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#!/usr/bin/perl -w
# (c) 2008, Steven Rostedt <srostedt@redhat.com>
# Licensed under the terms of the GNU GPL License version 2
#
# recordmcount.pl - makes a section called __mcount_loc that holds
# all the offsets to the calls to mcount.
#
#
# What we want to end up with is a section in vmlinux called
# __mcount_loc that contains a list of pointers to all the
# call sites in the kernel that call mcount. Later on boot up, the kernel
# will read this list, save the locations and turn them into nops.
# When tracing or profiling is later enabled, these locations will then
# be converted back to pointers to some function.
#
# This is no easy feat. This script is called just after the original
# object is compiled and before it is linked.
#
# The references to the call sites are offsets from the section of text
# that the call site is in. Hence, all functions in a section that
# has a call site to mcount, will have the offset from the beginning of
# the section and not the beginning of the function.
#
# The trick is to find a way to record the beginning of the section.
# The way we do this is to look at the first function in the section
# which will also be the location of that section after final link.
# e.g.
#
# .section ".sched.text", "ax"
# .globl my_func
# my_func:
# [...]
# call mcount (offset: 0x5)
# [...]
# ret
# other_func:
# [...]
# call mcount (offset: 0x1b)
# [...]
#
# Both relocation offsets for the mcounts in the above example will be
# offset from .sched.text. If we make another file called tmp.s with:
#
# .section __mcount_loc
# .quad my_func + 0x5
# .quad my_func + 0x1b
#
# We can then compile this tmp.s into tmp.o, and link it to the original
# object.
#
# But this gets hard if my_func is not globl (a static function).
# In such a case we have:
#
# .section ".sched.text", "ax"
# my_func:
# [...]
# call mcount (offset: 0x5)
# [...]
# ret
# .globl my_func
# other_func:
# [...]
# call mcount (offset: 0x1b)
# [...]
#
# If we make the tmp.s the same as above, when we link together with
# the original object, we will end up with two symbols for my_func:
# one local, one global. After final compile, we will end up with
# an undefined reference to my_func.
#
# Since local objects can reference local variables, we need to find
# a way to make tmp.o reference the local objects of the original object
# file after it is linked together. To do this, we convert the my_func
# into a global symbol before linking tmp.o. Then after we link tmp.o
# we will only have a single symbol for my_func that is global.
# We can convert my_func back into a local symbol and we are done.
#
# Here are the steps we take:
#
# 1) Record all the local symbols by using 'nm'
# 2) Use objdump to find all the call site offsets and sections for
# mcount.
# 3) Compile the list into its own object.
# 4) Do we have to deal with local functions? If not, go to step 8.
# 5) Make an object that converts these local functions to global symbols
# with objcopy.
# 6) Link together this new object with the list object.
# 7) Convert the local functions back to local symbols and rename
# the result as the original object.
# End.
# 8) Link the object with the list object.
# 9) Move the result back to the original object.
# End.
#
use strict;
my $P = $0;
$P =~ s@.*/@@g;
my $V = '0.1';
if ($#ARGV < 7) {
print "usage: $P arch bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
print "version: $V\n";
exit(1);
}
my ($arch, $bits, $objdump, $objcopy, $cc,
$ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
if ($inputfile eq "kernel/trace/ftrace.o") {
exit(0);
}
# Acceptable sections to record.
my %text_sections = (
".text" => 1,
".sched.text" => 1,
".spinlock.text" => 1,
".irqentry.text" => 1,
);
$objdump = "objdump" if ((length $objdump) == 0);
$objcopy = "objcopy" if ((length $objcopy) == 0);
$cc = "gcc" if ((length $cc) == 0);
$ld = "ld" if ((length $ld) == 0);
$nm = "nm" if ((length $nm) == 0);
$rm = "rm" if ((length $rm) == 0);
$mv = "mv" if ((length $mv) == 0);
#print STDERR "running: $P '$arch' '$objdump' '$objcopy' '$cc' '$ld' " .
# "'$nm' '$rm' '$mv' '$inputfile'\n";
my %locals; # List of local (static) functions
my %weak; # List of weak functions
my %convert; # List of local functions used that needs conversion
my $type;
my $nm_regex; # Find the local functions (return function)
my $section_regex; # Find the start of a section
my $function_regex; # Find the name of a function
# (return offset and func name)
my $mcount_regex; # Find the call site to mcount (return offset)
my $alignment; # The .align value to use for $mcount_section
my $section_type; # Section header plus possible alignment command
if ($arch eq "x86") {
if ($bits == 64) {
$arch = "x86_64";
} else {
$arch = "i386";
}
}
#
# We base the defaults off of i386, the other archs may
# feel free to change them in the below if statements.
#
$nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
$section_regex = "Disassembly of section\\s+(\\S+):";
$function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";
$section_type = '@progbits';
$type = ".long";
if ($arch eq "x86_64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount([+-]0x[0-9a-zA-Z]+)?\$";
$type = ".quad";
$alignment = 8;
# force flags for this arch
$ld .= " -m elf_x86_64";
$objdump .= " -M x86-64";
$objcopy .= " -O elf64-x86-64";
$cc .= " -m64";
} elsif ($arch eq "i386") {
$alignment = 4;
# force flags for this arch
$ld .= " -m elf_i386";
$objdump .= " -M i386";
$objcopy .= " -O elf32-i386";
$cc .= " -m32";
} elsif ($arch eq "s390" && $bits == 32) {
$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_32\\s+_mcount\$";
$alignment = 4;
$ld .= " -m elf_s390";
$cc .= " -m31";
} elsif ($arch eq "s390" && $bits == 64) {
$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$";
$alignment = 8;
$type = ".quad";
$ld .= " -m elf64_s390";
$cc .= " -m64";
} elsif ($arch eq "sh") {
$alignment = 2;
# force flags for this arch
$ld .= " -m shlelf_linux";
$objcopy .= " -O elf32-sh-linux";
$cc .= " -m32";
} elsif ($arch eq "powerpc") {
$nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
$function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?.*?)>:";
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
if ($bits == 64) {
$type = ".quad";
}
} elsif ($arch eq "arm") {
$alignment = 2;
$section_type = '%progbits';
} elsif ($arch eq "ia64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
$type = "data8";
if ($is_module eq "0") {
$cc .= " -mconstant-gp";
}
} elsif ($arch eq "sparc64") {
# In the objdump output there are giblets like:
# 0000000000000000 <igmp_net_exit-0x18>:
# As there's some data blobs that get emitted into the
# text section before the first instructions and the first
# real symbols. We don't want to match that, so to combat
# this we use '\w' so we'll match just plain symbol names,
# and not those that also include hex offsets inside of the
# '<>' brackets. Actually the generic function_regex setting
# could safely use this too.
$function_regex = "^([0-9a-fA-F]+)\\s+<(\\w*?)>:";
# Sparc64 calls '_mcount' instead of plain 'mcount'.
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
$alignment = 8;
$type = ".xword";
$ld .= " -m elf64_sparc";
$cc .= " -m64";
$objcopy .= " -O elf64-sparc";
} else {
die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
}
my $text_found = 0;
my $read_function = 0;
my $opened = 0;
my $mcount_section = "__mcount_loc";
my $dirname;
my $filename;
my $prefix;
my $ext;
if ($inputfile =~ m,^(.*)/([^/]*)$,) {
$dirname = $1;
$filename = $2;
} else {
$dirname = ".";
$filename = $inputfile;
}
if ($filename =~ m,^(.*)(\.\S),) {
$prefix = $1;
$ext = $2;
} else {
$prefix = $filename;
$ext = "";
}
my $mcount_s = $dirname . "/.tmp_mc_" . $prefix . ".s";
my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
#
# --globalize-symbols came out in 2.17, we must test the version
# of objcopy, and if it is less than 2.17, then we can not
# record local functions.
my $use_locals = 01;
my $local_warn_once = 0;
my $found_version = 0;
open (IN, "$objcopy --version |") || die "error running $objcopy";
while (<IN>) {
if (/objcopy.*\s(\d+)\.(\d+)/) {
my $major = $1;
my $minor = $2;
$found_version = 1;
if ($major < 2 ||
|