ardupilot/libraries/AP_HAL_Linux/Thread.cpp

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/*
* Copyright (C) 2016 Intel Corporation. All rights reserved.
*
* This file 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 file 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/>.
*/
#include "Thread.h"
#include <alloca.h>
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <utility>
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include "Scheduler.h"
#define STACK_POISON 0xBEBACAFE
extern const AP_HAL::HAL &hal;
namespace Linux {
void *Thread::_run_trampoline(void *arg)
{
Thread *thread = static_cast<Thread *>(arg);
thread->_poison_stack();
thread->_run();
if (thread->_auto_free) {
delete thread;
}
return nullptr;
}
bool Thread::_run()
{
if (!_task) {
return false;
}
_task();
return true;
}
/* Round up to the specified alignment.
*
* Let u be the address p rounded up to the alignment a. Then:
* u = p + a - 1 - r, where r = (p + a - 1) % a
*
* If p % a = 0, i.e. if p is already aligned, then:
* r = a - 1 ==> u = p
*
* Otherwise:
* r = p % a -1 ==> u = p + a - p % a
*
* p can be written p = q + p % a, where q is rounded down to the
* alignment a. Then u = q + a.
*/
static inline void *align_to(void *p, size_t align)
{
return (void *)(((uintptr_t)p + align - 1) & ~(align - 1));
}
void Thread::_poison_stack()
{
pthread_attr_t attr;
size_t stack_size, guard_size;
void *stackp;
uint32_t *p, *curr, *begin, *end;
if (pthread_getattr_np(_ctx, &attr) != 0 ||
pthread_attr_getstack(&attr, &stackp, &stack_size) != 0 ||
pthread_attr_getguardsize(&attr, &guard_size) != 0) {
return;
}
stack_size /= sizeof(uint32_t);
guard_size /= sizeof(uint32_t);
/* The stack either grows upward or downard. The guard part always
* protects the end */
end = (uint32_t *)stackp;
begin = end + stack_size;
curr = (uint32_t *)align_to(alloca(sizeof(uint32_t)), alignof(uint32_t));
/* if curr is closer to @end, the stack actually grows from low to high
* virtual address: this is because this function should be executing very
* early in the thread's life and close to the thread creation, assuming
* the actual stack size is greater than the guard size and the stack
* until now is resonably small */
if (abs(curr - begin) > abs(curr - end)) {
std::swap(end, begin);
end -= guard_size;
for (p = end; p > curr; p--) {
*p = STACK_POISON;
}
} else {
end += guard_size;
/* we aligned curr to the up boundary, make sure this didn't cause us
* to lose some bytes */
curr--;
for (p = end; p < curr; p++) {
*p = STACK_POISON;
}
}
_stack_debug.start = begin;
_stack_debug.end = end;
}
size_t Thread::get_stack_usage()
{
uint32_t *p;
size_t result = 0;
/* Make sure we are tracking usage for this thread */
if (_stack_debug.start == 0 || _stack_debug.end == 0) {
return 0;
}
if (_stack_debug.start < _stack_debug.end) {
for (p = _stack_debug.end; p > _stack_debug.start; p--) {
if (*p != STACK_POISON) {
break;
}
}
result = p - _stack_debug.start;
} else {
for (p = _stack_debug.end; p < _stack_debug.start; p++) {
if (*p != STACK_POISON) {
break;
}
}
result = _stack_debug.start - p;
}
return result;
}
bool Thread::start(const char *name, int policy, int prio)
{
if (_started) {
return false;
}
struct sched_param param = { .sched_priority = prio };
pthread_attr_t attr;
int r;
pthread_attr_init(&attr);
/*
we need to run as root to get realtime scheduling. Allow it to
run as non-root for debugging purposes, plus to allow the Replay
tool to run
*/
if (geteuid() == 0) {
if ((r = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED)) != 0 ||
(r = pthread_attr_setschedpolicy(&attr, policy)) != 0 ||
(r = pthread_attr_setschedparam(&attr, &param)) != 0) {
AP_HAL::panic("Failed to set attributes for thread '%s': %s",
name, strerror(r));
}
}
if (_stack_size) {
if (pthread_attr_setstacksize(&attr, _stack_size) != 0) {
return false;
}
}
r = pthread_create(&_ctx, &attr, &Thread::_run_trampoline, this);
if (r != 0) {
AP_HAL::panic("Failed to create thread '%s': %s",
name, strerror(r));
}
pthread_attr_destroy(&attr);
if (name) {
pthread_setname_np(_ctx, name);
}
_started = true;
return true;
}
bool Thread::is_current_thread()
{
return pthread_equal(pthread_self(), _ctx);
}
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bool Thread::join()
{
void *ret;
if (_ctx == 0) {
return false;
}
if (pthread_join(_ctx, &ret) != 0 ||
(intptr_t)ret != 0) {
return false;
}
return true;
}
bool PeriodicThread::set_rate(uint32_t rate_hz)
{
if (_started || rate_hz == 0) {
return false;
}
_period_usec = hz_to_usec(rate_hz);
return true;
}
bool Thread::set_stack_size(size_t stack_size)
{
if (_started) {
return false;
}
_stack_size = stack_size;
return true;
}
bool PeriodicThread::_run()
{
if (_period_usec == 0) {
return false;
}
uint64_t next_run_usec = AP_HAL::micros64() + _period_usec;
while (!_should_exit) {
uint64_t dt = next_run_usec - AP_HAL::micros64();
if (dt > _period_usec) {
// we've lost sync - restart
next_run_usec = AP_HAL::micros64();
} else {
Scheduler::from(hal.scheduler)->microsleep(dt);
}
next_run_usec += _period_usec;
_task();
}
_started = false;
_should_exit = false;
return true;
}
bool PeriodicThread::stop()
{
if (!is_started()) {
return false;
}
_should_exit = true;
return true;
}
}