| Current Path : /sys/kern/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/kern/subr_smp.c |
/*-
* Copyright (c) 2001, John Baldwin <jhb@FreeBSD.org>.
* 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 author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
/*
* This module holds the global variables and machine independent functions
* used for the kernel SMP support.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/kern/subr_smp.c 235796 2012-05-22 17:44:01Z iwasaki $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/proc.h>
#include <sys/bus.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/pcpu.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <machine/cpu.h>
#include <machine/smp.h>
#include "opt_sched.h"
#ifdef SMP
volatile cpuset_t stopped_cpus;
volatile cpuset_t started_cpus;
cpuset_t hlt_cpus_mask;
cpuset_t logical_cpus_mask;
void (*cpustop_restartfunc)(void);
#endif
/* This is used in modules that need to work in both SMP and UP. */
cpuset_t all_cpus;
int mp_ncpus;
/* export this for libkvm consumers. */
int mp_maxcpus = MAXCPU;
volatile int smp_started;
u_int mp_maxid;
SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD|CTLFLAG_CAPRD, NULL, "Kernel SMP");
SYSCTL_INT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxid, 0,
"Max CPU ID.");
SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxcpus,
0, "Max number of CPUs that the system was compiled for.");
int smp_active = 0; /* are the APs allowed to run? */
SYSCTL_INT(_kern_smp, OID_AUTO, active, CTLFLAG_RW, &smp_active, 0,
"Number of Auxillary Processors (APs) that were successfully started");
int smp_disabled = 0; /* has smp been disabled? */
SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN|CTLFLAG_CAPRD,
&smp_disabled, 0, "SMP has been disabled from the loader");
TUNABLE_INT("kern.smp.disabled", &smp_disabled);
int smp_cpus = 1; /* how many cpu's running */
SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD|CTLFLAG_CAPRD, &smp_cpus, 0,
"Number of CPUs online");
int smp_topology = 0; /* Which topology we're using. */
SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RD, &smp_topology, 0,
"Topology override setting; 0 is default provided by hardware.");
TUNABLE_INT("kern.smp.topology", &smp_topology);
#ifdef SMP
/* Enable forwarding of a signal to a process running on a different CPU */
static int forward_signal_enabled = 1;
SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW,
&forward_signal_enabled, 0,
"Forwarding of a signal to a process on a different CPU");
/* Variables needed for SMP rendezvous. */
static volatile int smp_rv_ncpus;
static void (*volatile smp_rv_setup_func)(void *arg);
static void (*volatile smp_rv_action_func)(void *arg);
static void (*volatile smp_rv_teardown_func)(void *arg);
static void *volatile smp_rv_func_arg;
static volatile int smp_rv_waiters[4];
/*
* Shared mutex to restrict busywaits between smp_rendezvous() and
* smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these
* functions trigger at once and cause multiple CPUs to busywait with
* interrupts disabled.
*/
struct mtx smp_ipi_mtx;
/*
* Let the MD SMP code initialize mp_maxid very early if it can.
*/
static void
mp_setmaxid(void *dummy)
{
cpu_mp_setmaxid();
}
SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL);
/*
* Call the MD SMP initialization code.
*/
static void
mp_start(void *dummy)
{
mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN);
/* Probe for MP hardware. */
if (smp_disabled != 0 || cpu_mp_probe() == 0) {
mp_ncpus = 1;
CPU_SETOF(PCPU_GET(cpuid), &all_cpus);
return;
}
cpu_mp_start();
printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n",
mp_ncpus);
cpu_mp_announce();
}
SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL);
void
forward_signal(struct thread *td)
{
int id;
/*
* signotify() has already set TDF_ASTPENDING and TDF_NEEDSIGCHECK on
* this thread, so all we need to do is poke it if it is currently
* executing so that it executes ast().
*/
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(TD_IS_RUNNING(td),
("forward_signal: thread is not TDS_RUNNING"));
CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc);
if (!smp_started || cold || panicstr)
return;
if (!forward_signal_enabled)
return;
/* No need to IPI ourself. */
if (td == curthread)
return;
id = td->td_oncpu;
if (id == NOCPU)
return;
ipi_cpu(id, IPI_AST);
}
/*
* When called the executing CPU will send an IPI to all other CPUs
* requesting that they halt execution.
*
* Usually (but not necessarily) called with 'other_cpus' as its arg.
*
* - Signals all CPUs in map to stop.
* - Waits for each to stop.
*
* Returns:
* -1: error
* 0: NA
* 1: ok
*
*/
static int
generic_stop_cpus(cpuset_t map, u_int type)
{
#ifdef KTR
char cpusetbuf[CPUSETBUFSIZ];
#endif
static volatile u_int stopping_cpu = NOCPU;
int i;
KASSERT(
#if defined(__amd64__) || defined(__i386__)
type == IPI_STOP || type == IPI_STOP_HARD || type == IPI_SUSPEND,
#else
type == IPI_STOP || type == IPI_STOP_HARD,
#endif
("%s: invalid stop type", __func__));
if (!smp_started)
return (0);
CTR2(KTR_SMP, "stop_cpus(%s) with %u type",
cpusetobj_strprint(cpusetbuf, &map), type);
if (stopping_cpu != PCPU_GET(cpuid))
while (atomic_cmpset_int(&stopping_cpu, NOCPU,
PCPU_GET(cpuid)) == 0)
while (stopping_cpu != NOCPU)
cpu_spinwait(); /* spin */
/* send the stop IPI to all CPUs in map */
ipi_selected(map, type);
i = 0;
while (!CPU_SUBSET(&stopped_cpus, &map)) {
/* spin */
cpu_spinwait();
i++;
if (i == 100000000) {
printf("timeout stopping cpus\n");
break;
}
}
stopping_cpu = NOCPU;
return (1);
}
int
stop_cpus(cpuset_t map)
{
return (generic_stop_cpus(map, IPI_STOP));
}
int
stop_cpus_hard(cpuset_t map)
{
return (generic_stop_cpus(map, IPI_STOP_HARD));
}
#if defined(__amd64__) || defined(__i386__)
int
suspend_cpus(cpuset_t map)
{
return (generic_stop_cpus(map, IPI_SUSPEND));
}
#endif
/*
* Called by a CPU to restart stopped CPUs.
*
* Usually (but not necessarily) called with 'stopped_cpus' as its arg.
*
* - Signals all CPUs in map to restart.
* - Waits for each to restart.
*
* Returns:
* -1: error
* 0: NA
* 1: ok
*/
int
restart_cpus(cpuset_t map)
{
#ifdef KTR
char cpusetbuf[CPUSETBUFSIZ];
#endif
if (!smp_started)
return 0;
CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map));
/* signal other cpus to restart */
CPU_COPY_STORE_REL(&map, &started_cpus);
/* wait for each to clear its bit */
while (CPU_OVERLAP(&stopped_cpus, &map))
cpu_spinwait();
return 1;
}
/*
* All-CPU rendezvous. CPUs are signalled, all execute the setup function
* (if specified), rendezvous, execute the action function (if specified),
* rendezvous again, execute the teardown function (if specified), and then
* resume.
*
* Note that the supplied external functions _must_ be reentrant and aware
* that they are running in parallel and in an unknown lock context.
*/
void
smp_rendezvous_action(void)
{
struct thread *td;
void *local_func_arg;
void (*local_setup_func)(void*);
void (*local_action_func)(void*);
void (*local_teardown_func)(void*);
#ifdef INVARIANTS
int owepreempt;
#endif
/* Ensure we have up-to-date values. */
atomic_add_acq_int(&smp_rv_waiters[0], 1);
while (smp_rv_waiters[0] < smp_rv_ncpus)
cpu_spinwait();
/* Fetch rendezvous parameters after acquire barrier. */
local_func_arg = smp_rv_func_arg;
local_setup_func = smp_rv_setup_func;
local_action_func = smp_rv_action_func;
local_teardown_func = smp_rv_teardown_func;
/*
* Use a nested critical section to prevent any preemptions
* from occurring during a rendezvous action routine.
* Specifically, if a rendezvous handler is invoked via an IPI
* and the interrupted thread was in the critical_exit()
* function after setting td_critnest to 0 but before
* performing a deferred preemption, this routine can be
* invoked with td_critnest set to 0 and td_owepreempt true.
* In that case, a critical_exit() during the rendezvous
* action would trigger a preemption which is not permitted in
* a rendezvous action. To fix this, wrap all of the
* rendezvous action handlers in a critical section. We
* cannot use a regular critical section however as having
* critical_exit() preempt from this routine would also be
* problematic (the preemption must not occur before the IPI
* has been acknowledged via an EOI). Instead, we
* intentionally ignore td_owepreempt when leaving the
* critical section. This should be harmless because we do
* not permit rendezvous action routines to schedule threads,
* and thus td_owepreempt should never transition from 0 to 1
* during this routine.
*/
td = curthread;
td->td_critnest++;
#ifdef INVARIANTS
owepreempt = td->td_owepreempt;
#endif
/*
* If requested, run a setup function before the main action
* function. Ensure all CPUs have completed the setup
* function before moving on to the action function.
*/
if (local_setup_func != smp_no_rendevous_barrier) {
if (smp_rv_setup_func != NULL)
smp_rv_setup_func(smp_rv_func_arg);
atomic_add_int(&smp_rv_waiters[1], 1);
while (smp_rv_waiters[1] < smp_rv_ncpus)
cpu_spinwait();
}
if (local_action_func != NULL)
local_action_func(local_func_arg);
if (local_teardown_func != smp_no_rendevous_barrier) {
/*
* Signal that the main action has been completed. If a
* full exit rendezvous is requested, then all CPUs will
* wait here until all CPUs have finished the main action.
*/
atomic_add_int(&smp_rv_waiters[2], 1);
while (smp_rv_waiters[2] < smp_rv_ncpus)
cpu_spinwait();
if (local_teardown_func != NULL)
local_teardown_func(local_func_arg);
}
/*
* Signal that the rendezvous is fully completed by this CPU.
* This means that no member of smp_rv_* pseudo-structure will be
* accessed by this target CPU after this point; in particular,
* memory pointed by smp_rv_func_arg.
*/
atomic_add_int(&smp_rv_waiters[3], 1);
td->td_critnest--;
KASSERT(owepreempt == td->td_owepreempt,
("rendezvous action changed td_owepreempt"));
}
void
smp_rendezvous_cpus(cpuset_t map,
void (* setup_func)(void *),
void (* action_func)(void *),
void (* teardown_func)(void *),
void *arg)
{
int curcpumap, i, ncpus = 0;
/* Look comments in the !SMP case. */
if (!smp_started) {
spinlock_enter();
if (setup_func != NULL)
setup_func(arg);
if (action_func != NULL)
action_func(arg);
if (teardown_func != NULL)
teardown_func(arg);
spinlock_exit();
return;
}
CPU_FOREACH(i) {
if (CPU_ISSET(i, &map))
ncpus++;
}
if (ncpus == 0)
panic("ncpus is 0 with non-zero map");
mtx_lock_spin(&smp_ipi_mtx);
/* Pass rendezvous parameters via global variables. */
smp_rv_ncpus = ncpus;
smp_rv_setup_func = setup_func;
smp_rv_action_func = action_func;
smp_rv_teardown_func = teardown_func;
smp_rv_func_arg = arg;
smp_rv_waiters[1] = 0;
smp_rv_waiters[2] = 0;
smp_rv_waiters[3] = 0;
atomic_store_rel_int(&smp_rv_waiters[0], 0);
/*
* Signal other processors, which will enter the IPI with
* interrupts off.
*/
curcpumap = CPU_ISSET(curcpu, &map);
CPU_CLR(curcpu, &map);
ipi_selected(map, IPI_RENDEZVOUS);
/* Check if the current CPU is in the map */
if (curcpumap != 0)
smp_rendezvous_action();
/*
* Ensure that the master CPU waits for all the other
* CPUs to finish the rendezvous, so that smp_rv_*
* pseudo-structure and the arg are guaranteed to not
* be in use.
*/
while (atomic_load_acq_int(&smp_rv_waiters[3]) < ncpus)
cpu_spinwait();
mtx_unlock_spin(&smp_ipi_mtx);
}
void
smp_rendezvous(void (* setup_func)(void *),
void (* action_func)(void *),
void (* teardown_func)(void *),
void *arg)
{
smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg);
}
static struct cpu_group group[MAXCPU];
struct cpu_group *
smp_topo(void)
{
char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ];
struct cpu_group *top;
/*
* Check for a fake topology request for debugging purposes.
*/
switch (smp_topology) {
case 1:
/* Dual core with no sharing. */
top = smp_topo_1level(CG_SHARE_NONE, 2, 0);
break;
case 2:
/* No topology, all cpus are equal. */
top = smp_topo_none();
break;
case 3:
/* Dual core with shared L2. */
top = smp_topo_1level(CG_SHARE_L2, 2, 0);
break;
case 4:
/* quad core, shared l3 among each package, private l2. */
top = smp_topo_1level(CG_SHARE_L3, 4, 0);
break;
case 5:
/* quad core, 2 dualcore parts on each package share l2. */
top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0);
break;
case 6:
/* Single-core 2xHTT */
top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT);
break;
case 7:
/* quad core with a shared l3, 8 threads sharing L2. */
top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8,
CG_FLAG_SMT);
break;
default:
/* Default, ask the system what it wants. */
top = cpu_topo();
break;
}
/*
* Verify the returned topology.
*/
if (top->cg_count != mp_ncpus)
panic("Built bad topology at %p. CPU count %d != %d",
top, top->cg_count, mp_ncpus);
if (CPU_CMP(&top->cg_mask, &all_cpus))
panic("Built bad topology at %p. CPU mask (%s) != (%s)",
top, cpusetobj_strprint(cpusetbuf, &top->cg_mask),
cpusetobj_strprint(cpusetbuf2, &all_cpus));
return (top);
}
struct cpu_group *
smp_topo_none(void)
{
struct cpu_group *top;
top = &group[0];
top->cg_parent = NULL;
top->cg_child = NULL;
top->cg_mask = all_cpus;
top->cg_count = mp_ncpus;
top->cg_children = 0;
top->cg_level = CG_SHARE_NONE;
top->cg_flags = 0;
return (top);
}
static int
smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share,
int count, int flags, int start)
{
char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ];
cpuset_t mask;
int i;
CPU_ZERO(&mask);
for (i = 0; i < count; i++, start++)
CPU_SET(start, &mask);
child->cg_parent = parent;
child->cg_child = NULL;
child->cg_children = 0;
child->cg_level = share;
child->cg_count = count;
child->cg_flags = flags;
child->cg_mask = mask;
parent->cg_children++;
for (; parent != NULL; parent = parent->cg_parent) {
if (CPU_OVERLAP(&parent->cg_mask, &child->cg_mask))
panic("Duplicate children in %p. mask (%s) child (%s)",
parent,
cpusetobj_strprint(cpusetbuf, &parent->cg_mask),
cpusetobj_strprint(cpusetbuf2, &child->cg_mask));
CPU_OR(&parent->cg_mask, &child->cg_mask);
parent->cg_count += child->cg_count;
}
return (start);
}
struct cpu_group *
smp_topo_1level(int share, int count, int flags)
{
struct cpu_group *child;
struct cpu_group *top;
int packages;
int cpu;
int i;
cpu = 0;
top = &group[0];
packages = mp_ncpus / count;
top->cg_child = child = &group[1];
top->cg_level = CG_SHARE_NONE;
for (i = 0; i < packages; i++, child++)
cpu = smp_topo_addleaf(top, child, share, count, flags, cpu);
return (top);
}
struct cpu_group *
smp_topo_2level(int l2share, int l2count, int l1share, int l1count,
int l1flags)
{
struct cpu_group *top;
struct cpu_group *l1g;
struct cpu_group *l2g;
int cpu;
int i;
int j;
cpu = 0;
top = &group[0];
l2g = &group[1];
top->cg_child = l2g;
top->cg_level = CG_SHARE_NONE;
top->cg_children = mp_ncpus / (l2count * l1count);
l1g = l2g + top->cg_children;
for (i = 0; i < top->cg_children; i++, l2g++) {
l2g->cg_parent = top;
l2g->cg_child = l1g;
l2g->cg_level = l2share;
for (j = 0; j < l2count; j++, l1g++)
cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count,
l1flags, cpu);
}
return (top);
}
struct cpu_group *
smp_topo_find(struct cpu_group *top, int cpu)
{
struct cpu_group *cg;
cpuset_t mask;
int children;
int i;
CPU_SETOF(cpu, &mask);
cg = top;
for (;;) {
if (!CPU_OVERLAP(&cg->cg_mask, &mask))
return (NULL);
if (cg->cg_children == 0)
return (cg);
children = cg->cg_children;
for (i = 0, cg = cg->cg_child; i < children; cg++, i++)
if (CPU_OVERLAP(&cg->cg_mask, &mask))
break;
}
return (NULL);
}
#else /* !SMP */
void
smp_rendezvous_cpus(cpuset_t map,
void (*setup_func)(void *),
void (*action_func)(void *),
void (*teardown_func)(void *),
void *arg)
{
/*
* In the !SMP case we just need to ensure the same initial conditions
* as the SMP case.
*/
spinlock_enter();
if (setup_func != NULL)
setup_func(arg);
if (action_func != NULL)
action_func(arg);
if (teardown_func != NULL)
teardown_func(arg);
spinlock_exit();
}
void
smp_rendezvous(void (*setup_func)(void *),
void (*action_func)(void *),
void (*teardown_func)(void *),
void *arg)
{
/* Look comments in the smp_rendezvous_cpus() case. */
spinlock_enter();
if (setup_func != NULL)
setup_func(arg);
if (action_func != NULL)
action_func(arg);
if (teardown_func != NULL)
teardown_func(arg);
spinlock_exit();
}
/*
* Provide dummy SMP support for UP kernels. Modules that need to use SMP
* APIs will still work using this dummy support.
*/
static void
mp_setvariables_for_up(void *dummy)
{
mp_ncpus = 1;
mp_maxid = PCPU_GET(cpuid);
CPU_SETOF(mp_maxid, &all_cpus);
KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero"));
}
SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST,
mp_setvariables_for_up, NULL);
#endif /* SMP */
void
smp_no_rendevous_barrier(void *dummy)
{
#ifdef SMP
KASSERT((!smp_started),("smp_no_rendevous called and smp is started"));
#endif
}