To implement QGetTlsAddr, gdbsrv has to know how to get the glibc dtv
address and the module id from the link_map.
These 2 things are dependent on the internals of glibc.
The dependency is mostly isolated in a few lines of arch dependent
code or in an external utility that used a hack + -ldl lib to find
the offset of the modid in the link_map structure.
Tested on x86/amd64/ppc64/s390x. Somewhat tested on ppc32 and arm64.
Untested/a few #ifdef-ed lines not compiled on arm/mips32/mips64
and darwin.
For more background info about thread local storage handling, see
'ELF Handling For Thread-Local Storage' http://www.akkadia.org/drepper/tls.pdf
Changes:
* auxprogs/getoff.c new auxilliary program to get platform specific offsets
(currently only the offset for the module id in struct link_map).
* configure.ac : check for dlinfo(RTLD_DI_TLS_MODID) needed for getoff.c
* new gdbserver_tests/hgtls, testing various types of __thread variables
* various m_gdbserver files:
- implement decoding of the QGetTlsAddr query
- for each platform: platform specific code to get the dtv
- call to external program getoff-<platform> the first time an
__thread variable is printed.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14283
