RE: [PING^2][PATCH 0/6] Fix inferior calls from breakpoint condition

["Saiapova, Natalia" <natalia.saiapova@intel.com>]

Kind ping for https://sourceware.org/pipermail/gdb-patches/2020-August/171592.html

Regards,
--Natalia

> Hi,
> 
> We have noticed that inferior calls evaluated from a breakpoint condition in a
> multithreaded program result in an assertion hit:
> 
>     (gdb) b 43 if foo()
>     Breakpoint 1 at 0x119b: file main.c, line 43.
>     (gdb) run
>     Starting program: main
>     [Thread debugging using libthread_db enabled]
>     Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
>     [New Thread 0x7ffff77c4700 (LWP 21421)]
>     [New Thread 0x7ffff6fc3700 (LWP 21422)]
>     gdb/nat/x86-linux-dregs.c:146: internal-error: void
> x86_linux_update_debug_registers(lwp_info*): Assertion `lwp_is_stopped (lwp)'
> failed.
>     A problem internal to GDB has been detected,
>     further debugging may prove unreliable.
> 
>     This is a bug, please report it.  For instructions, see:
>     <https://www.gnu.org/software/gdb/bugs/>.
> 
> This patch set aims to fix this and a few more follow-up issues in order to allow
> execution of an inferior call from a breakpoint condition.
> 
> We have introduced an indicator in_cond_eval in the thread_control_state
> struct.  It is set to true, when the correspoding thread is evaluating a breakpoint
> condition.  Based on its value, GDB can distinguish inferior calls issued by a user
> from inferior calls executed in breakpoint conditions.  As GDB decides whether
> to stop a thread based on the result of a condition, it has to try to not abandon
> such an inferior call and finish the condition evaluation whenever this is possible.
> 
> The patch set is tested on x86_64-pc-linux-gnu configuration, the default and
> gdbserver-native boards.
> 
> Regards,
> --Natalia
> 
> Natalia Saiapova:
> Tankut Baris Aktemur:
>   gdb: add in_cond_eval field to thread_control_state struct.
>   gdb/infrun: in condition evaluation resume only current thread.
>   gdb/infcall: in condition evaluation register target back after infcall.
>   gdb/infrun: in condition evaluation wait only for current inferor.
>   gdb/infrun: in condition evaluation do not stop all threads.
>   gdb/testsuite: add tests for inferior calls in breakpoint conditions.
> 
>  gdb/ChangeLog                                 | 34 +++++++++
>  gdb/breakpoint.c                              |  3 +
>  gdb/gdbthread.h                               |  3 +
>  gdb/infcall.c                                 |  3 +
>  gdb/infrun.c                                  | 35 +++++++--
>  gdb/testsuite/ChangeLog                       |  5 ++
>  gdb/testsuite/gdb.threads/infcall-bp-cond.c   | 58 +++++++++++++++
>  gdb/testsuite/gdb.threads/infcall-bp-cond.exp | 73 +++++++++++++++++++
>  8 files changed, 208 insertions(+), 6 deletions(-)  create mode 100644
> gdb/testsuite/gdb.threads/infcall-bp-cond.c
>  create mode 100644 gdb/testsuite/gdb.threads/infcall-bp-cond.exp
> 
> --
> 2.17.1

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