commit acb883e8d64d0174f76a2eacf06cdf62b76732af
author Abhinav Anil Sharma <sharmaabhinav@google.com> Fri Jul 22 20:31:59 2022
committer GitHub <noreply@github.com> Fri Jul 22 20:31:59 2022
tree 6bec0ce3953806159fe2b86027e551d2e65a966d
parent c07ffa8f73692d3c7aa6d607895794ccc7b32c0d

i#5570: Use unhide variant for linking DR statically (#5574)

Switches to dynamorio_static_unhide for configuring static DR so
that DR's symbols are visible when building static binaries.

Various symbols in dynamorio_static, like d_r_safe_read and
safe_read_if_fast in core/unix/os.c are non-weak symbols, but
they are not exported by the static DR library because we use
--localize_hidden during build.

$ nm --defined ../../lib64/debug/libdynamorio_static.a | grep d_r_safe_read
00000000002962e8 t d_r_safe_read
$ nm --defined ../../lib64/debug/libdynamorio_static.a | grep safe_read_if_fast
0000000000296272 t safe_read_if_fast

This causes drlibc code to use the wrong routines in is_elf_so_header.
The same would happen for other weakly linked routines in drlibc which
are actually supposed to be suppressed by their respective DR
definitions.

There's an existing version of static DR, libdynamorio_static_nohide,
which does not use --localize_hidden. Now, we use that instead
while configuring static DR.

This issue revealed itself on the recent Ubuntu 20 update which has a
non-readable vsyscall entry in maps. When drlibc tries to read it, it crashes,
and our main_signal_handler isn't able to recognize it as a safe_read crash
because the incorrect d_r_safe read is used. After this fix, the correct one
is used, which helps the DR signal handler to recover as intended.

Some cleanup will follow in the next PR: renaming the nohide version to
make it clear that it is the default, evaluating whether we still need the
static_nohide_api tests.

Issue: #5570