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gdbserver/win32: Rewrite debug registers handling

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Don't use debug_reg_state for both:

 * "intent" - what we want the debug registers to look like

 * "reality" - what/which were the contents of the DR registers when
   the event triggered

Reserve it for the former only, like in the GNU/Linux port.

Otherwise the core x86 debug registers code can get confused if the
inferior itself changes the debug registers since GDB last set them.

This is also a requirement for being able to set watchpoints while the
target is running, if/when we get to it on Windows.  See the big
comment in x86_dr_stopped_data_address.

Seems to me this may also fixes propagating watchpoints to all threads
-- continue_one_thread only calls win32_set_thread_context (what
copies the DR registers to the thread), if something already fetched
the thread's context before.  Something else may be masking this
issue, I haven't checked.

Smoke tested by running gdbserver under Wine, connecting to it from
GNU/Linux, and checking that I could trigger a watchpoint as expected.

Joel tested it on x86-windows using AdaCore's testsuite.

gdb/gdbserver/
2014-10-15  Pedro Alves  <palves@redhat.com>

	PR server/17487
	* win32-arm-low.c (arm_set_thread_context): Remove current_event
	parameter.
	(arm_set_thread_context): Delete.
	(the_low_target): Adjust.
	* win32-i386-low.c (debug_registers_changed)
	(debug_registers_used): Delete.
	(update_debug_registers_callback): New function.
	(x86_dr_low_set_addr, x86_dr_low_set_control): Mark all threads as
	needing to update their debug registers.
	(win32_get_current_dr): New function.
	(x86_dr_low_get_addr, x86_dr_low_get_control)
	(x86_dr_low_get_status): Fetch the debug register from the thread
	record's context.
	(i386_initial_stuff): Adjust.
	(i386_get_thread_context): Remove current_event parameter.  Don't
	clear debug_registers_changed nor copy DR values to
	debug_reg_state.
	(i386_set_thread_context): Delete.
	(i386_prepare_to_resume): New function.
	(i386_thread_added): Mark the thread as needing to update irs
	debug registers.
	(the_low_target): Remove i386_set_thread_context and install
	i386_prepare_to_resume.
	* win32-low.c (win32_get_thread_context): Adjust.
	(win32_set_thread_context): Use SetThreadContext
	directly.
	(win32_prepare_to_resume): New function.
	(win32_require_context): New function, factored out from ...
	(thread_rec): ... this.
	(continue_one_thread): Call win32_prepare_to_resume on each thread
	we're about to continue.
	(win32_resume): Call win32_prepare_to_resume on the event thread.
	* win32-low.h (struct win32_thread_info)
	<debug_registers_changed>: New field.
	(struct win32_target_ops): Change prototype of set_thread_context,
	delete set_thread_context and add prepare_to_resume.
	(win32_require_context): New declaration.
This commit is contained in:
Pedro Alves 2014-10-15 19:55:50 +01:00
parent 6979730b1b
commit a2abc7de68
5 changed files with 176 additions and 102 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
gdb/gdbserver/ChangeLog
View File

@ -1,3 +1,44 @@
2014-10-15 Pedro Alves <palves@redhat.com>
PR server/17487
* win32-arm-low.c (arm_set_thread_context): Remove current_event
parameter.
(arm_set_thread_context): Delete.
(the_low_target): Adjust.
* win32-i386-low.c (debug_registers_changed)
(debug_registers_used): Delete.
(update_debug_registers_callback): New function.
(x86_dr_low_set_addr, x86_dr_low_set_control): Mark all threads as
needing to update their debug registers.
(win32_get_current_dr): New function.
(x86_dr_low_get_addr, x86_dr_low_get_control)
(x86_dr_low_get_status): Fetch the debug register from the thread
record's context.
(i386_initial_stuff): Adjust.
(i386_get_thread_context): Remove current_event parameter. Don't
clear debug_registers_changed nor copy DR values to
debug_reg_state.
(i386_set_thread_context): Delete.
(i386_prepare_to_resume): New function.
(i386_thread_added): Mark the thread as needing to update irs
debug registers.
(the_low_target): Remove i386_set_thread_context and install
i386_prepare_to_resume.
* win32-low.c (win32_get_thread_context): Adjust.
(win32_set_thread_context): Use SetThreadContext
directly.
(win32_prepare_to_resume): New function.
(win32_require_context): New function, factored out from ...
(thread_rec): ... this.
(continue_one_thread): Call win32_prepare_to_resume on each thread
we're about to continue.
(win32_resume): Call win32_prepare_to_resume on the event thread.
* win32-low.h (struct win32_thread_info)
<debug_registers_changed>: New field.
(struct win32_target_ops): Change prototype of set_thread_context,
delete set_thread_context and add prepare_to_resume.
(win32_require_context): New declaration.
2014-10-08 Gary Benson <gbenson@redhat.com>
* server.h: Do not include common-exceptions.h.

10
gdb/gdbserver/win32-arm-low.c
View File

@ -27,7 +27,7 @@ void init_registers_arm (void);
extern const struct target_desc *tdesc_arm;
static void
arm_get_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
arm_get_thread_context (win32_thread_info *th)
{
th->context.ContextFlags = \
CONTEXT_FULL | \
@ -36,12 +36,6 @@ arm_get_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
GetThreadContext (th->h, &th->context);
}
static void
arm_set_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
{
SetThreadContext (th->h, &th->context);
}
#define context_offset(x) ((int)&(((CONTEXT *)NULL)->x))
static const int mappings[] = {
context_offset (R0),
@ -124,7 +118,7 @@ struct win32_target_ops the_low_target = {
sizeof (mappings) / sizeof (mappings[0]),
NULL, /* initial_stuff */
arm_get_thread_context,
arm_set_thread_context,
NULL, /* prepare_to_resume */
NULL, /* thread_added */
arm_fetch_inferior_register,
arm_store_inferior_register,

139
gdb/gdbserver/win32-i386-low.c
View File

@ -40,29 +40,36 @@ extern const struct target_desc *tdesc_i386;
static struct x86_debug_reg_state debug_reg_state;
static int debug_registers_changed = 0;
static int debug_registers_used = 0;
static int
update_debug_registers_callback (struct inferior_list_entry *entry,
void *pid_p)
{
struct thread_info *thr = (struct thread_info *) entry;
win32_thread_info *th = inferior_target_data (thr);
int pid = *(int *) pid_p;
/* Only update the threads of this process. */
if (pid_of (thr) == pid)
{
/* The actual update is done later just before resuming the lwp,
we just mark that the registers need updating. */
th->debug_registers_changed = 1;
}
return 0;
}
/* Update the inferior's debug register REGNUM from STATE. */
static void
x86_dr_low_set_addr (int regnum, CORE_ADDR addr)
{
/* Only update the threads of this process. */
int pid = pid_of (current_thread);
gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
/* debug_reg_state.dr_mirror is already set.
Just notify i386_set_thread_context, i386_thread_added
that the registers need to be updated. */
debug_registers_changed = 1;
debug_registers_used = 1;
}
static CORE_ADDR
x86_dr_low_get_addr (int regnum)
{
gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
return debug_reg_state.dr_mirror[regnum];
find_inferior (&all_threads, update_debug_registers_callback, &pid);
}
/* Update the inferior's DR7 debug control register from STATE. */
@ -70,17 +77,53 @@ x86_dr_low_get_addr (int regnum)
static void
x86_dr_low_set_control (unsigned long control)
{
/* debug_reg_state.dr_control_mirror is already set.
Just notify i386_set_thread_context, i386_thread_added
that the registers need to be updated. */
debug_registers_changed = 1;
debug_registers_used = 1;
/* Only update the threads of this process. */
int pid = pid_of (current_thread);
find_inferior (&all_threads, update_debug_registers_callback, &pid);
}
/* Return the current value of a DR register of the current thread's
context. */
static DWORD64
win32_get_current_dr (int dr)
{
win32_thread_info *th = inferior_target_data (current_thread);
win32_require_context (th);
#define RET_DR(DR) \
case DR: \
return th->context.Dr ## DR
switch (dr)
{
RET_DR (0);
RET_DR (1);
RET_DR (2);
RET_DR (3);
RET_DR (6);
RET_DR (7);
}
#undef RET_DR
gdb_assert_not_reached ("unhandled dr");
}
static CORE_ADDR
x86_dr_low_get_addr (int regnum)
{
gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
return win32_get_current_dr (regnum - DR_FIRSTADDR);
}
static unsigned long
x86_dr_low_get_control (void)
{
return debug_reg_state.dr_control_mirror;
return win32_get_current_dr (7);
}
/* Get the value of the DR6 debug status register from the inferior
@ -89,9 +132,7 @@ x86_dr_low_get_control (void)
static unsigned long
x86_dr_low_get_status (void)
{
/* We don't need to do anything here, the last call to thread_rec for
current_event.dwThreadId id has already set it. */
return debug_reg_state.dr_status_mirror;
return win32_get_current_dr (6);
}
/* Low-level function vector. */
@ -181,12 +222,10 @@ static void
i386_initial_stuff (void)
{
x86_low_init_dregs (&debug_reg_state);
debug_registers_changed = 0;
debug_registers_used = 0;
}
static void
i386_get_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
i386_get_thread_context (win32_thread_info *th)
{
/* Requesting the CONTEXT_EXTENDED_REGISTERS register set fails if
the system doesn't support extended registers. */
@ -210,28 +249,17 @@ i386_get_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
error ("GetThreadContext failure %ld\n", (long) e);
}
debug_registers_changed = 0;
if (th->tid == current_event->dwThreadId)
{
/* Copy dr values from the current thread. */
struct x86_debug_reg_state *dr = &debug_reg_state;
dr->dr_mirror[0] = th->context.Dr0;
dr->dr_mirror[1] = th->context.Dr1;
dr->dr_mirror[2] = th->context.Dr2;
dr->dr_mirror[3] = th->context.Dr3;
dr->dr_status_mirror = th->context.Dr6;
dr->dr_control_mirror = th->context.Dr7;
}
}
static void
i386_set_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
i386_prepare_to_resume (win32_thread_info *th)
{
if (debug_registers_changed)
if (th->debug_registers_changed)
{
struct x86_debug_reg_state *dr = &debug_reg_state;
win32_require_context (th);
th->context.Dr0 = dr->dr_mirror[0];
th->context.Dr1 = dr->dr_mirror[1];
th->context.Dr2 = dr->dr_mirror[2];
@ -239,32 +267,15 @@ i386_set_thread_context (win32_thread_info *th, DEBUG_EVENT* current_event)
/* th->context.Dr6 = dr->dr_status_mirror;
FIXME: should we set dr6 also ?? */
th->context.Dr7 = dr->dr_control_mirror;
}
SetThreadContext (th->h, &th->context);
th->debug_registers_changed = 0;
}
}
static void
i386_thread_added (win32_thread_info *th)
{
/* Set the debug registers for the new thread if they are used. */
if (debug_registers_used)
{
struct x86_debug_reg_state *dr = &debug_reg_state;
th->context.ContextFlags = CONTEXT_DEBUG_REGISTERS;
GetThreadContext (th->h, &th->context);
th->context.Dr0 = dr->dr_mirror[0];
th->context.Dr1 = dr->dr_mirror[1];
th->context.Dr2 = dr->dr_mirror[2];
th->context.Dr3 = dr->dr_mirror[3];
/* th->context.Dr6 = dr->dr_status_mirror;
FIXME: should we set dr6 also ?? */
th->context.Dr7 = dr->dr_control_mirror;
SetThreadContext (th->h, &th->context);
th->context.ContextFlags = 0;
}
th->debug_registers_changed = 1;
}
static void
@ -450,7 +461,7 @@ struct win32_target_ops the_low_target = {
sizeof (mappings) / sizeof (mappings[0]),
i386_initial_stuff,
i386_get_thread_context,
i386_set_thread_context,
i386_prepare_to_resume,
i386_thread_added,
i386_fetch_inferior_register,
i386_store_inferior_register,

53
gdb/gdbserver/win32-low.c
View File

@ -129,7 +129,7 @@ static void
win32_get_thread_context (win32_thread_info *th)
{
memset (&th->context, 0, sizeof (CONTEXT));
(*the_low_target.get_thread_context) (th, &current_event);
(*the_low_target.get_thread_context) (th);
#ifdef _WIN32_WCE
memcpy (&th->base_context, &th->context, sizeof (CONTEXT));
#endif
@ -153,23 +153,24 @@ win32_set_thread_context (win32_thread_info *th)
it between stopping and resuming. */
if (memcmp (&th->context, &th->base_context, sizeof (CONTEXT)) != 0)
#endif
(*the_low_target.set_thread_context) (th, &current_event);
SetThreadContext (th->h, &th->context);
}
/* Find a thread record given a thread id. If GET_CONTEXT is set then
also retrieve the context for this thread. */
static win32_thread_info *
thread_rec (ptid_t ptid, int get_context)
/* Set the thread context of the thread associated with TH. */
static void
win32_prepare_to_resume (win32_thread_info *th)
{
struct thread_info *thread;
win32_thread_info *th;
if (the_low_target.prepare_to_resume != NULL)
(*the_low_target.prepare_to_resume) (th);
}
thread = (struct thread_info *) find_inferior_id (&all_threads, ptid);
if (thread == NULL)
return NULL;
/* See win32-low.h. */
th = inferior_target_data (thread);
if (get_context && th->context.ContextFlags == 0)
void
win32_require_context (win32_thread_info *th)
{
if (th->context.ContextFlags == 0)
{
if (!th->suspended)
{
@ -185,7 +186,23 @@ thread_rec (ptid_t ptid, int get_context)
win32_get_thread_context (th);
}
}
/* Find a thread record given a thread id. If GET_CONTEXT is set then
also retrieve the context for this thread. */
static win32_thread_info *
thread_rec (ptid_t ptid, int get_context)
{
struct thread_info *thread;
win32_thread_info *th;
thread = (struct thread_info *) find_inferior_id (&all_threads, ptid);
if (thread == NULL)
return NULL;
th = inferior_target_data (thread);
if (get_context)
win32_require_context (th);
return th;
}
@ -419,8 +436,11 @@ continue_one_thread (struct inferior_list_entry *this_thread, void *id_ptr)
int thread_id = * (int *) id_ptr;
win32_thread_info *th = inferior_target_data (thread);
if ((thread_id == -1 || thread_id == th->tid)
&& th->suspended)
if (thread_id == -1 || thread_id == th->tid)
{
win32_prepare_to_resume (th);
if (th->suspended)
{
if (th->context.ContextFlags)
{
@ -436,6 +456,7 @@ continue_one_thread (struct inferior_list_entry *this_thread, void *id_ptr)
}
th->suspended = 0;
}
}
return 0;
}
@ -937,6 +958,8 @@ win32_resume (struct thread_resume *resume_info, size_t n)
th = thread_rec (ptid, FALSE);
if (th)
{
win32_prepare_to_resume (th);
if (th->context.ContextFlags)
{
/* Move register values from the inferior into the thread

15
gdb/gdbserver/win32-low.h
View File

@ -47,6 +47,10 @@ typedef struct win32_thread_info
/* The context of the thread, including any manipulations. */
CONTEXT context;
/* Whether debug registers changed since we last set CONTEXT back to
the thread. */
int debug_registers_changed;
} win32_thread_info;
struct win32_target_ops
@ -61,12 +65,10 @@ struct win32_target_ops
void (*initial_stuff) (void);
/* Fetch the context from the inferior. */
void (*get_thread_context) (win32_thread_info *th,
DEBUG_EVENT *current_event);
void (*get_thread_context) (win32_thread_info *th);
/* Flush the context back to the inferior. */
void (*set_thread_context) (win32_thread_info *th,
DEBUG_EVENT *current_event);
/* Called just before resuming the thread. */
void (*prepare_to_resume) (win32_thread_info *th);
/* Called when a thread was added. */
void (*thread_added) (win32_thread_info *th);
@ -96,6 +98,9 @@ struct win32_target_ops
extern struct win32_target_ops the_low_target;
/* Retrieve the context for this thread, if not already retrieved. */
extern void win32_require_context (win32_thread_info *th);
/* Map the Windows error number in ERROR to a locale-dependent error
message string and return a pointer to it. Typically, the values
for ERROR come from GetLastError.