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Correctly implement PMAP_ENTER_NOREPLACE in pmap_enter_{l2,pde}() on kernel

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mappings.

Reduce code duplication by defining a function, pmap_abort_ptp(), for
handling a common error case.

Simplify error handling in pmap_enter_quick_locked().

Reviewed by:	kib
Tested by:	pho
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D22890
This commit is contained in:
Alan Cox 2019-12-29 05:36:01 +00:00
parent 2d581b3a7c
commit e1ab406007
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=356168
1 changed files with 60 additions and 32 deletions
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92
sys/i386/i386/pmap.c
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@ -314,6 +314,7 @@ static pv_entry_t pmap_pvh_remove(struct md_page *pvh, pmap_t pmap,
vm_offset_t va);
static int pmap_pvh_wired_mappings(struct md_page *pvh, int count);
static void pmap_abort_ptp(pmap_t pmap, vm_offset_t va, vm_page_t mpte);
static boolean_t pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va);
static bool pmap_enter_4mpage(pmap_t pmap, vm_offset_t va, vm_page_t m,
vm_prot_t prot);
@ -2007,6 +2008,27 @@ pmap_unuse_pt(pmap_t pmap, vm_offset_t va, struct spglist *free)
return (pmap_unwire_ptp(pmap, mpte, free));
}
/*
* Release a page table page reference after a failed attempt to create a
* mapping.
*/
static void
pmap_abort_ptp(pmap_t pmap, vm_offset_t va, vm_page_t mpte)
{
struct spglist free;
SLIST_INIT(&free);
if (pmap_unwire_ptp(pmap, mpte, &free)) {
/*
* Although "va" was never mapped, paging-structure caches
* could nonetheless have entries that refer to the freed
* page table pages. Invalidate those entries.
*/
pmap_invalidate_page_int(pmap, va);
vm_page_free_pages_toq(&free, true);
}
}
/*
* Initialize the pmap for the swapper process.
*/
@ -3894,6 +3916,24 @@ pmap_enter_4mpage(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot)
KERN_SUCCESS);
}
/*
* Returns true if every page table entry in the page table page that maps
* the specified kernel virtual address is zero.
*/
static bool
pmap_every_pte_zero(vm_offset_t va)
{
pt_entry_t *pt_end, *pte;
KASSERT((va & PDRMASK) == 0, ("va is misaligned"));
pte = vtopte(va);
for (pt_end = pte + NPTEPG; pte < pt_end; pte++) {
if (*pte != 0)
return (false);
}
return (true);
}
/*
* Tries to create the specified 2 or 4 MB page mapping. Returns KERN_SUCCESS
* if the mapping was created, and either KERN_FAILURE or
@ -3921,7 +3961,9 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, pd_entry_t newpde, u_int flags,
pde = pmap_pde(pmap, va);
oldpde = *pde;
if ((oldpde & PG_V) != 0) {
if ((flags & PMAP_ENTER_NOREPLACE) != 0) {
if ((flags & PMAP_ENTER_NOREPLACE) != 0 && (pmap !=
kernel_pmap || (oldpde & PG_PS) != 0 ||
!pmap_every_pte_zero(va))) {
CTR2(KTR_PMAP, "pmap_enter_pde: failure for va %#lx"
" in pmap %p", va, pmap);
return (KERN_FAILURE);
@ -3940,8 +3982,14 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, pd_entry_t newpde, u_int flags,
if (pmap_remove_ptes(pmap, va, va + NBPDR, &free))
pmap_invalidate_all_int(pmap);
}
vm_page_free_pages_toq(&free, true);
if (pmap == kernel_pmap) {
if (pmap != kernel_pmap) {
vm_page_free_pages_toq(&free, true);
KASSERT(*pde == 0, ("pmap_enter_pde: non-zero pde %p",
pde));
} else {
KASSERT(SLIST_EMPTY(&free),
("pmap_enter_pde: freed kernel page table page"));
/*
* Both pmap_remove_pde() and pmap_remove_ptes() will
* leave the kernel page table page zero filled.
@ -3949,9 +3997,7 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, pd_entry_t newpde, u_int flags,
mt = PHYS_TO_VM_PAGE(*pde & PG_FRAME);
if (pmap_insert_pt_page(pmap, mt, false))
panic("pmap_enter_pde: trie insert failed");
} else
KASSERT(*pde == 0, ("pmap_enter_pde: non-zero pde %p",
pde));
}
}
if ((newpde & PG_MANAGED) != 0) {
/*
@ -3982,8 +4028,8 @@ pmap_enter_pde(pmap_t pmap, vm_offset_t va, pd_entry_t newpde, u_int flags,
pde_store(pde, newpde);
pmap_pde_mappings++;
CTR2(KTR_PMAP, "pmap_enter_pde: success for va %#lx"
" in pmap %p", va, pmap);
CTR2(KTR_PMAP, "pmap_enter_pde: success for va %#lx in pmap %p",
va, pmap);
return (KERN_SUCCESS);
}
@ -4055,7 +4101,6 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
vm_prot_t prot, vm_page_t mpte)
{
pt_entry_t newpte, *pte;
struct spglist free;
KASSERT(pmap != kernel_pmap || va < kmi.clean_sva ||
va >= kmi.clean_eva || (m->oflags & VPO_UNMANAGED) != 0,
@ -4106,12 +4151,10 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
sched_pin();
pte = pmap_pte_quick(pmap, va);
if (*pte) {
if (mpte != NULL) {
if (mpte != NULL)
mpte->ref_count--;
mpte = NULL;
}
sched_unpin();
return (mpte);
return (NULL);
}
/*
@ -4119,17 +4162,10 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
*/
if ((m->oflags & VPO_UNMANAGED) == 0 &&
!pmap_try_insert_pv_entry(pmap, va, m)) {
if (mpte != NULL) {
SLIST_INIT(&free);
if (pmap_unwire_ptp(pmap, mpte, &free)) {
pmap_invalidate_page_int(pmap, va);
vm_page_free_pages_toq(&free, true);
}
mpte = NULL;
}
if (mpte != NULL)
pmap_abort_ptp(pmap, va, mpte);
sched_unpin();
return (mpte);
return (NULL);
}
/*
@ -4351,7 +4387,6 @@ static void
__CONCAT(PMTYPE, copy)(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr,
vm_size_t len, vm_offset_t src_addr)
{
struct spglist free;
pt_entry_t *src_pte, *dst_pte, ptetemp;
pd_entry_t srcptepaddr;
vm_page_t dstmpte, srcmpte;
@ -4432,14 +4467,7 @@ __CONCAT(PMTYPE, copy)(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr,
PG_A);
dst_pmap->pm_stats.resident_count++;
} else {
SLIST_INIT(&free);
if (pmap_unwire_ptp(dst_pmap, dstmpte,
&free)) {
pmap_invalidate_page_int(
dst_pmap, addr);
vm_page_free_pages_toq(&free,
true);
}
pmap_abort_ptp(dst_pmap, addr, dstmpte);
goto out;
}
if (dstmpte->ref_count >= srcmpte->ref_count)