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757e686afb
Simon Marchi tried gdb on OpenBSD, and it immediately segfaults when
running a program. Simon tracked down the problem to x86_dr_low.get_status
being nullptr at this point:
(lldb) print x86_dr_low.get_status
(unsigned long (*)()) $0 = 0x0000000000000000
(lldb) bt
* thread #1, stop reason = step over
* frame #0: 0x0000033b64b764aa gdb`x86_dr_stopped_data_address(state=0x0000033d7162a310, addr_p=0x00007f7ffffc5688) at x86-dregs.c:645:12
frame #1: 0x0000033b64b766de gdb`x86_dr_stopped_by_watchpoint(state=0x0000033d7162a310) at x86-dregs.c:687:10
frame #2: 0x0000033b64ea5f72 gdb`x86_stopped_by_watchpoint() at x86-nat.c:206:10
frame #3: 0x0000033b64637fbb gdb`x86_nat_target<obsd_nat_target>::stopped_by_watchpoint(this=0x0000033b65252820) at x86-nat.h💯12
frame #4: 0x0000033b64d3ff11 gdb`target_stopped_by_watchpoint() at target.c:468:46
frame #5: 0x0000033b6469b001 gdb`watchpoints_triggered(ws=0x00007f7ffffc61c8) at breakpoint.c:4790:32
frame #6: 0x0000033b64a8bb8b gdb`handle_signal_stop(ecs=0x00007f7ffffc61a0) at infrun.c:6072:29
frame #7: 0x0000033b64a7e3a7 gdb`handle_inferior_event(ecs=0x00007f7ffffc61a0) at infrun.c:5694:7
frame #8: 0x0000033b64a7c1a0 gdb`fetch_inferior_event() at infrun.c:4090:5
frame #9: 0x0000033b64a51921 gdb`inferior_event_handler(event_type=INF_REG_EVENT) at inf-loop.c:41:7
frame #10: 0x0000033b64a827c9 gdb`infrun_async_inferior_event_handler(data=0x0000000000000000) at infrun.c:9384:3
frame #11: 0x0000033b6465bd4f gdb`check_async_event_handlers() at async-event.c:335:4
frame #12: 0x0000033b65070917 gdb`gdb_do_one_event() at event-loop.cc:216:10
frame #13: 0x0000033b64af0db1 gdb`start_event_loop() at main.c:421:13
frame #14: 0x0000033b64aefe9a gdb`captured_command_loop() at main.c:481:3
frame #15: 0x0000033b64aed5c2 gdb`captured_main(data=0x00007f7ffffc6470) at main.c:1353:4
frame #16: 0x0000033b64aed4f2 gdb`gdb_main(args=0x00007f7ffffc6470) at main.c:1368:7
frame #17: 0x0000033b6459d787 gdb`main(argc=5, argv=0x00007f7ffffc6518) at gdb.c:32:10
frame #18: 0x0000033b6459d521 gdb`___start + 321
On BSDs, get_status is set in _initialize_x86_bsd_nat, but only if
HAVE_PT_GETDBREGS is defined. PT_GETDBREGS doesn't exist on OpenBSD, so
get_status (and the other fields of x86_dr_low) are left as nullptr.
OpenBSD doesn't support getting or setting the x86 debug registers, so
fix by omitting debug register support entirely on OpenBSD:
- Change x86bsd_nat_target to only inherit from x86_nat_target if
PT_GETDBREGS is supported.
- Don't include x86-nat.o and nat/x86-dregs.o for OpenBSD/amd64. They
were already omitted for OpenBSD/i386.
50 lines
1.4 KiB
C++
50 lines
1.4 KiB
C++
/* Native-dependent code for x86 BSD's.
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Copyright (C) 2011-2021 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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#ifndef X86_BSD_NAT_H
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#define X86_BSD_NAT_H
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#include "x86-nat.h"
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/* Low level x86 XSAVE info. */
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extern size_t x86bsd_xsave_len;
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/* A prototype *BSD/x86 target. */
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#ifdef HAVE_PT_GETDBREGS
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template<typename BaseTarget>
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class x86bsd_nat_target : public x86_nat_target<BaseTarget>
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{
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using base_class = x86_nat_target<BaseTarget>;
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public:
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void mourn_inferior () override
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{
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x86_cleanup_dregs ();
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base_class::mourn_inferior ();
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}
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};
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#else /* !HAVE_PT_GETDBREGS */
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template<typename BaseTarget>
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class x86bsd_nat_target : public BaseTarget
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{
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};
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#endif /* HAVE_PT_GETDBREGS */
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#endif /* x86-bsd-nat.h */
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