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1da177e4
LT
1/*
2 * linux/kernel/acct.c
3 *
4 * BSD Process Accounting for Linux
5 *
6 * Author: Marco van Wieringen <mvw@planets.elm.net>
7 *
8 * Some code based on ideas and code from:
9 * Thomas K. Dyas <tdyas@eden.rutgers.edu>
10 *
11 * This file implements BSD-style process accounting. Whenever any
12 * process exits, an accounting record of type "struct acct" is
13 * written to the file specified with the acct() system call. It is
14 * up to user-level programs to do useful things with the accounting
15 * log. The kernel just provides the raw accounting information.
16 *
17 * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
18 *
19 * Plugged two leaks. 1) It didn't return acct_file into the free_filps if
20 * the file happened to be read-only. 2) If the accounting was suspended
21 * due to the lack of space it happily allowed to reopen it and completely
22 * lost the old acct_file. 3/10/98, Al Viro.
23 *
24 * Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
25 * XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
26 *
27 * Fixed a nasty interaction with with sys_umount(). If the accointing
28 * was suspeneded we failed to stop it on umount(). Messy.
29 * Another one: remount to readonly didn't stop accounting.
30 * Question: what should we do if we have CAP_SYS_ADMIN but not
31 * CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
32 * unless we are messing with the root. In that case we are getting a
33 * real mess with do_remount_sb(). 9/11/98, AV.
34 *
35 * Fixed a bunch of races (and pair of leaks). Probably not the best way,
36 * but this one obviously doesn't introduce deadlocks. Later. BTW, found
37 * one race (and leak) in BSD implementation.
38 * OK, that's better. ANOTHER race and leak in BSD variant. There always
39 * is one more bug... 10/11/98, AV.
40 *
41 * Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
42 * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
43 * a struct file opened for write. Fixed. 2/6/2000, AV.
44 */
45
46#include <linux/config.h>
47#include <linux/mm.h>
48#include <linux/slab.h>
49#include <linux/acct.h>
c59ede7b 50#include <linux/capability.h>
1da177e4
LT
51#include <linux/file.h>
52#include <linux/tty.h>
53#include <linux/security.h>
54#include <linux/vfs.h>
55#include <linux/jiffies.h>
56#include <linux/times.h>
57#include <linux/syscalls.h>
7b7b1ace 58#include <linux/mount.h>
1da177e4
LT
59#include <asm/uaccess.h>
60#include <asm/div64.h>
61#include <linux/blkdev.h> /* sector_div */
62
63/*
64 * These constants control the amount of freespace that suspend and
65 * resume the process accounting system, and the time delay between
66 * each check.
67 * Turned into sysctl-controllable parameters. AV, 12/11/98
68 */
69
70int acct_parm[3] = {4, 2, 30};
71#define RESUME (acct_parm[0]) /* >foo% free space - resume */
72#define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
73#define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
74
75/*
76 * External references and all of the globals.
77 */
f6ec29a4 78static void do_acct_process(struct file *);
1da177e4
LT
79
80/*
81 * This structure is used so that all the data protected by lock
82 * can be placed in the same cache line as the lock. This primes
83 * the cache line to have the data after getting the lock.
84 */
85struct acct_glbs {
86 spinlock_t lock;
87 volatile int active;
88 volatile int needcheck;
89 struct file *file;
90 struct timer_list timer;
91};
92
93static struct acct_glbs acct_globals __cacheline_aligned = {SPIN_LOCK_UNLOCKED};
94
95/*
96 * Called whenever the timer says to check the free space.
97 */
98static void acct_timeout(unsigned long unused)
99{
100 acct_globals.needcheck = 1;
101}
102
103/*
104 * Check the amount of free space and suspend/resume accordingly.
105 */
106static int check_free_space(struct file *file)
107{
108 struct kstatfs sbuf;
109 int res;
110 int act;
111 sector_t resume;
112 sector_t suspend;
113
114 spin_lock(&acct_globals.lock);
115 res = acct_globals.active;
116 if (!file || !acct_globals.needcheck)
117 goto out;
118 spin_unlock(&acct_globals.lock);
119
120 /* May block */
726c3342 121 if (vfs_statfs(file->f_dentry, &sbuf))
1da177e4
LT
122 return res;
123 suspend = sbuf.f_blocks * SUSPEND;
124 resume = sbuf.f_blocks * RESUME;
125
126 sector_div(suspend, 100);
127 sector_div(resume, 100);
128
129 if (sbuf.f_bavail <= suspend)
130 act = -1;
131 else if (sbuf.f_bavail >= resume)
132 act = 1;
133 else
134 act = 0;
135
136 /*
137 * If some joker switched acct_globals.file under us we'ld better be
138 * silent and _not_ touch anything.
139 */
140 spin_lock(&acct_globals.lock);
141 if (file != acct_globals.file) {
142 if (act)
143 res = act>0;
144 goto out;
145 }
146
147 if (acct_globals.active) {
148 if (act < 0) {
149 acct_globals.active = 0;
150 printk(KERN_INFO "Process accounting paused\n");
151 }
152 } else {
153 if (act > 0) {
154 acct_globals.active = 1;
155 printk(KERN_INFO "Process accounting resumed\n");
156 }
157 }
158
159 del_timer(&acct_globals.timer);
160 acct_globals.needcheck = 0;
161 acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
162 add_timer(&acct_globals.timer);
163 res = acct_globals.active;
164out:
165 spin_unlock(&acct_globals.lock);
166 return res;
167}
168
169/*
417ef531 170 * Close the old accounting file (if currently open) and then replace
1da177e4
LT
171 * it with file (if non-NULL).
172 *
173 * NOTE: acct_globals.lock MUST be held on entry and exit.
174 */
175static void acct_file_reopen(struct file *file)
176{
177 struct file *old_acct = NULL;
178
179 if (acct_globals.file) {
180 old_acct = acct_globals.file;
181 del_timer(&acct_globals.timer);
182 acct_globals.active = 0;
183 acct_globals.needcheck = 0;
184 acct_globals.file = NULL;
185 }
186 if (file) {
187 acct_globals.file = file;
188 acct_globals.needcheck = 0;
189 acct_globals.active = 1;
190 /* It's been deleted if it was used before so this is safe */
191 init_timer(&acct_globals.timer);
192 acct_globals.timer.function = acct_timeout;
193 acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
194 add_timer(&acct_globals.timer);
195 }
196 if (old_acct) {
7b7b1ace 197 mnt_unpin(old_acct->f_vfsmnt);
1da177e4 198 spin_unlock(&acct_globals.lock);
f6ec29a4 199 do_acct_process(old_acct);
1da177e4
LT
200 filp_close(old_acct, NULL);
201 spin_lock(&acct_globals.lock);
202 }
203}
204
7b7b1ace
AV
205static int acct_on(char *name)
206{
207 struct file *file;
208 int error;
209
210 /* Difference from BSD - they don't do O_APPEND */
211 file = filp_open(name, O_WRONLY|O_APPEND|O_LARGEFILE, 0);
212 if (IS_ERR(file))
213 return PTR_ERR(file);
214
215 if (!S_ISREG(file->f_dentry->d_inode->i_mode)) {
216 filp_close(file, NULL);
217 return -EACCES;
218 }
219
220 if (!file->f_op->write) {
221 filp_close(file, NULL);
222 return -EIO;
223 }
224
225 error = security_acct(file);
226 if (error) {
227 filp_close(file, NULL);
228 return error;
229 }
230
231 spin_lock(&acct_globals.lock);
232 mnt_pin(file->f_vfsmnt);
233 acct_file_reopen(file);
234 spin_unlock(&acct_globals.lock);
235
236 mntput(file->f_vfsmnt); /* it's pinned, now give up active reference */
237
238 return 0;
239}
240
417ef531
RD
241/**
242 * sys_acct - enable/disable process accounting
243 * @name: file name for accounting records or NULL to shutdown accounting
244 *
245 * Returns 0 for success or negative errno values for failure.
246 *
247 * sys_acct() is the only system call needed to implement process
248 * accounting. It takes the name of the file where accounting records
249 * should be written. If the filename is NULL, accounting will be
250 * shutdown.
1da177e4
LT
251 */
252asmlinkage long sys_acct(const char __user *name)
253{
1da177e4
LT
254 int error;
255
256 if (!capable(CAP_SYS_PACCT))
257 return -EPERM;
258
259 if (name) {
7b7b1ace
AV
260 char *tmp = getname(name);
261 if (IS_ERR(tmp))
1da177e4 262 return (PTR_ERR(tmp));
7b7b1ace 263 error = acct_on(tmp);
1da177e4 264 putname(tmp);
7b7b1ace
AV
265 } else {
266 error = security_acct(NULL);
267 if (!error) {
268 spin_lock(&acct_globals.lock);
269 acct_file_reopen(NULL);
270 spin_unlock(&acct_globals.lock);
1da177e4
LT
271 }
272 }
7b7b1ace
AV
273 return error;
274}
1da177e4 275
7b7b1ace
AV
276/**
277 * acct_auto_close - turn off a filesystem's accounting if it is on
278 * @m: vfsmount being shut down
279 *
280 * If the accounting is turned on for a file in the subtree pointed to
281 * to by m, turn accounting off. Done when m is about to die.
282 */
283void acct_auto_close_mnt(struct vfsmount *m)
284{
1da177e4 285 spin_lock(&acct_globals.lock);
7b7b1ace
AV
286 if (acct_globals.file && acct_globals.file->f_vfsmnt == m)
287 acct_file_reopen(NULL);
1da177e4 288 spin_unlock(&acct_globals.lock);
1da177e4
LT
289}
290
417ef531
RD
291/**
292 * acct_auto_close - turn off a filesystem's accounting if it is on
293 * @sb: super block for the filesystem
294 *
295 * If the accounting is turned on for a file in the filesystem pointed
296 * to by sb, turn accounting off.
1da177e4
LT
297 */
298void acct_auto_close(struct super_block *sb)
299{
300 spin_lock(&acct_globals.lock);
301 if (acct_globals.file &&
7b7b1ace
AV
302 acct_globals.file->f_vfsmnt->mnt_sb == sb) {
303 acct_file_reopen(NULL);
1da177e4
LT
304 }
305 spin_unlock(&acct_globals.lock);
306}
307
308/*
309 * encode an unsigned long into a comp_t
310 *
311 * This routine has been adopted from the encode_comp_t() function in
312 * the kern_acct.c file of the FreeBSD operating system. The encoding
313 * is a 13-bit fraction with a 3-bit (base 8) exponent.
314 */
315
316#define MANTSIZE 13 /* 13 bit mantissa. */
317#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
318#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
319
320static comp_t encode_comp_t(unsigned long value)
321{
322 int exp, rnd;
323
324 exp = rnd = 0;
325 while (value > MAXFRACT) {
326 rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
327 value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
328 exp++;
329 }
330
331 /*
332 * If we need to round up, do it (and handle overflow correctly).
333 */
334 if (rnd && (++value > MAXFRACT)) {
335 value >>= EXPSIZE;
336 exp++;
337 }
338
339 /*
340 * Clean it up and polish it off.
341 */
342 exp <<= MANTSIZE; /* Shift the exponent into place */
343 exp += value; /* and add on the mantissa. */
344 return exp;
345}
346
347#if ACCT_VERSION==1 || ACCT_VERSION==2
348/*
349 * encode an u64 into a comp2_t (24 bits)
350 *
351 * Format: 5 bit base 2 exponent, 20 bits mantissa.
352 * The leading bit of the mantissa is not stored, but implied for
353 * non-zero exponents.
354 * Largest encodable value is 50 bits.
355 */
356
357#define MANTSIZE2 20 /* 20 bit mantissa. */
358#define EXPSIZE2 5 /* 5 bit base 2 exponent. */
359#define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
360#define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */
361
362static comp2_t encode_comp2_t(u64 value)
363{
364 int exp, rnd;
365
366 exp = (value > (MAXFRACT2>>1));
367 rnd = 0;
368 while (value > MAXFRACT2) {
369 rnd = value & 1;
370 value >>= 1;
371 exp++;
372 }
373
374 /*
375 * If we need to round up, do it (and handle overflow correctly).
376 */
377 if (rnd && (++value > MAXFRACT2)) {
378 value >>= 1;
379 exp++;
380 }
381
382 if (exp > MAXEXP2) {
383 /* Overflow. Return largest representable number instead. */
384 return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
385 } else {
386 return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
387 }
388}
389#endif
390
391#if ACCT_VERSION==3
392/*
393 * encode an u64 into a 32 bit IEEE float
394 */
395static u32 encode_float(u64 value)
396{
397 unsigned exp = 190;
398 unsigned u;
399
400 if (value==0) return 0;
401 while ((s64)value > 0){
402 value <<= 1;
403 exp--;
404 }
405 u = (u32)(value >> 40) & 0x7fffffu;
406 return u | (exp << 23);
407}
408#endif
409
410/*
411 * Write an accounting entry for an exiting process
412 *
413 * The acct_process() call is the workhorse of the process
414 * accounting system. The struct acct is built here and then written
415 * into the accounting file. This function should only be called from
416 * do_exit().
417 */
418
419/*
420 * do_acct_process does all actual work. Caller holds the reference to file.
421 */
f6ec29a4 422static void do_acct_process(struct file *file)
1da177e4 423{
0e464814 424 struct pacct_struct *pacct = &current->signal->pacct;
1da177e4
LT
425 acct_t ac;
426 mm_segment_t fs;
1da177e4
LT
427 unsigned long flim;
428 u64 elapsed;
429 u64 run_time;
430 struct timespec uptime;
431
432 /*
433 * First check to see if there is enough free_space to continue
434 * the process accounting system.
435 */
436 if (!check_free_space(file))
437 return;
438
439 /*
440 * Fill the accounting struct with the needed info as recorded
441 * by the different kernel functions.
442 */
443 memset((caddr_t)&ac, 0, sizeof(acct_t));
444
445 ac.ac_version = ACCT_VERSION | ACCT_BYTEORDER;
446 strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));
447
448 /* calculate run_time in nsec*/
449 do_posix_clock_monotonic_gettime(&uptime);
450 run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
bb231fe3
KK
451 run_time -= (u64)current->group_leader->start_time.tv_sec * NSEC_PER_SEC
452 + current->group_leader->start_time.tv_nsec;
1da177e4
LT
453 /* convert nsec -> AHZ */
454 elapsed = nsec_to_AHZ(run_time);
455#if ACCT_VERSION==3
456 ac.ac_etime = encode_float(elapsed);
457#else
458 ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
459 (unsigned long) elapsed : (unsigned long) -1l);
460#endif
461#if ACCT_VERSION==1 || ACCT_VERSION==2
462 {
463 /* new enlarged etime field */
464 comp2_t etime = encode_comp2_t(elapsed);
465 ac.ac_etime_hi = etime >> 16;
466 ac.ac_etime_lo = (u16) etime;
467 }
468#endif
469 do_div(elapsed, AHZ);
470 ac.ac_btime = xtime.tv_sec - elapsed;
1da177e4
LT
471 /* we really need to bite the bullet and change layout */
472 ac.ac_uid = current->uid;
473 ac.ac_gid = current->gid;
474#if ACCT_VERSION==2
475 ac.ac_ahz = AHZ;
476#endif
477#if ACCT_VERSION==1 || ACCT_VERSION==2
478 /* backward-compatible 16 bit fields */
479 ac.ac_uid16 = current->uid;
480 ac.ac_gid16 = current->gid;
481#endif
482#if ACCT_VERSION==3
483 ac.ac_pid = current->tgid;
484 ac.ac_ppid = current->parent->tgid;
485#endif
486
487 read_lock(&tasklist_lock); /* pin current->signal */
488 ac.ac_tty = current->signal->tty ?
489 old_encode_dev(tty_devnum(current->signal->tty)) : 0;
490 read_unlock(&tasklist_lock);
491
0e464814 492 spin_lock(&current->sighand->siglock);
77787bfb
KK
493 ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime)));
494 ac.ac_stime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_stime)));
f6ec29a4 495 ac.ac_flag = pacct->ac_flag;
0e464814 496 ac.ac_mem = encode_comp_t(pacct->ac_mem);
77787bfb
KK
497 ac.ac_minflt = encode_comp_t(pacct->ac_minflt);
498 ac.ac_majflt = encode_comp_t(pacct->ac_majflt);
f6ec29a4 499 ac.ac_exitcode = pacct->ac_exitcode;
0e464814 500 spin_unlock(&current->sighand->siglock);
1da177e4
LT
501 ac.ac_io = encode_comp_t(0 /* current->io_usage */); /* %% */
502 ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
1da177e4 503 ac.ac_swaps = encode_comp_t(0);
1da177e4
LT
504
505 /*
506 * Kernel segment override to datasegment and write it
507 * to the accounting file.
508 */
509 fs = get_fs();
510 set_fs(KERNEL_DS);
511 /*
512 * Accounting records are not subject to resource limits.
513 */
514 flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
515 current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
516 file->f_op->write(file, (char *)&ac,
517 sizeof(acct_t), &file->f_pos);
518 current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
519 set_fs(fs);
520}
521
0e464814
KK
522/**
523 * acct_init_pacct - initialize a new pacct_struct
1dbe83c3 524 * @pacct: per-process accounting info struct to initialize
0e464814
KK
525 */
526void acct_init_pacct(struct pacct_struct *pacct)
527{
528 memset(pacct, 0, sizeof(struct pacct_struct));
77787bfb 529 pacct->ac_utime = pacct->ac_stime = cputime_zero;
0e464814
KK
530}
531
532/**
533 * acct_collect - collect accounting information into pacct_struct
f6ec29a4
KK
534 * @exitcode: task exit code
535 * @group_dead: not 0, if this thread is the last one in the process.
0e464814 536 */
f6ec29a4 537void acct_collect(long exitcode, int group_dead)
0e464814
KK
538{
539 struct pacct_struct *pacct = &current->signal->pacct;
540 unsigned long vsize = 0;
541
f6ec29a4 542 if (group_dead && current->mm) {
0e464814
KK
543 struct vm_area_struct *vma;
544 down_read(&current->mm->mmap_sem);
545 vma = current->mm->mmap;
546 while (vma) {
547 vsize += vma->vm_end - vma->vm_start;
548 vma = vma->vm_next;
549 }
550 up_read(&current->mm->mmap_sem);
551 }
552
77787bfb 553 spin_lock_irq(&current->sighand->siglock);
f6ec29a4
KK
554 if (group_dead)
555 pacct->ac_mem = vsize / 1024;
556 if (thread_group_leader(current)) {
557 pacct->ac_exitcode = exitcode;
558 if (current->flags & PF_FORKNOEXEC)
559 pacct->ac_flag |= AFORK;
560 }
561 if (current->flags & PF_SUPERPRIV)
562 pacct->ac_flag |= ASU;
563 if (current->flags & PF_DUMPCORE)
564 pacct->ac_flag |= ACORE;
565 if (current->flags & PF_SIGNALED)
566 pacct->ac_flag |= AXSIG;
77787bfb
KK
567 pacct->ac_utime = cputime_add(pacct->ac_utime, current->utime);
568 pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime);
569 pacct->ac_minflt += current->min_flt;
570 pacct->ac_majflt += current->maj_flt;
571 spin_unlock_irq(&current->sighand->siglock);
0e464814
KK
572}
573
417ef531 574/**
1da177e4 575 * acct_process - now just a wrapper around do_acct_process
417ef531
RD
576 * @exitcode: task exit code
577 *
578 * handles process accounting for an exiting task
1da177e4 579 */
7f32a25f 580void acct_process(void)
1da177e4
LT
581{
582 struct file *file = NULL;
583
584 /*
585 * accelerate the common fastpath:
586 */
587 if (!acct_globals.file)
588 return;
589
590 spin_lock(&acct_globals.lock);
591 file = acct_globals.file;
592 if (unlikely(!file)) {
593 spin_unlock(&acct_globals.lock);
594 return;
595 }
596 get_file(file);
597 spin_unlock(&acct_globals.lock);
598
f6ec29a4 599 do_acct_process(file);
1da177e4
LT
600 fput(file);
601}
602
603
417ef531
RD
604/**
605 * acct_update_integrals - update mm integral fields in task_struct
606 * @tsk: task_struct for accounting
1da177e4
LT
607 */
608void acct_update_integrals(struct task_struct *tsk)
609{
610 if (likely(tsk->mm)) {
089545f0
MS
611 long delta =
612 cputime_to_jiffies(tsk->stime) - tsk->acct_stimexpd;
1da177e4
LT
613
614 if (delta == 0)
615 return;
616 tsk->acct_stimexpd = tsk->stime;
4294621f 617 tsk->acct_rss_mem1 += delta * get_mm_rss(tsk->mm);
1da177e4
LT
618 tsk->acct_vm_mem1 += delta * tsk->mm->total_vm;
619 }
620}
621
417ef531
RD
622/**
623 * acct_clear_integrals - clear the mm integral fields in task_struct
624 * @tsk: task_struct whose accounting fields are cleared
1da177e4
LT
625 */
626void acct_clear_integrals(struct task_struct *tsk)
627{
11e64757
MH
628 tsk->acct_stimexpd = 0;
629 tsk->acct_rss_mem1 = 0;
630 tsk->acct_vm_mem1 = 0;
1da177e4 631}