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![Jake Edge](/assets/img/avatar_default.png)
By using the same test as is used for /proc/pid/maps and /proc/pid/smaps, only allow processes that can ptrace() a given process to see information that might be used to bypass address space layout randomization (ASLR). These include eip, esp, wchan, and start_stack in /proc/pid/stat as well as the non-symbolic output from /proc/pid/wchan. ASLR can be bypassed by sampling eip as shown by the proof-of-concept code at http://code.google.com/p/fuzzyaslr/ As part of a presentation (http://www.cr0.org/paper/to-jt-linux-alsr-leak.pdf) esp and wchan were also noted as possibly usable information leaks as well. The start_stack address also leaks potentially useful information. Cc: Stable Team <stable@kernel.org> Signed-off-by: Jake Edge <jake@lwn.net> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
536 lines
13 KiB
C
536 lines
13 KiB
C
/*
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* linux/fs/proc/array.c
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*
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* Copyright (C) 1992 by Linus Torvalds
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* based on ideas by Darren Senn
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*
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* Fixes:
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* Michael. K. Johnson: stat,statm extensions.
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* <johnsonm@stolaf.edu>
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*
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* Pauline Middelink : Made cmdline,envline only break at '\0's, to
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* make sure SET_PROCTITLE works. Also removed
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* bad '!' which forced address recalculation for
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* EVERY character on the current page.
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* <middelin@polyware.iaf.nl>
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*
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* Danny ter Haar : added cpuinfo
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* <dth@cistron.nl>
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*
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* Alessandro Rubini : profile extension.
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* <rubini@ipvvis.unipv.it>
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*
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* Jeff Tranter : added BogoMips field to cpuinfo
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* <Jeff_Tranter@Mitel.COM>
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*
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* Bruno Haible : remove 4K limit for the maps file
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* <haible@ma2s2.mathematik.uni-karlsruhe.de>
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*
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* Yves Arrouye : remove removal of trailing spaces in get_array.
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* <Yves.Arrouye@marin.fdn.fr>
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*
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* Jerome Forissier : added per-CPU time information to /proc/stat
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* and /proc/<pid>/cpu extension
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* <forissier@isia.cma.fr>
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* - Incorporation and non-SMP safe operation
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* of forissier patch in 2.1.78 by
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* Hans Marcus <crowbar@concepts.nl>
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*
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* aeb@cwi.nl : /proc/partitions
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*
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*
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* Alan Cox : security fixes.
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* <alan@lxorguk.ukuu.org.uk>
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*
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* Al Viro : safe handling of mm_struct
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*
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* Gerhard Wichert : added BIGMEM support
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* Siemens AG <Gerhard.Wichert@pdb.siemens.de>
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*
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* Al Viro & Jeff Garzik : moved most of the thing into base.c and
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* : proc_misc.c. The rest may eventually go into
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* : base.c too.
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*/
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/kernel.h>
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#include <linux/kernel_stat.h>
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#include <linux/tty.h>
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#include <linux/string.h>
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#include <linux/mman.h>
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#include <linux/proc_fs.h>
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#include <linux/ioport.h>
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/slab.h>
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#include <linux/smp.h>
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#include <linux/signal.h>
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#include <linux/highmem.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/times.h>
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#include <linux/cpuset.h>
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#include <linux/rcupdate.h>
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#include <linux/delayacct.h>
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#include <linux/seq_file.h>
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#include <linux/pid_namespace.h>
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#include <linux/ptrace.h>
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#include <linux/tracehook.h>
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#include <asm/pgtable.h>
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#include <asm/processor.h>
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#include "internal.h"
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static inline void task_name(struct seq_file *m, struct task_struct *p)
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{
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int i;
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char *buf, *end;
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char *name;
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char tcomm[sizeof(p->comm)];
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get_task_comm(tcomm, p);
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seq_printf(m, "Name:\t");
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end = m->buf + m->size;
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buf = m->buf + m->count;
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name = tcomm;
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i = sizeof(tcomm);
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while (i && (buf < end)) {
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unsigned char c = *name;
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name++;
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i--;
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*buf = c;
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if (!c)
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break;
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if (c == '\\') {
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buf++;
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if (buf < end)
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*buf++ = c;
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continue;
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}
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if (c == '\n') {
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*buf++ = '\\';
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if (buf < end)
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*buf++ = 'n';
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continue;
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}
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buf++;
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}
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m->count = buf - m->buf;
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seq_printf(m, "\n");
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}
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/*
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* The task state array is a strange "bitmap" of
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* reasons to sleep. Thus "running" is zero, and
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* you can test for combinations of others with
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* simple bit tests.
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*/
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static const char *task_state_array[] = {
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"R (running)", /* 0 */
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"S (sleeping)", /* 1 */
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"D (disk sleep)", /* 2 */
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"T (stopped)", /* 4 */
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"T (tracing stop)", /* 8 */
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"Z (zombie)", /* 16 */
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"X (dead)" /* 32 */
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};
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static inline const char *get_task_state(struct task_struct *tsk)
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{
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unsigned int state = (tsk->state & TASK_REPORT) | tsk->exit_state;
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const char **p = &task_state_array[0];
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while (state) {
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p++;
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state >>= 1;
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}
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return *p;
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}
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static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
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struct pid *pid, struct task_struct *p)
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{
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struct group_info *group_info;
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int g;
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struct fdtable *fdt = NULL;
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const struct cred *cred;
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pid_t ppid, tpid;
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rcu_read_lock();
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ppid = pid_alive(p) ?
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task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
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tpid = 0;
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if (pid_alive(p)) {
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struct task_struct *tracer = tracehook_tracer_task(p);
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if (tracer)
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tpid = task_pid_nr_ns(tracer, ns);
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}
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cred = get_cred((struct cred *) __task_cred(p));
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seq_printf(m,
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"State:\t%s\n"
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"Tgid:\t%d\n"
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"Pid:\t%d\n"
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"PPid:\t%d\n"
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"TracerPid:\t%d\n"
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"Uid:\t%d\t%d\t%d\t%d\n"
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"Gid:\t%d\t%d\t%d\t%d\n",
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get_task_state(p),
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task_tgid_nr_ns(p, ns),
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pid_nr_ns(pid, ns),
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ppid, tpid,
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cred->uid, cred->euid, cred->suid, cred->fsuid,
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cred->gid, cred->egid, cred->sgid, cred->fsgid);
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task_lock(p);
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if (p->files)
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fdt = files_fdtable(p->files);
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seq_printf(m,
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"FDSize:\t%d\n"
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"Groups:\t",
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fdt ? fdt->max_fds : 0);
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rcu_read_unlock();
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group_info = cred->group_info;
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task_unlock(p);
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for (g = 0; g < min(group_info->ngroups, NGROUPS_SMALL); g++)
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seq_printf(m, "%d ", GROUP_AT(group_info, g));
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put_cred(cred);
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seq_printf(m, "\n");
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}
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static void render_sigset_t(struct seq_file *m, const char *header,
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sigset_t *set)
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{
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int i;
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seq_printf(m, "%s", header);
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i = _NSIG;
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do {
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int x = 0;
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i -= 4;
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if (sigismember(set, i+1)) x |= 1;
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if (sigismember(set, i+2)) x |= 2;
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if (sigismember(set, i+3)) x |= 4;
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if (sigismember(set, i+4)) x |= 8;
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seq_printf(m, "%x", x);
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} while (i >= 4);
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seq_printf(m, "\n");
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}
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static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
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sigset_t *catch)
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{
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struct k_sigaction *k;
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int i;
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k = p->sighand->action;
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for (i = 1; i <= _NSIG; ++i, ++k) {
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if (k->sa.sa_handler == SIG_IGN)
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sigaddset(ign, i);
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else if (k->sa.sa_handler != SIG_DFL)
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sigaddset(catch, i);
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}
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}
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static inline void task_sig(struct seq_file *m, struct task_struct *p)
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{
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unsigned long flags;
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sigset_t pending, shpending, blocked, ignored, caught;
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int num_threads = 0;
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unsigned long qsize = 0;
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unsigned long qlim = 0;
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sigemptyset(&pending);
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sigemptyset(&shpending);
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sigemptyset(&blocked);
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sigemptyset(&ignored);
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sigemptyset(&caught);
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if (lock_task_sighand(p, &flags)) {
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pending = p->pending.signal;
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shpending = p->signal->shared_pending.signal;
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blocked = p->blocked;
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collect_sigign_sigcatch(p, &ignored, &caught);
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num_threads = atomic_read(&p->signal->count);
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qsize = atomic_read(&__task_cred(p)->user->sigpending);
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qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
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unlock_task_sighand(p, &flags);
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}
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seq_printf(m, "Threads:\t%d\n", num_threads);
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seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim);
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/* render them all */
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render_sigset_t(m, "SigPnd:\t", &pending);
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render_sigset_t(m, "ShdPnd:\t", &shpending);
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render_sigset_t(m, "SigBlk:\t", &blocked);
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render_sigset_t(m, "SigIgn:\t", &ignored);
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render_sigset_t(m, "SigCgt:\t", &caught);
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}
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static void render_cap_t(struct seq_file *m, const char *header,
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kernel_cap_t *a)
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{
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unsigned __capi;
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seq_printf(m, "%s", header);
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CAP_FOR_EACH_U32(__capi) {
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seq_printf(m, "%08x",
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a->cap[(_KERNEL_CAPABILITY_U32S-1) - __capi]);
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}
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seq_printf(m, "\n");
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}
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static inline void task_cap(struct seq_file *m, struct task_struct *p)
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{
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const struct cred *cred;
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kernel_cap_t cap_inheritable, cap_permitted, cap_effective, cap_bset;
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rcu_read_lock();
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cred = __task_cred(p);
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cap_inheritable = cred->cap_inheritable;
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cap_permitted = cred->cap_permitted;
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cap_effective = cred->cap_effective;
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cap_bset = cred->cap_bset;
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rcu_read_unlock();
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render_cap_t(m, "CapInh:\t", &cap_inheritable);
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render_cap_t(m, "CapPrm:\t", &cap_permitted);
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render_cap_t(m, "CapEff:\t", &cap_effective);
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render_cap_t(m, "CapBnd:\t", &cap_bset);
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}
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static inline void task_context_switch_counts(struct seq_file *m,
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struct task_struct *p)
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{
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seq_printf(m, "voluntary_ctxt_switches:\t%lu\n"
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"nonvoluntary_ctxt_switches:\t%lu\n",
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p->nvcsw,
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p->nivcsw);
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}
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int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
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struct pid *pid, struct task_struct *task)
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{
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struct mm_struct *mm = get_task_mm(task);
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task_name(m, task);
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task_state(m, ns, pid, task);
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if (mm) {
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task_mem(m, mm);
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mmput(mm);
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}
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task_sig(m, task);
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task_cap(m, task);
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cpuset_task_status_allowed(m, task);
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#if defined(CONFIG_S390)
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task_show_regs(m, task);
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#endif
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task_context_switch_counts(m, task);
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return 0;
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}
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static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
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struct pid *pid, struct task_struct *task, int whole)
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{
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unsigned long vsize, eip, esp, wchan = ~0UL;
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long priority, nice;
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int tty_pgrp = -1, tty_nr = 0;
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sigset_t sigign, sigcatch;
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char state;
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pid_t ppid = 0, pgid = -1, sid = -1;
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int num_threads = 0;
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int permitted;
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struct mm_struct *mm;
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unsigned long long start_time;
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unsigned long cmin_flt = 0, cmaj_flt = 0;
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unsigned long min_flt = 0, maj_flt = 0;
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cputime_t cutime, cstime, utime, stime;
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cputime_t cgtime, gtime;
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unsigned long rsslim = 0;
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char tcomm[sizeof(task->comm)];
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unsigned long flags;
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state = *get_task_state(task);
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vsize = eip = esp = 0;
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permitted = ptrace_may_access(task, PTRACE_MODE_READ);
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mm = get_task_mm(task);
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if (mm) {
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vsize = task_vsize(mm);
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if (permitted) {
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eip = KSTK_EIP(task);
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esp = KSTK_ESP(task);
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}
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}
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get_task_comm(tcomm, task);
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sigemptyset(&sigign);
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sigemptyset(&sigcatch);
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cutime = cstime = utime = stime = cputime_zero;
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cgtime = gtime = cputime_zero;
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if (lock_task_sighand(task, &flags)) {
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struct signal_struct *sig = task->signal;
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if (sig->tty) {
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struct pid *pgrp = tty_get_pgrp(sig->tty);
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tty_pgrp = pid_nr_ns(pgrp, ns);
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put_pid(pgrp);
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tty_nr = new_encode_dev(tty_devnum(sig->tty));
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}
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num_threads = atomic_read(&sig->count);
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collect_sigign_sigcatch(task, &sigign, &sigcatch);
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cmin_flt = sig->cmin_flt;
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cmaj_flt = sig->cmaj_flt;
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cutime = sig->cutime;
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cstime = sig->cstime;
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cgtime = sig->cgtime;
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rsslim = sig->rlim[RLIMIT_RSS].rlim_cur;
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/* add up live thread stats at the group level */
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if (whole) {
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struct task_cputime cputime;
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struct task_struct *t = task;
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do {
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min_flt += t->min_flt;
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maj_flt += t->maj_flt;
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gtime = cputime_add(gtime, task_gtime(t));
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t = next_thread(t);
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} while (t != task);
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min_flt += sig->min_flt;
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maj_flt += sig->maj_flt;
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thread_group_cputime(task, &cputime);
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utime = cputime.utime;
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stime = cputime.stime;
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gtime = cputime_add(gtime, sig->gtime);
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}
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sid = task_session_nr_ns(task, ns);
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ppid = task_tgid_nr_ns(task->real_parent, ns);
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pgid = task_pgrp_nr_ns(task, ns);
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unlock_task_sighand(task, &flags);
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}
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if (permitted && (!whole || num_threads < 2))
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wchan = get_wchan(task);
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if (!whole) {
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min_flt = task->min_flt;
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maj_flt = task->maj_flt;
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utime = task_utime(task);
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stime = task_stime(task);
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gtime = task_gtime(task);
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}
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/* scale priority and nice values from timeslices to -20..20 */
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/* to make it look like a "normal" Unix priority/nice value */
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priority = task_prio(task);
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nice = task_nice(task);
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/* Temporary variable needed for gcc-2.96 */
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/* convert timespec -> nsec*/
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start_time =
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(unsigned long long)task->real_start_time.tv_sec * NSEC_PER_SEC
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+ task->real_start_time.tv_nsec;
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/* convert nsec -> ticks */
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start_time = nsec_to_clock_t(start_time);
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seq_printf(m, "%d (%s) %c %d %d %d %d %d %u %lu \
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%lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
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%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld\n",
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pid_nr_ns(pid, ns),
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tcomm,
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state,
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ppid,
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pgid,
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sid,
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tty_nr,
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tty_pgrp,
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task->flags,
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min_flt,
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cmin_flt,
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maj_flt,
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cmaj_flt,
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cputime_to_clock_t(utime),
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cputime_to_clock_t(stime),
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cputime_to_clock_t(cutime),
|
|
cputime_to_clock_t(cstime),
|
|
priority,
|
|
nice,
|
|
num_threads,
|
|
start_time,
|
|
vsize,
|
|
mm ? get_mm_rss(mm) : 0,
|
|
rsslim,
|
|
mm ? mm->start_code : 0,
|
|
mm ? mm->end_code : 0,
|
|
(permitted && mm) ? mm->start_stack : 0,
|
|
esp,
|
|
eip,
|
|
/* The signal information here is obsolete.
|
|
* It must be decimal for Linux 2.0 compatibility.
|
|
* Use /proc/#/status for real-time signals.
|
|
*/
|
|
task->pending.signal.sig[0] & 0x7fffffffUL,
|
|
task->blocked.sig[0] & 0x7fffffffUL,
|
|
sigign .sig[0] & 0x7fffffffUL,
|
|
sigcatch .sig[0] & 0x7fffffffUL,
|
|
wchan,
|
|
0UL,
|
|
0UL,
|
|
task->exit_signal,
|
|
task_cpu(task),
|
|
task->rt_priority,
|
|
task->policy,
|
|
(unsigned long long)delayacct_blkio_ticks(task),
|
|
cputime_to_clock_t(gtime),
|
|
cputime_to_clock_t(cgtime));
|
|
if (mm)
|
|
mmput(mm);
|
|
return 0;
|
|
}
|
|
|
|
int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
|
|
struct pid *pid, struct task_struct *task)
|
|
{
|
|
return do_task_stat(m, ns, pid, task, 0);
|
|
}
|
|
|
|
int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
|
|
struct pid *pid, struct task_struct *task)
|
|
{
|
|
return do_task_stat(m, ns, pid, task, 1);
|
|
}
|
|
|
|
int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
|
|
struct pid *pid, struct task_struct *task)
|
|
{
|
|
int size = 0, resident = 0, shared = 0, text = 0, lib = 0, data = 0;
|
|
struct mm_struct *mm = get_task_mm(task);
|
|
|
|
if (mm) {
|
|
size = task_statm(mm, &shared, &text, &data, &resident);
|
|
mmput(mm);
|
|
}
|
|
seq_printf(m, "%d %d %d %d %d %d %d\n",
|
|
size, resident, shared, text, lib, data, 0);
|
|
|
|
return 0;
|
|
}
|