4a556533cf
Even though this was supposedly in the gdb 7.2 timeframe, the testcase in PR11094 crashes current GDB with a segfault: Program received signal SIGSEGV, Segmentation fault. 0x00000000005ee894 in event_location_to_string (location=0x0) at src/gdb/location.c:412 412 if (EL_STRING (location) == NULL) (top-gdb) bt #0 0x00000000005ee894 in event_location_to_string (location=0x0) at src/gdb/location.c:412 #1 0x000000000057411a in print_breakpoint_location (b=0x18288e0, loc=0x0) at src/gdb/breakpoint.c:6201 #2 0x000000000057483f in print_one_breakpoint_location (b=0x18288e0, loc=0x182cf10, loc_number=0, last_loc=0x7fffffffd258, allflag=1) at src/gdb/breakpoint.c:6473 #3 0x00000000005751e1 in print_one_breakpoint (b=0x18288e0, last_loc=0x7fffffffd258, allflag=1) at src/gdb/breakpoint.c:6707 #4 0x000000000057589c in breakpoint_1 (args=0x0, allflag=1, filter=0x0) at src/gdb/breakpoint.c:6947 #5 0x0000000000575aa8 in maintenance_info_breakpoints (args=0x0, from_tty=0) at src/gdb/breakpoint.c:7026 [...] This is GDB trying to print the location spec of the JIT event breakpoint, but that's an internal breakpoint without one. If I add a NULL check, then we see that the JIT breakpoint is now pending (because its location has shlib_disabled set): (gdb) maint info breakpoints Num Type Disp Enb Address What [...] -8 jit events keep y <PENDING> inf 1 [...] But that's incorrect. GDB should have managed to recreate the JIT breakpoint's location for the second run. So the problem is elsewhere. The problem is that if the JIT loads at the same address on the second run, we never recreate the JIT breakpoint, because we hit this early return: static int jit_breakpoint_re_set_internal (struct gdbarch *gdbarch, struct jit_program_space_data *ps_data) { [...] if (ps_data->cached_code_address == addr) return 0; [...] delete_breakpoint (ps_data->jit_breakpoint); [...] ps_data->jit_breakpoint = create_jit_event_breakpoint (gdbarch, addr); Fix this by deleting the breakpoint and discarding the cached code address when the objfile where the previous JIT breakpoint was found is deleted/unloaded in the first place. The test that was originally added for PR11094 doesn't trip on this because: #1 - It doesn't test the case of the JIT descriptor's address _not_ changing between reruns. #2 - And then it doesn't do "maint info breakpoints", or really anything with the JIT at all. #3 - and even then, to trigger the problem the JIT descriptor needs to be in a separate library, while the current test puts it in the main program. The patch extends the test to cover all combinations of these scenarios. gdb/ChangeLog: 2016-10-06 Pedro Alves <palves@redhat.com> * jit.c (free_objfile_data): Delete the JIT breakpoint and clear the cached code address. gdb/testsuite/ChangeLog: 2016-10-06 Pedro Alves <palves@redhat.com> * gdb.base/jit-simple-dl.c: New file. * gdb.base/jit-simple-jit.c: New file, factored out from ... * gdb.base/jit-simple.c: ... this. * gdb.base/jit-simple.exp (jit_run): Delete. (build_jit): New proc. (jit_test_reread): Recompile either the main program or the shared library, depending on what is being tested. Skip changing address if caller wants to. Compare before/after addresses. If testing standalone, explicitly load the binary. Test "maint info breakpoints". (top level): Add "standalone vs shared lib" and "change address" vs "same address" axes. |
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README
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.