thread specific informations.
In order to do that, and in order to avoid KBI breakage with existing
infrastructure the following semantic is implemented:
- For live programs, a new member to the PT_LWPINFO is added (pl_tdname)
- For cores, a new ELF note is added (NT_THRMISC) that can be used for
storing thread specific, miscellaneous, informations. Right now it is
just popluated with a thread name.
GDB, then, retrieves the correct informations from the corefile via the
BFD interface, as it groks the ELF notes and create appropriate
pseudo-sections.
Sponsored by: Sandvine Incorporated
Tested by: gianni
Discussed with: dim, kan, kib
MFC after: 2 weeks
ABI change on ILP32 platforms and relating to events. However
it's harmless on little-endian ILP32 platforms in the sense
that it doesn't cause breakages. Old ILP32 thread libraries
write a 32-bit th_p and new thread libraries write a 64-bit
th_p. But due to the fact that we have an unused 32-bit data
field right after th_p and that field is always initialized to
zero, little-endian ILP32 machines effectively have a valid
64-bit th_p by accident. Likewise for new thread libraries and
old libthread_db: little endian ILP32 is unaffected.
At this time we don't support big-endian threaded applications
in GDB, so the breakage for the ILP32 case goes unnoticed.
force the FreeBSD multithreaded core target to not register any target
for handling core dumps. This is analogous to the
'coreops_suppress_target' variable that GDB provides for suppressing the
default core dump target. KGDB will use this new variable so it can
provide its own core dump target that uses libkvm to work with vmcore
files.
- Adjust the long name and documentation of the FreeBSD multithreaded core
dump target so it better matches what GDB's core dump target uses.
MFC after: 1 week
Reviewed by: davidxu, marcel
first getting the current state with td_thr_getxmmregs_p. Without this,
debugging a threaded app that uses libthr resulted in kernel panics or
spurious SIGFPEs for me.
(As of revision 1.6, sys/i386/i386/ptrace_machdep.c masks off the
reserved bits in the mxcsr register, which prevents the kernel panics.)
Architectures without PT_GETXMMREGS are not affected.
MFC after: 1 week
lwp ID before invoking the underlying target operation.
For corefiles, we rely on gdb internals to do this, and it uses the
pid as an index, rather than the lwpid, so previously, backtraces
for multithreaded core files wasn't working correctly. For processes,
we currently use ptrace directly, so fixup that code to also use
the pid directly.
Discussed With: marcel, davidxu
MFC After: 4 days
