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The IRIX support wants to set a breakpoint to be hit when the startup
phase is complete, which is where shared libraries have been mapped
in. AFAIU, for most IRIX ports, that location is the entry point.
For MIPS IRIX however, GDB needs to set a breakpoint earlier, in
__dbx_link, as explained by:
#ifdef SYS_syssgi
/* On mips-irix, we need to stop the inferior early enough during
the startup phase in order to be able to load the shared library
symbols and insert the breakpoints that are located in these shared
libraries. Stopping at the program entry point is not good enough
because the -init code is executed before the execution reaches
that point.
So what we need to do is to insert a breakpoint in the runtime
loader (rld), more precisely in __dbx_link(). This procedure is
called by rld once all shared libraries have been mapped, but before
the -init code is executed. Unfortuantely, this is not straightforward,
as rld is not part of the executable we are running, and thus we need
the inferior to run until rld itself has been mapped in memory.
For this, we trace all syssgi() syscall exit events. Each time
we detect such an event, we iterate over each text memory maps,
get its associated fd, and scan the symbol table for __dbx_link().
When found, we know that rld has been mapped, and that we can insert
the breakpoint at the symbol address. Once the dbx_link() breakpoint
has been inserted, the syssgi() notifications are no longer necessary,
so they should be canceled. */
proc_trace_syscalls_1 (pi, SYS_syssgi, PR_SYSEXIT, FLAG_SET, 0);
#endif
The loop in irix_solib_create_inferior_hook then runs until whichever
breakpoint is hit first, the one set by solib-irix.c or the one set by
procfs.c.
Note the comment in disable_break talks about __dbx_init, but I think
that's a typo for __dbx_link:
- /* Note that it is possible that we have stopped at a location that
- is different from the location where we inserted our breakpoint.
- On mips-irix, we can actually land in __dbx_init(), so we should
- not check the PC against our breakpoint address here. See procfs.c
- for more details. */
This looks very much like referring to the loop in
irix_solib_create_inferior_hook stopping at __dbx_link instead of at
the entry point.
What this patch does is convert these deprecated raw breakpoints to
standard solib_event breakpoints. When the first solib-event
breakpoint is hit, we delete all solib-event breakpoints. We do that
in the so_ops->handle_event hook.
This allows getting rid of the loop in irix_solib_create_inferior_hook
completely, which should allow properly handling signals and other
events in the early startup phase, like in SVR4.
Built on x86_64 Fedora 20 with --enable-targets=all (builds
solib-irix.c).
Joel tested that with an earlier version of this patch "info shared"
after starting a program gave the same list of shared libraries as
before.
gdb/ChangeLog:
2014-09-12 Pedro Alves <palves@redhat.com>
* breakpoint.c (remove_solib_event_breakpoints_at_next_stop)
(create_and_insert_solib_event_breakpoint): New functions.
* breakpoint.h (create_and_insert_solib_event_breakpoint)
(remove_solib_event_breakpoints_at_next_stop): New declarations.
* procfs.c (dbx_link_bpt_addr, dbx_link_bpt): Delete globals.
(remove_dbx_link_breakpoint): Delete function.
(insert_dbx_link_bpt_in_file): Use
create_and_insert_solib_event_breakpoint instead of
deprecated_insert_raw_breakpoint.
(procfs_wait): Don't check whether we hit __dbx_link here.
(procfs_mourn_inferior): Don't delete the __dbx_link breakpoint
here.
* solib-irix.c (base_breakpoint): Delete global.
(disable_break): Delete function.
(enable_break): Use create_solib_event_breakpoint
instead of deprecated_insert_raw_breakpoint.
(irix_solib_handle_event): New function.
(irix_solib_create_inferior_hook): Don't run the target or disable
the mapping-complete breakpoint here.
(_initialize_irix_solib): Install irix_solib_handle_event as
so_ops->handle_event hook.
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| binutils | ||
| config | ||
| cpu | ||
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| etc | ||
| gas | ||
| gdb | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
| libdecnumber | ||
| libiberty | ||
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| ltsugar.m4 | ||
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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.