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Code Issues Releases Activity

Three changes to pmap_enter():

Browse Source 
1. Use _pmap_alloc_l3() instead of pmap_alloc_l3() in order to handle the
possibility that a superpage mapping for "va" was created while we slept.
(This is derived from the amd64 version.)

2. Eliminate code for allocating kernel page table pages.  Kernel page
table pages are preallocated by pmap_growkernel().

3. Eliminate duplicated unlock operations when KERN_RESOURCE_SHORTAGE is
returned.

MFC after:	2 weeks
This commit is contained in:
Alan Cox 2019-07-07 06:06:48 +00:00
parent 8c95181495
commit b9e19259d7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=349798
1 changed files with 30 additions and 75 deletions
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105
sys/arm64/arm64/pmap.c
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@ -3134,8 +3134,8 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
pt_entry_t new_l3, orig_l3;
pt_entry_t *l2, *l3;
pv_entry_t pv;
vm_paddr_t opa, pa, l1_pa, l2_pa, l3_pa;
vm_page_t mpte, om, l1_m, l2_m, l3_m;
vm_paddr_t opa, pa;
vm_page_t mpte, om;
boolean_t nosleep;
int lvl, rv;
@ -3159,7 +3159,6 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
CTR2(KTR_PMAP, "pmap_enter: %.16lx -> %.16lx", va, pa);
lock = NULL;
mpte = NULL;
PMAP_LOCK(pmap);
if (psind == 1) {
/* Assert the required virtual and physical alignment. */
@ -3169,9 +3168,22 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
flags, m, &lock);
goto out;
}
mpte = NULL;
/*
* In the case that a page table page is not
* resident, we are creating it here.
*/
retry:
pde = pmap_pde(pmap, va, &lvl);
if (pde != NULL && lvl == 1) {
if (pde != NULL && lvl == 2) {
l3 = pmap_l2_to_l3(pde, va);
if (va < VM_MAXUSER_ADDRESS && mpte == NULL) {
mpte = PHYS_TO_VM_PAGE(pmap_load(pde) & ~ATTR_MASK);
mpte->wire_count++;
}
goto havel3;
} else if (pde != NULL && lvl == 1) {
l2 = pmap_l1_to_l2(pde, va);
if ((pmap_load(l2) & ATTR_DESCR_MASK) == L2_BLOCK &&
(l3 = pmap_demote_l2_locked(pmap, l2, va, &lock)) != NULL) {
@ -3183,83 +3195,26 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
}
goto havel3;
}
/* We need to allocate an L3 table. */
}
if (va < VM_MAXUSER_ADDRESS) {
nosleep = (flags & PMAP_ENTER_NOSLEEP) != 0;
mpte = pmap_alloc_l3(pmap, va, nosleep ? NULL : &lock);
/*
* We use _pmap_alloc_l3() instead of pmap_alloc_l3() in order
* to handle the possibility that a superpage mapping for "va"
* was created while we slept.
*/
mpte = _pmap_alloc_l3(pmap, pmap_l2_pindex(va),
nosleep ? NULL : &lock);
if (mpte == NULL && nosleep) {
CTR0(KTR_PMAP, "pmap_enter: mpte == NULL");
if (lock != NULL)
rw_wunlock(lock);
PMAP_UNLOCK(pmap);
return (KERN_RESOURCE_SHORTAGE);
rv = KERN_RESOURCE_SHORTAGE;
goto out;
}
pde = pmap_pde(pmap, va, &lvl);
KASSERT(pde != NULL,
("pmap_enter: Invalid page entry, va: 0x%lx", va));
KASSERT(lvl == 2,
("pmap_enter: Invalid level %d", lvl));
} else {
/*
* If we get a level 2 pde it must point to a level 3 entry
* otherwise we will need to create the intermediate tables
*/
if (lvl < 2) {
switch (lvl) {
default:
case -1:
/* Get the l0 pde to update */
pde = pmap_l0(pmap, va);
KASSERT(pde != NULL, ("..."));
l1_m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
VM_ALLOC_NOOBJ | VM_ALLOC_WIRED |
VM_ALLOC_ZERO);
if (l1_m == NULL)
panic("pmap_enter: l1 pte_m == NULL");
if ((l1_m->flags & PG_ZERO) == 0)
pmap_zero_page(l1_m);
l1_pa = VM_PAGE_TO_PHYS(l1_m);
pmap_load_store(pde, l1_pa | L0_TABLE);
/* FALLTHROUGH */
case 0:
/* Get the l1 pde to update */
pde = pmap_l1_to_l2(pde, va);
KASSERT(pde != NULL, ("..."));
l2_m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
VM_ALLOC_NOOBJ | VM_ALLOC_WIRED |
VM_ALLOC_ZERO);
if (l2_m == NULL)
panic("pmap_enter: l2 pte_m == NULL");
if ((l2_m->flags & PG_ZERO) == 0)
pmap_zero_page(l2_m);
l2_pa = VM_PAGE_TO_PHYS(l2_m);
pmap_load_store(pde, l2_pa | L1_TABLE);
/* FALLTHROUGH */
case 1:
/* Get the l2 pde to update */
pde = pmap_l1_to_l2(pde, va);
KASSERT(pde != NULL, ("..."));
l3_m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
VM_ALLOC_NOOBJ | VM_ALLOC_WIRED |
VM_ALLOC_ZERO);
if (l3_m == NULL)
panic("pmap_enter: l3 pte_m == NULL");
if ((l3_m->flags & PG_ZERO) == 0)
pmap_zero_page(l3_m);
l3_pa = VM_PAGE_TO_PHYS(l3_m);
pmap_load_store(pde, l3_pa | L2_TABLE);
break;
}
}
}
l3 = pmap_l2_to_l3(pde, va);
goto retry;
} else
panic("pmap_enter: missing L3 table for kernel va %#lx", va);
havel3:
orig_l3 = pmap_load(l3);