3 # This script handles linking the tool executables on Linux,
4 # statically and at an alternative load address.
6 # Linking statically sidesteps all sorts of complications to do with
7 # having two copies of the dynamic linker (valgrind's and the
8 # client's) coexisting in the same process. The alternative load
9 # address is needed because Valgrind itself will load the client at
10 # whatever address it specifies, which is almost invariably the
11 # default load address. Hence we can't allow Valgrind itself (viz,
12 # the tool executable) to be loaded at that address.
14 # Unfortunately there's no standard way to do 'static link at
15 # alternative address', so these link_tool_exe_*.in scripts handle
16 # the per-platform hoop-jumping.
18 # What we get passed here is:
20 # the alternative load address
21 # all the rest of the args
22 # the gcc invokation to do the final link, that
23 # the build system would have done, left to itself
25 # We just let the script 'die' if something is wrong, rather than do
26 # proper error reporting. We don't expect the users to run this
27 # directly. It is only run as part of the build process, with
28 # carefully constrained inputs.
31 # So: what we actually do is:
33 # Look at the specified gcc invokation. Ignore all parts of it except
34 # the *.a, *.o and -o outfile parts. Wrap them up in a new command
35 # which looks (eg) as follows:
39 # /usr/bin/ld -static -arch x86_64 -macosx_version_min 10.5 \
40 # -o memcheck-amd64-darwin -u __start -e __start \
41 # -image_base 0x138000000 -stack_addr 0x13c000000 \
42 # -stack_size 0x800000 \
44 # ../coregrind/libcoregrind-amd64-darwin.a \
45 # ../VEX/libvex-amd64-darwin.a
49 # /usr/bin/ld -static -arch i386 -macosx_version_min 10.5 \
50 # -o memcheck-x86-darwin -u __start -e __start \
51 # -image_base 0x38000000 -stack_addr 0x3c000000 \
52 # -stack_size 0x800000 \
54 # ../coregrind/libcoregrind-x86-darwin.a \
55 # ../VEX/libvex-x86-darwin.a
57 # The addresses shown above will actually work, although "for real" we
58 # of course need to take it from argv[1]. In these examples the stack
59 # is placed 64M after the executable start. It is probably safer to
60 # place it 64M before the executable's start point, so the executable
61 # + data + bss can grow arbitrarily in future without colliding with
64 # There's one more twist: we need to know the word size of the
65 # executable for which we are linking. We need to know this because
66 # we must tell the linker that, by handing it either "-arch x86_64" or
67 # "-arch i386". Fortunately we can figure this out by scanning the
68 # gcc invokation, which itself must contain either "-arch x86_64" or
73 # we need to be able to do 64-bit arithmetic:
77 # User configurable constants: how far before the exe should we
79 my $TX_STACK_OFFSET_BEFORE_TEXT = 64 * 1024 * 1024;
81 # and how big should the stack be?
82 my $TX_STACK_SIZE = 8 * 1024 * 1024;
86 sub is_dota_or_doto($)
89 if ($str =~ /.\.a$/ || $str =~ /.\.o$/) {
97 # expect at least: alt-load-address gcc -o foo bar.o
98 die "Not enough arguments"
99 if (($#ARGV + 1) < 5);
103 # check for plausible-ish alt load address
104 die "Bogus alt-load address (1)"
105 if (length($ala) < 3 || index($ala, "0x") != 0);
107 die "Bogus alt-load address (2)"
108 if ($ala !~ /^0x[0-9a-fA-F]+$/);
111 # get hold of the outfile name (following "-o")
114 foreach my $n (2 .. $#ARGV - 1) {
116 if ($str eq "-o" && $outname eq "") {
117 $outname = $ARGV[$n + 1];
121 die "Can't find '-o outfilename' in command line"
125 # get hold of the string following "-arch"
128 foreach my $n (2 .. $#ARGV - 1) {
130 if ($str eq "-arch" && $archstr eq "") {
131 $archstr = $ARGV[$n + 1];
135 die "Can't find '-arch archstr' in command line"
139 # build the command line
140 my $cmd = "/usr/bin/ld";
142 $cmd = "$cmd -static";
143 $cmd = "$cmd -arch $archstr";
144 $cmd = "$cmd -macosx_version_min 10.5";
145 $cmd = "$cmd -o $outname";
146 $cmd = "$cmd -u __start -e __start";
148 my $stack_addr = Math::BigInt->new( $ala ) - $TX_STACK_OFFSET_BEFORE_TEXT;
149 my $stack_addr_str = $stack_addr->as_hex();
150 my $stack_size_str = Math::BigInt::as_hex($TX_STACK_SIZE);
152 $cmd = "$cmd -image_base $ala";
153 $cmd = "$cmd -stack_addr $stack_addr_str";
154 $cmd = "$cmd -stack_size $stack_size_str";
156 foreach my $n (2 .. $#ARGV) {
158 if (is_dota_or_doto($str)) {
163 print "link_tool_exe_darwin: $cmd\n";
165 # Execute the command:
166 my $r = system("$cmd");
173 # and now kludge the tool exe
176 $cmd = "../coregrind/fixup_macho_loadcmds";
177 $cmd = "$cmd $stack_addr_str $stack_size_str $outname";
179 print "link_tool_exe_darwin: $cmd\n";