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* [binutils-gdb] Fix Windows debugging regression
@ 2020-04-24 13:12 Tom Tromey
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From: Tom Tromey @ 2020-04-24 13:12 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7be2bb4f47b7b25d4f60b52f6ebaade0644827f2
commit 7be2bb4f47b7b25d4f60b52f6ebaade0644827f2
Author: Tom Tromey <tromey@adacore.com>
Date: Fri Apr 24 06:48:01 2020 -0600
Fix Windows debugging regression
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.
Diff:
---
gdb/ChangeLog | 9 +++++++++
gdb/nat/windows-nat.h | 5 +++++
gdb/windows-nat.c | 10 +++++++++-
3 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index c2dc2b6ba80..102edfcbc1f 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -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>
* contrib/cc-with-tweaks.sh: Remove <exec>.gdb-index file handling.
diff --git a/gdb/nat/windows-nat.h b/gdb/nat/windows-nat.h
index 8d0fa9bd216..80c652b22a7 100644
--- a/gdb/nat/windows-nat.h
+++ b/gdb/nat/windows-nat.h
@@ -93,6 +93,11 @@ struct windows_thread_info
breakpoint. This is used to offset the PC when needed. */
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. */
gdb::unique_xmalloc_ptr<char> name;
};
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index b857f82eb89..f52af9a1274 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -604,6 +604,7 @@ windows_fetch_one_register (struct regcache *regcache,
else
{
if (th->stopped_at_software_breakpoint
+ && !th->pc_adjusted
&& r == gdbarch_pc_regnum (gdbarch))
{
int size = register_size (gdbarch, r);
@@ -622,6 +623,8 @@ windows_fetch_one_register (struct regcache *regcache,
value -= gdbarch_decr_pc_after_break (gdbarch);
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);
}
@@ -1757,6 +1760,7 @@ windows_nat_target::get_windows_debug_event (int pid,
ptid_t ptid = ptid_t (current_event.dwProcessId, thread_id, 0);
th = thread_rec (ptid, INVALIDATE_CONTEXT);
th->stopped_at_software_breakpoint = true;
+ th->pc_adjusted = false;
}
pending_stops.push_back ({thread_id, *ourstatus, current_event});
thread_id = 0;
@@ -1835,7 +1839,11 @@ windows_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
|| (current_event.u.Exception.ExceptionRecord.ExceptionCode
== STATUS_WX86_BREAKPOINT))
&& 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;
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