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f3a5df7bd6
While reviewing the Linux and FreeBSD core dumping code within GDB for another patch series, I noticed that the code that collects the registers for each thread and writes these into ELF note format is basically identical between Linux and FreeBSD. This commit merges this code and moves it into a new file gcore-elf.c. The function find_signalled_thread is moved from linux-tdep.c to gcore.c despite not being shared. A later commit will make use of this function. I did merge, and then revert a previous version of this patch (commit82a1fd3a49for the original patch and03642b7189for the revert). The problem with the original patch is that it introduced a unconditional dependency between GDB and some ELF specific functions in the BFD library, e.g. elfcore_write_prstatus and elfcore_write_register_note. It was pointed out in this mailing list post: https://sourceware.org/pipermail/gdb-patches/2021-February/175750.html that this change was breaking any build of GDB for non-ELF targets. To confirm this breakage, and to test this new version of GDB I configured and built for the target x86_64-apple-darwin20.3.0. Where the previous version of this patch placed all of the common code into gcore.c, which is included in all builds of GDB, this new patch only places non-ELF specific generic code (i.e. find_signalled_thread) into gcore.c, the ELF specific code is put into the new gcore-elf.c file, which is only included in GDB if BFD has ELF support. The contents of gcore-elf.c are referenced unconditionally from linux-tdep.c and fbsd-tdep.c, this is fine, we previously always assumed that these two targets required ELF support, and we continue to make that assumption after this patch; nothing has changed there. With my previous version of this patch the darwin target mentioned above failed to build, but with the new version, the target builds fine. There are a couple of minor changes to the FreeBSD target after this commit, but I believe that these are changes for the better: (1) For FreeBSD we always used to record the thread-id in the core file by using ptid_t.lwp (). In contrast the Linux code did this: /* For remote targets the LWP may not be available, so use the TID. */ long lwp = ptid.lwp (); if (lwp == 0) lwp = ptid.tid (); Both target now do this: /* The LWP is often not available for bare metal target, in which case use the tid instead. */ if (ptid.lwp_p ()) lwp = ptid.lwp (); else lwp = ptid.tid (); Which is equivalent for Linux, but is a change for FreeBSD. I think that all this means is that in some cases where GDB might have previously recorded a thread-id of 0 for each thread, we might now get something more useful. (2) When collecting the registers for Linux we collected into a zero initialised buffer. By contrast on FreeBSD the buffer is left uninitialised. In the new code the buffer is always zero initialised. I suspect once the registers are copied into the buffer there's probably no gaps left so this makes no difference, but if it does then using zeros rather than random bits of GDB's memory is probably a good thing. Otherwise, there should be no other user visible changes after this commit. Tested this on x86-64/GNU-Linux and x86-64/FreeBSD-12.2 with no regressions. gdb/ChangeLog: * Makefile.in (SFILES): Add gcore-elf.c. (HFILES_NO_SRCDIR): Add gcore-elf.h * configure: Regenerate. * configure.ac: Add gcore-elf.o to CONFIG_OBS if we have ELF support. * fbsd-tdep.c: Add 'gcore-elf.h' include. (struct fbsd_collect_regset_section_cb_data): Delete. (fbsd_collect_regset_section_cb): Delete. (fbsd_collect_thread_registers): Delete. (struct fbsd_corefile_thread_data): Delete. (fbsd_corefile_thread): Delete. (fbsd_make_corefile_notes): Call gcore_elf_build_thread_register_notes instead of the now deleted FreeBSD code. * gcore-elf.c: New file, the content was moved here from linux-tdep.c, functions were renamed and given minor cleanup. * gcore-elf.h: New file. * gcore.c (gcore_find_signalled_thread): Moved here from linux-tdep.c and given a new name. Minor cleanups. * gcore.h (gcore_find_signalled_thread): Declare. * linux-tdep.c: Add 'gcore.h' and 'gcore-elf.h' includes. (struct linux_collect_regset_section_cb_data): Delete. (linux_collect_regset_section_cb): Delete. (linux_collect_thread_registers): Delete. (linux_corefile_thread): Call gcore_elf_build_thread_register_notes. (find_signalled_thread): Delete. (linux_make_corefile_notes): Call gcore_find_signalled_thread.
41 lines
1.4 KiB
C
41 lines
1.4 KiB
C
/* Support for reading/writing gcore files.
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Copyright (C) 2009-2021 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#if !defined (GCORE_H)
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#define GCORE_H 1
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#include "gdb_bfd.h"
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struct thread_info;
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extern gdb_bfd_ref_ptr create_gcore_bfd (const char *filename);
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extern void write_gcore_file (bfd *obfd);
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extern int objfile_find_memory_regions (struct target_ops *self,
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find_memory_region_ftype func,
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void *obfd);
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/* Find the signalled thread. In case there's more than one signalled
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thread, prefer the current thread, if it is signalled. If no thread was
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signalled, default to the current thread, unless it has exited, in which
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case return NULL. */
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extern thread_info *gcore_find_signalled_thread ();
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#endif /* GCORE_H */
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