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Rootless preempt-rt mode (Work in Progress) #918

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49fea88
Use TEMP_FAILURE_RETRY() to handle EINTR properly
dwrobel May 23, 2020
9ca6c26
Remove unused thread_lock
dwrobel May 23, 2020
339d84f
Unify FIFO_SCHED between root and non-root user
dwrobel May 23, 2020
789445d
Always report realtime from rtapi_is_realtime()
dwrobel May 25, 2020
c1ea763
Disable using iptables (work in progress)
dwrobel May 23, 2020
502b84d
Run tests in verbose mode and with timeout (github)
dwrobel Jun 8, 2020
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8 changes: 6 additions & 2 deletions .github/workflows/ci.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -29,8 +29,12 @@ jobs:
./configure --with-realtime=uspace --disable-check-runtime-deps
make -O -j$((1+$(nproc))) default pycheck V=1
# Note that the package build covers html docs
../scripts/rip-environment runtests -p

sudo setcap cap_ipc_lock,cap_net_admin,cap_sys_rawio,cap_sys_nice+ep ../bin/rtapi_app
timeout --signal=9 3600 ../scripts/rip-environment runtests -vp || \
([ -e ~/linuxcnc_debug.txt ] && (echo linuxcnc_debug.txt; cat ~/linuxcnc_debug.txt); \
[ -e ~/linuxcnc_print.txt ] && (echo linuxcnc_print.txt; cat ~/linuxcnc_print.txt); \
false)

htmldocs:
runs-on: ubuntu-16.04
steps:
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2 changes: 1 addition & 1 deletion src/hal/drivers/mesa-hostmot2/hm2_eth.c
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Expand Up @@ -368,7 +368,7 @@ static bool chain_exists() {
return result == EXIT_SUCCESS;
}

static int iptables_state = -1;
static int iptables_state = 0;
static bool use_iptables() {
if(iptables_state == -1) {
if(!chain_exists()) {
Expand Down
43 changes: 2 additions & 41 deletions src/rtapi/uspace_common.h
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Expand Up @@ -321,32 +321,6 @@ int rtapi_exit(int module_id)
}

int rtapi_is_kernelspace() { return 0; }
static int _rtapi_is_realtime = -1;
#ifdef __linux__
static int detect_preempt_rt() {
struct utsname u;
int crit1, crit2 = 0;
FILE *fd;

uname(&u);
crit1 = strcasestr (u.version, "PREEMPT RT") != 0;

//"PREEMPT_RT" is used in the version string instead of "PREEMPT RT" starting with kernel version 5.4
crit1 = crit1 || (strcasestr(u.version, "PREEMPT_RT") != 0);

if ((fd = fopen("/sys/kernel/realtime","r")) != NULL) {
int flag;
crit2 = ((fscanf(fd, "%d", &flag) == 1) && (flag == 1));
fclose(fd);
}

return crit1 && crit2;
}
#else
static int detect_preempt_rt() {
return 0;
}
#endif
#ifdef USPACE_RTAI
static int detect_rtai() {
struct utsname u;
Expand All @@ -369,22 +343,9 @@ static int detect_xenomai() {
return 0;
}
#endif
static int detect_env_override() {
char *p = getenv("LINUXCNC_FORCE_REALTIME");
return p != NULL && atoi(p) != 0;
}

static int detect_realtime() {
struct stat st;
if ((stat(EMC2_BIN_DIR "/rtapi_app", &st) < 0)
|| st.st_uid != 0 || !(st.st_mode & S_ISUID))
return 0;
return detect_env_override() || detect_preempt_rt() || detect_rtai() || detect_xenomai();
}

int rtapi_is_realtime() {
if(_rtapi_is_realtime == -1) _rtapi_is_realtime = detect_realtime();
return _rtapi_is_realtime;
return 1; // now it's always realtime
}

/* Like clock_nanosleep, except that an optional 'estimate of now' parameter may
Expand All @@ -397,7 +358,7 @@ static int rtapi_clock_nanosleep(clockid_t clock_id, int flags,
const struct timespec *pnow)
{
#if defined(HAVE_CLOCK_NANOSLEEP)
return clock_nanosleep(clock_id, flags, prequest, remain);
return TEMP_FAILURE_RETRY(clock_nanosleep(clock_id, flags, prequest, remain));
#else
if(flags == 0)
return nanosleep(prequest, remain);
Expand Down
73 changes: 24 additions & 49 deletions src/rtapi/uspace_rtapi_app.cc
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Expand Up @@ -598,10 +598,8 @@ struct PosixTask : rtapi_task

struct Posix : RtapiApp
{
Posix(int policy = SCHED_FIFO) : RtapiApp(policy), do_thread_lock(policy != SCHED_FIFO) {
Posix(int policy = SCHED_FIFO) : RtapiApp(policy) {
pthread_once(&key_once, init_key);
if(do_thread_lock)
pthread_mutex_init(&thread_lock, 0);
}
int task_delete(int id);
int task_start(int task_id, unsigned long period_nsec);
Expand All @@ -618,8 +616,6 @@ struct Posix : RtapiApp
void do_outb(unsigned char value, unsigned int port);
int run_threads(int fd, int (*callback)(int fd));
static void *wrapper(void *arg);
bool do_thread_lock;
pthread_mutex_t thread_lock;

static pthread_once_t key_once;
static pthread_key_t key;
Expand Down Expand Up @@ -664,14 +660,21 @@ static void signal_handler(int sig, siginfo_t *si, void *uctx)
}

const size_t PRE_ALLOC_SIZE = 1024*1024*32;
const static struct rlimit unlimited = {RLIM_INFINITY, RLIM_INFINITY};
static void configure_memory()
{
int res = setrlimit(RLIMIT_MEMLOCK, &unlimited);
if(res < 0) perror("setrlimit");
struct rlimit limit;
int res = getrlimit(RLIMIT_MEMLOCK, &limit);
if(res < 0)
perror("getrlimit");
else {
rtapi_print_msg(RTAPI_MSG_WARN,"RLIMIT_MEMLOCK: curr: %ju, max: %ju\n",
(uintmax_t)limit.rlim_cur, (uintmax_t)limit.rlim_max);

res = mlockall(MCL_CURRENT | MCL_FUTURE);
if(res < 0) perror("mlockall");
if (limit.rlim_max >= 2* PRE_ALLOC_SIZE) {
res = mlockall(MCL_CURRENT | MCL_FUTURE);
if(res < 0) perror("mlockall");
}
}

#ifdef __linux__
/* Turn off malloc trimming.*/
Expand Down Expand Up @@ -703,40 +706,24 @@ static void configure_memory()

static int harden_rt()
{
if(!rtapi_is_realtime()) return -EINVAL;

WITH_ROOT;
#if defined(__linux__) && (defined(__x86_64__) || defined(__i386__))
if (iopl(3) < 0) {
rtapi_print_msg(RTAPI_MSG_ERR,
rtapi_print_msg(RTAPI_MSG_WARN,
"cannot gain I/O privileges - "
"forgot 'sudo make setuid'?\n");
return -EPERM;
}
#endif

struct sigaction sig_act = {};
#ifdef __linux__
// enable realtime
if (setrlimit(RLIMIT_RTPRIO, &unlimited) < 0)
{
rtapi_print_msg(RTAPI_MSG_WARN,
"setrlimit(RTLIMIT_RTPRIO): %s\n",
strerror(errno));
return -errno;
}
struct rlimit limit;

// enable core dumps
if (setrlimit(RLIMIT_CORE, &unlimited) < 0)
rtapi_print_msg(RTAPI_MSG_WARN,
"setrlimit: %s - core dumps may be truncated or non-existant\n",
strerror(errno));

// even when setuid root
if (prctl(PR_SET_DUMPABLE, 1) < 0)
rtapi_print_msg(RTAPI_MSG_WARN,
"prctl(PR_SET_DUMPABLE) failed: no core dumps will be created - %d - %s\n",
errno, strerror(errno));
int res = getrlimit(RLIMIT_MEMLOCK, &limit);
if(res < 0)
perror("getrlimit");
else
rtapi_print_msg(RTAPI_MSG_WARN,"RLIMIT_RTPRIO: curr: %ju, max: %ju\n",
(uintmax_t)limit.rlim_cur, (uintmax_t)limit.rlim_max);
#endif /* __linux__ */

configure_memory();
Expand Down Expand Up @@ -776,11 +763,8 @@ static int harden_rt()

static RtapiApp *makeApp()
{
if(euid != 0 || harden_rt() < 0)
{
rtapi_print_msg(RTAPI_MSG_ERR, "Note: Using POSIX non-realtime\n");
return new Posix(SCHED_OTHER);
}
harden_rt();

WithRoot r;
void *dll = nullptr;
if(detect_xenomai()) {
Expand All @@ -799,8 +783,7 @@ static RtapiApp *makeApp()
return result;
}
}
rtapi_print_msg(RTAPI_MSG_ERR, "Note: Using POSIX realtime\n");
return new Posix(SCHED_FIFO);
return new Posix();
}
RtapiApp &App()
{
Expand Down Expand Up @@ -1041,10 +1024,6 @@ void *Posix::wrapper(void *arg)

pthread_setspecific(key, arg);

Posix &papp = reinterpret_cast<Posix&>(App());
if(papp.do_thread_lock)
pthread_mutex_lock(&papp.thread_lock);

struct timespec now;
clock_gettime(RTAPI_CLOCK, &now);
rtapi_timespec_advance(task->nextstart, now, task->period + task->pll_correction);
Expand Down Expand Up @@ -1086,8 +1065,6 @@ int Posix::task_self() {
}

void Posix::wait() {
if(do_thread_lock)
pthread_mutex_unlock(&thread_lock);
pthread_testcancel();
struct rtapi_task *task = reinterpret_cast<rtapi_task*>(pthread_getspecific(key));
rtapi_timespec_advance(task->nextstart, task->nextstart, task->period + task->pll_correction);
Expand All @@ -1103,8 +1080,6 @@ void Posix::wait() {
int res = rtapi_clock_nanosleep(RTAPI_CLOCK, TIMER_ABSTIME, &task->nextstart, nullptr, &now);
if(res < 0) perror("clock_nanosleep");
}
if(do_thread_lock)
pthread_mutex_lock(&thread_lock);
}

unsigned char Posix::do_inb(unsigned int port)
Expand Down