy .= " -O elf64-sparc";
337} elsif ($arch eq "mips") {
338 # To enable module support, we need to enable the -mlong-calls option
339 # of gcc for module, after using this option, we can not get the real
340 # offset of the calling to _mcount, but the offset of the lui
341 # instruction or the addiu one. herein, we record the address of the
342 # first one, and then we can replace this instruction by a branch
343 # instruction to jump over the profiling function to filter the
344 # indicated functions, or switch back to the lui instruction to trace
345 # them, which means dynamic tracing.
346 #
347 # c: 3c030000 lui v1,0x0
348 # c: R_MIPS_HI16 _mcount
349 # c: R_MIPS_NONE *ABS*
350 # c: R_MIPS_NONE *ABS*
351 # 10: 64630000 daddiu v1,v1,0
352 # 10: R_MIPS_LO16 _mcount
353 # 10: R_MIPS_NONE *ABS*
354 # 10: R_MIPS_NONE *ABS*
355 # 14: 03e0082d move at,ra
356 # 18: 0060f809 jalr v1
357 #
358 # for the kernel:
359 #
360 # 10: 03e0082d move at,ra
361 # 14: 0c000000 jal 0 <loongson_halt>
362 # 14: R_MIPS_26 _mcount
363 # 14: R_MIPS_NONE *ABS*
364 # 14: R_MIPS_NONE *ABS*
365 # 18: 00020021 nop
366 if ($is_module eq "0") {
367 $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_26\\s+_mcount\$";
368 } else {
369 $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_HI16\\s+_mcount\$";
370 }
371 $objdump .= " -Melf-trad".$endian."mips ";
372
373 if ($endian eq "big") {
374 $endian = " -EB ";
375 $ld .= " -melf".$bits."btsmip";
376 } else {
377 $endian = " -EL ";
378 $ld .= " -melf".$bits."ltsmip";
379 }
380
381 $cc .= " -mno-abicalls -fno-pic -mabi=" . $bits . $endian;
382 $ld .= $endian;
383
384 if ($bits == 64) {
385 $function_regex =
386 "^([0-9a-fA-F]+)\\s+<(.|[^\$]L.*?|\$[^L].*?|[^\$][^L].*?)>:";
387 $type = ".dword";
388 }
389} elsif ($arch eq "microblaze") {
390 # Microblaze calls '_mcount' instead of plain 'mcount'.
391 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
392} elsif ($arch eq "riscv") {
393 $function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
394 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL\\s_mcount\$";
395 $type = ".quad";
396 $alignment = 2;
397} elsif ($arch eq "nds32") {
398 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_NDS32_HI20_RELA\\s+_mcount\$";
399 $alignment = 2;
400} elsif ($arch eq "csky") {
401 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_CKCORE_PCREL_JSR_IMM26BY2\\s+_mcount\$";
402 $alignment = 2;
403} else {
404 die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
405}
406
407my $text_found = 0;
408my $read_function = 0;
409my $opened = 0;
410my $mcount_section = "__mcount_loc";
411
412my $dirname;
413my $filename;
414my $prefix;
415my $ext;
416
417if ($inputfile =~ m,^(.*)/([^/]*)$,) {
418 $dirname = $1;
419 $filename = $2;
420} else {
421 $dirname = ".";
422 $filename = $inputfile;
423}
424
425if ($filename =~ m,^(.*)(\.\S),) {
426 $prefix = $1;
427 $ext = $2;
428} else {
429 $prefix = $filename;
430 $ext = "";
431}
432
433my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
434my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
435
436check_objcopy();
437
438#
439# Step 1: find all the local (static functions) and weak symbols.
440# 't' is local, 'w/W' is weak
441#
442open (IN, "$nm $inputfile|") || die "error running $nm";
443while (<IN>) {
444 if (/$local_regex/) {
445 $locals{$1} = 1;
446 } elsif (/$weak_regex/) {
447 $weak{$2} = $1;
448 }
449}
450close(IN);
451
452my @offsets; # Array of offsets of mcount callers
453my $ref_func; # reference function to use for offsets
454my $offset = 0; # offset of ref_func to section beginning
455
456##
457# update_funcs - print out the current mcount callers
458#
459# Go through the list of offsets to callers and write them to
460# the output file in a format that can be read by an assembler.
461#
462sub update_funcs
463{
464 return unless ($ref_func and @offsets);
465
466 # Sanity check on weak function. A weak function may be overwritten by
467 # another function of the same name, making all these offsets incorrect.
468 if (defined $weak{$ref_func}) {
469 die "$inputfile: ERROR: referencing weak function" .
470 " $ref_func for mcount\n";
471 }
472
473 # is this function static? If so, note this fact.
474 if (defined $locals{$ref_func}) {
475
476 # only use locals if objcopy supports globalize-symbols
477 if (!$can_use_local) {
478 return;
479 }
480 $convert{$ref_func} = 1;
481 }
482
483 # Loop through all the mcount caller offsets and print a reference
484 # to the caller based from the ref_func.
485 if (!$opened) {
486 open(FILE, ">$mcount_s") || die "can't create $mcount_s\n";
487 $opened = 1;
488 print FILE "\t.section $mcount_section,\"a\",$section_type\n";
489 print FILE "\t.align $alignment\n" if (defined($alignment));
490 }
491 foreach my $cur_offset (@offsets) {
492 printf FILE "\t%s %s + %d\n", $type, $ref_func, $cur_offset - $offset;
493 }
494}
495
496#
497# Step 2: find the sections and mcount call sites
498#
499open(IN, "LANG=C $objdump -hdr $inputfile|") || die "error running $objdump";
500
501my $text;
502
503
504# read headers first
505my $read_headers = 1;
506
507while (<IN>) {
508
509 if ($read_headers && /$mcount_section/) {
510 #
511 # Somehow the make process can execute this script on an
512 # object twice. If it does, we would duplicate the mcount
513 # section and it will cause the function tracer self test
514 # to fail. Check if the mcount section exists, and if it does,
515 # warn and exit.
516 #
517 print STDERR "ERROR: $mcount_section already in $inputfile\n" .
518 "\tThis may be an indication that your build is corrupted.\n" .
519 "\tDelete $inputfile and try again. If the same object file\n" .
520 "\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n";
521 exit(-1);
522 }
523
524 # is it a section?
525 if (/$section_regex/) {
526 $read_headers = 0;
527
528 # Only record text sections that we know are safe
529 $read_function = defined($text_sections{$1});
530 if (!$read_function) {
531 foreach my $prefix (keys %text_section_prefixes) {
532 if (substr($1, 0, length $prefix) eq $prefix) {
533 $read_function = 1;
534 last;
535 }
536 }
537 }
538 # print out any recorded offsets
539 update_funcs();
540
541 # reset all markers and arrays
542 $text_found = 0;
543 undef($ref_func);
544 undef(@offsets);
545
546 # section found, now is this a start of a function?
547 } elsif ($read_function && /$function_regex/) {
548 $text_found = 1;
549 $text = $2;
550
551 # if this is either a local function or a weak function
552 # keep looking for functions that are global that
553 # we can use safely.
554 if (!defined($locals{$text}) && !defined($weak{$text})) {
555 $ref_func = $text;
556 $read_function = 0;
557 $offset = hex $1;
558 } else {
559 # if we already have a function, and this is weak, skip it
560 if (!defined($ref_func) && !defined($weak{$text}) &&
561 # PPC64 can have symbols that start with .L and
562 # gcc considers these special. Don't use them!
563 $text !~ /^\.L/) {
564 $ref_func = $text;
565 $offset = hex $1;
566 }
567 }
568 }
569 # is this a call site to mcount? If so, record it to print later
570 if ($text_found && /$mcount_regex/) {
571 push(@offsets, (hex $1) + $mcount_adjust);
572 }
573}
574
575# dump out anymore offsets that may have been found
576update_funcs();
577
578# If we did not find any mcount callers, we are done (do nothing).
579if (!$opened) {
580 exit(0);
581}
582
583close(FILE);
584
585#
586# Step 3: Compile the file that holds the list of call sites to mcount.
587#
588`$cc -o $mcount_o -c $mcount_s`;
589
590my @converts = keys %convert;
591
592#
593# Step 4: Do we have sections that started with local functions?
594#
595if ($#converts >= 0) {
596 my $globallist = "";
597 my $locallist = "";
598
599 foreach my $con (@converts) {
600 $globallist .= " --globalize-symbol $con";
601 $locallist .= " --localize-symbol $con";
602 }
603
604 my $globalobj = $dirname . "/.tmp_gl_" . $filename;
605 my $globalmix = $dirname . "/.tmp_mx_" . $filename;
606
607 #
608 # Step 5: set up each local function as a global
609 #
610 `$objcopy $globallist $inputfile $globalobj`;
611
612 #
613 # Step 6: Link the global version to our list.
614 #
615 `$ld -r $globalobj $mcount_o -o $globalmix`;
616
617 #
618 # Step 7: Convert the local functions back into local symbols
619 #
620 `$objcopy $locallist $globalmix $inputfile`;
621
622 # Remove the temp files
623 `$rm $globalobj $globalmix`;
624
625} else {
626
627 my $mix = $dirname . "/.tmp_mx_" . $filename;
628
629 #
630 # Step 8: Link the object with our list of call sites object.
631 #
632 `$ld -r $inputfile $mcount_o -o $mix`;
633
634 #
635 # Step 9: Move the result back to the original object.
636 #
637 `$mv $mix $inputfile`;
638}
639
640# Clean up the temp files
641`$rm $mcount_o $mcount_s`;
642
643exit(0);