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Merge various changes from i386/i386/pmap.c:

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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().
This commit is contained in:
Alan Cox 2010-05-30 04:44:32 +00:00
parent 4affd62610
commit a1192299b3
1 changed files with 57 additions and 72 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

129
sys/i386/xen/pmap.c
View File

@ -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, mappings, CTLFLAG_RD,
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 *pmap, vm_offset_t va,
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 vpgqueues *vpq)
("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);
return (pv);
}
static void
pmap_pvh_free(struct md_page *pvh, pmap_t pmap, vm_offset_t va)
{
pv_entry_t pv;
pv = pmap_pvh_remove(pvh, pmap, va);
KASSERT(pv != NULL, ("pmap_pvh_free: pv not found"));
free_pv_entry(pmap, 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_remove_entry(pmap_t pmap, vm_page_t m, vm_offset_t va)
{
pv_entry_t pv;
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
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 *ptq, vm_offset_t va, vm_page_t *free)
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, vm_prot_t access, vm_page_t m,
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, vm_prot_t access, vm_page_t m,
* 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, vm_prot_t access, vm_page_t m,
}
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, vm_prot_t access, vm_page_t m,
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, vm_prot_t access, vm_page_t m,
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_pmap, vm_offset_t dst_addr, vm_size_t len,
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_pmap, vm_offset_t dst_addr, vm_size_t len,
}
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;