5ca5a72bf6
into LSSUSPENDED state, have that LWP save its PCU state for the coredump and release its PCU status since its probably going to be exiting very soon. Make pcu_save_all tolerate for being called for non-curlwp if that lwp belongs to the same process, has a state of LSSUSPENDED, and no PCUs are in use. Make the MD coredump code use pcu_save_all(l) since it'll need to save all the PCU state anyways and can take advantage of the above tests.
365 lines
9.6 KiB
C
365 lines
9.6 KiB
C
/* $NetBSD: subr_pcu.c,v 1.9 2011/06/13 21:32:42 matt Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 2011 The NetBSD Foundation, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* This code is derived from software contributed to The NetBSD Foundation
|
|
* by Mindaugas Rasiukevicius.
|
|
*
|
|
* 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.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
|
|
*/
|
|
|
|
/*
|
|
* Per CPU Unit (PCU) - is an interface to manage synchronization of any
|
|
* per CPU context (unit) tied with LWP context. Typical use: FPU state.
|
|
*
|
|
* Concurrency notes:
|
|
*
|
|
* PCU state may be loaded only by the current LWP, that is, curlwp.
|
|
* Therefore, only LWP itself can set a CPU for lwp_t::l_pcu_cpu[id].
|
|
*
|
|
* Request for a PCU release can be from owner LWP (whether PCU state
|
|
* is on current CPU or remote CPU) or any other LWP running on that
|
|
* CPU (in such case, owner LWP is on a remote CPU or sleeping).
|
|
*
|
|
* In any case, PCU state can only be changed from the running CPU.
|
|
* If said PCU state is on the remote CPU, a cross-call will be sent
|
|
* by the owner LWP. Therefore struct cpu_info::ci_pcu_curlwp[id]
|
|
* may only be changed by current CPU, and lwp_t::l_pcu_cpu[id] may
|
|
* only be unset by the CPU which has PCU state loaded.
|
|
*
|
|
* There is a race condition: LWP may have a PCU state on a remote CPU,
|
|
* which it requests to be released via cross-call. At the same time,
|
|
* other LWP on remote CPU might release existing PCU state and load
|
|
* its own one. Cross-call may arrive after this and release different
|
|
* PCU state than intended. In such case, such LWP would re-load its
|
|
* PCU state again.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__KERNEL_RCSID(0, "$NetBSD: subr_pcu.c,v 1.9 2011/06/13 21:32:42 matt Exp $");
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/cpu.h>
|
|
#include <sys/lwp.h>
|
|
#include <sys/pcu.h>
|
|
#include <sys/xcall.h>
|
|
|
|
#if PCU_UNIT_COUNT > 0
|
|
|
|
static void pcu_lwp_op(const pcu_ops_t *, lwp_t *, int);
|
|
|
|
#define PCU_SAVE 0x01 /* Save PCU state to the LWP. */
|
|
#define PCU_RELEASE 0x02 /* Release PCU state on the CPU. */
|
|
|
|
/* XXX */
|
|
extern const pcu_ops_t * const pcu_ops_md_defs[];
|
|
|
|
void
|
|
pcu_switchpoint(lwp_t *l)
|
|
{
|
|
const uint32_t pcu_inuse = l->l_pcu_used;
|
|
u_int id;
|
|
/* int s; */
|
|
|
|
KASSERT(l == curlwp);
|
|
|
|
if (__predict_true(pcu_inuse == 0)) {
|
|
/* PCUs are not in use. */
|
|
return;
|
|
}
|
|
/* s = splsoftclock(); */
|
|
for (id = 0; id < PCU_UNIT_COUNT; id++) {
|
|
if ((pcu_inuse & (1 << id)) == 0) {
|
|
continue;
|
|
}
|
|
struct cpu_info * const pcu_ci = l->l_pcu_cpu[id];
|
|
if (pcu_ci == NULL || pcu_ci == l->l_cpu) {
|
|
continue;
|
|
}
|
|
const pcu_ops_t * const pcu = pcu_ops_md_defs[id];
|
|
pcu->pcu_state_release(l);
|
|
}
|
|
/* splx(s); */
|
|
}
|
|
|
|
void
|
|
pcu_discard_all(lwp_t *l)
|
|
{
|
|
const uint32_t pcu_inuse = l->l_pcu_used;
|
|
|
|
KASSERT(l == curlwp || ((l->l_flag & LW_SYSTEM) && pcu_inuse == 0));
|
|
|
|
if (__predict_true(pcu_inuse == 0)) {
|
|
/* PCUs are not in use. */
|
|
return;
|
|
}
|
|
const int s = splsoftclock();
|
|
for (u_int id = 0; id < PCU_UNIT_COUNT; id++) {
|
|
if ((pcu_inuse & (1 << id)) == 0) {
|
|
continue;
|
|
}
|
|
if (__predict_true(l->l_pcu_cpu[id] == NULL)) {
|
|
continue;
|
|
}
|
|
const pcu_ops_t * const pcu = pcu_ops_md_defs[id];
|
|
/*
|
|
* We aren't releasing since this LWP isn't giving up PCU,
|
|
* just saving it.
|
|
*/
|
|
pcu_lwp_op(pcu, l, PCU_RELEASE);
|
|
}
|
|
l->l_pcu_used = 0;
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
pcu_save_all(lwp_t *l)
|
|
{
|
|
const uint32_t pcu_inuse = l->l_pcu_used;
|
|
const int flags = PCU_SAVE | (l->l_flag & LW_WCORE ? PCU_RELEASE : 0);
|
|
|
|
/*
|
|
* Normally we save for the current LWP, but sometimes we get called
|
|
* with a different LWP (forking a system LWP or doing a coredump of
|
|
* a process with multiple threads) and we need to deal with that.
|
|
*/
|
|
KASSERT(l == curlwp
|
|
|| (((l->l_flag & LW_SYSTEM)
|
|
|| (curlwp->l_proc == l->l_proc && l->l_stat == LSSUSPENDED))
|
|
&& pcu_inuse == 0));
|
|
|
|
if (__predict_true(pcu_inuse == 0)) {
|
|
/* PCUs are not in use. */
|
|
return;
|
|
}
|
|
const int s = splsoftclock();
|
|
for (u_int id = 0; id < PCU_UNIT_COUNT; id++) {
|
|
if ((pcu_inuse & (1 << id)) == 0) {
|
|
continue;
|
|
}
|
|
if (__predict_true(l->l_pcu_cpu[id] == NULL)) {
|
|
continue;
|
|
}
|
|
const pcu_ops_t * const pcu = pcu_ops_md_defs[id];
|
|
/*
|
|
* We aren't releasing since this LWP isn't giving up PCU,
|
|
* just saving it.
|
|
*/
|
|
pcu_lwp_op(pcu, l, flags);
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* pcu_do_op: save/release PCU state on the current CPU.
|
|
*
|
|
* => Must be called at IPL_SOFTCLOCK or from the soft-interrupt.
|
|
*/
|
|
static inline void
|
|
pcu_do_op(const pcu_ops_t *pcu, lwp_t * const l, const int flags)
|
|
{
|
|
struct cpu_info * const ci = curcpu();
|
|
const u_int id = pcu->pcu_id;
|
|
|
|
KASSERT(l->l_pcu_cpu[id] == ci);
|
|
|
|
if (flags & PCU_SAVE) {
|
|
pcu->pcu_state_save(l);
|
|
}
|
|
if (flags & PCU_RELEASE) {
|
|
pcu->pcu_state_release(l);
|
|
ci->ci_pcu_curlwp[id] = NULL;
|
|
l->l_pcu_cpu[id] = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* pcu_cpu_op: helper routine to call pcu_do_op() via xcall(9) or
|
|
* by pcu_load.
|
|
*/
|
|
static void
|
|
pcu_cpu_op(const pcu_ops_t *pcu, const int flags)
|
|
{
|
|
const u_int id = pcu->pcu_id;
|
|
lwp_t * const l = curcpu()->ci_pcu_curlwp[id];
|
|
|
|
//KASSERT(cpu_softintr_p());
|
|
|
|
/* If no state - nothing to do. */
|
|
if (l == NULL) {
|
|
return;
|
|
}
|
|
pcu_do_op(pcu, l, flags);
|
|
}
|
|
|
|
/*
|
|
* pcu_lwp_op: perform PCU state save, release or both operations on LWP.
|
|
*/
|
|
static void
|
|
pcu_lwp_op(const pcu_ops_t *pcu, lwp_t *l, int flags)
|
|
{
|
|
const u_int id = pcu->pcu_id;
|
|
struct cpu_info *ci;
|
|
uint64_t where;
|
|
int s;
|
|
|
|
/*
|
|
* Caller should have re-checked if there is any state to manage.
|
|
* Block the interrupts and inspect again, since cross-call sent
|
|
* by remote CPU could have changed the state.
|
|
*/
|
|
s = splsoftclock();
|
|
ci = l->l_pcu_cpu[id];
|
|
if (ci == curcpu()) {
|
|
/*
|
|
* State is on the current CPU - just perform the operations.
|
|
*/
|
|
KASSERTMSG(ci->ci_pcu_curlwp[id] == l,
|
|
("%s: cpu%u: pcu_curlwp[%u] (%p) != l (%p)",
|
|
__func__, cpu_index(ci), id, ci->ci_pcu_curlwp[id], l));
|
|
pcu_do_op(pcu, l, flags);
|
|
splx(s);
|
|
return;
|
|
}
|
|
splx(s);
|
|
|
|
if (__predict_false(ci == NULL)) {
|
|
/* Cross-call has won the race - no state to manage. */
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* State is on the remote CPU - perform the operations there.
|
|
* Note: there is a race condition; see description in the top.
|
|
*/
|
|
where = xc_unicast(XC_HIGHPRI, (xcfunc_t)pcu_cpu_op,
|
|
__UNCONST(pcu), (void *)(uintptr_t)flags, ci);
|
|
xc_wait(where);
|
|
|
|
KASSERT((flags & PCU_RELEASE) == 0 || l->l_pcu_cpu[id] == NULL);
|
|
}
|
|
|
|
/*
|
|
* pcu_load: load/initialize the PCU state of current LWP on current CPU.
|
|
*/
|
|
void
|
|
pcu_load(const pcu_ops_t *pcu)
|
|
{
|
|
const u_int id = pcu->pcu_id;
|
|
struct cpu_info *ci, *curci;
|
|
lwp_t * const l = curlwp;
|
|
uint64_t where;
|
|
int s;
|
|
|
|
KASSERT(!cpu_intr_p() && !cpu_softintr_p());
|
|
|
|
s = splsoftclock();
|
|
curci = curcpu();
|
|
ci = l->l_pcu_cpu[id];
|
|
|
|
/* Does this CPU already have our PCU state loaded? */
|
|
if (ci == curci) {
|
|
KASSERT(curci->ci_pcu_curlwp[id] == l);
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
/* If PCU state of this LWP is on the remote CPU - save it there. */
|
|
if (ci) {
|
|
splx(s);
|
|
/* Note: there is a race; see description in the top. */
|
|
where = xc_unicast(XC_HIGHPRI, (xcfunc_t)pcu_cpu_op,
|
|
__UNCONST(pcu), (void *)(PCU_SAVE | PCU_RELEASE), ci);
|
|
xc_wait(where);
|
|
|
|
/* Enter IPL_SOFTCLOCK and re-fetch the current CPU. */
|
|
s = splsoftclock();
|
|
curci = curcpu();
|
|
}
|
|
KASSERT(l->l_pcu_cpu[id] == NULL);
|
|
|
|
/* Save the PCU state on the current CPU, if there is any. */
|
|
pcu_cpu_op(pcu, PCU_SAVE | PCU_RELEASE);
|
|
KASSERT(curci->ci_pcu_curlwp[id] == NULL);
|
|
|
|
/*
|
|
* Finally, load the state for this LWP on this CPU. Indicate to
|
|
* load function whether PCU was used before. Note the usage.
|
|
*/
|
|
pcu->pcu_state_load(l, ((1 << id) & l->l_pcu_used) != 0);
|
|
curci->ci_pcu_curlwp[id] = l;
|
|
l->l_pcu_cpu[id] = curci;
|
|
l->l_pcu_used |= (1 << id);
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* pcu_discard: discard the PCU state of current LWP.
|
|
*/
|
|
void
|
|
pcu_discard(const pcu_ops_t *pcu)
|
|
{
|
|
const u_int id = pcu->pcu_id;
|
|
lwp_t * const l = curlwp;
|
|
|
|
KASSERT(!cpu_intr_p() && !cpu_softintr_p());
|
|
|
|
if (__predict_true(l->l_pcu_cpu[id] == NULL)) {
|
|
return;
|
|
}
|
|
pcu_lwp_op(pcu, l, PCU_RELEASE);
|
|
l->l_pcu_used &= ~(1 << id);
|
|
}
|
|
|
|
/*
|
|
* pcu_save_lwp: save PCU state to the given LWP.
|
|
*/
|
|
void
|
|
pcu_save(const pcu_ops_t *pcu)
|
|
{
|
|
const u_int id = pcu->pcu_id;
|
|
lwp_t * const l = curlwp;
|
|
|
|
KASSERT(!cpu_intr_p() && !cpu_softintr_p());
|
|
|
|
if (__predict_true(l->l_pcu_cpu[id] == NULL)) {
|
|
return;
|
|
}
|
|
pcu_lwp_op(pcu, l, PCU_SAVE | PCU_RELEASE);
|
|
}
|
|
|
|
/*
|
|
* pcu_used: return true if PCU was used (pcu_load() case) by the LWP.
|
|
*/
|
|
bool
|
|
pcu_used_p(const pcu_ops_t *pcu)
|
|
{
|
|
const u_int id = pcu->pcu_id;
|
|
lwp_t * const l = curlwp;
|
|
|
|
return l->l_pcu_used & (1 << id);
|
|
}
|
|
|
|
#endif /* PCU_UNIT_COUNT > 0 */
|