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      1 #! @PERL@
      2 
      3 # This script handles linking the tool executables on Linux,
      4 # statically and at an alternative load address.
      5 #
      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.
     13 #
     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.
     17 #
     18 # What we get passed here is:
     19 #   first arg
     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
     24 #
     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.
     29 #
     30 # Linux specific complications:
     31 #
     32 # - need to support both old GNU ld and gold: use -Ttext= to
     33 #   set the text segment address.
     34 #
     35 # - need to pass --build-id=none (that is, -Wl,--build-id=none to
     36 #   gcc) if it accepts it, to ensure the linker doesn't add a
     37 #   notes section which ends up at the default load address and
     38 #   so defeats our attempts to keep that address clear for the
     39 #   client.  However, older linkers don't support this flag, so it
     40 #   is tested for by configure.in and is shipped to us as part of
     41 #   argv[2 ..].
     42 #
     43 #
     44 # So: what we actually do:
     45 # 
     46 #   pass the specified command to the linker as-is, except, add
     47 #   "-static" and "-Ttext=<argv[1]>" to it.
     48 #
     49 
     50 use warnings;
     51 use strict;
     52 
     53 # expect at least: alt-load-address gcc -o foo bar.o
     54 die "Not enough arguments"
     55     if (($#ARGV + 1) < 5);
     56 
     57 my $ala = $ARGV[0];
     58 
     59 # check for plausible-ish alt load address
     60 die "Bogus alt-load address"
     61     if (length($ala) < 3 || index($ala, "0x") != 0);
     62 
     63 # The cc invokation to do the final link
     64 my $cc = $ARGV[1];
     65 
     66 # and the 'restargs' are argv[2 ..]
     67 
     68 # so, build up the complete command here:
     69 # 'cc' -static -Ttext='ala' 'restargs'
     70 
     71 # For mips we need to use "--section-start=.reginfo=$ala" because
     72 # "--section-start=.reginfo=$ala" will put all the sections to the 
     73 # specificed address ($ala)
     74 my $x=`$cc -v 2>&1 | grep Target | sed 's/Target: //g'`;
     75 my $arch=substr($x, 0, index($x, '-'));
     76 my $cmd;
     77 
     78 if (($arch eq 'mips') || ($arch eq 'mipsel')) {
     79    $cmd = "$cc -static -Wl,--section-start=.reginfo=$ala";
     80 } else {
     81    $cmd = "$cc -static -Wl,-Ttext=$ala";
     82 }
     83 
     84 # Add the rest of the parameters
     85 foreach my $n (2 .. $#ARGV) {
     86    $cmd = "$cmd $ARGV[$n]";
     87 }
     88 
     89 #print "link_tool_exe_linux: $cmd\n";
     90 
     91 
     92 # Execute the command:
     93 my $r = system("$cmd");
     94 
     95 if ($r == 0) {
     96     exit 0;
     97 } else {
     98     exit 1;
     99 }
    100