binutils-gdb/sim/common/sim-events.h

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/* The common simulator framework for GDB, the GNU Debugger.
2011-01-01 23:34:07 +08:00
Copyright 2002, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
Contributed by Andrew Cagney and Red Hat.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef SIM_EVENTS_H
#define SIM_EVENTS_H
/* Notes:
When scheduling an event, the a delta of zero/one refers to the
timeline as follows:
epoch 0|1 1|2 2|3 3|
**queue**|--insn--|*queue*|--insn--|*queue*|--insn--|*queue*|
| ^ ^ | ^ ^
`- +0 ------------ +1 --.. `----- +0 ------------- +1 --..
When the queue is initialized, the time is set to zero with a
number of initialization events scheduled. Consequently, as also
illustrated above, the event queue should be processed before the
first instruction. That instruction being executed during tick 1.
The simulator main loop may take a form similar to:
if (halt-/restart-setjmp)
{
.... // Determine who should go next
last-cpu-nr = get-last-cpu-nr (sd);
next-cpu-nr = get-next-cpu-nr (sd);
events-were-last? = (last-cpu-nr >= nr-cpus);
events-were-next? = (next-cpu-nr >= nr-cpus);
.... // process any outstanding events
sim_events_preprocess (sd, events-were-last?, events-were-next?);
if (events-were-next)
next-cpu-nr = 0;
2011-03-15 11:16:17 +08:00
.... // prime main loop
while (1)
{
.... // model one insn of next-cpu-nr .. nr-cpus
if (sim_events_tick (sd))
sim_events_process (sd);
next-cpu-nr = 0
}
}
NB. In the above pseudo code it is assumed that any cpu-nr >=
nr-cpus is a marker for the event queue. */
typedef void sim_event_handler(SIM_DESC sd, void *data);
typedef struct _sim_event sim_event;
typedef struct _sim_events sim_events;
struct _sim_events {
int nr_ticks_to_process;
sim_event *queue;
sim_event *watchpoints;
sim_event *watchedpoints;
sim_event *free_list;
/* flag additional work needed */
volatile int work_pending;
/* the asynchronous event queue */
#ifndef MAX_NR_SIGNAL_SIM_EVENTS
#define MAX_NR_SIGNAL_SIM_EVENTS 2
#endif
sim_event *held;
volatile int nr_held;
/* timekeeping */
unsigned long elapsed_wallclock;
SIM_ELAPSED_TIME resume_wallclock;
signed64 time_of_event;
sim: change to 64bit time keeping to avoid 32bit overflows The sim-events code jumps through some hoops to avoid using 64bit math to manage the current time. One fundamental assumption here is that by constantly scheduling the sim poll event a short time into the future, the 64bit difference will always fall into a signed 32bit value. This does work most of the time, except for when processing the sim poll event itself. Normally, sim_events_process() will dequeue the sim poll event, update the current time (time_from_event) according to the next pending event, process the sim poll event (which will then requeue the sim poll event), and then continue on. The problem here of course is that the current time is updated in that small window before the sim poll event gets a chance to reschedule itself. So if the 64bit difference between the current time and the next event does not fit into the signed 32bit value, time_from_event overflows, and the internal assert at the end of update_time_from_event() triggers. Since attempts at tweaking sim_events_process() logic introduced other subtle bugs (due to tangled assumptions between most pieces of the sim time keeping code), change the time_from_event to a real 64bit value. Tests on my system between a 32bit ELF and a 64bit ELF show no practical difference (it's all lost in the system noise). Basically, I booted a Linux kernel to userspace and then paniced it; this gave me a constant sample size of about 18 million insns. This was noticed when simulating Blackfin Das U-Boot. The simulated core timer is given the max unsigned timeout value possible on a 32bit processor (0xffffffff). This timeout value is used directly to schedule a hw event in the sim future (the IRQ firing). Once the sim poll event is kicked off, the next pending event is the core timer event which is more than 2^31 ticks in the future, and the sim aborts with: sim-events.c:435: assertion failed - current_time == sim_events_time (sd) Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2011-02-14 12:58:12 +08:00
signed64 time_from_event;
int trace;
};
/* Install the "events" module. */
extern SIM_RC sim_events_install (SIM_DESC sd);
/* Schedule an event DELTA_TIME ticks into the future */
extern sim_event *sim_events_schedule
(SIM_DESC sd,
signed64 delta_time,
sim_event_handler *handler,
void *data);
extern sim_event *sim_events_schedule_tracef
(SIM_DESC sd,
signed64 delta_time,
sim_event_handler *handler,
void *data,
const char *fmt,
...) __attribute__ ((format (printf, 5, 6)));
extern sim_event *sim_events_schedule_vtracef
(SIM_DESC sd,
signed64 delta_time,
sim_event_handler *handler,
void *data,
const char *fmt,
va_list ap);
extern void sim_events_schedule_after_signal
(SIM_DESC sd,
signed64 delta_time,
sim_event_handler *handler,
void *data);
/* NB: signal level events can't have trace strings as malloc isn't
available */
/* Schedule an event milli-seconds from NOW. The exact interpretation
of wallclock is host dependant. */
extern sim_event *sim_events_watch_clock
(SIM_DESC sd,
unsigned delta_ms_time,
sim_event_handler *handler,
void *data);
/* Schedule an event when the test (IS_WITHIN == (VAL >= LB && VAL <=
UB)) of the NR_BYTES value at HOST_ADDR with BYTE_ORDER endian is
true.
HOST_ADDR: pointer into the host address space.
BYTE_ORDER: 0 - host endian; BIG_ENDIAN; LITTLE_ENDIAN */
extern sim_event *sim_events_watch_sim
(SIM_DESC sd,
void *host_addr,
int nr_bytes,
int byte_order,
int is_within,
unsigned64 lb,
unsigned64 ub,
sim_event_handler *handler,
void *data);
/* Schedule an event when the test (IS_WITHIN == (VAL >= LB && VAL <=
UB)) of the NR_BYTES value at CORE_ADDR in BYTE_ORDER endian is
true.
CORE_ADDR/MAP: pointer into the target address space.
BYTE_ORDER: 0 - current target endian; BIG_ENDIAN; LITTLE_ENDIAN */
extern sim_event *sim_events_watch_core
(SIM_DESC sd,
address_word core_addr,
unsigned map,
int nr_bytes,
int byte_order,
int is_within,
unsigned64 lb,
unsigned64 ub,
sim_event_handler *handler,
void *data);
/* Deschedule the specified event */
extern void sim_events_deschedule
(SIM_DESC sd,
sim_event *event_to_remove);
/* Prepare for main simulator loop. Ensure that the next thing to do
is not event processing.
If the simulator halted part way through event processing then both
EVENTS_WERE_LAST and EVENTS_WERE_NEXT shall be true.
If the simulator halted after processing the last cpu, then only
EVENTS_WERE_NEXT shall be true. */
INLINE_SIM_EVENTS\
(void) sim_events_preprocess
(SIM_DESC sd,
int events_were_last,
int events_were_next);
/* Progress time.
Separated into two parts so that the main loop can save its context
before the event queue is processed. When sim_events_tick*()
returns true, any simulation context should be saved and
sim_events_process() called.
SIM_EVENTS_TICK advances the clock by 1 cycle.
SIM_EVENTS_TICKN advances the clock by N cycles (1..MAXINT). */
INLINE_SIM_EVENTS\
(int) sim_events_tick
(SIM_DESC sd);
INLINE_SIM_EVENTS\
(int) sim_events_tickn
(SIM_DESC sd,
int n);
INLINE_SIM_EVENTS\
(void) sim_events_process
(SIM_DESC sd);
/* Advance the clock by an additional SLIP cycles at the next call to
sim_events_tick*(). For multiple calls, the effect is
accumulative. */
INLINE_SIM_EVENTS\
(void) sim_events_slip
(SIM_DESC sd,
int slip);
/* Progress time such that an event shall occur upon the next call to
sim_events tick */
#if 0
INLINE_SIM_EVENTS\
(void) sim_events_timewarp
(SIM_DESC sd);
#endif
/* local concept of elapsed target time */
INLINE_SIM_EVENTS\
(signed64) sim_events_time
(SIM_DESC sd);
/* local concept of elapsed host time (milliseconds) */
INLINE_SIM_EVENTS\
(unsigned long) sim_events_elapsed_time
(SIM_DESC sd);
/* Returns the time that remains before the event is raised. */
INLINE_SIM_EVENTS\
(signed64) sim_events_remain_time
(SIM_DESC sd, sim_event *event);
#endif