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[src/trunk]: src/sys/arch/aarch64/aarch64 Fix race conditions about pmap_page...
details: https://anonhg.NetBSD.org/src/rev/d38b6cbfa6e2
branches: trunk
changeset: 455577:d38b6cbfa6e2
user: ryo <ryo%NetBSD.org@localhost>
date: Sat Apr 06 18:30:20 2019 +0000
description:
Fix race conditions about pmap_page_protect() and pmap_enter().
while handling same PTE by these functions in same time, there
is a critical path that the number of valid PTEs and wire_count
are inconsistent, and it caused KASSERT.
Need to hold a pv_lock while modifying them.
diffstat:
sys/arch/aarch64/aarch64/pmap.c | 144 ++++++++++++++++++++-------------------
1 files changed, 74 insertions(+), 70 deletions(-)
diffs (truncated from 321 to 300 lines):
diff -r 9ddf117c94ff -r d38b6cbfa6e2 sys/arch/aarch64/aarch64/pmap.c
--- a/sys/arch/aarch64/aarch64/pmap.c Sat Apr 06 17:42:28 2019 +0000
+++ b/sys/arch/aarch64/aarch64/pmap.c Sat Apr 06 18:30:20 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: pmap.c,v 1.38 2019/03/20 07:05:06 ryo Exp $ */
+/* $NetBSD: pmap.c,v 1.39 2019/04/06 18:30:20 ryo Exp $ */
/*
* Copyright (c) 2017 Ryo Shimizu <ryo%nerv.org@localhost>
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.38 2019/03/20 07:05:06 ryo Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.39 2019/04/06 18:30:20 ryo Exp $");
#include "opt_arm_debug.h"
#include "opt_ddb.h"
@@ -908,8 +908,6 @@
md = VM_PAGE_TO_MD(pg);
- pmap_pv_lock(md);
-
TAILQ_FOREACH(pv, &md->mdpg_pvhead, pv_link) {
if ((pm == pv->pv_pmap) && (va == pv->pv_va)) {
TAILQ_REMOVE(&md->mdpg_pvhead, pv, pv_link);
@@ -923,8 +921,6 @@
}
#endif
- pmap_pv_unlock(md);
-
return pv;
}
@@ -1008,8 +1004,6 @@
md = VM_PAGE_TO_MD(pg);
- pmap_pv_lock(md);
-
/* pv is already registered? */
TAILQ_FOREACH(pv, &md->mdpg_pvhead, pv_link) {
if ((pm == pv->pv_pmap) && (va == pv->pv_va)) {
@@ -1018,8 +1012,6 @@
}
if (pv == NULL) {
- pmap_pv_unlock(md);
-
/*
* create and link new pv.
* pv is already allocated at beginning of _pmap_enter().
@@ -1034,7 +1026,6 @@
pv->pv_pa = pa;
pv->pv_ptep = ptep;
- pmap_pv_lock(md);
TAILQ_INSERT_HEAD(&md->mdpg_pvhead, pv, pv_link);
PMAP_COUNT(pv_enter);
@@ -1047,7 +1038,6 @@
#endif
}
- pmap_pv_unlock(md);
return 0;
}
@@ -1283,6 +1273,7 @@
pm->pm_asid = -1;
TAILQ_INIT(&pm->pm_vmlist);
mutex_init(&pm->pm_lock, MUTEX_DEFAULT, IPL_VM);
+
pm->pm_l0table_pa = pmap_alloc_pdp(pm, NULL, true);
KASSERT(pm->pm_l0table_pa != POOL_PADDR_INVALID);
pm->pm_l0table = (pd_entry_t *)AARCH64_PA_TO_KVA(pm->pm_l0table_pa);
@@ -1438,17 +1429,14 @@
struct vm_page *pg, *pdppg, *pdppg0;
struct pv_entry *spv, *opv = NULL;
pd_entry_t pde;
- pt_entry_t attr, pte, *ptep;
-#ifdef UVMHIST
- pt_entry_t opte;
-#endif
+ pt_entry_t attr, pte, opte, *ptep;
pd_entry_t *l0, *l1, *l2, *l3;
paddr_t pdppa, pdppa0;
uint32_t mdattr;
unsigned int idx;
int error = 0;
const bool user = (pm != pmap_kernel());
- bool need_sync_icache, exists;
+ bool need_sync_icache, need_update_pv;
bool l3only = true;
UVMHIST_FUNC(__func__);
@@ -1496,9 +1484,11 @@
* pool_cache_get() may call pmap_kenter() internally.
*/
spv = pool_cache_get(&_pmap_pv_pool, PR_NOWAIT);
+ need_update_pv = true;
} else {
PMAP_COUNT(unmanaged_mappings);
spv = NULL;
+ need_update_pv = false;
}
pm_lock(pm);
@@ -1512,12 +1502,13 @@
pde = l0[idx];
if (!l0pde_valid(pde)) {
/* no need to increment L0 occupancy. L0 page never freed */
- pdppa = pmap_alloc_pdp(pm, &pdppg, false); /* L1 pdp */
+ pdppa = pmap_alloc_pdp(pm, &pdppg, flags); /* L1 pdp */
if (pdppa == POOL_PADDR_INVALID) {
if (flags & PMAP_CANFAIL) {
error = ENOMEM;
- goto done;
+ goto fail0;
}
+ pm_unlock(pm);
panic("%s: cannot allocate L1 table", __func__);
}
atomic_swap_64(&l0[idx], pdppa | L0_TABLE);
@@ -1534,12 +1525,13 @@
if (!l1pde_valid(pde)) {
pdppa0 = pdppa;
pdppg0 = pdppg;
- pdppa = pmap_alloc_pdp(pm, &pdppg, false); /* L2 pdp */
+ pdppa = pmap_alloc_pdp(pm, &pdppg, flags); /* L2 pdp */
if (pdppa == POOL_PADDR_INVALID) {
if (flags & PMAP_CANFAIL) {
error = ENOMEM;
- goto done;
+ goto fail0;
}
+ pm_unlock(pm);
panic("%s: cannot allocate L2 table", __func__);
}
atomic_swap_64(&l1[idx], pdppa | L1_TABLE);
@@ -1557,12 +1549,13 @@
if (!l2pde_valid(pde)) {
pdppa0 = pdppa;
pdppg0 = pdppg;
- pdppa = pmap_alloc_pdp(pm, &pdppg, false); /* L3 pdp */
+ pdppa = pmap_alloc_pdp(pm, &pdppg, flags); /* L3 pdp */
if (pdppa == POOL_PADDR_INVALID) {
if (flags & PMAP_CANFAIL) {
error = ENOMEM;
- goto done;
+ goto fail0;
}
+ pm_unlock(pm);
panic("%s: cannot allocate L3 table", __func__);
}
atomic_swap_64(&l2[idx], pdppa | L2_TABLE);
@@ -1578,10 +1571,7 @@
idx = l3pte_index(va);
ptep = &l3[idx]; /* as PTE */
- pte = *ptep;
-#ifdef UVMHIST
- opte = pte;
-#endif
+ opte = atomic_swap_64(ptep, 0);
need_sync_icache = (prot & VM_PROT_EXECUTE);
#ifdef KASAN
@@ -1590,45 +1580,47 @@
}
#endif
- if (l3pte_valid(pte)) {
+ if (pg != NULL)
+ pmap_pv_lock(VM_PAGE_TO_MD(pg));
+
+ /* remap? */
+ if (l3pte_valid(opte)) {
+ struct vm_page *opg;
+ bool need_remove_pv;
+
KASSERT(!kenter); /* pmap_kenter_pa() cannot override */
-
- PMAP_COUNT(remappings);
-
- /* pte is Already mapped */
- if (l3pte_pa(pte) == pa) {
- if (need_sync_icache && l3pte_executable(pte, user))
- need_sync_icache = false;
-
- } else {
- struct vm_page *opg;
-
#ifdef PMAPCOUNTERS
- if (user) {
- PMAP_COUNT(user_mappings_changed);
- } else {
- PMAP_COUNT(kern_mappings_changed);
- }
-#endif
-
- UVMHIST_LOG(pmaphist,
- "va=%016lx has already mapped."
- " old-pa=%016lx new-pa=%016lx, pte=%016llx\n",
- va, l3pte_pa(pte), pa, pte);
-
- opg = PHYS_TO_VM_PAGE(l3pte_pa(pte));
- if (opg != NULL)
- opv = _pmap_remove_pv(opg, pm, va, pte);
- }
-
- if (pte & LX_BLKPAG_OS_WIRED) {
+ PMAP_COUNT(remappings);
+ if (opte & LX_BLKPAG_OS_WIRED) {
PMSTAT_DEC_WIRED_COUNT(pm);
}
PMSTAT_DEC_RESIDENT_COUNT(pm);
-
- exists = true; /* already exists */
- } else {
- exists = false;
+ if (user) {
+ PMAP_COUNT(user_mappings_changed);
+ } else {
+ PMAP_COUNT(kern_mappings_changed);
+ }
+#endif
+ UVMHIST_LOG(pmaphist,
+ "va=%016lx has already mapped."
+ " old-pa=%016lx new-pa=%016lx, old-pte=%016llx\n",
+ va, l3pte_pa(opte), pa, opte);
+
+ if (pa == l3pte_pa(opte)) {
+ /* old and new pte have same pa, no need to update pv */
+ need_remove_pv = (pg == NULL);
+ need_update_pv = false;
+ if (need_sync_icache && l3pte_executable(opte, user))
+ need_sync_icache = false;
+ } else {
+ need_remove_pv = true;
+ }
+ if (need_remove_pv) {
+ opg = PHYS_TO_VM_PAGE(l3pte_pa(opte));
+ if (opg != NULL) {
+ opv = _pmap_remove_pv(opg, pm, va, opte);
+ }
+ }
}
/*
@@ -1640,23 +1632,28 @@
prot |= VM_PROT_READ;
mdattr = VM_PROT_READ | VM_PROT_WRITE;
- if (pg != NULL) {
+ if (need_update_pv) {
error = _pmap_enter_pv(pg, pm, &spv, va, ptep, pa, flags);
-
if (error != 0) {
/*
* If pmap_enter() fails,
* it must not leave behind an existing pmap entry.
*/
- if (!kenter && ((pte & LX_BLKPAG_OS_WIRED) == 0))
- atomic_swap_64(ptep, 0);
-
+ if (lxpde_valid(opte)) {
+ bool pdpremoved = _pmap_pdp_delref(pm,
+ AARCH64_KVA_TO_PA(trunc_page(
+ (vaddr_t)ptep)), true);
+ AARCH64_TLBI_BY_ASID_VA(pm->pm_asid,
+ va, !pdpremoved);
+ }
PMAP_COUNT(pv_entry_cannotalloc);
if (flags & PMAP_CANFAIL)
- goto done;
+ goto fail1;
panic("pmap_enter: failed to allocate pv_entry");
}
-
+ }
+
+ if (pg != NULL) {
/* update referenced/modified flags */
VM_PAGE_TO_MD(pg)->mdpg_flags |=
(flags & (VM_PROT_READ | VM_PROT_WRITE));
@@ -1702,7 +1699,8 @@
atomic_swap_64(ptep, pte);
AARCH64_TLBI_BY_ASID_VA(pm->pm_asid, va, l3only);
}
- if (!exists)
+
+ if (!l3pte_valid(opte))
_pmap_pdp_addref(pm, pdppa, pdppg); /* L3 occupancy++ */
if (pte & LX_BLKPAG_OS_WIRED) {
@@ -1710,7 +1708,10 @@
}
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