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In infrun.c's 'displaced_step_fixup', as part of the 'finish_step_over' flow, switch to the eventing thread *before* calling 'displaced_step_restore', because down in the flow ptid-dependent memory accesses are used via current_inferior() and current_top_target(). Without this patch, the problem is exposed with the scenario below: $ gdb -q (gdb) maint set target-non-stop on (gdb) file a.out Reading symbols from a.out... (gdb) set remote exec-file a.out (gdb) target extended-remote | gdbserver --once --multi - ... (gdb) add-inferior [New inferior 2] Added inferior 2 on connection 1 (extended-remote ...) (gdb) inferior 2 [Switching to inferior 2 [<null>] (<noexec>)] (gdb) file a.out Reading symbols from a.out... (gdb) set remote exec-file a.out (gdb) run ... Cannot access memory at address 0x555555555042 (gdb) The problem is, down inside 'displaced_step_restore', GDB wants to access the memory for inferior 2 because of an internal breakpoint. However, the current inferior and inferior_ptid are out of sync. While inferior_ptid correctly points to the process of inf 2 that was just started, current_inferior points to inf 1. Then, the attempt to access the memory fails, because target_has_execution results in false since inf 1 was not started. I was not able to simplify the failing scenario, but it shows the problem. After this patch, we get ... same steps above... (gdb) run ... [Inferior 2 (process 28652) exited normally] (gdb) Regression-tested on X86_64 Linux with `make check`s default board file and also `--target_board=native-extended-gdbserver`. In fact, the bug fixed by this patch was exposed when using the native-extended-gdbserver board file. gdb/ChangeLog: 2020-04-21 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com> * infrun.c (displaced_step_fixup): Switch to the event_thread before calling displaced_step_restore, not after. gdb/testsuite/ChangeLog: 2020-04-21 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com> * gdb.multi/run-only-second-inf.c: New file. * gdb.multi/run-only-second-inf.exp: New file.
23 lines
777 B
C
23 lines
777 B
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2020 Free Software Foundation, Inc.
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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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int
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main ()
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{
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return 0;
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}
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