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For every stop, Linux GDB and GDBserver save the stopped thread's PC,
in lwp->stop_pc. This is done in save_stop_reason, in both
gdb/linux-nat.c and gdbserver/linux-low.cc. However, while we're
going through the shell after "run", in startup_inferior, we shouldn't
be reading registers, as we haven't yet determined the target's
architecture -- the shell's architecture may not even be the same as
the final inferior's.
In gdb/linux-nat.c, lwp->stop_pc is only needed when the thread has
stopped for a breakpoint, and since when going through the shell, no
breakpoint is going to hit, we could simply teach save_stop_reason to
only record the stop pc when the thread stopped for a breakpoint.
However, in gdbserver/linux-low.cc, lwp->stop_pc is used in more cases
than breakpoint hits (e.g., it's used in tracepoints & the
"while-stepping" feature).
So to avoid GDB vs GDBserver divergence, we apply the same approach to
both implementations.
We set a flag in the inferior (process in GDBserver) whenever it is
being nursed through the shell, and when that flag is set,
save_stop_reason bails out early. While going through the shell,
we'll only ever get process exits (normal or signalled), random
signals, and exec events, so nothing is lost.
Change-Id: If0f01831514d3a74d17efd102875de7d2c6401ad
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This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
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Same idea as the previous patch, but for m_cwd.
To keep things consistent across the board, change get_inferior_cwd as
well, which is shared with GDBserver. So update the related GDBserver
code too.
Change-Id: Ia2c047fda738d45f3d18bc999eb67ceb8400ce4e
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The declaration of set_inferior_cwd is currently shared between gdb and
gdbserver, in gdbsupport/common-inferior.h. It doesn't need to be, as
set_inferior_cwd is not called from common code. Only get_inferior_cwd
needs to.
The motivation for this is that a future patch will change the prototype
of set_inferior_cwd in gdb, and I don't want to change it for gdbserver
unnecessarily. I see this as a good cleanup in any case, to reduce to
just the essential what is shared between GDB and GDBserver.
Change-Id: I3127d27d078f0503ebf5ccc6fddf14f212426a73
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The 'all_dlls' list is global. This would cause the complete dll list
to be reported for individual processes. Move the list into the
process_info struct.
Currently the dll list is used only by the win32-low target, which
does not support the multi-process feature. Therefore, it practically
does not matter whether the list is global or per-process. However,
there may be targets that are outside the binutils-gdb repo (e.g. we,
at Intel, have such a target) that have multi-process and use the dll
list. So, it makes sense to do the right thing.
gdbserver/ChangeLog:
2021-03-22 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* inferiors.h (struct process_info) <all_dlls, dlls_changed>: New
fields.
* dll.h (loaded_dll)
(unloaded_dll): Declare an overloaded version that takes a proc
parameter.
* dll.cc (loaded_dll)
(unloaded_dll): Implement the overloaded versions.
(clear_dlls): Clear all process' dll lists.
(all_dlls, dlls_changed): Remove the global variables.
* remote-utils.cc (prepare_resume_reply): Update to consider a dll
list per proc.
* server.cc (handle_qxfer_libraries): Ditto.
(handle_v_attach): Ditto.
(captured_main): Ditto.
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This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
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Many spots incorrectly use only spaces for indentation (for example,
there are a lot of spots in ada-lang.c). I've always found it awkward
when I needed to edit one of these spots: do I keep the original wrong
indentation, or do I fix it? What if the lines around it are also
wrong, do I fix them too? I probably don't want to fix them in the same
patch, to avoid adding noise to my patch.
So I propose to fix as much as possible once and for all (hopefully).
One typical counter argument for this is that it makes code archeology
more difficult, because git-blame will show this commit as the last
change for these lines. My counter counter argument is: when
git-blaming, you often need to do "blame the file at the parent commit"
anyway, to go past some other refactor that touched the line you are
interested in, but is not the change you are looking for. So you
already need a somewhat efficient way to do this.
Using some interactive tool, rather than plain git-blame, makes this
trivial. For example, I use "tig blame <file>", where going back past
the commit that changed the currently selected line is one keystroke.
It looks like Magit in Emacs does it too (though I've never used it).
Web viewers of Github and Gitlab do it too. My point is that it won't
really make archeology more difficult.
The other typical counter argument is that it will cause conflicts with
existing patches. That's true... but it's a one time cost, and those
are not conflicts that are difficult to resolve. I have also tried "git
rebase --ignore-whitespace", it seems to work well. Although that will
re-introduce the faulty indentation, so one needs to take care of fixing
the indentation in the patch after that (which is easy).
gdb/ChangeLog:
* aarch64-linux-tdep.c: Fix indentation.
* aarch64-ravenscar-thread.c: Fix indentation.
* aarch64-tdep.c: Fix indentation.
* aarch64-tdep.h: Fix indentation.
* ada-lang.c: Fix indentation.
* ada-lang.h: Fix indentation.
* ada-tasks.c: Fix indentation.
* ada-typeprint.c: Fix indentation.
* ada-valprint.c: Fix indentation.
* ada-varobj.c: Fix indentation.
* addrmap.c: Fix indentation.
* addrmap.h: Fix indentation.
* agent.c: Fix indentation.
* aix-thread.c: Fix indentation.
* alpha-bsd-nat.c: Fix indentation.
* alpha-linux-tdep.c: Fix indentation.
* alpha-mdebug-tdep.c: Fix indentation.
* alpha-nbsd-tdep.c: Fix indentation.
* alpha-obsd-tdep.c: Fix indentation.
* alpha-tdep.c: Fix indentation.
* amd64-bsd-nat.c: Fix indentation.
* amd64-darwin-tdep.c: Fix indentation.
* amd64-linux-nat.c: Fix indentation.
* amd64-linux-tdep.c: Fix indentation.
* amd64-nat.c: Fix indentation.
* amd64-obsd-tdep.c: Fix indentation.
* amd64-tdep.c: Fix indentation.
* amd64-windows-tdep.c: Fix indentation.
* annotate.c: Fix indentation.
* arc-tdep.c: Fix indentation.
* arch-utils.c: Fix indentation.
* arch/arm-get-next-pcs.c: Fix indentation.
* arch/arm.c: Fix indentation.
* arm-linux-nat.c: Fix indentation.
* arm-linux-tdep.c: Fix indentation.
* arm-nbsd-tdep.c: Fix indentation.
* arm-pikeos-tdep.c: Fix indentation.
* arm-tdep.c: Fix indentation.
* arm-tdep.h: Fix indentation.
* arm-wince-tdep.c: Fix indentation.
* auto-load.c: Fix indentation.
* auxv.c: Fix indentation.
* avr-tdep.c: Fix indentation.
* ax-gdb.c: Fix indentation.
* ax-general.c: Fix indentation.
* bfin-linux-tdep.c: Fix indentation.
* block.c: Fix indentation.
* block.h: Fix indentation.
* blockframe.c: Fix indentation.
* bpf-tdep.c: Fix indentation.
* break-catch-sig.c: Fix indentation.
* break-catch-syscall.c: Fix indentation.
* break-catch-throw.c: Fix indentation.
* breakpoint.c: Fix indentation.
* breakpoint.h: Fix indentation.
* bsd-uthread.c: Fix indentation.
* btrace.c: Fix indentation.
* build-id.c: Fix indentation.
* buildsym-legacy.h: Fix indentation.
* buildsym.c: Fix indentation.
* c-typeprint.c: Fix indentation.
* c-valprint.c: Fix indentation.
* c-varobj.c: Fix indentation.
* charset.c: Fix indentation.
* cli/cli-cmds.c: Fix indentation.
* cli/cli-decode.c: Fix indentation.
* cli/cli-decode.h: Fix indentation.
* cli/cli-script.c: Fix indentation.
* cli/cli-setshow.c: Fix indentation.
* coff-pe-read.c: Fix indentation.
* coffread.c: Fix indentation.
* compile/compile-cplus-types.c: Fix indentation.
* compile/compile-object-load.c: Fix indentation.
* compile/compile-object-run.c: Fix indentation.
* completer.c: Fix indentation.
* corefile.c: Fix indentation.
* corelow.c: Fix indentation.
* cp-abi.h: Fix indentation.
* cp-namespace.c: Fix indentation.
* cp-support.c: Fix indentation.
* cp-valprint.c: Fix indentation.
* cris-linux-tdep.c: Fix indentation.
* cris-tdep.c: Fix indentation.
* darwin-nat-info.c: Fix indentation.
* darwin-nat.c: Fix indentation.
* darwin-nat.h: Fix indentation.
* dbxread.c: Fix indentation.
* dcache.c: Fix indentation.
* disasm.c: Fix indentation.
* dtrace-probe.c: Fix indentation.
* dwarf2/abbrev.c: Fix indentation.
* dwarf2/attribute.c: Fix indentation.
* dwarf2/expr.c: Fix indentation.
* dwarf2/frame.c: Fix indentation.
* dwarf2/index-cache.c: Fix indentation.
* dwarf2/index-write.c: Fix indentation.
* dwarf2/line-header.c: Fix indentation.
* dwarf2/loc.c: Fix indentation.
* dwarf2/macro.c: Fix indentation.
* dwarf2/read.c: Fix indentation.
* dwarf2/read.h: Fix indentation.
* elfread.c: Fix indentation.
* eval.c: Fix indentation.
* event-top.c: Fix indentation.
* exec.c: Fix indentation.
* exec.h: Fix indentation.
* expprint.c: Fix indentation.
* f-lang.c: Fix indentation.
* f-typeprint.c: Fix indentation.
* f-valprint.c: Fix indentation.
* fbsd-nat.c: Fix indentation.
* fbsd-tdep.c: Fix indentation.
* findvar.c: Fix indentation.
* fork-child.c: Fix indentation.
* frame-unwind.c: Fix indentation.
* frame-unwind.h: Fix indentation.
* frame.c: Fix indentation.
* frv-linux-tdep.c: Fix indentation.
* frv-tdep.c: Fix indentation.
* frv-tdep.h: Fix indentation.
* ft32-tdep.c: Fix indentation.
* gcore.c: Fix indentation.
* gdb_bfd.c: Fix indentation.
* gdbarch.sh: Fix indentation.
* gdbarch.c: Re-generate
* gdbarch.h: Re-generate.
* gdbcore.h: Fix indentation.
* gdbthread.h: Fix indentation.
* gdbtypes.c: Fix indentation.
* gdbtypes.h: Fix indentation.
* glibc-tdep.c: Fix indentation.
* gnu-nat.c: Fix indentation.
* gnu-nat.h: Fix indentation.
* gnu-v2-abi.c: Fix indentation.
* gnu-v3-abi.c: Fix indentation.
* go32-nat.c: Fix indentation.
* guile/guile-internal.h: Fix indentation.
* guile/scm-cmd.c: Fix indentation.
* guile/scm-frame.c: Fix indentation.
* guile/scm-iterator.c: Fix indentation.
* guile/scm-math.c: Fix indentation.
* guile/scm-ports.c: Fix indentation.
* guile/scm-pretty-print.c: Fix indentation.
* guile/scm-value.c: Fix indentation.
* h8300-tdep.c: Fix indentation.
* hppa-linux-nat.c: Fix indentation.
* hppa-linux-tdep.c: Fix indentation.
* hppa-nbsd-nat.c: Fix indentation.
* hppa-nbsd-tdep.c: Fix indentation.
* hppa-obsd-nat.c: Fix indentation.
* hppa-tdep.c: Fix indentation.
* hppa-tdep.h: Fix indentation.
* i386-bsd-nat.c: Fix indentation.
* i386-darwin-nat.c: Fix indentation.
* i386-darwin-tdep.c: Fix indentation.
* i386-dicos-tdep.c: Fix indentation.
* i386-gnu-nat.c: Fix indentation.
* i386-linux-nat.c: Fix indentation.
* i386-linux-tdep.c: Fix indentation.
* i386-nto-tdep.c: Fix indentation.
* i386-obsd-tdep.c: Fix indentation.
* i386-sol2-nat.c: Fix indentation.
* i386-tdep.c: Fix indentation.
* i386-tdep.h: Fix indentation.
* i386-windows-tdep.c: Fix indentation.
* i387-tdep.c: Fix indentation.
* i387-tdep.h: Fix indentation.
* ia64-libunwind-tdep.c: Fix indentation.
* ia64-libunwind-tdep.h: Fix indentation.
* ia64-linux-nat.c: Fix indentation.
* ia64-linux-tdep.c: Fix indentation.
* ia64-tdep.c: Fix indentation.
* ia64-tdep.h: Fix indentation.
* ia64-vms-tdep.c: Fix indentation.
* infcall.c: Fix indentation.
* infcmd.c: Fix indentation.
* inferior.c: Fix indentation.
* infrun.c: Fix indentation.
* iq2000-tdep.c: Fix indentation.
* language.c: Fix indentation.
* linespec.c: Fix indentation.
* linux-fork.c: Fix indentation.
* linux-nat.c: Fix indentation.
* linux-tdep.c: Fix indentation.
* linux-thread-db.c: Fix indentation.
* lm32-tdep.c: Fix indentation.
* m2-lang.c: Fix indentation.
* m2-typeprint.c: Fix indentation.
* m2-valprint.c: Fix indentation.
* m32c-tdep.c: Fix indentation.
* m32r-linux-tdep.c: Fix indentation.
* m32r-tdep.c: Fix indentation.
* m68hc11-tdep.c: Fix indentation.
* m68k-bsd-nat.c: Fix indentation.
* m68k-linux-nat.c: Fix indentation.
* m68k-linux-tdep.c: Fix indentation.
* m68k-tdep.c: Fix indentation.
* machoread.c: Fix indentation.
* macrocmd.c: Fix indentation.
* macroexp.c: Fix indentation.
* macroscope.c: Fix indentation.
* macrotab.c: Fix indentation.
* macrotab.h: Fix indentation.
* main.c: Fix indentation.
* mdebugread.c: Fix indentation.
* mep-tdep.c: Fix indentation.
* mi/mi-cmd-catch.c: Fix indentation.
* mi/mi-cmd-disas.c: Fix indentation.
* mi/mi-cmd-env.c: Fix indentation.
* mi/mi-cmd-stack.c: Fix indentation.
* mi/mi-cmd-var.c: Fix indentation.
* mi/mi-cmds.c: Fix indentation.
* mi/mi-main.c: Fix indentation.
* mi/mi-parse.c: Fix indentation.
* microblaze-tdep.c: Fix indentation.
* minidebug.c: Fix indentation.
* minsyms.c: Fix indentation.
* mips-linux-nat.c: Fix indentation.
* mips-linux-tdep.c: Fix indentation.
* mips-nbsd-tdep.c: Fix indentation.
* mips-tdep.c: Fix indentation.
* mn10300-linux-tdep.c: Fix indentation.
* mn10300-tdep.c: Fix indentation.
* moxie-tdep.c: Fix indentation.
* msp430-tdep.c: Fix indentation.
* namespace.h: Fix indentation.
* nat/fork-inferior.c: Fix indentation.
* nat/gdb_ptrace.h: Fix indentation.
* nat/linux-namespaces.c: Fix indentation.
* nat/linux-osdata.c: Fix indentation.
* nat/netbsd-nat.c: Fix indentation.
* nat/x86-dregs.c: Fix indentation.
* nbsd-nat.c: Fix indentation.
* nbsd-tdep.c: Fix indentation.
* nios2-linux-tdep.c: Fix indentation.
* nios2-tdep.c: Fix indentation.
* nto-procfs.c: Fix indentation.
* nto-tdep.c: Fix indentation.
* objfiles.c: Fix indentation.
* objfiles.h: Fix indentation.
* opencl-lang.c: Fix indentation.
* or1k-tdep.c: Fix indentation.
* osabi.c: Fix indentation.
* osabi.h: Fix indentation.
* osdata.c: Fix indentation.
* p-lang.c: Fix indentation.
* p-typeprint.c: Fix indentation.
* p-valprint.c: Fix indentation.
* parse.c: Fix indentation.
* ppc-linux-nat.c: Fix indentation.
* ppc-linux-tdep.c: Fix indentation.
* ppc-nbsd-nat.c: Fix indentation.
* ppc-nbsd-tdep.c: Fix indentation.
* ppc-obsd-nat.c: Fix indentation.
* ppc-ravenscar-thread.c: Fix indentation.
* ppc-sysv-tdep.c: Fix indentation.
* ppc64-tdep.c: Fix indentation.
* printcmd.c: Fix indentation.
* proc-api.c: Fix indentation.
* producer.c: Fix indentation.
* producer.h: Fix indentation.
* prologue-value.c: Fix indentation.
* prologue-value.h: Fix indentation.
* psymtab.c: Fix indentation.
* python/py-arch.c: Fix indentation.
* python/py-bpevent.c: Fix indentation.
* python/py-event.c: Fix indentation.
* python/py-event.h: Fix indentation.
* python/py-finishbreakpoint.c: Fix indentation.
* python/py-frame.c: Fix indentation.
* python/py-framefilter.c: Fix indentation.
* python/py-inferior.c: Fix indentation.
* python/py-infthread.c: Fix indentation.
* python/py-objfile.c: Fix indentation.
* python/py-prettyprint.c: Fix indentation.
* python/py-registers.c: Fix indentation.
* python/py-signalevent.c: Fix indentation.
* python/py-stopevent.c: Fix indentation.
* python/py-stopevent.h: Fix indentation.
* python/py-threadevent.c: Fix indentation.
* python/py-tui.c: Fix indentation.
* python/py-unwind.c: Fix indentation.
* python/py-value.c: Fix indentation.
* python/py-xmethods.c: Fix indentation.
* python/python-internal.h: Fix indentation.
* python/python.c: Fix indentation.
* ravenscar-thread.c: Fix indentation.
* record-btrace.c: Fix indentation.
* record-full.c: Fix indentation.
* record.c: Fix indentation.
* reggroups.c: Fix indentation.
* regset.h: Fix indentation.
* remote-fileio.c: Fix indentation.
* remote.c: Fix indentation.
* reverse.c: Fix indentation.
* riscv-linux-tdep.c: Fix indentation.
* riscv-ravenscar-thread.c: Fix indentation.
* riscv-tdep.c: Fix indentation.
* rl78-tdep.c: Fix indentation.
* rs6000-aix-tdep.c: Fix indentation.
* rs6000-lynx178-tdep.c: Fix indentation.
* rs6000-nat.c: Fix indentation.
* rs6000-tdep.c: Fix indentation.
* rust-lang.c: Fix indentation.
* rx-tdep.c: Fix indentation.
* s12z-tdep.c: Fix indentation.
* s390-linux-tdep.c: Fix indentation.
* score-tdep.c: Fix indentation.
* ser-base.c: Fix indentation.
* ser-mingw.c: Fix indentation.
* ser-uds.c: Fix indentation.
* ser-unix.c: Fix indentation.
* serial.c: Fix indentation.
* sh-linux-tdep.c: Fix indentation.
* sh-nbsd-tdep.c: Fix indentation.
* sh-tdep.c: Fix indentation.
* skip.c: Fix indentation.
* sol-thread.c: Fix indentation.
* solib-aix.c: Fix indentation.
* solib-darwin.c: Fix indentation.
* solib-frv.c: Fix indentation.
* solib-svr4.c: Fix indentation.
* solib.c: Fix indentation.
* source.c: Fix indentation.
* sparc-linux-tdep.c: Fix indentation.
* sparc-nbsd-tdep.c: Fix indentation.
* sparc-obsd-tdep.c: Fix indentation.
* sparc-ravenscar-thread.c: Fix indentation.
* sparc-tdep.c: Fix indentation.
* sparc64-linux-tdep.c: Fix indentation.
* sparc64-nbsd-tdep.c: Fix indentation.
* sparc64-obsd-tdep.c: Fix indentation.
* sparc64-tdep.c: Fix indentation.
* stabsread.c: Fix indentation.
* stack.c: Fix indentation.
* stap-probe.c: Fix indentation.
* stubs/ia64vms-stub.c: Fix indentation.
* stubs/m32r-stub.c: Fix indentation.
* stubs/m68k-stub.c: Fix indentation.
* stubs/sh-stub.c: Fix indentation.
* stubs/sparc-stub.c: Fix indentation.
* symfile-mem.c: Fix indentation.
* symfile.c: Fix indentation.
* symfile.h: Fix indentation.
* symmisc.c: Fix indentation.
* symtab.c: Fix indentation.
* symtab.h: Fix indentation.
* target-float.c: Fix indentation.
* target.c: Fix indentation.
* target.h: Fix indentation.
* tic6x-tdep.c: Fix indentation.
* tilegx-linux-tdep.c: Fix indentation.
* tilegx-tdep.c: Fix indentation.
* top.c: Fix indentation.
* tracefile-tfile.c: Fix indentation.
* tracepoint.c: Fix indentation.
* tui/tui-disasm.c: Fix indentation.
* tui/tui-io.c: Fix indentation.
* tui/tui-regs.c: Fix indentation.
* tui/tui-stack.c: Fix indentation.
* tui/tui-win.c: Fix indentation.
* tui/tui-winsource.c: Fix indentation.
* tui/tui.c: Fix indentation.
* typeprint.c: Fix indentation.
* ui-out.h: Fix indentation.
* unittests/copy_bitwise-selftests.c: Fix indentation.
* unittests/memory-map-selftests.c: Fix indentation.
* utils.c: Fix indentation.
* v850-tdep.c: Fix indentation.
* valarith.c: Fix indentation.
* valops.c: Fix indentation.
* valprint.c: Fix indentation.
* valprint.h: Fix indentation.
* value.c: Fix indentation.
* value.h: Fix indentation.
* varobj.c: Fix indentation.
* vax-tdep.c: Fix indentation.
* windows-nat.c: Fix indentation.
* windows-tdep.c: Fix indentation.
* xcoffread.c: Fix indentation.
* xml-syscall.c: Fix indentation.
* xml-tdesc.c: Fix indentation.
* xstormy16-tdep.c: Fix indentation.
* xtensa-config.c: Fix indentation.
* xtensa-linux-nat.c: Fix indentation.
* xtensa-linux-tdep.c: Fix indentation.
* xtensa-tdep.c: Fix indentation.
gdbserver/ChangeLog:
* ax.cc: Fix indentation.
* dll.cc: Fix indentation.
* inferiors.h: Fix indentation.
* linux-low.cc: Fix indentation.
* linux-nios2-low.cc: Fix indentation.
* linux-ppc-ipa.cc: Fix indentation.
* linux-ppc-low.cc: Fix indentation.
* linux-x86-low.cc: Fix indentation.
* linux-xtensa-low.cc: Fix indentation.
* regcache.cc: Fix indentation.
* server.cc: Fix indentation.
* tracepoint.cc: Fix indentation.
gdbsupport/ChangeLog:
* common-exceptions.h: Fix indentation.
* event-loop.cc: Fix indentation.
* fileio.cc: Fix indentation.
* filestuff.cc: Fix indentation.
* gdb-dlfcn.cc: Fix indentation.
* gdb_string_view.h: Fix indentation.
* job-control.cc: Fix indentation.
* signals.cc: Fix indentation.
Change-Id: I4bad7ae6be0fbe14168b8ebafb98ffe14964a695
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On some systems, the gdb.multi/multi-target.exp testcase occasionally
fails like so:
Running src/gdb/testsuite/gdb.multi/multi-target.exp ...
FAIL: gdb.multi/multi-target.exp: info-inferiors: multi_process=on: inferior 1: info connections
FAIL: gdb.multi/multi-target.exp: info-inferiors: multi_process=on: inferior 1: info inferiors
FAIL: gdb.multi/multi-target.exp: info-inferiors: multi_process=on: inferior 2: info connections
FAIL: gdb.multi/multi-target.exp: info-inferiors: multi_process=on: inferior 2: info inferiors
FAIL: gdb.multi/multi-target.exp: info-inferiors: multi_process=on: inferior 3: inferior 3
... many more cascading fails.
The problem starts when the testcase runs an inferior against GDBserver:
(gdb) run
Starting program: build/gdb/testsuite/outputs/gdb.multi/multi-target/multi-target
Reading /lib64/ld-linux-x86-64.so.2 from remote target...
warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
Reading /lib64/ld-linux-x86-64.so.2 from remote target...
Reading /lib64/ld-2.31.so from remote target...
Reading /lib64/.debug/ld-2.31.so from remote target...
Reading /usr/lib/debug//lib64/ld-2.31.so from remote target...
Reading /usr/lib/debug/lib64//ld-2.31.so from remote target...
Reading target:/usr/lib/debug/lib64//ld-2.31.so from remote target...
Reading /lib/x86_64-linux-gnu/libpthread.so.0 from remote target...
Reading /lib/x86_64-linux-gnu/libc.so.6 from remote target...
Reading /lib/x86_64-linux-gnu/libc-2.31.so from remote target...
Reading /lib/x86_64-linux-gnu/.debug/libc-2.31.so from remote target...
Reading /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.31.so from remote target...
Reading /usr/lib/debug//lib/x86_64-linux-gnu/libc-2.31.so from remote target...
Remote connection closed
...
Note the "Remote connection closed" message. That means GDBserver
exited abruptly.
I traced it down to the fact that GDB fetches the thread list from
GDBserver while the main thread of the process is still running. On
my main system where I wrote the testcase, I have not observed the
failure because it is slow enough that the thread stops before
GDBserver fetches the thread list in the problem scenario which I'll
describe below.
With some --remote-debug logging from GDBserver side, we see the last
packets before the connection closes:
...
getpkt ("vCont;c"); [no ack sent]
putpkt ("$OK#9a"); [noack mode]
getpkt ("Tp10f9a.10f9a"); [no ack sent]
putpkt ("$OK#9a"); [noack mode]
getpkt ("Hgp0.0"); [no ack sent]
putpkt ("$OK#9a"); [noack mode]
getpkt ("qXfer:threads:read::0,1000"); [no ack sent]
Note the vCont;c , which sets the program running, and then a
qXfer:threads:read packet at the end.
The problem happens when the thread list refresh (qXfer:threads:read)
is sent just while the main thread is running and it still hasn't
initialized its libpthread id internally. In that state, the main
thread's lwp will remain with the thread_known flag clear. See in
find_one_thread:
/* If the new thread ID is zero, a final thread ID will be available
later. Do not enable thread debugging yet. */
if (ti.ti_tid == 0)
return 0;
Now, back in server.cc, to handle the qXfer:threads:read, we reach
handle_qxfer_threads -> handle_qxfer_threads_proper, and the latter
then calls handle_qxfer_threads_worker for each known thread. In
handle_qxfer_threads_worker, we call target_thread_handle. This ends
up in thread_db_thread_handle, here:
if (!lwp->thread_known && !find_one_thread (thread->id))
return false;
Since the thread ID isn't known yet, we call find_one_thread. This
calls into libthread_db.so, which accesses memory. Because the
current thread is running, that fails and we throw an error, here:
/* Get information about this thread. */
err = thread_db->td_ta_map_lwp2thr_p (thread_db->thread_agent, lwpid, &th);
if (err != TD_OK)
error ("Cannot get thread handle for LWP %d: %s",
lwpid, thread_db_err_str (err));
The current design is that whenever GDB-facing packets/requests need
to accesses memory, server.cc is supposed to prepare the target for
the access. See gdb_read_memory / gdb_write_memory. This preparation
means pausing threads if in non-stop mode (someday we could lift this
requirement, but we will still need to pause to access registers or do
other related ptrace accesses like PTRACE_GET_THREAD_AREA). Note that
the multi-target.exp testcase forces "maint set target-non-stop on".
So the fix here is to prepare the target to access memory when
handling qXfer:threads:read too.
gdbserver/ChangeLog:
* inferiors.cc (switch_to_process): New, moved here from
thread-db.cc, and made extern.
* inferiors.h (switch_to_process): Declare.
* server.cc: Include "gdbsupport/scoped_restore.h".
(handle_qxfer_threads_proper): Now returns bool. Prepare to
access memory around target calls.
(handle_qxfer_threads): Handle errors.
* thread-db.cc (switch_to_process): Moved to inferiors.cc.
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This patch moves gdbserver to the top level.
This patch is as close to a pure move as possible -- gdbserver still
builds its own variant of gnulib and gdbsupport. Changing this will
be done in a separate patch.
[v2] Note that, per Simon's review comment, this patch changes the
tree so that gdbserver is not built for or1k or score. This makes
sense, because there is apparently not actually a gdbserver port here.
[v3] This version of the patch also splits out some configury into a
new file, gdbserver/configure.host, so that the top-level configure
script can simply rely on it in order to decide whether gdbserver
should be built.
[v4] This version adds documentation and removes some unnecessary
top-level dependencies.
[v5] Update docs to mention "make all-gdbserver" and change how
top-level configure decides whether to build gdbserver, switching to a
single, shared script.
Tested by the buildbot.
ChangeLog
2020-02-07 Tom Tromey <tom@tromey.com>
Pedro Alves <palves@redhat.com>
* src-release.sh (GDB_SUPPORT_DIRS): Add gdbserver.
* gdbserver: New directory, moved from gdb/gdbserver.
* configure.ac (host_tools): Add gdbserver.
Only build gdbserver on certain systems.
* Makefile.in, configure: Rebuild.
* Makefile.def (host_modules, dependencies): Add gdbserver.
* MAINTAINERS: Add gdbserver.
gdb/ChangeLog
2020-02-07 Tom Tromey <tom@tromey.com>
* README: Update gdbserver documentation.
* gdbserver: Move to top level.
* configure.tgt (build_gdbserver): Remove.
* configure.ac: Remove --enable-gdbserver.
* configure: Rebuild.
* Makefile.in (distclean): Don't mention gdbserver.
Change-Id: I826b7565b54604711dc7a11edea0499cd51ff39e
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