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[src/trunk]: src/sys/arch/x86/x86 - Give pmap uvm_objects an empty pagerops t...
details: https://anonhg.NetBSD.org/src/rev/f7719db6049a
branches: trunk
changeset: 745427:f7719db6049a
user: ad <ad%NetBSD.org@localhost>
date: Sun Mar 01 21:42:58 2020 +0000
description:
- Give pmap uvm_objects an empty pagerops to avoid special casing in UVM.
(This use of uvm_object causes a disproportionate amount of work.)
- Undo the pmap_destroy()/pmap_delref() split. I misunderstood the flow of
control, and there's no need for this.
- For pmap_remove_pv(), always look up the pv_entry in advance as those
calls will need to be covered by lock again soon.
diffstat:
sys/arch/x86/x86/pmap.c | 88 +++++++++++++++++++++---------------------------
1 files changed, 38 insertions(+), 50 deletions(-)
diffs (252 lines):
diff -r 60251f8ec392 -r f7719db6049a sys/arch/x86/x86/pmap.c
--- a/sys/arch/x86/x86/pmap.c Sun Mar 01 21:40:45 2020 +0000
+++ b/sys/arch/x86/x86/pmap.c Sun Mar 01 21:42:58 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: pmap.c,v 1.360 2020/02/29 20:17:11 ad Exp $ */
+/* $NetBSD: pmap.c,v 1.361 2020/03/01 21:42:58 ad Exp $ */
/*
* Copyright (c) 2008, 2010, 2016, 2017, 2019, 2020 The NetBSD Foundation, Inc.
@@ -130,7 +130,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.360 2020/02/29 20:17:11 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.361 2020/03/01 21:42:58 ad Exp $");
#include "opt_user_ldt.h"
#include "opt_lockdebug.h"
@@ -252,6 +252,10 @@
#define PMAP_DUMMY_UNLOCK(pm)
#endif
+static const struct uvm_pagerops pmap_pager = {
+ /* nothing */
+};
+
const vaddr_t ptp_masks[] = PTP_MASK_INITIALIZER;
const vaddr_t ptp_frames[] = PTP_FRAME_INITIALIZER;
const int ptp_shifts[] = PTP_SHIFT_INITIALIZER;
@@ -444,7 +448,6 @@
static void pmap_load1(struct lwp *, struct pmap *, struct pmap *);
static void pmap_reactivate(struct pmap *);
-static void pmap_dropref(struct pmap *);
/*
* p m a p h e l p e r f u n c t i o n s
@@ -677,7 +680,7 @@
/* Toss reference to other pmap taken earlier. */
if (pmap2 != NULL) {
- pmap_dropref(pmap2);
+ pmap_destroy(pmap2);
}
}
@@ -1024,16 +1027,12 @@
*
* The kernel pmap's pm_obj is not used for much. However, in user pmaps
* the pm_obj contains the list of active PTPs.
- *
- * The pm_obj currently does not have a pager. It might be possible to
- * add a pager that would allow a process to read-only mmap its own page
- * tables (fast user-level vtophys?). This may or may not be useful.
*/
kpm = pmap_kernel();
mutex_init(&kpm->pm_lock, MUTEX_DEFAULT, IPL_NONE);
rw_init(&kpm->pm_dummy_lock);
for (i = 0; i < PTP_LEVELS - 1; i++) {
- uvm_obj_init(&kpm->pm_obj[i], NULL, false, 1);
+ uvm_obj_init(&kpm->pm_obj[i], &pmap_pager, false, 1);
uvm_obj_setlock(&kpm->pm_obj[i], &kpm->pm_dummy_lock);
kpm->pm_ptphint[i] = NULL;
}
@@ -1930,7 +1929,7 @@
* => we return the removed pve
* => caller can optionally supply pve, if looked up already
*/
-static struct pv_entry *
+static void
pmap_remove_pv(struct pmap *pmap, struct pmap_page *pp, struct vm_page *ptp,
vaddr_t va, struct pv_entry *pve)
{
@@ -1947,19 +1946,13 @@
pp->pp_flags &= ~PP_EMBEDDED;
pp->pp_pte.pte_ptp = NULL;
pp->pp_pte.pte_va = 0;
- return NULL;
- }
-
- if (pve == NULL) {
- pve = pmap_pvmap_lookup(pmap, va);
+ } else {
KASSERT(pve != NULL);
- } else {
KASSERT(pve == pmap_pvmap_lookup(pmap, va));
- }
- KASSERT(pve->pve_pte.pte_ptp == ptp);
- KASSERT(pve->pve_pte.pte_va == va);
- LIST_REMOVE(pve, pve_list);
- return pve;
+ KASSERT(pve->pve_pte.pte_ptp == ptp);
+ KASSERT(pve->pve_pte.pte_va == va);
+ LIST_REMOVE(pve, pve_list);
+ }
}
/*
@@ -2487,7 +2480,7 @@
/* init uvm_object */
for (i = 0; i < PTP_LEVELS - 1; i++) {
- uvm_obj_init(&pmap->pm_obj[i], NULL, false, 1);
+ uvm_obj_init(&pmap->pm_obj[i], &pmap_pager, false, 1);
uvm_obj_setlock(&pmap->pm_obj[i], &pmap->pm_dummy_lock);
pmap->pm_ptphint[i] = NULL;
}
@@ -2545,7 +2538,7 @@
for (int i = 0; i < PDIR_SLOT_USERLIM; i++) {
if (pmap->pm_pdir[i] != 0 &&
ci->ci_kpm_pdir[i] == pmap->pm_pdir[i]) {
- printf("pmap_dropref(%p) pmap_kernel %p "
+ printf("pmap_destroy(%p) pmap_kernel %p "
"curcpu %d cpu %d ci_pmap %p "
"ci->ci_kpm_pdir[%d]=%" PRIx64
" pmap->pm_pdir[%d]=%" PRIx64 "\n",
@@ -2562,29 +2555,22 @@
}
/*
- * pmap_destroy: pmap is being destroyed by UVM.
- */
-void
-pmap_destroy(struct pmap *pmap)
-{
-
- /* Undo pmap_remove_all(), then drop the reference. */
- pmap_update(pmap);
- pmap_dropref(pmap);
-}
-
-/*
- * pmap_dropref: drop reference count on pmap. free pmap if reference
+ * pmap_destroy: drop reference count on pmap. free pmap if reference
* count goes to zero.
*
* => we can be called from pmap_unmap_ptes() with a different, unrelated
* pmap's lock held. be careful!
*/
-static void
-pmap_dropref(struct pmap *pmap)
+void
+pmap_destroy(struct pmap *pmap)
{
int i;
+ /* Undo pmap_remove_all(). */
+ if (pmap->pm_remove_all == curlwp) {
+ pmap_update(pmap);
+ }
+
/*
* drop reference count
*/
@@ -2972,7 +2958,7 @@
* to the old pmap. if we block, we need to go around again.
*/
- pmap_dropref(oldpmap);
+ pmap_destroy(oldpmap);
__insn_barrier();
if (l->l_ncsw != ncsw) {
goto retry;
@@ -3597,8 +3583,9 @@
}
/* Sync R/M bits. */
+ pve = pmap_pvmap_lookup(pmap, va);
pp->pp_attrs |= pmap_pte_to_pp_attrs(opte);
- pve = pmap_remove_pv(pmap, pp, ptp, va, NULL);
+ pmap_remove_pv(pmap, pp, ptp, va, pve);
if (pve) {
pve->pve_next = *pv_tofree;
@@ -3868,16 +3855,17 @@
KERNEL_UNLOCK_ALL(curlwp, &hold_count);
mutex_exit(&pmap->pm_lock);
if (ptp != NULL) {
- pmap_dropref(pmap);
+ pmap_destroy(pmap);
}
SPINLOCK_BACKOFF(count);
KERNEL_LOCK(hold_count, curlwp);
goto startover;
}
+ va = pvpte->pte_va;
+ pve = pmap_pvmap_lookup(pmap, va);
pp->pp_attrs |= oattrs;
- va = pvpte->pte_va;
- pve = pmap_remove_pv(pmap, pp, ptp, va, NULL);
+ pmap_remove_pv(pmap, pp, ptp, va, pve);
/* Update the PTP reference count. Free if last reference. */
if (ptp != NULL) {
@@ -3902,7 +3890,7 @@
}
mutex_exit(&pmap->pm_lock);
if (ptp != NULL) {
- pmap_dropref(pmap);
+ pmap_destroy(pmap);
}
}
pmap_tlb_shootnow();
@@ -4345,7 +4333,7 @@
return error;
}
panic("%s: alloc pve failed", __func__);
- }
+ }
error = pmap_pvmap_insert(pmap, va, pve);
if (error != 0) {
if (flags & PMAP_CANFAIL) {
@@ -4445,7 +4433,7 @@
__func__, va, oldpa, atop(pa));
}
- (void)pmap_remove_pv(pmap, old_pp, ptp, va, pve);
+ pmap_remove_pv(pmap, old_pp, ptp, va, pve);
old_pp->pp_attrs |= pmap_pte_to_pp_attrs(opte);
}
@@ -4797,8 +4785,7 @@
* removed.
*/
kpreempt_disable();
- if (pmap->pm_remove_all != NULL) {
- KASSERT(pmap->pm_remove_all == curlwp);
+ if (pmap->pm_remove_all == curlwp) {
pmap->pm_remove_all = NULL;
pmap_tlb_shootdown(pmap, (vaddr_t)-1LL, 0, TLBSHOOT_UPDATE);
}
@@ -5324,7 +5311,7 @@
__func__, va, oldpa, atop(pa));
}
- (void)pmap_remove_pv(pmap, old_pp, ptp, va, pve);
+ pmap_remove_pv(pmap, old_pp, ptp, va, pve);
old_pp->pp_attrs |= pmap_ept_to_pp_attrs(opte);
}
@@ -5490,8 +5477,9 @@
}
/* Sync R/M bits. */
+ pve = pmap_pvmap_lookup(pmap, va);
pp->pp_attrs |= pmap_ept_to_pp_attrs(opte);
- pve = pmap_remove_pv(pmap, pp, ptp, va, NULL);
+ pmap_remove_pv(pmap, pp, ptp, va, pve);
if (pve) {
pve->pve_next = *pv_tofree;
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