ftrace: handle generic arch calls
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / scripts / recordmcount.pl
CommitLineData
8da3821b
SR
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 is a section in vmlinux called
10# __mcount_loc that contains a list of pointers to all the
11# call sites in the kernel that call mcount. Later on boot up, the kernel
12# will read this list, save the locations and turn them into nops.
13# When tracing or profiling is later enabled, these locations will then
14# be converted back to pointers to some function.
15#
16# This is no easy feat. This script is called just after the original
17# object is compiled and before it is linked.
18#
19# The references to the call sites are offsets from the section of text
20# that the call site is in. Hence, all functions in a section that
21# has a call site to mcount, will have the offset from the beginning of
22# the section and not the beginning of the function.
23#
24# The trick is to find a way to record the beginning of the section.
25# The way we do this is to look at the first function in the section
26# which will also be the location of that section after final link.
27# e.g.
28#
29# .section ".text.sched"
30# .globl my_func
31# my_func:
32# [...]
33# call mcount (offset: 0x5)
34# [...]
35# ret
36# other_func:
37# [...]
38# call mcount (offset: 0x1b)
39# [...]
40#
41# Both relocation offsets for the mcounts in the above example will be
42# offset from .text.sched. If we make another file called tmp.s with:
43#
44# .section __mcount_loc
45# .quad my_func + 0x5
46# .quad my_func + 0x1b
47#
48# We can then compile this tmp.s into tmp.o, and link it to the original
49# object.
50#
51# But this gets hard if my_func is not globl (a static function).
52# In such a case we have:
53#
54# .section ".text.sched"
55# my_func:
56# [...]
57# call mcount (offset: 0x5)
58# [...]
59# ret
60# .globl my_func
61# other_func:
62# [...]
63# call mcount (offset: 0x1b)
64# [...]
65#
66# If we make the tmp.s the same as above, when we link together with
67# the original object, we will end up with two symbols for my_func:
68# one local, one global. After final compile, we will end up with
69# an undefined reference to my_func.
70#
71# Since local objects can reference local variables, we need to find
72# a way to make tmp.o reference the local objects of the original object
73# file after it is linked together. To do this, we convert the my_func
74# into a global symbol before linking tmp.o. Then after we link tmp.o
75# we will only have a single symbol for my_func that is global.
76# We can convert my_func back into a local symbol and we are done.
77#
78# Here are the steps we take:
79#
80# 1) Record all the local symbols by using 'nm'
81# 2) Use objdump to find all the call site offsets and sections for
82# mcount.
83# 3) Compile the list into its own object.
84# 4) Do we have to deal with local functions? If not, go to step 8.
85# 5) Make an object that converts these local functions to global symbols
86# with objcopy.
87# 6) Link together this new object with the list object.
88# 7) Convert the local functions back to local symbols and rename
89# the result as the original object.
90# End.
91# 8) Link the object with the list object.
92# 9) Move the result back to the original object.
93# End.
94#
95
96use strict;
97
98my $P = $0;
99$P =~ s@.*/@@g;
100
101my $V = '0.1';
102
103if ($#ARGV < 6) {
104 print "usage: $P arch objdump objcopy cc ld nm rm mv inputfile\n";
105 print "version: $V\n";
106 exit(1);
107}
108
dce9d18a
SR
109my ($arch, $bits, $objdump, $objcopy, $cc,
110 $ld, $nm, $rm, $mv, $inputfile) = @ARGV;
8da3821b
SR
111
112$objdump = "objdump" if ((length $objdump) == 0);
113$objcopy = "objcopy" if ((length $objcopy) == 0);
114$cc = "gcc" if ((length $cc) == 0);
115$ld = "ld" if ((length $ld) == 0);
116$nm = "nm" if ((length $nm) == 0);
117$rm = "rm" if ((length $rm) == 0);
118$mv = "mv" if ((length $mv) == 0);
119
120#print STDERR "running: $P '$arch' '$objdump' '$objcopy' '$cc' '$ld' " .
121# "'$nm' '$rm' '$mv' '$inputfile'\n";
122
8feff1ca
SR
123my %locals; # List of local (static) functions
124my %weak; # List of weak functions
125my %convert; # List of local functions used that needs conversion
8da3821b
SR
126
127my $type;
128my $section_regex; # Find the start of a section
8feff1ca
SR
129my $function_regex; # Find the name of a function
130 # (return offset and func name)
8da3821b
SR
131my $mcount_regex; # Find the call site to mcount (return offset)
132
dce9d18a
SR
133if ($arch eq "x86") {
134 if ($bits == 64) {
135 $arch = "x86_64";
136 } else {
137 $arch = "i386";
138 }
139}
140
8da3821b
SR
141if ($arch eq "x86_64") {
142 $section_regex = "Disassembly of section";
8feff1ca 143 $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
8da3821b
SR
144 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount([+-]0x[0-9a-zA-Z]+)?\$";
145 $type = ".quad";
d74fcd1e
SR
146
147 # force flags for this arch
148 $ld .= " -m elf_x86_64";
149 $objdump .= " -M x86-64";
150 $objcopy .= " -O elf64-x86-64";
151 $cc .= " -m64";
152
8da3821b
SR
153} elsif ($arch eq "i386") {
154 $section_regex = "Disassembly of section";
8feff1ca 155 $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
8da3821b
SR
156 $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";
157 $type = ".long";
d74fcd1e
SR
158
159 # force flags for this arch
160 $ld .= " -m elf_i386";
161 $objdump .= " -M i386";
162 $objcopy .= " -O elf32-i386";
163 $cc .= " -m32";
164
8da3821b
SR
165} else {
166 die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
167}
168
169my $text_found = 0;
170my $read_function = 0;
171my $opened = 0;
8da3821b
SR
172my $mcount_section = "__mcount_loc";
173
174my $dirname;
175my $filename;
176my $prefix;
177my $ext;
178
179if ($inputfile =~ m,^(.*)/([^/]*)$,) {
180 $dirname = $1;
181 $filename = $2;
182} else {
183 $dirname = ".";
184 $filename = $inputfile;
185}
186
187if ($filename =~ m,^(.*)(\.\S),) {
188 $prefix = $1;
189 $ext = $2;
190} else {
191 $prefix = $filename;
192 $ext = "";
193}
194
195my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
196my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
197
f2f8458e
SR
198#
199# --globalize-symbols came out in 2.17, we must test the version
200# of objcopy, and if it is less than 2.17, then we can not
201# record local functions.
202my $use_locals = 01;
203my $local_warn_once = 0;
204my $found_version = 0;
205
206open (IN, "$objcopy --version |") || die "error running $objcopy";
207while (<IN>) {
208 if (/objcopy.*\s(\d+)\.(\d+)/) {
209 my $major = $1;
210 my $minor = $2;
211
212 $found_version = 1;
213 if ($major < 2 ||
214 ($major == 2 && $minor < 17)) {
215 $use_locals = 0;
216 }
217 last;
218 }
219}
220close (IN);
221
222if (!$found_version) {
223 print STDERR "WARNING: could not find objcopy version.\n" .
224 "\tDisabling local function references.\n";
225}
226
227
8da3821b 228#
8feff1ca
SR
229# Step 1: find all the local (static functions) and weak symbols.
230# 't' is local, 'w/W' is weak (we never use a weak function)
8da3821b
SR
231#
232open (IN, "$nm $inputfile|") || die "error running $nm";
233while (<IN>) {
234 if (/^[0-9a-fA-F]+\s+t\s+(\S+)/) {
235 $locals{$1} = 1;
8feff1ca
SR
236 } elsif (/^[0-9a-fA-F]+\s+([wW])\s+(\S+)/) {
237 $weak{$2} = $1;
8da3821b
SR
238 }
239}
240close(IN);
241
8feff1ca
SR
242my @offsets; # Array of offsets of mcount callers
243my $ref_func; # reference function to use for offsets
244my $offset = 0; # offset of ref_func to section beginning
245
246##
247# update_funcs - print out the current mcount callers
248#
249# Go through the list of offsets to callers and write them to
250# the output file in a format that can be read by an assembler.
251#
252sub update_funcs
253{
254 return if ($#offsets < 0);
255
256 defined($ref_func) || die "No function to reference";
257
258 # A section only had a weak function, to represent it.
259 # Unfortunately, a weak function may be overwritten by another
260 # function of the same name, making all these offsets incorrect.
261 # To be safe, we simply print a warning and bail.
262 if (defined $weak{$ref_func}) {
263 print STDERR
264 "$inputfile: WARNING: referencing weak function" .
265 " $ref_func for mcount\n";
266 return;
267 }
268
269 # is this function static? If so, note this fact.
270 if (defined $locals{$ref_func}) {
f2f8458e
SR
271
272 # only use locals if objcopy supports globalize-symbols
273 if (!$use_locals) {
f2f8458e
SR
274 return;
275 }
8feff1ca
SR
276 $convert{$ref_func} = 1;
277 }
278
279 # Loop through all the mcount caller offsets and print a reference
280 # to the caller based from the ref_func.
281 for (my $i=0; $i <= $#offsets; $i++) {
282 if (!$opened) {
283 open(FILE, ">$mcount_s") || die "can't create $mcount_s\n";
284 $opened = 1;
285 print FILE "\t.section $mcount_section,\"a\",\@progbits\n";
286 }
287 printf FILE "\t%s %s + %d\n", $type, $ref_func, $offsets[$i] - $offset;
288 }
289}
290
8da3821b
SR
291#
292# Step 2: find the sections and mcount call sites
293#
294open(IN, "$objdump -dr $inputfile|") || die "error running $objdump";
295
8feff1ca
SR
296my $text;
297
8da3821b
SR
298while (<IN>) {
299 # is it a section?
300 if (/$section_regex/) {
301 $read_function = 1;
8feff1ca
SR
302 # print out any recorded offsets
303 update_funcs() if ($text_found);
304
305 # reset all markers and arrays
8da3821b 306 $text_found = 0;
8feff1ca
SR
307 undef($ref_func);
308 undef(@offsets);
309
8da3821b
SR
310 # section found, now is this a start of a function?
311 } elsif ($read_function && /$function_regex/) {
8da3821b 312 $text_found = 1;
8feff1ca
SR
313 $offset = hex $1;
314 $text = $2;
315
316 # if this is either a local function or a weak function
317 # keep looking for functions that are global that
318 # we can use safely.
319 if (!defined($locals{$text}) && !defined($weak{$text})) {
320 $ref_func = $text;
321 $read_function = 0;
322 } else {
323 # if we already have a function, and this is weak, skip it
324 if (!defined($ref_func) || !defined($weak{$text})) {
325 $ref_func = $text;
326 }
8da3821b 327 }
8feff1ca
SR
328 }
329
330 # is this a call site to mcount? If so, record it to print later
331 if ($text_found && /$mcount_regex/) {
332 $offsets[$#offsets + 1] = hex $1;
8da3821b
SR
333 }
334}
335
8feff1ca
SR
336# dump out anymore offsets that may have been found
337update_funcs() if ($text_found);
338
8da3821b
SR
339# If we did not find any mcount callers, we are done (do nothing).
340if (!$opened) {
341 exit(0);
342}
343
344close(FILE);
345
346#
347# Step 3: Compile the file that holds the list of call sites to mcount.
348#
349`$cc -o $mcount_o -c $mcount_s`;
350
351my @converts = keys %convert;
352
353#
354# Step 4: Do we have sections that started with local functions?
355#
356if ($#converts >= 0) {
357 my $globallist = "";
358 my $locallist = "";
359
360 foreach my $con (@converts) {
361 $globallist .= " --globalize-symbol $con";
362 $locallist .= " --localize-symbol $con";
363 }
364
365 my $globalobj = $dirname . "/.tmp_gl_" . $filename;
366 my $globalmix = $dirname . "/.tmp_mx_" . $filename;
367
368 #
369 # Step 5: set up each local function as a global
370 #
371 `$objcopy $globallist $inputfile $globalobj`;
372
373 #
374 # Step 6: Link the global version to our list.
375 #
376 `$ld -r $globalobj $mcount_o -o $globalmix`;
377
378 #
379 # Step 7: Convert the local functions back into local symbols
380 #
381 `$objcopy $locallist $globalmix $inputfile`;
382
383 # Remove the temp files
384 `$rm $globalobj $globalmix`;
385
386} else {
387
388 my $mix = $dirname . "/.tmp_mx_" . $filename;
389
390 #
391 # Step 8: Link the object with our list of call sites object.
392 #
393 `$ld -r $inputfile $mcount_o -o $mix`;
394
395 #
396 # Step 9: Move the result back to the original object.
397 #
398 `$mv $mix $inputfile`;
399}
400
401# Clean up the temp files
402`$rm $mcount_o $mcount_s`;
403
404exit(0);