svn commit: r208651 - head/sys/i386/xen
Alan Cox
alc at FreeBSD.org
Sun May 30 04:44:33 UTC 2010
Author: alc
Date: Sun May 30 04:44:32 2010
New Revision: 208651
URL: http://svn.freebsd.org/changeset/base/208651
Log:
Merge various changes from i386/i386/pmap.c:
The remaining, unmerged portions of r175404
Retire PMAP_DIAGNOSTIC. Any useful diagnostics that were conditionally
compiled under PMAP_DIAGNOSTIC are now KASSERT()s. (Note: The kernel
option DIAGNOSTIC still disables inlining of certain pmap functions.)
Eliminate dead code from pmap_enter(). This code implemented an assertion.
On i386, an equivalent check is already implemented. However, on amd64,
a small change is required to implement an equivalent check.
Eliminate \n from a nearby panic string.
Use KASSERT() to reimplement pmap_copy()'s two assertions.
Merge portions of r177659
To date, we have assumed that the TLB will only set the PG_M bit in a
PTE if that PTE has the PG_RW bit set. However, this assumption does
not hold on recent processors from Intel. For example, consider a PTE
that has the PG_RW bit set but the PG_M bit clear. Suppose this PTE
is cached in the TLB and later the PG_RW bit is cleared in the PTE,
but the corresponding TLB entry is not (yet) invalidated.
Historically, upon a write access using this (stale) TLB entry, the
TLB would observe that the PG_RW bit had been cleared and initiate a
page fault, aborting the setting of the PG_M bit in the PTE. Now,
however, P4- and Core2-family processors will set the PG_M bit before
observing that the PG_RW bit is clear and initiating a page fault. In
other words, the write does not occur but the PG_M bit is still set.
The real impact of this difference is not that great. Specifically,
we should no longer assert that any PTE with the PG_M bit set must
also have the PG_RW bit set, and we should ignore the state of the
PG_M bit unless the PG_RW bit is set.
r208609
Defer freeing any page table pages in pmap_remove_all() until after the
page queues lock is released. This may reduce the amount of time that the
page queues lock is held by pmap_remove_all().
r208645
When I pushed down the page queues lock into pmap_is_modified(), I created
an ordering dependence: A pmap operation that clears PG_WRITEABLE and calls
vm_page_dirty() must perform the call first. Otherwise, pmap_is_modified()
could return FALSE without acquiring the page queues lock because the page
is not (currently) writeable, and the caller to pmap_is_modified() might
believe that the page's dirty field is clear because it has not seen the
effect of the vm_page_dirty() call.
When I pushed down the page queues lock into pmap_is_modified(), I
overlooked one place where this ordering dependence is violated:
pmap_enter(). In a rare situation pmap_enter() can be called to replace a
dirty mapping to one page with a mapping to another page. (I say rare
because replacements generally occur as a result of a copy-on-write fault,
and so the old page is not dirty.) This change delays clearing PG_WRITEABLE
until after vm_page_dirty() has been called.
Fixing the ordering dependency also makes it easy to introduce a small
optimization: When pmap_enter() used to replace a mapping to one page with a
mapping to another page, it freed the pv entry for the first mapping and
later called the pv entry allocator for the new mapping. Now, pmap_enter()
attempts to recycle the old pv entry, saving two calls to the pv entry
allocator.
There is no point in setting PG_WRITEABLE on unmanaged pages, so don't.
Update a comment to reflect this.
Tidy up the variable declarations at the start of pmap_enter().
Modified:
head/sys/i386/xen/pmap.c
Modified: head/sys/i386/xen/pmap.c
==============================================================================
--- head/sys/i386/xen/pmap.c Sun May 30 03:45:41 2010 (r208650)
+++ head/sys/i386/xen/pmap.c Sun May 30 04:44:32 2010 (r208651)
@@ -103,8 +103,6 @@ __FBSDID("$FreeBSD$");
* and to when physical maps must be made correct.
*/
-#define PMAP_DIAGNOSTIC
-
#include "opt_cpu.h"
#include "opt_pmap.h"
#include "opt_msgbuf.h"
@@ -168,13 +166,11 @@ __FBSDID("$FreeBSD$");
#define PMAP_SHPGPERPROC 200
#endif
-#if defined(DIAGNOSTIC)
-#define PMAP_DIAGNOSTIC
-#endif
+#define DIAGNOSTIC
-#if !defined(PMAP_DIAGNOSTIC)
+#if !defined(DIAGNOSTIC)
#ifdef __GNUC_GNU_INLINE__
-#define PMAP_INLINE inline
+#define PMAP_INLINE __attribute__((__gnu_inline__)) inline
#else
#define PMAP_INLINE extern inline
#endif
@@ -298,6 +294,9 @@ SYSCTL_ULONG(_vm_pmap_pde, OID_AUTO, map
static void free_pv_entry(pmap_t pmap, pv_entry_t pv);
static pv_entry_t get_pv_entry(pmap_t locked_pmap, int try);
+static void pmap_pvh_free(struct md_page *pvh, pmap_t pmap, vm_offset_t va);
+static pv_entry_t pmap_pvh_remove(struct md_page *pvh, pmap_t pmap,
+ vm_offset_t va);
static vm_page_t pmap_enter_quick_locked(multicall_entry_t **mcl, int *count, pmap_t pmap, vm_offset_t va,
vm_page_t m, vm_prot_t prot, vm_page_t mpte);
@@ -307,7 +306,6 @@ static void pmap_remove_page(struct pmap
vm_page_t *free);
static void pmap_remove_entry(struct pmap *pmap, vm_page_t m,
vm_offset_t va);
-static void pmap_insert_entry(pmap_t pmap, vm_offset_t va, vm_page_t m);
static boolean_t pmap_try_insert_pv_entry(pmap_t pmap, vm_offset_t va,
vm_page_t m);
@@ -2073,12 +2071,8 @@ pmap_collect(pmap_t locked_pmap, struct
("pmap_collect: wired pte %#jx", (uintmax_t)tpte));
if (tpte & PG_A)
vm_page_flag_set(m, PG_REFERENCED);
- if (tpte & PG_M) {
- KASSERT((tpte & PG_RW),
- ("pmap_collect: modified page not writable: va: %#x, pte: %#jx",
- va, (uintmax_t)tpte));
+ if ((tpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
vm_page_dirty(m);
- }
free = NULL;
pmap_unuse_pt(pmap, va, &free);
pmap_invalidate_page(pmap, va);
@@ -2229,38 +2223,39 @@ retry:
return (pv);
}
-static void
-pmap_remove_entry(pmap_t pmap, vm_page_t m, vm_offset_t va)
+static __inline pv_entry_t
+pmap_pvh_remove(struct md_page *pvh, pmap_t pmap, vm_offset_t va)
{
pv_entry_t pv;
- PMAP_LOCK_ASSERT(pmap, MA_OWNED);
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
- TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
- if (pmap == PV_PMAP(pv) && va == pv->pv_va)
+ TAILQ_FOREACH(pv, &pvh->pv_list, pv_list) {
+ if (pmap == PV_PMAP(pv) && va == pv->pv_va) {
+ TAILQ_REMOVE(&pvh->pv_list, pv, pv_list);
break;
+ }
}
- KASSERT(pv != NULL, ("pmap_remove_entry: pv not found"));
- TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
- if (TAILQ_EMPTY(&m->md.pv_list))
- vm_page_flag_clear(m, PG_WRITEABLE);
- free_pv_entry(pmap, pv);
+ return (pv);
}
-/*
- * Create a pv entry for page at pa for
- * (pmap, va).
- */
static void
-pmap_insert_entry(pmap_t pmap, vm_offset_t va, vm_page_t m)
+pmap_pvh_free(struct md_page *pvh, pmap_t pmap, vm_offset_t va)
{
pv_entry_t pv;
- PMAP_LOCK_ASSERT(pmap, MA_OWNED);
+ pv = pmap_pvh_remove(pvh, pmap, va);
+ KASSERT(pv != NULL, ("pmap_pvh_free: pv not found"));
+ free_pv_entry(pmap, pv);
+}
+
+static void
+pmap_remove_entry(pmap_t pmap, vm_page_t m, vm_offset_t va)
+{
+
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
- pv = get_pv_entry(pmap, FALSE);
- pv->pv_va = va;
- TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
+ pmap_pvh_free(&m->md, pmap, va);
+ if (TAILQ_EMPTY(&m->md.pv_list))
+ vm_page_flag_clear(m, PG_WRITEABLE);
}
/*
@@ -2320,12 +2315,8 @@ pmap_remove_pte(pmap_t pmap, pt_entry_t
if (!(oldpte & PG_MANAGED))
printf("va=0x%x is unmanaged :-( pte=0x%llx\n", va, oldpte);
- if (oldpte & PG_M) {
- KASSERT((oldpte & PG_RW),
- ("pmap_remove_pte: modified page not writable: va: %#x, pte: %#jx",
- va, (uintmax_t)oldpte));
+ if ((oldpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
vm_page_dirty(m);
- }
if (oldpte & PG_A)
vm_page_flag_set(m, PG_REFERENCED);
pmap_remove_entry(pmap, m, va);
@@ -2487,6 +2478,7 @@ pmap_remove_all(vm_page_t m)
KASSERT((m->flags & PG_FICTITIOUS) == 0,
("pmap_remove_all: page %p is fictitious", m));
+ free = NULL;
vm_page_lock_queues();
sched_pin();
while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
@@ -2505,16 +2497,10 @@ pmap_remove_all(vm_page_t m)
/*
* Update the vm_page_t clean and reference bits.
*/
- if (tpte & PG_M) {
- KASSERT((tpte & PG_RW),
- ("pmap_remove_all: modified page not writable: va: %#x, pte: %#jx",
- pv->pv_va, (uintmax_t)tpte));
+ if ((tpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
vm_page_dirty(m);
- }
- free = NULL;
pmap_unuse_pt(pmap, pv->pv_va, &free);
pmap_invalidate_page(pmap, pv->pv_va);
- pmap_free_zero_pages(free);
TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
free_pv_entry(pmap, pv);
PMAP_UNLOCK(pmap);
@@ -2525,6 +2511,7 @@ pmap_remove_all(vm_page_t m)
PT_SET_MA(PADDR1, 0);
sched_unpin();
vm_page_unlock_queues();
+ pmap_free_zero_pages(free);
}
/*
@@ -2671,19 +2658,19 @@ void
pmap_enter(pmap_t pmap, vm_offset_t va, vm_prot_t access, vm_page_t m,
vm_prot_t prot, boolean_t wired)
{
- vm_paddr_t pa;
pd_entry_t *pde;
pt_entry_t *pte;
- vm_paddr_t opa;
- pt_entry_t origpte, newpte;
+ pt_entry_t newpte, origpte;
+ pv_entry_t pv;
+ vm_paddr_t opa, pa;
vm_page_t mpte, om;
boolean_t invlva;
CTR6(KTR_PMAP, "pmap_enter: pmap=%08p va=0x%08x access=0x%x ma=0x%08x prot=0x%x wired=%d",
pmap, va, access, xpmap_ptom(VM_PAGE_TO_PHYS(m)), prot, wired);
va = trunc_page(va);
- KASSERT(va <= VM_MAX_KERNEL_ADDRESS, ("pmap_enter: toobig"));
- KASSERT(va < UPT_MIN_ADDRESS || va >= UPT_MAX_ADDRESS,
+ KASSERT(va <= VM_MAX_KERNEL_ADDRESS, ("pmap_enter: toobig"));
+ KASSERT(va < UPT_MIN_ADDRESS || va >= UPT_MAX_ADDRESS,
("pmap_enter: invalid to pmap_enter page table pages (va: 0x%x)",
va));
KASSERT((m->oflags & VPO_BUSY) != 0,
@@ -2702,16 +2689,6 @@ pmap_enter(pmap_t pmap, vm_offset_t va,
if (va < VM_MAXUSER_ADDRESS) {
mpte = pmap_allocpte(pmap, va, M_WAITOK);
}
-#if 0 && defined(PMAP_DIAGNOSTIC)
- else {
- pd_entry_t *pdeaddr = pmap_pde(pmap, va);
- origpte = *pdeaddr;
- if ((origpte & PG_V) == 0) {
- panic("pmap_enter: invalid kernel page table page, pdir=%p, pde=%p, va=%p\n",
- pmap->pm_pdir[PTDPTDI], origpte, va);
- }
- }
-#endif
pde = pmap_pde(pmap, va);
if ((*pde & PG_PS) != 0)
@@ -2722,7 +2699,7 @@ pmap_enter(pmap_t pmap, vm_offset_t va,
* Page Directory table entry not valid, we need a new PT page
*/
if (pte == NULL) {
- panic("pmap_enter: invalid page directory pdir=%#jx, va=%#x\n",
+ panic("pmap_enter: invalid page directory pdir=%#jx, va=%#x",
(uintmax_t)pmap->pm_pdir[va >> PDRSHIFT], va);
}
@@ -2770,6 +2747,9 @@ pmap_enter(pmap_t pmap, vm_offset_t va,
}
goto validate;
}
+
+ pv = NULL;
+
/*
* Mapping has changed, invalidate old range and fall through to
* handle validating new mapping.
@@ -2779,7 +2759,7 @@ pmap_enter(pmap_t pmap, vm_offset_t va,
pmap->pm_stats.wired_count--;
if (origpte & PG_MANAGED) {
om = PHYS_TO_VM_PAGE(opa);
- pmap_remove_entry(pmap, om, va);
+ pv = pmap_pvh_remove(&om->md, pmap, va);
} else if (va < VM_MAXUSER_ADDRESS)
printf("va=0x%x is unmanaged :-( \n", va);
@@ -2798,9 +2778,13 @@ pmap_enter(pmap_t pmap, vm_offset_t va,
if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0) {
KASSERT(va < kmi.clean_sva || va >= kmi.clean_eva,
("pmap_enter: managed mapping within the clean submap"));
- pmap_insert_entry(pmap, va, m);
+ if (pv == NULL)
+ pv = get_pv_entry(pmap, FALSE);
+ pv->pv_va = va;
+ TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
pa |= PG_MANAGED;
- }
+ } else if (pv != NULL)
+ free_pv_entry(pmap, pv);
/*
* Increment counters
@@ -2815,7 +2799,8 @@ validate:
newpte = (pt_entry_t)(pa | PG_V);
if ((prot & VM_PROT_WRITE) != 0) {
newpte |= PG_RW;
- vm_page_flag_set(m, PG_WRITEABLE);
+ if ((newpte & PG_MANAGED) != 0)
+ vm_page_flag_set(m, PG_WRITEABLE);
}
#ifdef PAE
if ((prot & VM_PROT_EXECUTE) == 0)
@@ -2849,15 +2834,15 @@ validate:
invlva = TRUE;
#endif
}
- if (origpte & PG_M) {
- KASSERT((origpte & PG_RW),
- ("pmap_enter: modified page not writable: va: %#x, pte: %#jx",
- va, (uintmax_t)origpte));
+ if ((origpte & (PG_M | PG_RW)) == (PG_M | PG_RW)) {
if ((origpte & PG_MANAGED) != 0)
vm_page_dirty(om);
if ((prot & VM_PROT_WRITE) == 0)
invlva = TRUE;
}
+ if ((origpte & PG_MANAGED) != 0 &&
+ TAILQ_EMPTY(&om->md.pv_list))
+ vm_page_flag_clear(om, PG_WRITEABLE);
if (invlva)
pmap_invalidate_page(pmap, va);
} else{
@@ -3270,8 +3255,8 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pm
pd_entry_t srcptepaddr;
unsigned ptepindex;
- if (addr >= UPT_MIN_ADDRESS)
- panic("pmap_copy: invalid to pmap_copy page tables");
+ KASSERT(addr < UPT_MIN_ADDRESS,
+ ("pmap_copy: invalid to pmap_copy page tables"));
pdnxt = (addr + NBPDR) & ~PDRMASK;
ptepindex = addr >> PDRSHIFT;
@@ -3290,8 +3275,8 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pm
}
srcmpte = PHYS_TO_VM_PAGE(srcptepaddr & PG_FRAME);
- if (srcmpte->wire_count == 0)
- panic("pmap_copy: source page table page is unused");
+ KASSERT(srcmpte->wire_count > 0,
+ ("pmap_copy: source page table page is unused"));
if (pdnxt > end_addr)
pdnxt = end_addr;
More information about the svn-src-head
mailing list