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+/*
+ * linux/kernel/acct.c
+ *
+ * BSD Process Accounting for Linux
+ *
+ * Author: Marco van Wieringen <mvw@planets.elm.net>
+ *
+ * Some code based on ideas and code from:
+ * Thomas K. Dyas <tdyas@eden.rutgers.edu>
+ *
+ * This file implements BSD-style process accounting. Whenever any
+ * process exits, an accounting record of type "struct acct" is
+ * written to the file specified with the acct() system call. It is
+ * up to user-level programs to do useful things with the accounting
+ * log. The kernel just provides the raw accounting information.
+ *
+ * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
+ *
+ * Plugged two leaks. 1) It didn't return acct_file into the free_filps if
+ * the file happened to be read-only. 2) If the accounting was suspended
+ * due to the lack of space it happily allowed to reopen it and completely
+ * lost the old acct_file. 3/10/98, Al Viro.
+ *
+ * Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
+ * XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
+ *
+ * Fixed a nasty interaction with with sys_umount(). If the accointing
+ * was suspeneded we failed to stop it on umount(). Messy.
+ * Another one: remount to readonly didn't stop accounting.
+ * Question: what should we do if we have CAP_SYS_ADMIN but not
+ * CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
+ * unless we are messing with the root. In that case we are getting a
+ * real mess with do_remount_sb(). 9/11/98, AV.
+ *
+ * Fixed a bunch of races (and pair of leaks). Probably not the best way,
+ * but this one obviously doesn't introduce deadlocks. Later. BTW, found
+ * one race (and leak) in BSD implementation.
+ * OK, that's better. ANOTHER race and leak in BSD variant. There always
+ * is one more bug... 10/11/98, AV.
+ *
+ * Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
+ * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
+ * a struct file opened for write. Fixed. 2/6/2000, AV.
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/acct.h>
+#include <linux/file.h>
+#include <linux/tty.h>
+#include <linux/security.h>
+#include <linux/vfs.h>
+#include <linux/jiffies.h>
+#include <linux/times.h>
+#include <linux/syscalls.h>
+#include <asm/uaccess.h>
+#include <asm/div64.h>
+#include <linux/blkdev.h> /* sector_div */
+
+/*
+ * These constants control the amount of freespace that suspend and
+ * resume the process accounting system, and the time delay between
+ * each check.
+ * Turned into sysctl-controllable parameters. AV, 12/11/98
+ */
+
+int acct_parm[3] = {4, 2, 30};
+#define RESUME (acct_parm[0]) /* >foo% free space - resume */
+#define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
+#define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
+
+/*
+ * External references and all of the globals.
+ */
+static void do_acct_process(long, struct file *);
+
+/*
+ * This structure is used so that all the data protected by lock
+ * can be placed in the same cache line as the lock. This primes
+ * the cache line to have the data after getting the lock.
+ */
+struct acct_glbs {
+ spinlock_t lock;
+ volatile int active;
+ volatile int needcheck;
+ struct file *file;
+ struct timer_list timer;
+};
+
+static struct acct_glbs acct_globals __cacheline_aligned = {SPIN_LOCK_UNLOCKED};
+
+/*
+ * Called whenever the timer says to check the free space.
+ */
+static void acct_timeout(unsigned long unused)
+{
+ acct_globals.needcheck = 1;
+}
+
+/*
+ * Check the amount of free space and suspend/resume accordingly.
+ */
+static int check_free_space(struct file *file)
+{
+ struct kstatfs sbuf;
+ int res;
+ int act;
+ sector_t resume;
+ sector_t suspend;
+
+ spin_lock(&acct_globals.lock);
+ res = acct_globals.active;
+ if (!file || !acct_globals.needcheck)
+ goto out;
+ spin_unlock(&acct_globals.lock);
+
+ /* May block */
+ if (vfs_statfs(file->f_dentry->d_inode->i_sb, &sbuf))
+ return res;
+ suspend = sbuf.f_blocks * SUSPEND;
+ resume = sbuf.f_blocks * RESUME;
+
+ sector_div(suspend, 100);
+ sector_div(resume, 100);
+
+ if (sbuf.f_bavail <= suspend)
+ act = -1;
+ else if (sbuf.f_bavail >= resume)
+ act = 1;
+ else
+ act = 0;
+
+ /*
+ * If some joker switched acct_globals.file under us we'ld better be
+ * silent and _not_ touch anything.
+ */
+ spin_lock(&acct_globals.lock);
+ if (file != acct_globals.file) {
+ if (act)
+ res = act>0;
+ goto out;
+ }
+
+ if (acct_globals.active) {
+ if (act < 0) {
+ acct_globals.active = 0;
+ printk(KERN_INFO "Process accounting paused\n");
+ }
+ } else {
+ if (act > 0) {
+ acct_globals.active = 1;
+ printk(KERN_INFO "Process accounting resumed\n");
+ }
+ }
+
+ del_timer(&acct_globals.timer);
+ acct_globals.needcheck = 0;
+ acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
+ add_timer(&acct_globals.timer);
+ res = acct_globals.active;
+out:
+ spin_unlock(&acct_globals.lock);
+ return res;
+}
+
+/*
+ * Close the old accouting file (if currently open) and then replace
+ * it with file (if non-NULL).
+ *
+ * NOTE: acct_globals.lock MUST be held on entry and exit.
+ */
+static void acct_file_reopen(struct file *file)
+{
+ struct file *old_acct = NULL;
+
+ if (acct_globals.file) {
+ old_acct = acct_globals.file;
+ del_timer(&acct_globals.timer);
+ acct_globals.active = 0;
+ acct_globals.needcheck = 0;
+ acct_globals.file = NULL;
+ }
+ if (file) {
+ acct_globals.file = file;
+ acct_globals.needcheck = 0;
+ acct_globals.active = 1;
+ /* It's been deleted if it was used before so this is safe */
+ init_timer(&acct_globals.timer);
+ acct_globals.timer.function = acct_timeout;
+ acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ;
+ add_timer(&acct_globals.timer);
+ }
+ if (old_acct) {
+ spin_unlock(&acct_globals.lock);
+ do_acct_process(0, old_acct);
+ filp_close(old_acct, NULL);
+ spin_lock(&acct_globals.lock);
+ }
+}
+
+/*
+ * sys_acct() is the only system call needed to implement process
+ * accounting. It takes the name of the file where accounting records
+ * should be written. If the filename is NULL, accounting will be
+ * shutdown.
+ */
+asmlinkage long sys_acct(const char __user *name)
+{
+ struct file *file = NULL;
+ char *tmp;
+ int error;
+
+ if (!capable(CAP_SYS_PACCT))
+ return -EPERM;
+
+ if (name) {
+ tmp = getname(name);
+ if (IS_ERR(tmp)) {
+ return (PTR_ERR(tmp));
+ }
+ /* Difference from BSD - they don't do O_APPEND */
+ file = filp_open(tmp, O_WRONLY|O_APPEND, 0);
+ putname(tmp);
+ if (IS_ERR(file)) {
+ return (PTR_ERR(file));
+ }
+ if (!S_ISREG(file->f_dentry->d_inode->i_mode)) {
+ filp_close(file, NULL);
+ return (-EACCES);
+ }
+
+ if (!file->f_op->write) {
+ filp_close(file, NULL);
+ return (-EIO);
+ }
+ }
+
+ error = security_acct(file);
+ if (error) {
+ if (file)
+ filp_close(file, NULL);
+ return error;
+ }
+
+ spin_lock(&acct_globals.lock);
+ acct_file_reopen(file);
+ spin_unlock(&acct_globals.lock);
+
+ return (0);
+}
+
+/*
+ * If the accouting is turned on for a file in the filesystem pointed
+ * to by sb, turn accouting off.
+ */
+void acct_auto_close(struct super_block *sb)
+{
+ spin_lock(&acct_globals.lock);
+ if (acct_globals.file &&
+ acct_globals.file->f_dentry->d_inode->i_sb == sb) {
+ acct_file_reopen((struct file *)NULL);
+ }
+ spin_unlock(&acct_globals.lock);
+}
+
+/*
+ * encode an unsigned long into a comp_t
+ *
+ * This routine has been adopted from the encode_comp_t() function in
+ * the kern_acct.c file of the FreeBSD operating system. The encoding
+ * is a 13-bit fraction with a 3-bit (base 8) exponent.
+ */
+
+#define MANTSIZE 13 /* 13 bit mantissa. */
+#define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
+#define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
+
+static comp_t encode_comp_t(unsigned long value)
+{
+ int exp, rnd;
+
+ exp = rnd = 0;
+ while (value > MAXFRACT) {
+ rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
+ value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
+ exp++;
+ }
+
+ /*
+ * If we need to round up, do it (and handle overflow correctly).
+ */
+ if (rnd && (++value > MAXFRACT)) {
+ value >>= EXPSIZE;
+ exp++;
+ }
+
+ /*
+ * Clean it up and polish it off.
+ */
+ exp <<= MANTSIZE; /* Shift the exponent into place */
+ exp += value; /* and add on the mantissa. */
+ return exp;
+}
+
+#if ACCT_VERSION==1 || ACCT_VERSION==2
+/*
+ * encode an u64 into a comp2_t (24 bits)
+ *
+ * Format: 5 bit base 2 exponent, 20 bits mantissa.
+ * The leading bit of the mantissa is not stored, but implied for
+ * non-zero exponents.
+ * Largest encodable value is 50 bits.
+ */
+
+#define MANTSIZE2 20 /* 20 bit mantissa. */
+#define EXPSIZE2 5 /* 5 bit base 2 exponent. */
+#define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
+#define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */
+
+static comp2_t encode_comp2_t(u64 value)
+{
+ int exp, rnd;
+
+ exp = (value > (MAXFRACT2>>1));
+ rnd = 0;
+ while (value > MAXFRACT2) {
+ rnd = value & 1;
+ value >>= 1;
+ exp++;
+ }
+
+ /*
+ * If we need to round up, do it (and handle overflow correctly).
+ */
+ if (rnd && (++value > MAXFRACT2)) {
+ value >>= 1;
+ exp++;
+ }
+
+ if (exp > MAXEXP2) {
+ /* Overflow. Return largest representable number instead. */
+ return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1;
+ } else {
+ return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1));
+ }
+}
+#endif
+
+#if ACCT_VERSION==3
+/*
+ * encode an u64 into a 32 bit IEEE float
+ */
+static u32 encode_float(u64 value)
+{
+ unsigned exp = 190;
+ unsigned u;
+
+ if (value==0) return 0;
+ while ((s64)value > 0){
+ value <<= 1;
+ exp--;
+ }
+ u = (u32)(value >> 40) & 0x7fffffu;
+ return u | (exp << 23);
+}
+#endif
+
+/*
+ * Write an accounting entry for an exiting process
+ *
+ * The acct_process() call is the workhorse of the process
+ * accounting system. The struct acct is built here and then written
+ * into the accounting file. This function should only be called from
+ * do_exit().
+ */
+
+/*
+ * do_acct_process does all actual work. Caller holds the reference to file.
+ */
+static void do_acct_process(long exitcode, struct file *file)
+{
+ acct_t ac;
+ mm_segment_t fs;
+ unsigned long vsize;
+ unsigned long flim;
+ u64 elapsed;
+ u64 run_time;
+ struct timespec uptime;
+
+ /*
+ * First check to see if there is enough free_space to continue
+ * the process accounting system.
+ */
+ if (!check_free_space(file))
+ return;
+
+ /*
+ * Fill the accounting struct with the needed info as recorded
+ * by the different kernel functions.
+ */
+ memset((caddr_t)&ac, 0, sizeof(acct_t));
+
+ ac.ac_version = ACCT_VERSION | ACCT_BYTEORDER;
+ strlcpy(ac.ac_comm, current->comm, sizeof(ac.ac_comm));
+
+ /* calculate run_time in nsec*/
+ do_posix_clock_monotonic_gettime(&uptime);
+ run_time = (u64)uptime.tv_sec*NSEC_PER_SEC + uptime.tv_nsec;
+ run_time -= (u64)current->start_time.tv_sec*NSEC_PER_SEC
+ + current->start_time.tv_nsec;
+ /* convert nsec -> AHZ */
+ elapsed = nsec_to_AHZ(run_time);
+#if ACCT_VERSION==3
+ ac.ac_etime = encode_float(elapsed);
+#else
+ ac.ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ?
+ (unsigned long) elapsed : (unsigned long) -1l);
+#endif
+#if ACCT_VERSION==1 || ACCT_VERSION==2
+ {
+ /* new enlarged etime field */
+ comp2_t etime = encode_comp2_t(elapsed);
+ ac.ac_etime_hi = etime >> 16;
+ ac.ac_etime_lo = (u16) etime;
+ }
+#endif
+ do_div(elapsed, AHZ);
+ ac.ac_btime = xtime.tv_sec - elapsed;
+ ac.ac_utime = encode_comp_t(jiffies_to_AHZ(
+ current->signal->utime +
+ current->group_leader->utime));
+ ac.ac_stime = encode_comp_t(jiffies_to_AHZ(
+ current->signal->stime +
+ current->group_leader->stime));
+ /* we really need to bite the bullet and change layout */
+ ac.ac_uid = current->uid;
+ ac.ac_gid = current->gid;
+#if ACCT_VERSION==2
+ ac.ac_ahz = AHZ;
+#endif
+#if ACCT_VERSION==1 || ACCT_VERSION==2
+ /* backward-compatible 16 bit fields */
+ ac.ac_uid16 = current->uid;
+ ac.ac_gid16 = current->gid;
+#endif
+#if ACCT_VERSION==3
+ ac.ac_pid = current->tgid;
+ ac.ac_ppid = current->parent->tgid;
+#endif
+
+ read_lock(&tasklist_lock); /* pin current->signal */
+ ac.ac_tty = current->signal->tty ?
+ old_encode_dev(tty_devnum(current->signal->tty)) : 0;
+ read_unlock(&tasklist_lock);
+
+ ac.ac_flag = 0;
+ if (current->flags & PF_FORKNOEXEC)
+ ac.ac_flag |= AFORK;
+ if (current->flags & PF_SUPERPRIV)
+ ac.ac_flag |= ASU;
+ if (current->flags & PF_DUMPCORE)
+ ac.ac_flag |= ACORE;
+ if (current->flags & PF_SIGNALED)
+ ac.ac_flag |= AXSIG;
+
+ vsize = 0;
+ if (current->mm) {
+ struct vm_area_struct *vma;
+ down_read(&current->mm->mmap_sem);
+ vma = current->mm->mmap;
+ while (vma) {
+ vsize += vma->vm_end - vma->vm_start;
+ vma = vma->vm_next;
+ }
+ up_read(&current->mm->mmap_sem);
+ }
+ vsize = vsize / 1024;
+ ac.ac_mem = encode_comp_t(vsize);
+ ac.ac_io = encode_comp_t(0 /* current->io_usage */); /* %% */
+ ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
+ ac.ac_minflt = encode_comp_t(current->signal->min_flt +
+ current->group_leader->min_flt);
+ ac.ac_majflt = encode_comp_t(current->signal->maj_flt +
+ current->group_leader->maj_flt);
+ ac.ac_swaps = encode_comp_t(0);
+ ac.ac_exitcode = exitcode;
+
+ /*
+ * Kernel segment override to datasegment and write it
+ * to the accounting file.
+ */
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ /*
+ * Accounting records are not subject to resource limits.
+ */
+ flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+ current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
+ file->f_op->write(file, (char *)&ac,
+ sizeof(acct_t), &file->f_pos);
+ current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim;
+ set_fs(fs);
+}
+
+/*
+ * acct_process - now just a wrapper around do_acct_process
+ */
+void acct_process(long exitcode)
+{
+ struct file *file = NULL;
+
+ /*
+ * accelerate the common fastpath:
+ */
+ if (!acct_globals.file)
+ return;
+
+ spin_lock(&acct_globals.lock);
+ file = acct_globals.file;
+ if (unlikely(!file)) {
+ spin_unlock(&acct_globals.lock);
+ return;
+ }
+ get_file(file);
+ spin_unlock(&acct_globals.lock);
+
+ do_acct_process(exitcode, file);
+ fput(file);
+}
+
+
+/*
+ * acct_update_integrals
+ * - update mm integral fields in task_struct
+ */
+void acct_update_integrals(struct task_struct *tsk)
+{
+ if (likely(tsk->mm)) {
+ long delta = tsk->stime - tsk->acct_stimexpd;
+
+ if (delta == 0)
+ return;
+ tsk->acct_stimexpd = tsk->stime;
+ tsk->acct_rss_mem1 += delta * get_mm_counter(tsk->mm, rss);
+ tsk->acct_vm_mem1 += delta * tsk->mm->total_vm;
+ }
+}
+
+/*
+ * acct_clear_integrals
+ * - clear the mm integral fields in task_struct
+ */
+void acct_clear_integrals(struct task_struct *tsk)
+{
+ if (tsk) {
+ tsk->acct_stimexpd = 0;
+ tsk->acct_rss_mem1 = 0;
+ tsk->acct_vm_mem1 = 0;
+ }
+}
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