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Implement stopped_by_sw_breakpoint for Windows gdbserver

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This changes the Windows gdbserver port to implement the
stopped_by_sw_breakpoint target method.  This is needed to support
pending stops.

This is a separate patch now, because Pedro suggested splitting it out
for simpler bisecting, in the case that it introduces a bug.

gdbserver/ChangeLog
2020-04-08  Tom Tromey  <tromey@adacore.com>

	* win32-low.h  (win32_process_target::stopped_by_sw_breakpoint)
	(win32_process_target::supports_stopped_by_sw_breakpoint):
	Declare.
	* win32-low.c (win32_supports_z_point_type): Always handle
	Z_PACKET_SW_BP.
	(win32_insert_point): Call insert_memory_breakpoint when needed.
	(win32_remove_point): Call remove_memory_breakpoint when needed.
	(win32_process_target::stopped_by_sw_breakpoint)
	(win32_process_target::supports_stopped_by_sw_breakpoint): New
	methods.
	(win32_target_ops): Update.
	(maybe_adjust_pc): New function.
	(win32_wait): Call maybe_adjust_pc.
This commit is contained in:
Tom Tromey 2020-04-08 14:33:35 -06:00
parent e54e59297a
commit 523d4f80c3
3 changed files with 75 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

16
gdbserver/ChangeLog
View file

@ -1,3 +1,19 @@
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.h (win32_process_target::stopped_by_sw_breakpoint)
(win32_process_target::supports_stopped_by_sw_breakpoint):
Declare.
* win32-low.c (win32_supports_z_point_type): Always handle
Z_PACKET_SW_BP.
(win32_insert_point): Call insert_memory_breakpoint when needed.
(win32_remove_point): Call remove_memory_breakpoint when needed.
(win32_process_target::stopped_by_sw_breakpoint)
(win32_process_target::supports_stopped_by_sw_breakpoint): New
methods.
(win32_target_ops): Update.
(maybe_adjust_pc): New function.
(win32_wait): Call maybe_adjust_pc.
2020-04-08 Tom Tromey <tromey@adacore.com>
* win32-low.h (struct win32_target_ops) <decr_pc_after_break>: New

67
gdbserver/win32-low.cc
View file

@ -236,15 +236,18 @@ child_delete_thread (DWORD pid, DWORD tid)
bool
win32_process_target::supports_z_point_type (char z_type)
{
return (the_low_target.supports_z_point_type != NULL
&& the_low_target.supports_z_point_type (z_type));
return (z_type == Z_PACKET_SW_BP
|| (the_low_target.supports_z_point_type != NULL
&& the_low_target.supports_z_point_type (z_type)));
}
int
win32_process_target::insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
int size, raw_breakpoint *bp)
{
if (the_low_target.insert_point != NULL)
if (type == raw_bkpt_type_sw)
return insert_memory_breakpoint (bp);
else if (the_low_target.insert_point != NULL)
return the_low_target.insert_point (type, addr, size, bp);
else
/* Unsupported (see target.h). */
@ -255,7 +258,9 @@ int
win32_process_target::remove_point (enum raw_bkpt_type type, CORE_ADDR addr,
int size, raw_breakpoint *bp)
{
if (the_low_target.remove_point != NULL)
if (type == raw_bkpt_type_sw)
return remove_memory_breakpoint (bp);
else if (the_low_target.remove_point != NULL)
return the_low_target.remove_point (type, addr, size, bp);
else
/* Unsupported (see target.h). */
@ -1189,6 +1194,32 @@ windows_nat::handle_ms_vc_exception (const EXCEPTION_RECORD *rec)
return false;
}
/* A helper function that will, if needed, set
'stopped_at_software_breakpoint' on the thread and adjust the
PC. */
static void
maybe_adjust_pc ()
{
struct regcache *regcache = get_thread_regcache (current_thread, 1);
child_fetch_inferior_registers (regcache, -1);
windows_thread_info *th = thread_rec (current_thread_ptid (),
DONT_INVALIDATE_CONTEXT);
th->stopped_at_software_breakpoint = false;
if (current_event.dwDebugEventCode == EXCEPTION_DEBUG_EVENT
&& (current_event.u.Exception.ExceptionRecord.ExceptionCode
== EXCEPTION_BREAKPOINT)
&& child_initialization_done)
{
th->stopped_at_software_breakpoint = true;
CORE_ADDR pc = regcache_read_pc (regcache);
CORE_ADDR sw_breakpoint_pc = pc - the_low_target.decr_pc_after_break;
regcache_write_pc (regcache, sw_breakpoint_pc);
}
}
/* Get the next event from the child. */
static int
@ -1417,8 +1448,6 @@ ptid_t
win32_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus,
int options)
{
struct regcache *regcache;
if (cached_status.kind != TARGET_WAITKIND_IGNORE)
{
/* The core always does a wait after creating the inferior, and
@ -1446,12 +1475,12 @@ win32_process_target::wait (ptid_t ptid, target_waitstatus *ourstatus,
case TARGET_WAITKIND_STOPPED:
case TARGET_WAITKIND_SIGNALLED:
case TARGET_WAITKIND_LOADED:
OUTMSG2 (("Child Stopped with signal = %d \n",
ourstatus->value.sig));
regcache = get_thread_regcache (current_thread, 1);
child_fetch_inferior_registers (regcache, -1);
return debug_event_ptid (&current_event);
{
OUTMSG2 (("Child Stopped with signal = %d \n",
ourstatus->value.sig));
maybe_adjust_pc ();
return debug_event_ptid (&current_event);
}
default:
OUTMSG (("Ignoring unknown internal event, %d\n", ourstatus->kind));
/* fall-through */
@ -1659,6 +1688,20 @@ win32_process_target::sw_breakpoint_from_kind (int kind, int *size)
return the_low_target.breakpoint;
}
bool
win32_process_target::stopped_by_sw_breakpoint ()
{
windows_thread_info *th = thread_rec (current_thread_ptid (),
DONT_INVALIDATE_CONTEXT);
return th == nullptr ? false : th->stopped_at_software_breakpoint;
}
bool
win32_process_target::supports_stopped_by_sw_breakpoint ()
{
return true;
}
CORE_ADDR
win32_process_target::read_pc (struct regcache *regcache)
{

4
gdbserver/win32-low.h
View file

@ -155,6 +155,10 @@ public:
CORE_ADDR read_pc (regcache *regcache) override;
void write_pc (regcache *regcache, CORE_ADDR pc) override;
bool stopped_by_sw_breakpoint () override;
bool supports_stopped_by_sw_breakpoint () override;
};
/* Retrieve the context for this thread, if not already retrieved. */