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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#
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LH
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.
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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#
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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.
8da3821b 33#
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34# e.g.
35#
31b6e76e 36# .section ".sched.text", "ax"
8da3821b 37# [...]
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38# func1:
39# [...]
40# call mcount (offset: 0x10)
41# [...]
42# ret
43# .globl fun2
44# func2: (offset: 0x20)
45# [...]
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46# [...]
47# ret
d49f6aa7 48# func3:
8da3821b 49# [...]
d49f6aa7 50# call mcount (offset: 0x30)
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51# [...]
52#
53# Both relocation offsets for the mcounts in the above example will be
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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:
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56#
57# .section __mcount_loc
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58# .quad func2 - 0x10
59# .quad func2 + 0x10
8da3821b 60#
d49f6aa7 61# We can then compile this tmp.s into tmp.o, and link it back to the original
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62# object.
63#
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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:
8da3821b 67#
31b6e76e 68# .section ".sched.text", "ax"
d49f6aa7 69# func1:
8da3821b 70# [...]
d49f6aa7 71# call mcount (offset: 0x10)
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SR
72# [...]
73# ret
d49f6aa7 74# func2:
8da3821b 75# [...]
d49f6aa7 76# call mcount (offset: 0x20)
8da3821b 77# [...]
d49f6aa7 78# .section "other.section"
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79#
80# If we make the tmp.s the same as above, when we link together with
d49f6aa7 81# the original object, we will end up with two symbols for func1:
8da3821b 82# one local, one global. After final compile, we will end up with
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83# an undefined reference to func1 or a wrong reference to another global
84# func1 in other files.
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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
d49f6aa7 88# file after it is linked together. To do this, we convert func1
8da3821b 89# into a global symbol before linking tmp.o. Then after we link tmp.o
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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.
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92#
93# Here are the steps we take:
94#
306dcf47 95# 1) Record all the local and weak symbols by using 'nm'
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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.
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105# 8) Link the object with the list object.
106# 9) Move the result back to the original object.
8da3821b
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107#
108
109use strict;
110
111my $P = $0;
112$P =~ s@.*/@@g;
113
114my $V = '0.1';
115
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116if ($#ARGV != 11) {
117 print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
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118 print "version: $V\n";
119 exit(1);
120}
121
e6299d26 122my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
18c167fd 123 $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
8da3821b 124
25aac9dc 125# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
bdd3b052 126if ($inputfile =~ m,kernel/trace/ftrace\.o$,) {
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127 exit(0);
128}
129
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130# Acceptable sections to record.
131my %text_sections = (
132 ".text" => 1,
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133 ".sched.text" => 1,
134 ".spinlock.text" => 1,
a0343e82 135 ".irqentry.text" => 1,
4d828949 136 ".text.unlikely" => 1,
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137);
138
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139# Note: we are nice to C-programmers here, thus we skip the '||='-idiom.
140$objdump = 'objdump' if (!$objdump);
141$objcopy = 'objcopy' if (!$objcopy);
142$cc = 'gcc' if (!$cc);
143$ld = 'ld' if (!$ld);
144$nm = 'nm' if (!$nm);
145$rm = 'rm' if (!$rm);
146$mv = 'mv' if (!$mv);
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147
148#print STDERR "running: $P '$arch' '$objdump' '$objcopy' '$cc' '$ld' " .
149# "'$nm' '$rm' '$mv' '$inputfile'\n";
150
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151my %locals; # List of local (static) functions
152my %weak; # List of weak functions
153my %convert; # List of local functions used that needs conversion
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154
155my $type;
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156my $local_regex; # Match a local function (return function)
157my $weak_regex; # Match a weak function (return function)
8da3821b 158my $section_regex; # Find the start of a section
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SR
159my $function_regex; # Find the name of a function
160 # (return offset and func name)
8da3821b 161my $mcount_regex; # Find the call site to mcount (return offset)
465c6cca 162my $mcount_adjust; # Address adjustment to mcount offset
3a3d04ae 163my $alignment; # The .align value to use for $mcount_section
e58918ab 164my $section_type; # Section header plus possible alignment command
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165my $can_use_local = 0; # If we can use local function references
166
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167# Shut up recordmcount if user has older objcopy
168my $quiet_recordmcount = ".tmp_quiet_recordmcount";
169my $print_warning = 1;
170$print_warning = 0 if ( -f $quiet_recordmcount);
171
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172##
173# check_objcopy - whether objcopy supports --globalize-symbols
174#
175# --globalize-symbols came out in 2.17, we must test the version
176# of objcopy, and if it is less than 2.17, then we can not
177# record local functions.
178sub check_objcopy
179{
180 open (IN, "$objcopy --version |") or die "error running $objcopy";
181 while (<IN>) {
182 if (/objcopy.*\s(\d+)\.(\d+)/) {
183 $can_use_local = 1 if ($1 > 2 || ($1 == 2 && $2 >= 17));
184 last;
185 }
186 }
187 close (IN);
188
638adb05 189 if (!$can_use_local && $print_warning) {
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190 print STDERR "WARNING: could not find objcopy version or version " .
191 "is less than 2.17.\n" .
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192 "\tLocal function references are disabled.\n";
193 open (QUIET, ">$quiet_recordmcount");
194 printf QUIET "Disables the warning from recordmcount.pl\n";
195 close QUIET;
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196 }
197}
8da3821b 198
b82a4045 199if ($arch =~ /(x86(_64)?)|(i386)/) {
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200 if ($bits == 64) {
201 $arch = "x86_64";
202 } else {
203 $arch = "i386";
204 }
205}
206
c204f726
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207#
208# We base the defaults off of i386, the other archs may
209# feel free to change them in the below if statements.
210#
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211$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
212$weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)";
c204f726
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213$section_regex = "Disassembly of section\\s+(\\S+):";
214$function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
215$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";
e58918ab 216$section_type = '@progbits';
465c6cca 217$mcount_adjust = 0;
c204f726
SR
218$type = ".long";
219
8da3821b 220if ($arch eq "x86_64") {
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221 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount([+-]0x[0-9a-zA-Z]+)?\$";
222 $type = ".quad";
7d5222a6 223 $alignment = 8;
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224
225 # force flags for this arch
226 $ld .= " -m elf_x86_64";
227 $objdump .= " -M x86-64";
228 $objcopy .= " -O elf64-x86-64";
229 $cc .= " -m64";
230
8da3821b 231} elsif ($arch eq "i386") {
7d5222a6 232 $alignment = 4;
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233
234 # force flags for this arch
235 $ld .= " -m elf_i386";
236 $objdump .= " -M i386";
237 $objcopy .= " -O elf32-i386";
238 $cc .= " -m32";
239
dfd9f7ab
HC
240} elsif ($arch eq "s390" && $bits == 32) {
241 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_32\\s+_mcount\$";
242 $alignment = 4;
243 $ld .= " -m elf_s390";
244 $cc .= " -m31";
245
246} elsif ($arch eq "s390" && $bits == 64) {
247 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$";
248 $alignment = 8;
249 $type = ".quad";
250 $ld .= " -m elf64_s390";
251 $cc .= " -m64";
252
0da85c09 253} elsif ($arch eq "sh") {
3a3d04ae 254 $alignment = 2;
0da85c09
MF
255
256 # force flags for this arch
257 $ld .= " -m shlelf_linux";
258 $objcopy .= " -O elf32-sh-linux";
259 $cc .= " -m32";
260
42e007d0 261} elsif ($arch eq "powerpc") {
306dcf47 262 $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
42e007d0
SR
263 $function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?.*?)>:";
264 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
c204f726 265
42e007d0
SR
266 if ($bits == 64) {
267 $type = ".quad";
42e007d0
SR
268 }
269
e58918ab
JR
270} elsif ($arch eq "arm") {
271 $alignment = 2;
272 $section_type = '%progbits';
72dc43a9 273 $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24|THM_CALL)" .
3b6c223b 274 "\\s+(__gnu_mcount_nc|mcount)\$";
e58918ab 275
418071eb
SL
276} elsif ($arch eq "ia64") {
277 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
278 $type = "data8";
279
280 if ($is_module eq "0") {
281 $cc .= " -mconstant-gp";
282 }
9be12f9b
DM
283} elsif ($arch eq "sparc64") {
284 # In the objdump output there are giblets like:
285 # 0000000000000000 <igmp_net_exit-0x18>:
286 # As there's some data blobs that get emitted into the
287 # text section before the first instructions and the first
288 # real symbols. We don't want to match that, so to combat
289 # this we use '\w' so we'll match just plain symbol names,
290 # and not those that also include hex offsets inside of the
291 # '<>' brackets. Actually the generic function_regex setting
292 # could safely use this too.
293 $function_regex = "^([0-9a-fA-F]+)\\s+<(\\w*?)>:";
294
295 # Sparc64 calls '_mcount' instead of plain 'mcount'.
296 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
297
298 $alignment = 8;
299 $type = ".xword";
300 $ld .= " -m elf64_sparc";
301 $cc .= " -m64";
302 $objcopy .= " -O elf64-sparc";
538f1952
WZ
303} elsif ($arch eq "mips") {
304 # To enable module support, we need to enable the -mlong-calls option
305 # of gcc for module, after using this option, we can not get the real
306 # offset of the calling to _mcount, but the offset of the lui
307 # instruction or the addiu one. herein, we record the address of the
308 # first one, and then we can replace this instruction by a branch
309 # instruction to jump over the profiling function to filter the
310 # indicated functions, or swith back to the lui instruction to trace
311 # them, which means dynamic tracing.
312 #
313 # c: 3c030000 lui v1,0x0
314 # c: R_MIPS_HI16 _mcount
315 # c: R_MIPS_NONE *ABS*
316 # c: R_MIPS_NONE *ABS*
317 # 10: 64630000 daddiu v1,v1,0
318 # 10: R_MIPS_LO16 _mcount
319 # 10: R_MIPS_NONE *ABS*
320 # 10: R_MIPS_NONE *ABS*
321 # 14: 03e0082d move at,ra
322 # 18: 0060f809 jalr v1
323 #
324 # for the kernel:
325 #
326 # 10: 03e0082d move at,ra
327 # 14: 0c000000 jal 0 <loongson_halt>
328 # 14: R_MIPS_26 _mcount
329 # 14: R_MIPS_NONE *ABS*
330 # 14: R_MIPS_NONE *ABS*
331 # 18: 00020021 nop
332 if ($is_module eq "0") {
a484e54f 333 $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_26\\s+_mcount\$";
538f1952
WZ
334 } else {
335 $mcount_regex = "^\\s*([0-9a-fA-F]+): R_MIPS_HI16\\s+_mcount\$";
336 }
337 $objdump .= " -Melf-trad".$endian."mips ";
338
339 if ($endian eq "big") {
340 $endian = " -EB ";
341 $ld .= " -melf".$bits."btsmip";
342 } else {
343 $endian = " -EL ";
344 $ld .= " -melf".$bits."ltsmip";
345 }
346
347 $cc .= " -mno-abicalls -fno-pic -mabi=" . $bits . $endian;
348 $ld .= $endian;
349
350 if ($bits == 64) {
351 $function_regex =
352 "^([0-9a-fA-F]+)\\s+<(.|[^\$]L.*?|\$[^L].*?|[^\$][^L].*?)>:";
353 $type = ".dword";
354 }
7d241ff0
MS
355} elsif ($arch eq "microblaze") {
356 # Microblaze calls '_mcount' instead of plain 'mcount'.
357 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
465c6cca
MF
358} elsif ($arch eq "blackfin") {
359 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
360 $mcount_adjust = -4;
8da3821b
SR
361} else {
362 die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
363}
364
365my $text_found = 0;
366my $read_function = 0;
367my $opened = 0;
8da3821b
SR
368my $mcount_section = "__mcount_loc";
369
370my $dirname;
371my $filename;
372my $prefix;
373my $ext;
374
375if ($inputfile =~ m,^(.*)/([^/]*)$,) {
376 $dirname = $1;
377 $filename = $2;
378} else {
379 $dirname = ".";
380 $filename = $inputfile;
381}
382
383if ($filename =~ m,^(.*)(\.\S),) {
384 $prefix = $1;
385 $ext = $2;
386} else {
387 $prefix = $filename;
388 $ext = "";
389}
390
391my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
392my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
393
7b7edc27 394check_objcopy();
f2f8458e 395
8da3821b 396#
8feff1ca 397# Step 1: find all the local (static functions) and weak symbols.
306dcf47 398# 't' is local, 'w/W' is weak
8da3821b
SR
399#
400open (IN, "$nm $inputfile|") || die "error running $nm";
401while (<IN>) {
306dcf47 402 if (/$local_regex/) {
8da3821b 403 $locals{$1} = 1;
306dcf47 404 } elsif (/$weak_regex/) {
8feff1ca 405 $weak{$2} = $1;
8da3821b
SR
406 }
407}
408close(IN);
409
8feff1ca
SR
410my @offsets; # Array of offsets of mcount callers
411my $ref_func; # reference function to use for offsets
412my $offset = 0; # offset of ref_func to section beginning
413
414##
415# update_funcs - print out the current mcount callers
416#
417# Go through the list of offsets to callers and write them to
418# the output file in a format that can be read by an assembler.
419#
420sub update_funcs
421{
6092858c 422 return unless ($ref_func and @offsets);
8feff1ca 423
c4b8ac2c
LH
424 # Sanity check on weak function. A weak function may be overwritten by
425 # another function of the same name, making all these offsets incorrect.
8feff1ca 426 if (defined $weak{$ref_func}) {
c4b8ac2c 427 die "$inputfile: ERROR: referencing weak function" .
8feff1ca 428 " $ref_func for mcount\n";
8feff1ca
SR
429 }
430
431 # is this function static? If so, note this fact.
432 if (defined $locals{$ref_func}) {
f2f8458e
SR
433
434 # only use locals if objcopy supports globalize-symbols
7b7edc27 435 if (!$can_use_local) {
f2f8458e
SR
436 return;
437 }
8feff1ca
SR
438 $convert{$ref_func} = 1;
439 }
440
441 # Loop through all the mcount caller offsets and print a reference
442 # to the caller based from the ref_func.
dc4f8845
WS
443 if (!$opened) {
444 open(FILE, ">$mcount_s") || die "can't create $mcount_s\n";
445 $opened = 1;
446 print FILE "\t.section $mcount_section,\"a\",$section_type\n";
447 print FILE "\t.align $alignment\n" if (defined($alignment));
448 }
449 foreach my $cur_offset (@offsets) {
450 printf FILE "\t%s %s + %d\n", $type, $ref_func, $cur_offset - $offset;
8feff1ca
SR
451 }
452}
453
8da3821b
SR
454#
455# Step 2: find the sections and mcount call sites
456#
b43f7093 457open(IN, "$objdump -hdr $inputfile|") || die "error running $objdump";
8da3821b 458
8feff1ca
SR
459my $text;
460
db24c7dc
LH
461
462# read headers first
b43f7093
SR
463my $read_headers = 1;
464
8da3821b 465while (<IN>) {
db24c7dc
LH
466
467 if ($read_headers && /$mcount_section/) {
468 #
469 # Somehow the make process can execute this script on an
470 # object twice. If it does, we would duplicate the mcount
471 # section and it will cause the function tracer self test
472 # to fail. Check if the mcount section exists, and if it does,
473 # warn and exit.
474 #
475 print STDERR "ERROR: $mcount_section already in $inputfile\n" .
476 "\tThis may be an indication that your build is corrupted.\n" .
477 "\tDelete $inputfile and try again. If the same object file\n" .
478 "\tstill causes an issue, then disable CONFIG_DYNAMIC_FTRACE.\n";
479 exit(-1);
480 }
481
8da3821b
SR
482 # is it a section?
483 if (/$section_regex/) {
b43f7093 484 $read_headers = 0;
34698bcb
SR
485
486 # Only record text sections that we know are safe
dfaa9e2c 487 $read_function = defined($text_sections{$1});
8feff1ca 488 # print out any recorded offsets
6092858c 489 update_funcs();
8feff1ca
SR
490
491 # reset all markers and arrays
8da3821b 492 $text_found = 0;
8feff1ca
SR
493 undef($ref_func);
494 undef(@offsets);
495
8da3821b
SR
496 # section found, now is this a start of a function?
497 } elsif ($read_function && /$function_regex/) {
8da3821b 498 $text_found = 1;
8feff1ca
SR
499 $text = $2;
500
501 # if this is either a local function or a weak function
502 # keep looking for functions that are global that
503 # we can use safely.
504 if (!defined($locals{$text}) && !defined($weak{$text})) {
505 $ref_func = $text;
506 $read_function = 0;
bd171d5f 507 $offset = hex $1;
8feff1ca
SR
508 } else {
509 # if we already have a function, and this is weak, skip it
3f6e968e
SR
510 if (!defined($ref_func) && !defined($weak{$text}) &&
511 # PPC64 can have symbols that start with .L and
512 # gcc considers these special. Don't use them!
513 $text !~ /^\.L/) {
8feff1ca 514 $ref_func = $text;
bd171d5f 515 $offset = hex $1;
8feff1ca 516 }
8da3821b 517 }
8feff1ca 518 }
8feff1ca
SR
519 # is this a call site to mcount? If so, record it to print later
520 if ($text_found && /$mcount_regex/) {
465c6cca 521 push(@offsets, (hex $1) + $mcount_adjust);
8da3821b
SR
522 }
523}
524
8feff1ca 525# dump out anymore offsets that may have been found
6092858c 526update_funcs();
8feff1ca 527
8da3821b
SR
528# If we did not find any mcount callers, we are done (do nothing).
529if (!$opened) {
530 exit(0);
531}
532
533close(FILE);
534
535#
536# Step 3: Compile the file that holds the list of call sites to mcount.
537#
538`$cc -o $mcount_o -c $mcount_s`;
539
540my @converts = keys %convert;
541
542#
543# Step 4: Do we have sections that started with local functions?
544#
545if ($#converts >= 0) {
546 my $globallist = "";
547 my $locallist = "";
548
549 foreach my $con (@converts) {
550 $globallist .= " --globalize-symbol $con";
551 $locallist .= " --localize-symbol $con";
552 }
553
554 my $globalobj = $dirname . "/.tmp_gl_" . $filename;
555 my $globalmix = $dirname . "/.tmp_mx_" . $filename;
556
557 #
558 # Step 5: set up each local function as a global
559 #
560 `$objcopy $globallist $inputfile $globalobj`;
561
562 #
563 # Step 6: Link the global version to our list.
564 #
565 `$ld -r $globalobj $mcount_o -o $globalmix`;
566
567 #
568 # Step 7: Convert the local functions back into local symbols
569 #
570 `$objcopy $locallist $globalmix $inputfile`;
571
572 # Remove the temp files
573 `$rm $globalobj $globalmix`;
574
575} else {
576
577 my $mix = $dirname . "/.tmp_mx_" . $filename;
578
579 #
580 # Step 8: Link the object with our list of call sites object.
581 #
582 `$ld -r $inputfile $mcount_o -o $mix`;
583
584 #
585 # Step 9: Move the result back to the original object.
586 #
587 `$mv $mix $inputfile`;
588}
589
590# Clean up the temp files
591`$rm $mcount_o $mcount_s`;
592
593exit(0);