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Fix Windows debugging regression

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The updated pending stop series introduced a regression in Windows
debugging.  When stopped at a software breakpoint, we would adjust the
PC each time it was requested -- however, more than a single
adjustment is incorrect.  This patch introduces a new flag that is
used to ensure the adjustment only happens a single time.

No similar change is needed in gdbserver, because it adjusts the PC in
a different way.

I still can't run the gdb test suite on Windows, but I can run the
internal AdaCore test suite there; and this fixes the regressions
there.

gdb/ChangeLog
2020-04-24  Tom Tromey  <tromey@adacore.com>

	* nat/windows-nat.h (struct windows_thread_info)
	<pc_adjusted>: New member.
	* windows-nat.c (windows_fetch_one_register): Check
	pc_adjusted.
	(windows_nat_target::get_windows_debug_event)
	(windows_nat_target::wait): Set pc_adjusted.
This commit is contained in:
Tom Tromey 2020-04-24 06:48:01 -06:00
parent 884287754e
commit 7be2bb4f47
3 changed files with 23 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
gdb/ChangeLog
View File

@ -1,3 +1,12 @@
2020-04-24 Tom Tromey <tromey@adacore.com>
* nat/windows-nat.h (struct windows_thread_info)
<pc_adjusted>: New member.
* windows-nat.c (windows_fetch_one_register): Check
pc_adjusted.
(windows_nat_target::get_windows_debug_event)
(windows_nat_target::wait): Set pc_adjusted.
2020-04-24 Tom de Vries <tdevries@suse.de> 2020-04-24 Tom de Vries <tdevries@suse.de>
* contrib/cc-with-tweaks.sh: Remove <exec>.gdb-index file handling. * contrib/cc-with-tweaks.sh: Remove <exec>.gdb-index file handling.

5
gdb/nat/windows-nat.h
View File

@ -93,6 +93,11 @@ struct windows_thread_info
breakpoint. This is used to offset the PC when needed. */ breakpoint. This is used to offset the PC when needed. */
bool stopped_at_software_breakpoint = false; bool stopped_at_software_breakpoint = false;
/* True if we've adjusted the PC after hitting a software
breakpoint, false otherwise. This lets us avoid multiple
adjustments if the registers are read multiple times. */
bool pc_adjusted = false;
/* The name of the thread, allocated by xmalloc. */ /* The name of the thread, allocated by xmalloc. */
gdb::unique_xmalloc_ptr<char> name; gdb::unique_xmalloc_ptr<char> name;
}; };

10
gdb/windows-nat.c
View File

@ -604,6 +604,7 @@ windows_fetch_one_register (struct regcache *regcache,
else else
{ {
if (th->stopped_at_software_breakpoint if (th->stopped_at_software_breakpoint
&& !th->pc_adjusted
&& r == gdbarch_pc_regnum (gdbarch)) && r == gdbarch_pc_regnum (gdbarch))
{ {
int size = register_size (gdbarch, r); int size = register_size (gdbarch, r);
@ -622,6 +623,8 @@ windows_fetch_one_register (struct regcache *regcache,
value -= gdbarch_decr_pc_after_break (gdbarch); value -= gdbarch_decr_pc_after_break (gdbarch);
memcpy (context_offset, &value, size); memcpy (context_offset, &value, size);
} }
/* Make sure we only rewrite the PC a single time. */
th->pc_adjusted = true;
} }
regcache->raw_supply (r, context_offset); regcache->raw_supply (r, context_offset);
} }
@ -1757,6 +1760,7 @@ windows_nat_target::get_windows_debug_event (int pid,
ptid_t ptid = ptid_t (current_event.dwProcessId, thread_id, 0); ptid_t ptid = ptid_t (current_event.dwProcessId, thread_id, 0);
th = thread_rec (ptid, INVALIDATE_CONTEXT); th = thread_rec (ptid, INVALIDATE_CONTEXT);
th->stopped_at_software_breakpoint = true; th->stopped_at_software_breakpoint = true;
th->pc_adjusted = false;
} }
pending_stops.push_back ({thread_id, *ourstatus, current_event}); pending_stops.push_back ({thread_id, *ourstatus, current_event});
thread_id = 0; thread_id = 0;
@ -1835,7 +1839,11 @@ windows_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
|| (current_event.u.Exception.ExceptionRecord.ExceptionCode || (current_event.u.Exception.ExceptionRecord.ExceptionCode
== STATUS_WX86_BREAKPOINT)) == STATUS_WX86_BREAKPOINT))
&& windows_initialization_done) && windows_initialization_done)
current_windows_thread->stopped_at_software_breakpoint = true; {
current_windows_thread->stopped_at_software_breakpoint
= true;
current_windows_thread->pc_adjusted = false;
}
} }
return result; return result;