This patch makes single-step breakpoints "real" breakpoints on the global location list. There are several benefits to this: - It removes the currently limitation that only 2 single-step breakpoints can be inserted. See an example here of a discussion around a case that wants more than 2, possibly unbounded: https://sourceware.org/ml/gdb-patches/2014-03/msg00663.html - makes software single-step work on read-only code regions. The logic to convert a software breakpoint to a hardware breakpoint if the memory map says the breakpoint address is in read only memory is in insert_bp_location. Because software single-step breakpoints bypass all that go and straight to target_insert_breakpoint, we can't software single-step over read only memory. This patch removes that limitation, and adds a test that makes sure that works, by forcing a code region to read-only with "mem LOW HIGH ro" and then stepping through that. - Fixes PR breakpoints/9649 This is an assertion failure in insert_single_step_breakpoint in breakpoint.c, because we may leave stale single-step breakpoints behind on error. The tests for stepping through read-only regions exercise the root cause of the bug, which is that we leave single-step breakpoints behind if we fail to insert any single-step breakpoint. Deleting the single-step breakpoints in resume_cleanups, delete_just_stopped_threads_infrun_breakpoints, and fetch_inferior_event fixes this. Without that, we'd no longer hit the assertion, as that code is deleted, but we'd instead run into errors/warnings trying to insert/remove the stale breakpoints on next resume. - Paves the way to have multiple threads software single-stepping at the same time, leaving update_global_location_list to worry about duplicate locations. - Makes the moribund location machinery aware of software single-step breakpoints, paving the way to enable software single-step on non-stop, instead of forcing serialized displaced stepping for all single steps. - It's generaly cleaner. We no longer have to play games with single-step breakpoints inserted at the same address as regular breakpoints, like we recently had to do for 7.8. See this discussion: https://sourceware.org/ml/gdb-patches/2014-06/msg00052.html. Tested on x86_64 Fedora 20, on top of my 'single-step breakpoints on x86' series. gdb/ 2014-10-15 Pedro Alves <palves@redhat.com> PR breakpoints/9649 * breakpoint.c (single_step_breakpoints, single_step_gdbarch): Delete array globals. (single_step_breakpoints): New global. (breakpoint_xfer_memory): Remove special handling for single-step breakpoints. (update_breakpoints_after_exec): Delete bp_single_step breakpoints. (detach_breakpoints): Remove special handling for single-step breakpoints. (breakpoint_init_inferior): Delete bp_single_step breakpoints. (bpstat_stop_status): Add comment. (bpstat_what, bptype_string, print_one_breakpoint_location) (adjust_breakpoint_address, init_bp_location): Handle bp_single_step. (new_single_step_breakpoint): New function. (set_momentary_breakpoint, bkpt_remove_location): Remove special handling for single-step breakpoints. (insert_single_step_breakpoint, single_step_breakpoints_inserted) (remove_single_step_breakpoints, cancel_single_step_breakpoints): Rewrite. (detach_single_step_breakpoints, find_single_step_breakpoint): Delete functions. (breakpoint_has_location_inserted_here): New function. (single_step_breakpoint_inserted_here_p): Rewrite. * breakpoint.h: Remove FIXME. (enum bptype) <bp_single_step>: New enum value. (insert_single_step_breakpoint): Update comment. * infrun.c (resume_cleanups) (delete_step_thread_step_resume_breakpoint): Remove single-step breakpoints. (fetch_inferior_event): Install a cleanup that removes infrun breakpoints. (switch_back_to_stepped_thread) <expect thread advanced also>: Clear step-over info. gdb/testsuite/ 2014-10-15 Pedro Alves <palves@redhat.com> PR breakpoints/9649 * gdb.base/breakpoint-in-ro-region.c (main): Add more instructions. * gdb.base/breakpoint-in-ro-region.exp (probe_target_hardware_step): New procedure. (top level): Probe hardware stepping and hardware breakpoint support. Test stepping through a read-only region, with both "breakpoint auto-hw" on and off and both "always-inserted" on and off.
…
…
…
…
…
…
…
…
…
…
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.
Description