xref: /linux/fs/proc/array.c (revision f5ad1c747956d501516610ee7900f4a6d57ee2f5)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/proc/array.c
4  *
5  *  Copyright (C) 1992  by Linus Torvalds
6  *  based on ideas by Darren Senn
7  *
8  * Fixes:
9  * Michael. K. Johnson: stat,statm extensions.
10  *                      <johnsonm@stolaf.edu>
11  *
12  * Pauline Middelink :  Made cmdline,envline only break at '\0's, to
13  *                      make sure SET_PROCTITLE works. Also removed
14  *                      bad '!' which forced address recalculation for
15  *                      EVERY character on the current page.
16  *                      <middelin@polyware.iaf.nl>
17  *
18  * Danny ter Haar    :	added cpuinfo
19  *			<dth@cistron.nl>
20  *
21  * Alessandro Rubini :  profile extension.
22  *                      <rubini@ipvvis.unipv.it>
23  *
24  * Jeff Tranter      :  added BogoMips field to cpuinfo
25  *                      <Jeff_Tranter@Mitel.COM>
26  *
27  * Bruno Haible      :  remove 4K limit for the maps file
28  *			<haible@ma2s2.mathematik.uni-karlsruhe.de>
29  *
30  * Yves Arrouye      :  remove removal of trailing spaces in get_array.
31  *			<Yves.Arrouye@marin.fdn.fr>
32  *
33  * Jerome Forissier  :  added per-CPU time information to /proc/stat
34  *                      and /proc/<pid>/cpu extension
35  *                      <forissier@isia.cma.fr>
36  *			- Incorporation and non-SMP safe operation
37  *			of forissier patch in 2.1.78 by
38  *			Hans Marcus <crowbar@concepts.nl>
39  *
40  * aeb@cwi.nl        :  /proc/partitions
41  *
42  *
43  * Alan Cox	     :  security fixes.
44  *			<alan@lxorguk.ukuu.org.uk>
45  *
46  * Al Viro           :  safe handling of mm_struct
47  *
48  * Gerhard Wichert   :  added BIGMEM support
49  * Siemens AG           <Gerhard.Wichert@pdb.siemens.de>
50  *
51  * Al Viro & Jeff Garzik :  moved most of the thing into base.c and
52  *			 :  proc_misc.c. The rest may eventually go into
53  *			 :  base.c too.
54  */
55 
56 #include <linux/types.h>
57 #include <linux/errno.h>
58 #include <linux/time.h>
59 #include <linux/time_namespace.h>
60 #include <linux/kernel.h>
61 #include <linux/kernel_stat.h>
62 #include <linux/tty.h>
63 #include <linux/string.h>
64 #include <linux/mman.h>
65 #include <linux/sched/mm.h>
66 #include <linux/sched/numa_balancing.h>
67 #include <linux/sched/task_stack.h>
68 #include <linux/sched/task.h>
69 #include <linux/sched/cputime.h>
70 #include <linux/proc_fs.h>
71 #include <linux/ioport.h>
72 #include <linux/uaccess.h>
73 #include <linux/io.h>
74 #include <linux/mm.h>
75 #include <linux/hugetlb.h>
76 #include <linux/pagemap.h>
77 #include <linux/swap.h>
78 #include <linux/smp.h>
79 #include <linux/signal.h>
80 #include <linux/highmem.h>
81 #include <linux/file.h>
82 #include <linux/fdtable.h>
83 #include <linux/times.h>
84 #include <linux/cpuset.h>
85 #include <linux/rcupdate.h>
86 #include <linux/delayacct.h>
87 #include <linux/seq_file.h>
88 #include <linux/pid_namespace.h>
89 #include <linux/prctl.h>
90 #include <linux/ptrace.h>
91 #include <linux/tracehook.h>
92 #include <linux/string_helpers.h>
93 #include <linux/user_namespace.h>
94 #include <linux/fs_struct.h>
95 
96 #include <asm/processor.h>
97 #include "internal.h"
98 
99 void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
100 {
101 	char *buf;
102 	size_t size;
103 	char tcomm[64];
104 	int ret;
105 
106 	if (p->flags & PF_WQ_WORKER)
107 		wq_worker_comm(tcomm, sizeof(tcomm), p);
108 	else
109 		__get_task_comm(tcomm, sizeof(tcomm), p);
110 
111 	size = seq_get_buf(m, &buf);
112 	if (escape) {
113 		ret = string_escape_str(tcomm, buf, size,
114 					ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
115 		if (ret >= size)
116 			ret = -1;
117 	} else {
118 		ret = strscpy(buf, tcomm, size);
119 	}
120 
121 	seq_commit(m, ret);
122 }
123 
124 /*
125  * The task state array is a strange "bitmap" of
126  * reasons to sleep. Thus "running" is zero, and
127  * you can test for combinations of others with
128  * simple bit tests.
129  */
130 static const char * const task_state_array[] = {
131 
132 	/* states in TASK_REPORT: */
133 	"R (running)",		/* 0x00 */
134 	"S (sleeping)",		/* 0x01 */
135 	"D (disk sleep)",	/* 0x02 */
136 	"T (stopped)",		/* 0x04 */
137 	"t (tracing stop)",	/* 0x08 */
138 	"X (dead)",		/* 0x10 */
139 	"Z (zombie)",		/* 0x20 */
140 	"P (parked)",		/* 0x40 */
141 
142 	/* states beyond TASK_REPORT: */
143 	"I (idle)",		/* 0x80 */
144 };
145 
146 static inline const char *get_task_state(struct task_struct *tsk)
147 {
148 	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
149 	return task_state_array[task_state_index(tsk)];
150 }
151 
152 static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
153 				struct pid *pid, struct task_struct *p)
154 {
155 	struct user_namespace *user_ns = seq_user_ns(m);
156 	struct group_info *group_info;
157 	int g, umask = -1;
158 	struct task_struct *tracer;
159 	const struct cred *cred;
160 	pid_t ppid, tpid = 0, tgid, ngid;
161 	unsigned int max_fds = 0;
162 
163 	rcu_read_lock();
164 	ppid = pid_alive(p) ?
165 		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
166 
167 	tracer = ptrace_parent(p);
168 	if (tracer)
169 		tpid = task_pid_nr_ns(tracer, ns);
170 
171 	tgid = task_tgid_nr_ns(p, ns);
172 	ngid = task_numa_group_id(p);
173 	cred = get_task_cred(p);
174 
175 	task_lock(p);
176 	if (p->fs)
177 		umask = p->fs->umask;
178 	if (p->files)
179 		max_fds = files_fdtable(p->files)->max_fds;
180 	task_unlock(p);
181 	rcu_read_unlock();
182 
183 	if (umask >= 0)
184 		seq_printf(m, "Umask:\t%#04o\n", umask);
185 	seq_puts(m, "State:\t");
186 	seq_puts(m, get_task_state(p));
187 
188 	seq_put_decimal_ull(m, "\nTgid:\t", tgid);
189 	seq_put_decimal_ull(m, "\nNgid:\t", ngid);
190 	seq_put_decimal_ull(m, "\nPid:\t", pid_nr_ns(pid, ns));
191 	seq_put_decimal_ull(m, "\nPPid:\t", ppid);
192 	seq_put_decimal_ull(m, "\nTracerPid:\t", tpid);
193 	seq_put_decimal_ull(m, "\nUid:\t", from_kuid_munged(user_ns, cred->uid));
194 	seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->euid));
195 	seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->suid));
196 	seq_put_decimal_ull(m, "\t", from_kuid_munged(user_ns, cred->fsuid));
197 	seq_put_decimal_ull(m, "\nGid:\t", from_kgid_munged(user_ns, cred->gid));
198 	seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->egid));
199 	seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->sgid));
200 	seq_put_decimal_ull(m, "\t", from_kgid_munged(user_ns, cred->fsgid));
201 	seq_put_decimal_ull(m, "\nFDSize:\t", max_fds);
202 
203 	seq_puts(m, "\nGroups:\t");
204 	group_info = cred->group_info;
205 	for (g = 0; g < group_info->ngroups; g++)
206 		seq_put_decimal_ull(m, g ? " " : "",
207 				from_kgid_munged(user_ns, group_info->gid[g]));
208 	put_cred(cred);
209 	/* Trailing space shouldn't have been added in the first place. */
210 	seq_putc(m, ' ');
211 
212 #ifdef CONFIG_PID_NS
213 	seq_puts(m, "\nNStgid:");
214 	for (g = ns->level; g <= pid->level; g++)
215 		seq_put_decimal_ull(m, "\t", task_tgid_nr_ns(p, pid->numbers[g].ns));
216 	seq_puts(m, "\nNSpid:");
217 	for (g = ns->level; g <= pid->level; g++)
218 		seq_put_decimal_ull(m, "\t", task_pid_nr_ns(p, pid->numbers[g].ns));
219 	seq_puts(m, "\nNSpgid:");
220 	for (g = ns->level; g <= pid->level; g++)
221 		seq_put_decimal_ull(m, "\t", task_pgrp_nr_ns(p, pid->numbers[g].ns));
222 	seq_puts(m, "\nNSsid:");
223 	for (g = ns->level; g <= pid->level; g++)
224 		seq_put_decimal_ull(m, "\t", task_session_nr_ns(p, pid->numbers[g].ns));
225 #endif
226 	seq_putc(m, '\n');
227 }
228 
229 void render_sigset_t(struct seq_file *m, const char *header,
230 				sigset_t *set)
231 {
232 	int i;
233 
234 	seq_puts(m, header);
235 
236 	i = _NSIG;
237 	do {
238 		int x = 0;
239 
240 		i -= 4;
241 		if (sigismember(set, i+1)) x |= 1;
242 		if (sigismember(set, i+2)) x |= 2;
243 		if (sigismember(set, i+3)) x |= 4;
244 		if (sigismember(set, i+4)) x |= 8;
245 		seq_putc(m, hex_asc[x]);
246 	} while (i >= 4);
247 
248 	seq_putc(m, '\n');
249 }
250 
251 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *sigign,
252 				    sigset_t *sigcatch)
253 {
254 	struct k_sigaction *k;
255 	int i;
256 
257 	k = p->sighand->action;
258 	for (i = 1; i <= _NSIG; ++i, ++k) {
259 		if (k->sa.sa_handler == SIG_IGN)
260 			sigaddset(sigign, i);
261 		else if (k->sa.sa_handler != SIG_DFL)
262 			sigaddset(sigcatch, i);
263 	}
264 }
265 
266 static inline void task_sig(struct seq_file *m, struct task_struct *p)
267 {
268 	unsigned long flags;
269 	sigset_t pending, shpending, blocked, ignored, caught;
270 	int num_threads = 0;
271 	unsigned int qsize = 0;
272 	unsigned long qlim = 0;
273 
274 	sigemptyset(&pending);
275 	sigemptyset(&shpending);
276 	sigemptyset(&blocked);
277 	sigemptyset(&ignored);
278 	sigemptyset(&caught);
279 
280 	if (lock_task_sighand(p, &flags)) {
281 		pending = p->pending.signal;
282 		shpending = p->signal->shared_pending.signal;
283 		blocked = p->blocked;
284 		collect_sigign_sigcatch(p, &ignored, &caught);
285 		num_threads = get_nr_threads(p);
286 		rcu_read_lock();  /* FIXME: is this correct? */
287 		qsize = atomic_read(&__task_cred(p)->user->sigpending);
288 		rcu_read_unlock();
289 		qlim = task_rlimit(p, RLIMIT_SIGPENDING);
290 		unlock_task_sighand(p, &flags);
291 	}
292 
293 	seq_put_decimal_ull(m, "Threads:\t", num_threads);
294 	seq_put_decimal_ull(m, "\nSigQ:\t", qsize);
295 	seq_put_decimal_ull(m, "/", qlim);
296 
297 	/* render them all */
298 	render_sigset_t(m, "\nSigPnd:\t", &pending);
299 	render_sigset_t(m, "ShdPnd:\t", &shpending);
300 	render_sigset_t(m, "SigBlk:\t", &blocked);
301 	render_sigset_t(m, "SigIgn:\t", &ignored);
302 	render_sigset_t(m, "SigCgt:\t", &caught);
303 }
304 
305 static void render_cap_t(struct seq_file *m, const char *header,
306 			kernel_cap_t *a)
307 {
308 	unsigned __capi;
309 
310 	seq_puts(m, header);
311 	CAP_FOR_EACH_U32(__capi) {
312 		seq_put_hex_ll(m, NULL,
313 			   a->cap[CAP_LAST_U32 - __capi], 8);
314 	}
315 	seq_putc(m, '\n');
316 }
317 
318 static inline void task_cap(struct seq_file *m, struct task_struct *p)
319 {
320 	const struct cred *cred;
321 	kernel_cap_t cap_inheritable, cap_permitted, cap_effective,
322 			cap_bset, cap_ambient;
323 
324 	rcu_read_lock();
325 	cred = __task_cred(p);
326 	cap_inheritable	= cred->cap_inheritable;
327 	cap_permitted	= cred->cap_permitted;
328 	cap_effective	= cred->cap_effective;
329 	cap_bset	= cred->cap_bset;
330 	cap_ambient	= cred->cap_ambient;
331 	rcu_read_unlock();
332 
333 	render_cap_t(m, "CapInh:\t", &cap_inheritable);
334 	render_cap_t(m, "CapPrm:\t", &cap_permitted);
335 	render_cap_t(m, "CapEff:\t", &cap_effective);
336 	render_cap_t(m, "CapBnd:\t", &cap_bset);
337 	render_cap_t(m, "CapAmb:\t", &cap_ambient);
338 }
339 
340 static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
341 {
342 	seq_put_decimal_ull(m, "NoNewPrivs:\t", task_no_new_privs(p));
343 #ifdef CONFIG_SECCOMP
344 	seq_put_decimal_ull(m, "\nSeccomp:\t", p->seccomp.mode);
345 	seq_put_decimal_ull(m, "\nSeccomp_filters:\t",
346 			    atomic_read(&p->seccomp.filter_count));
347 #endif
348 	seq_puts(m, "\nSpeculation_Store_Bypass:\t");
349 	switch (arch_prctl_spec_ctrl_get(p, PR_SPEC_STORE_BYPASS)) {
350 	case -EINVAL:
351 		seq_puts(m, "unknown");
352 		break;
353 	case PR_SPEC_NOT_AFFECTED:
354 		seq_puts(m, "not vulnerable");
355 		break;
356 	case PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE:
357 		seq_puts(m, "thread force mitigated");
358 		break;
359 	case PR_SPEC_PRCTL | PR_SPEC_DISABLE:
360 		seq_puts(m, "thread mitigated");
361 		break;
362 	case PR_SPEC_PRCTL | PR_SPEC_ENABLE:
363 		seq_puts(m, "thread vulnerable");
364 		break;
365 	case PR_SPEC_DISABLE:
366 		seq_puts(m, "globally mitigated");
367 		break;
368 	default:
369 		seq_puts(m, "vulnerable");
370 		break;
371 	}
372 	seq_putc(m, '\n');
373 }
374 
375 static inline void task_context_switch_counts(struct seq_file *m,
376 						struct task_struct *p)
377 {
378 	seq_put_decimal_ull(m, "voluntary_ctxt_switches:\t", p->nvcsw);
379 	seq_put_decimal_ull(m, "\nnonvoluntary_ctxt_switches:\t", p->nivcsw);
380 	seq_putc(m, '\n');
381 }
382 
383 static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
384 {
385 	seq_printf(m, "Cpus_allowed:\t%*pb\n",
386 		   cpumask_pr_args(&task->cpus_mask));
387 	seq_printf(m, "Cpus_allowed_list:\t%*pbl\n",
388 		   cpumask_pr_args(&task->cpus_mask));
389 }
390 
391 static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm)
392 {
393 	seq_put_decimal_ull(m, "CoreDumping:\t", !!mm->core_state);
394 	seq_putc(m, '\n');
395 }
396 
397 static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm)
398 {
399 	bool thp_enabled = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE);
400 
401 	if (thp_enabled)
402 		thp_enabled = !test_bit(MMF_DISABLE_THP, &mm->flags);
403 	seq_printf(m, "THP_enabled:\t%d\n", thp_enabled);
404 }
405 
406 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
407 			struct pid *pid, struct task_struct *task)
408 {
409 	struct mm_struct *mm = get_task_mm(task);
410 
411 	seq_puts(m, "Name:\t");
412 	proc_task_name(m, task, true);
413 	seq_putc(m, '\n');
414 
415 	task_state(m, ns, pid, task);
416 
417 	if (mm) {
418 		task_mem(m, mm);
419 		task_core_dumping(m, mm);
420 		task_thp_status(m, mm);
421 		mmput(mm);
422 	}
423 	task_sig(m, task);
424 	task_cap(m, task);
425 	task_seccomp(m, task);
426 	task_cpus_allowed(m, task);
427 	cpuset_task_status_allowed(m, task);
428 	task_context_switch_counts(m, task);
429 	return 0;
430 }
431 
432 static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
433 			struct pid *pid, struct task_struct *task, int whole)
434 {
435 	unsigned long vsize, eip, esp, wchan = 0;
436 	int priority, nice;
437 	int tty_pgrp = -1, tty_nr = 0;
438 	sigset_t sigign, sigcatch;
439 	char state;
440 	pid_t ppid = 0, pgid = -1, sid = -1;
441 	int num_threads = 0;
442 	int permitted;
443 	struct mm_struct *mm;
444 	unsigned long long start_time;
445 	unsigned long cmin_flt = 0, cmaj_flt = 0;
446 	unsigned long  min_flt = 0,  maj_flt = 0;
447 	u64 cutime, cstime, utime, stime;
448 	u64 cgtime, gtime;
449 	unsigned long rsslim = 0;
450 	unsigned long flags;
451 
452 	state = *get_task_state(task);
453 	vsize = eip = esp = 0;
454 	permitted = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS | PTRACE_MODE_NOAUDIT);
455 	mm = get_task_mm(task);
456 	if (mm) {
457 		vsize = task_vsize(mm);
458 		/*
459 		 * esp and eip are intentionally zeroed out.  There is no
460 		 * non-racy way to read them without freezing the task.
461 		 * Programs that need reliable values can use ptrace(2).
462 		 *
463 		 * The only exception is if the task is core dumping because
464 		 * a program is not able to use ptrace(2) in that case. It is
465 		 * safe because the task has stopped executing permanently.
466 		 */
467 		if (permitted && (task->flags & (PF_EXITING|PF_DUMPCORE))) {
468 			if (try_get_task_stack(task)) {
469 				eip = KSTK_EIP(task);
470 				esp = KSTK_ESP(task);
471 				put_task_stack(task);
472 			}
473 		}
474 	}
475 
476 	sigemptyset(&sigign);
477 	sigemptyset(&sigcatch);
478 	cutime = cstime = utime = stime = 0;
479 	cgtime = gtime = 0;
480 
481 	if (lock_task_sighand(task, &flags)) {
482 		struct signal_struct *sig = task->signal;
483 
484 		if (sig->tty) {
485 			struct pid *pgrp = tty_get_pgrp(sig->tty);
486 			tty_pgrp = pid_nr_ns(pgrp, ns);
487 			put_pid(pgrp);
488 			tty_nr = new_encode_dev(tty_devnum(sig->tty));
489 		}
490 
491 		num_threads = get_nr_threads(task);
492 		collect_sigign_sigcatch(task, &sigign, &sigcatch);
493 
494 		cmin_flt = sig->cmin_flt;
495 		cmaj_flt = sig->cmaj_flt;
496 		cutime = sig->cutime;
497 		cstime = sig->cstime;
498 		cgtime = sig->cgtime;
499 		rsslim = READ_ONCE(sig->rlim[RLIMIT_RSS].rlim_cur);
500 
501 		/* add up live thread stats at the group level */
502 		if (whole) {
503 			struct task_struct *t = task;
504 			do {
505 				min_flt += t->min_flt;
506 				maj_flt += t->maj_flt;
507 				gtime += task_gtime(t);
508 			} while_each_thread(task, t);
509 
510 			min_flt += sig->min_flt;
511 			maj_flt += sig->maj_flt;
512 			thread_group_cputime_adjusted(task, &utime, &stime);
513 			gtime += sig->gtime;
514 		}
515 
516 		sid = task_session_nr_ns(task, ns);
517 		ppid = task_tgid_nr_ns(task->real_parent, ns);
518 		pgid = task_pgrp_nr_ns(task, ns);
519 
520 		unlock_task_sighand(task, &flags);
521 	}
522 
523 	if (permitted && (!whole || num_threads < 2))
524 		wchan = get_wchan(task);
525 	if (!whole) {
526 		min_flt = task->min_flt;
527 		maj_flt = task->maj_flt;
528 		task_cputime_adjusted(task, &utime, &stime);
529 		gtime = task_gtime(task);
530 	}
531 
532 	/* scale priority and nice values from timeslices to -20..20 */
533 	/* to make it look like a "normal" Unix priority/nice value  */
534 	priority = task_prio(task);
535 	nice = task_nice(task);
536 
537 	/* apply timens offset for boottime and convert nsec -> ticks */
538 	start_time =
539 		nsec_to_clock_t(timens_add_boottime_ns(task->start_boottime));
540 
541 	seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns));
542 	seq_puts(m, " (");
543 	proc_task_name(m, task, false);
544 	seq_puts(m, ") ");
545 	seq_putc(m, state);
546 	seq_put_decimal_ll(m, " ", ppid);
547 	seq_put_decimal_ll(m, " ", pgid);
548 	seq_put_decimal_ll(m, " ", sid);
549 	seq_put_decimal_ll(m, " ", tty_nr);
550 	seq_put_decimal_ll(m, " ", tty_pgrp);
551 	seq_put_decimal_ull(m, " ", task->flags);
552 	seq_put_decimal_ull(m, " ", min_flt);
553 	seq_put_decimal_ull(m, " ", cmin_flt);
554 	seq_put_decimal_ull(m, " ", maj_flt);
555 	seq_put_decimal_ull(m, " ", cmaj_flt);
556 	seq_put_decimal_ull(m, " ", nsec_to_clock_t(utime));
557 	seq_put_decimal_ull(m, " ", nsec_to_clock_t(stime));
558 	seq_put_decimal_ll(m, " ", nsec_to_clock_t(cutime));
559 	seq_put_decimal_ll(m, " ", nsec_to_clock_t(cstime));
560 	seq_put_decimal_ll(m, " ", priority);
561 	seq_put_decimal_ll(m, " ", nice);
562 	seq_put_decimal_ll(m, " ", num_threads);
563 	seq_put_decimal_ull(m, " ", 0);
564 	seq_put_decimal_ull(m, " ", start_time);
565 	seq_put_decimal_ull(m, " ", vsize);
566 	seq_put_decimal_ull(m, " ", mm ? get_mm_rss(mm) : 0);
567 	seq_put_decimal_ull(m, " ", rsslim);
568 	seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->start_code : 1) : 0);
569 	seq_put_decimal_ull(m, " ", mm ? (permitted ? mm->end_code : 1) : 0);
570 	seq_put_decimal_ull(m, " ", (permitted && mm) ? mm->start_stack : 0);
571 	seq_put_decimal_ull(m, " ", esp);
572 	seq_put_decimal_ull(m, " ", eip);
573 	/* The signal information here is obsolete.
574 	 * It must be decimal for Linux 2.0 compatibility.
575 	 * Use /proc/#/status for real-time signals.
576 	 */
577 	seq_put_decimal_ull(m, " ", task->pending.signal.sig[0] & 0x7fffffffUL);
578 	seq_put_decimal_ull(m, " ", task->blocked.sig[0] & 0x7fffffffUL);
579 	seq_put_decimal_ull(m, " ", sigign.sig[0] & 0x7fffffffUL);
580 	seq_put_decimal_ull(m, " ", sigcatch.sig[0] & 0x7fffffffUL);
581 
582 	/*
583 	 * We used to output the absolute kernel address, but that's an
584 	 * information leak - so instead we show a 0/1 flag here, to signal
585 	 * to user-space whether there's a wchan field in /proc/PID/wchan.
586 	 *
587 	 * This works with older implementations of procps as well.
588 	 */
589 	if (wchan)
590 		seq_puts(m, " 1");
591 	else
592 		seq_puts(m, " 0");
593 
594 	seq_put_decimal_ull(m, " ", 0);
595 	seq_put_decimal_ull(m, " ", 0);
596 	seq_put_decimal_ll(m, " ", task->exit_signal);
597 	seq_put_decimal_ll(m, " ", task_cpu(task));
598 	seq_put_decimal_ull(m, " ", task->rt_priority);
599 	seq_put_decimal_ull(m, " ", task->policy);
600 	seq_put_decimal_ull(m, " ", delayacct_blkio_ticks(task));
601 	seq_put_decimal_ull(m, " ", nsec_to_clock_t(gtime));
602 	seq_put_decimal_ll(m, " ", nsec_to_clock_t(cgtime));
603 
604 	if (mm && permitted) {
605 		seq_put_decimal_ull(m, " ", mm->start_data);
606 		seq_put_decimal_ull(m, " ", mm->end_data);
607 		seq_put_decimal_ull(m, " ", mm->start_brk);
608 		seq_put_decimal_ull(m, " ", mm->arg_start);
609 		seq_put_decimal_ull(m, " ", mm->arg_end);
610 		seq_put_decimal_ull(m, " ", mm->env_start);
611 		seq_put_decimal_ull(m, " ", mm->env_end);
612 	} else
613 		seq_puts(m, " 0 0 0 0 0 0 0");
614 
615 	if (permitted)
616 		seq_put_decimal_ll(m, " ", task->exit_code);
617 	else
618 		seq_puts(m, " 0");
619 
620 	seq_putc(m, '\n');
621 	if (mm)
622 		mmput(mm);
623 	return 0;
624 }
625 
626 int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
627 			struct pid *pid, struct task_struct *task)
628 {
629 	return do_task_stat(m, ns, pid, task, 0);
630 }
631 
632 int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
633 			struct pid *pid, struct task_struct *task)
634 {
635 	return do_task_stat(m, ns, pid, task, 1);
636 }
637 
638 int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
639 			struct pid *pid, struct task_struct *task)
640 {
641 	struct mm_struct *mm = get_task_mm(task);
642 
643 	if (mm) {
644 		unsigned long size;
645 		unsigned long resident = 0;
646 		unsigned long shared = 0;
647 		unsigned long text = 0;
648 		unsigned long data = 0;
649 
650 		size = task_statm(mm, &shared, &text, &data, &resident);
651 		mmput(mm);
652 
653 		/*
654 		 * For quick read, open code by putting numbers directly
655 		 * expected format is
656 		 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n",
657 		 *               size, resident, shared, text, data);
658 		 */
659 		seq_put_decimal_ull(m, "", size);
660 		seq_put_decimal_ull(m, " ", resident);
661 		seq_put_decimal_ull(m, " ", shared);
662 		seq_put_decimal_ull(m, " ", text);
663 		seq_put_decimal_ull(m, " ", 0);
664 		seq_put_decimal_ull(m, " ", data);
665 		seq_put_decimal_ull(m, " ", 0);
666 		seq_putc(m, '\n');
667 	} else {
668 		seq_write(m, "0 0 0 0 0 0 0\n", 14);
669 	}
670 	return 0;
671 }
672 
673 #ifdef CONFIG_PROC_CHILDREN
674 static struct pid *
675 get_children_pid(struct inode *inode, struct pid *pid_prev, loff_t pos)
676 {
677 	struct task_struct *start, *task;
678 	struct pid *pid = NULL;
679 
680 	read_lock(&tasklist_lock);
681 
682 	start = pid_task(proc_pid(inode), PIDTYPE_PID);
683 	if (!start)
684 		goto out;
685 
686 	/*
687 	 * Lets try to continue searching first, this gives
688 	 * us significant speedup on children-rich processes.
689 	 */
690 	if (pid_prev) {
691 		task = pid_task(pid_prev, PIDTYPE_PID);
692 		if (task && task->real_parent == start &&
693 		    !(list_empty(&task->sibling))) {
694 			if (list_is_last(&task->sibling, &start->children))
695 				goto out;
696 			task = list_first_entry(&task->sibling,
697 						struct task_struct, sibling);
698 			pid = get_pid(task_pid(task));
699 			goto out;
700 		}
701 	}
702 
703 	/*
704 	 * Slow search case.
705 	 *
706 	 * We might miss some children here if children
707 	 * are exited while we were not holding the lock,
708 	 * but it was never promised to be accurate that
709 	 * much.
710 	 *
711 	 * "Just suppose that the parent sleeps, but N children
712 	 *  exit after we printed their tids. Now the slow paths
713 	 *  skips N extra children, we miss N tasks." (c)
714 	 *
715 	 * So one need to stop or freeze the leader and all
716 	 * its children to get a precise result.
717 	 */
718 	list_for_each_entry(task, &start->children, sibling) {
719 		if (pos-- == 0) {
720 			pid = get_pid(task_pid(task));
721 			break;
722 		}
723 	}
724 
725 out:
726 	read_unlock(&tasklist_lock);
727 	return pid;
728 }
729 
730 static int children_seq_show(struct seq_file *seq, void *v)
731 {
732 	struct inode *inode = file_inode(seq->file);
733 
734 	seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(inode->i_sb)));
735 	return 0;
736 }
737 
738 static void *children_seq_start(struct seq_file *seq, loff_t *pos)
739 {
740 	return get_children_pid(file_inode(seq->file), NULL, *pos);
741 }
742 
743 static void *children_seq_next(struct seq_file *seq, void *v, loff_t *pos)
744 {
745 	struct pid *pid;
746 
747 	pid = get_children_pid(file_inode(seq->file), v, *pos + 1);
748 	put_pid(v);
749 
750 	++*pos;
751 	return pid;
752 }
753 
754 static void children_seq_stop(struct seq_file *seq, void *v)
755 {
756 	put_pid(v);
757 }
758 
759 static const struct seq_operations children_seq_ops = {
760 	.start	= children_seq_start,
761 	.next	= children_seq_next,
762 	.stop	= children_seq_stop,
763 	.show	= children_seq_show,
764 };
765 
766 static int children_seq_open(struct inode *inode, struct file *file)
767 {
768 	return seq_open(file, &children_seq_ops);
769 }
770 
771 const struct file_operations proc_tid_children_operations = {
772 	.open    = children_seq_open,
773 	.read    = seq_read,
774 	.llseek  = seq_lseek,
775 	.release = seq_release,
776 };
777 #endif /* CONFIG_PROC_CHILDREN */
778