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bd6bb49397
freebsd/sys/ddb/db_ps.c
Alex Richardson fa2528ac64 Use atomic loads/stores when updating td->td_state 
KCSAN complains about racy accesses in the locking code. Those races are
fine since they are inside a TD_SET_RUNNING() loop that expects the value
to be changed by another CPU.

Use relaxed atomic stores/loads to indicate that this variable can be
written/read by multiple CPUs at the same time. This will also prevent
the compiler from doing unexpected re-ordering.

Reported by:	GENERIC-KCSAN
Test Plan:	KCSAN no longer complains, kernel still runs fine.
Reviewed By:	markj, mjg (earlier version)
Differential Revision: https://reviews.freebsd.org/D28569
2021-02-18 14:02:48 +00:00

534 lines
13 KiB
C
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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1993 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_kstack_pages.h"
#include <sys/param.h>
#include <sys/cons.h>
#include <sys/jail.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <ddb/ddb.h>
#define PRINT_NONE 0
#define PRINT_ARGS 1
static void dumpthread(volatile struct proc *p, volatile struct thread *td,
int all);
static void db_ps_proc(struct proc *p);
static int ps_mode;
/*
* At least one non-optional show-command must be implemented using
* DB_SHOW_ALL_COMMAND() so that db_show_all_cmd_set gets created.
* Here is one.
*/
DB_SHOW_ALL_COMMAND(procs, db_procs_cmd)
{
db_ps(addr, have_addr, count, modif);
}
static void
dump_args(volatile struct proc *p)
{
char *args;
int i, len;
if (p->p_args == NULL)
return;
args = p->p_args->ar_args;
len = (int)p->p_args->ar_length;
for (i = 0; i < len; i++) {
if (args[i] == '\0')
db_printf(" ");
else
db_printf("%c", args[i]);
}
}
/*
* Layout:
* - column counts
* - header
* - single-threaded process
* - multi-threaded process
* - thread in a MT process
*
* 1 2 3 4 5 6 7
* 1234567890123456789012345678901234567890123456789012345678901234567890
* pid ppid pgrp uid state wmesg wchan cmd
* <pid> <ppi> <pgi> <uid> <stat> <wmesg> <wchan > <name>
* <pid> <ppi> <pgi> <uid> <stat> (threaded) <command>
* <tid > <stat> <wmesg> <wchan > <name>
*
* For machines with 64-bit pointers, we expand the wchan field 8 more
* characters.
*/
void
db_ps(db_expr_t addr, bool hasaddr, db_expr_t count, char *modif)
{
struct proc *p;
int i;
ps_mode = modif[0] == 'a' ? PRINT_ARGS : PRINT_NONE;
#ifdef __LP64__
db_printf(" pid ppid pgrp uid state wmesg wchan cmd\n");
#else
db_printf(" pid ppid pgrp uid state wmesg wchan cmd\n");
#endif
if (!LIST_EMPTY(&allproc))
p = LIST_FIRST(&allproc);
else
p = &proc0;
for (; p != NULL && !db_pager_quit; p = LIST_NEXT(p, p_list))
db_ps_proc(p);
/*
* Processes such as zombies not in allproc.
*/
for (i = 0; i <= pidhash && !db_pager_quit; i++) {
LIST_FOREACH(p, &pidhashtbl[i], p_hash) {
if (p->p_list.le_prev == NULL)
db_ps_proc(p);
}
}
}
static void
db_ps_proc(struct proc *p)
{
volatile struct proc *pp;
volatile struct thread *td;
struct ucred *cred;
struct pgrp *pgrp;
char state[9];
int rflag, sflag, dflag, lflag, wflag;
pp = p->p_pptr;
if (pp == NULL)
pp = p;
cred = p->p_ucred;
pgrp = p->p_pgrp;
db_printf("%5d %5d %5d %5d ", p->p_pid, pp->p_pid,
pgrp != NULL ? pgrp->pg_id : 0,
cred != NULL ? cred->cr_ruid : 0);
/* Determine our primary process state. */
switch (p->p_state) {
case PRS_NORMAL:
if (P_SHOULDSTOP(p))
state[0] = 'T';
else {
/*
* One of D, L, R, S, W. For a
* multithreaded process we will use
* the state of the thread with the
* highest precedence. The
* precendence order from high to low
* is R, L, D, S, W. If no thread is
* in a sane state we use '?' for our
* primary state.
*/
rflag = sflag = dflag = lflag = wflag = 0;
FOREACH_THREAD_IN_PROC(p, td) {
if (TD_GET_STATE(td) == TDS_RUNNING ||
TD_GET_STATE(td) == TDS_RUNQ ||
TD_GET_STATE(td) == TDS_CAN_RUN)
rflag++;
if (TD_ON_LOCK(td))
lflag++;
if (TD_IS_SLEEPING(td)) {
if (!(td->td_flags & TDF_SINTR))
dflag++;
else
sflag++;
}
if (TD_AWAITING_INTR(td))
wflag++;
}
if (rflag)
state[0] = 'R';
else if (lflag)
state[0] = 'L';
else if (dflag)
state[0] = 'D';
else if (sflag)
state[0] = 'S';
else if (wflag)
state[0] = 'W';
else
state[0] = '?';
}
break;
case PRS_NEW:
state[0] = 'N';
break;
case PRS_ZOMBIE:
state[0] = 'Z';
break;
default:
state[0] = 'U';
break;
}
state[1] = '\0';
/* Additional process state flags. */
if (!(p->p_flag & P_INMEM))
strlcat(state, "W", sizeof(state));
if (p->p_flag & P_TRACED)
strlcat(state, "X", sizeof(state));
if (p->p_flag & P_WEXIT && p->p_state != PRS_ZOMBIE)
strlcat(state, "E", sizeof(state));
if (p->p_flag & P_PPWAIT)
strlcat(state, "V", sizeof(state));
if (p->p_flag & P_SYSTEM || p->p_lock > 0)
strlcat(state, "L", sizeof(state));
if (p->p_pgrp != NULL && p->p_session != NULL &&
SESS_LEADER(p))
strlcat(state, "s", sizeof(state));
/* Cheated here and didn't compare pgid's. */
if (p->p_flag & P_CONTROLT)
strlcat(state, "+", sizeof(state));
if (cred != NULL && jailed(cred))
strlcat(state, "J", sizeof(state));
db_printf(" %-6.6s ", state);
if (p->p_flag & P_HADTHREADS) {
#ifdef __LP64__
db_printf(" (threaded) ");
#else
db_printf(" (threaded) ");
#endif
if (p->p_flag & P_SYSTEM)
db_printf("[");
db_printf("%s", p->p_comm);
if (p->p_flag & P_SYSTEM)
db_printf("]");
if (ps_mode == PRINT_ARGS) {
db_printf(" ");
dump_args(p);
}
db_printf("\n");
}
FOREACH_THREAD_IN_PROC(p, td) {
dumpthread(p, td, p->p_flag & P_HADTHREADS);
if (db_pager_quit)
break;
}
}
static void
dumpthread(volatile struct proc *p, volatile struct thread *td, int all)
{
char state[9], wprefix;
const char *wmesg;
const void *wchan;
if (all) {
db_printf("%6d ", td->td_tid);
switch (TD_GET_STATE(td)) {
case TDS_RUNNING:
snprintf(state, sizeof(state), "Run");
break;
case TDS_RUNQ:
snprintf(state, sizeof(state), "RunQ");
break;
case TDS_CAN_RUN:
snprintf(state, sizeof(state), "CanRun");
break;
case TDS_INACTIVE:
snprintf(state, sizeof(state), "Inactv");
break;
case TDS_INHIBITED:
state[0] = '\0';
if (TD_ON_LOCK(td))
strlcat(state, "L", sizeof(state));
if (TD_IS_SLEEPING(td)) {
if (td->td_flags & TDF_SINTR)
strlcat(state, "S", sizeof(state));
else
strlcat(state, "D", sizeof(state));
}
if (TD_IS_SWAPPED(td))
strlcat(state, "W", sizeof(state));
if (TD_AWAITING_INTR(td))
strlcat(state, "I", sizeof(state));
if (TD_IS_SUSPENDED(td))
strlcat(state, "s", sizeof(state));
if (state[0] != '\0')
break;
default:
snprintf(state, sizeof(state), "???");
}
db_printf(" %-6.6s ", state);
}
wprefix = ' ';
if (TD_ON_LOCK(td)) {
wprefix = '*';
wmesg = td->td_lockname;
wchan = td->td_blocked;
} else if (TD_ON_SLEEPQ(td)) {
wmesg = td->td_wmesg;
wchan = td->td_wchan;
} else if (TD_IS_RUNNING(td)) {
snprintf(state, sizeof(state), "CPU %d", td->td_oncpu);
wmesg = state;
wchan = NULL;
} else {
wmesg = "";
wchan = NULL;
}
db_printf("%c%-7.7s ", wprefix, wmesg);
if (wchan == NULL)
#ifdef __LP64__
db_printf("%18s ", "");
#else
db_printf("%10s ", "");
#endif
else
db_printf("%p ", wchan);
if (p->p_flag & P_SYSTEM)
db_printf("[");
if (td->td_name[0] != '\0')
db_printf("%s", td->td_name);
else
db_printf("%s", td->td_proc->p_comm);
if (p->p_flag & P_SYSTEM)
db_printf("]");
if (ps_mode == PRINT_ARGS && all == 0) {
db_printf(" ");
dump_args(p);
}
db_printf("\n");
}
DB_SHOW_COMMAND(thread, db_show_thread)
{
struct thread *td;
struct lock_object *lock;
u_int delta;
bool comma;
/* Determine which thread to examine. */
if (have_addr)
td = db_lookup_thread(addr, false);
else
td = kdb_thread;
lock = (struct lock_object *)td->td_lock;
db_printf("Thread %d at %p:\n", td->td_tid, td);
db_printf(" proc (pid %d): %p\n", td->td_proc->p_pid, td->td_proc);
if (td->td_name[0] != '\0')
db_printf(" name: %s\n", td->td_name);
db_printf(" pcb: %p\n", td->td_pcb);
db_printf(" stack: %p-%p\n", (void *)td->td_kstack,
(void *)(td->td_kstack + td->td_kstack_pages * PAGE_SIZE - 1));
db_printf(" flags: %#x ", td->td_flags);
db_printf(" pflags: %#x\n", td->td_pflags);
db_printf(" state: ");
switch (TD_GET_STATE(td)) {
case TDS_INACTIVE:
db_printf("INACTIVE\n");
break;
case TDS_CAN_RUN:
db_printf("CAN RUN\n");
break;
case TDS_RUNQ:
db_printf("RUNQ\n");
break;
case TDS_RUNNING:
db_printf("RUNNING (CPU %d)\n", td->td_oncpu);
break;
case TDS_INHIBITED:
db_printf("INHIBITED: {");
comma = false;
if (TD_IS_SLEEPING(td)) {
db_printf("SLEEPING");
comma = true;
}
if (TD_IS_SUSPENDED(td)) {
if (comma)
db_printf(", ");
db_printf("SUSPENDED");
comma = true;
}
if (TD_IS_SWAPPED(td)) {
if (comma)
db_printf(", ");
db_printf("SWAPPED");
comma = true;
}
if (TD_ON_LOCK(td)) {
if (comma)
db_printf(", ");
db_printf("LOCK");
comma = true;
}
if (TD_AWAITING_INTR(td)) {
if (comma)
db_printf(", ");
db_printf("IWAIT");
}
db_printf("}\n");
break;
default:
db_printf("??? (%#x)\n", TD_GET_STATE(td));
break;
}
if (TD_ON_LOCK(td))
db_printf(" lock: %s turnstile: %p\n", td->td_lockname,
td->td_blocked);
if (TD_ON_SLEEPQ(td))
db_printf(
" wmesg: %s wchan: %p sleeptimo %lx. %jx (curr %lx. %jx)\n",
td->td_wmesg, td->td_wchan,
(long)sbttobt(td->td_sleeptimo).sec,
(uintmax_t)sbttobt(td->td_sleeptimo).frac,
(long)sbttobt(sbinuptime()).sec,
(uintmax_t)sbttobt(sbinuptime()).frac);
db_printf(" priority: %d\n", td->td_priority);
db_printf(" container lock: %s (%p)\n", lock->lo_name, lock);
if (td->td_swvoltick != 0) {
delta = ticks - td->td_swvoltick;
db_printf(" last voluntary switch: %u.%03u s ago\n",
delta / hz, (delta % hz) * 1000 / hz);
}
if (td->td_swinvoltick != 0) {
delta = ticks - td->td_swinvoltick;
db_printf(" last involuntary switch: %u.%03u s ago\n",
delta / hz, (delta % hz) * 1000 / hz);
}
}
DB_SHOW_COMMAND(proc, db_show_proc)
{
struct thread *td;
struct proc *p;
int i;
/* Determine which process to examine. */
if (have_addr)
p = db_lookup_proc(addr);
else
p = kdb_thread->td_proc;
db_printf("Process %d (%s) at %p:\n", p->p_pid, p->p_comm, p);
db_printf(" state: ");
switch (p->p_state) {
case PRS_NEW:
db_printf("NEW\n");
break;
case PRS_NORMAL:
db_printf("NORMAL\n");
break;
case PRS_ZOMBIE:
db_printf("ZOMBIE\n");
break;
default:
db_printf("??? (%#x)\n", p->p_state);
}
if (p->p_ucred != NULL) {
db_printf(" uid: %d gids: ", p->p_ucred->cr_uid);
for (i = 0; i < p->p_ucred->cr_ngroups; i++) {
db_printf("%d", p->p_ucred->cr_groups[i]);
if (i < (p->p_ucred->cr_ngroups - 1))
db_printf(", ");
}
db_printf("\n");
}
if (p->p_pptr != NULL)
db_printf(" parent: pid %d at %p\n", p->p_pptr->p_pid,
p->p_pptr);
if (p->p_leader != NULL && p->p_leader != p)
db_printf(" leader: pid %d at %p\n", p->p_leader->p_pid,
p->p_leader);
if (p->p_sysent != NULL)
db_printf(" ABI: %s\n", p->p_sysent->sv_name);
db_printf(" flag: %#x ", p->p_flag);
db_printf(" flag2: %#x\n", p->p_flag2);
if (p->p_args != NULL) {
db_printf(" arguments: ");
dump_args(p);
db_printf("\n");
}
db_printf(" reaper: %p reapsubtree: %d\n",
p->p_reaper, p->p_reapsubtree);
db_printf(" sigparent: %d\n", p->p_sigparent);
db_printf(" vmspace: %p\n", p->p_vmspace);
db_printf(" (map %p)\n",
(p->p_vmspace != NULL) ? &p->p_vmspace->vm_map : 0);
db_printf(" (map.pmap %p)\n",
(p->p_vmspace != NULL) ? &p->p_vmspace->vm_map.pmap : 0);
db_printf(" (pmap %p)\n",
(p->p_vmspace != NULL) ? &p->p_vmspace->vm_pmap : 0);
db_printf(" threads: %d\n", p->p_numthreads);
FOREACH_THREAD_IN_PROC(p, td) {
dumpthread(p, td, 1);
if (db_pager_quit)
break;
}
}
void
db_findstack_cmd(db_expr_t addr, bool have_addr, db_expr_t dummy3 __unused,
char *dummy4 __unused)
{
struct thread *td;
vm_offset_t saddr;
if (have_addr)
saddr = addr;
else {
db_printf("Usage: findstack <address>\n");
return;
}
for (td = kdb_thr_first(); td != NULL; td = kdb_thr_next(td)) {
if (kstack_contains(td, saddr, 1)) {
db_printf("Thread %p\n", td);
return;
}
}
}
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