On 04/11/20(Wed) 11:04, Martin Pieuchot wrote:
> Diff below introduces a helper that looks for existing mapping. The
> value returned by this lookup function determines if there's an anon
> at the faulting address which tells us if we're dealign with a fault
> of type 1 or 2.
>
> This small refactoring is part of the current work to separate the code
> handling faults of type 1 and 2. The end goal being to move the type 1
> faults handling out of the KERNEL_LOCK().
>
> The function name is taken from NetBSD to not introduce more difference
> than there's already.
New diff now that the other one has been committed, ok?
Index: uvm/uvm_fault.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_fault.c,v
retrieving revision 1.105
diff -u -p -r1.105 uvm_fault.c
--- uvm/uvm_fault.c 13 Nov 2020 11:16:08 -0000 1.105
+++ uvm/uvm_fault.c 13 Nov 2020 11:17:52 -0000
@@ -801,6 +801,84 @@ uvm_fault_upper(struct uvm_faultinfo *uf
return 0;
}
+
+/*
+ * uvm_fault_upper_lookup: look up existing h/w mapping and amap.
+ *
+ * iterate range of interest:
+ * 1. check if h/w mapping exists. if yes, we don't care
+ * 2. check if anon exists. if not, page is lower.
+ * 3. if anon exists, enter h/w mapping for neighbors.
+ */
+boolean_t
+uvm_fault_upper_lookup(struct uvm_faultinfo *ufi,
+ const struct uvm_faultctx *flt, struct vm_anon **anons,
+ struct vm_page **pages)
+{
+ struct vm_amap *amap = ufi->entry->aref.ar_amap;
+ struct vm_anon *anon;
+ boolean_t shadowed;
+ vaddr_t currva;
+ paddr_t pa;
+ int lcv;
+
+ /*
+ * map in the backpages and frontpages we found in the amap in hopes
+ * of preventing future faults. we also init the pages[] array as
+ * we go.
+ */
+ currva = flt->startva;
+ shadowed = FALSE;
+ for (lcv = 0 ; lcv < flt->npages ; lcv++, currva += PAGE_SIZE) {
+ /*
+ * dont play with VAs that are already mapped
+ * except for center)
+ */
+ if (lcv != flt->centeridx &&
+ pmap_extract(ufi->orig_map->pmap, currva, &pa)) {
+ pages[lcv] = PGO_DONTCARE;
+ continue;
+ }
+
+ /* unmapped or center page. check if any anon at this level. */
+ if (amap == NULL || anons[lcv] == NULL) {
+ pages[lcv] = NULL;
+ continue;
+ }
+
+ /* check for present page and map if possible. re-activate it */
+ pages[lcv] = PGO_DONTCARE;
+ if (lcv == flt->centeridx) { /* save center for later! */
+ shadowed = TRUE;
+ continue;
+ }
+ anon = anons[lcv];
+ if (anon->an_page &&
+ (anon->an_page->pg_flags & (PG_RELEASED|PG_BUSY)) == 0) {
+ uvm_lock_pageq();
+ uvm_pageactivate(anon->an_page); /* reactivate */
+ uvm_unlock_pageq();
+ uvmexp.fltnamap++;
+
+ /*
+ * Since this isn't the page that's actually faulting,
+ * ignore pmap_enter() failures; it's not critical
+ * that we enter these right now.
+ */
+ (void) pmap_enter(ufi->orig_map->pmap, currva,
+ VM_PAGE_TO_PHYS(anon->an_page) | flt->pa_flags,
+ (anon->an_ref > 1) ?
+ (flt->enter_prot & ~PROT_WRITE) : flt->enter_prot,
+ PMAP_CANFAIL |
+ (VM_MAPENT_ISWIRED(ufi->entry) ? PMAP_WIRED : 0));
+ }
+ }
+ if (flt->npages > 1)
+ pmap_update(ufi->orig_map->pmap);
+
+ return shadowed;
+}
+
/*
* F A U L T - m a i n e n t r y p o i n t
*/
@@ -827,7 +905,6 @@ uvm_fault(vm_map_t orig_map, vaddr_t vad
int result, lcv, gotpages;
vaddr_t currva;
voff_t uoff;
- paddr_t pa;
struct vm_amap *amap;
struct uvm_object *uobj;
struct vm_anon *anons_store[UVM_MAXRANGE], **anons, *anon;
@@ -868,61 +945,9 @@ ReFault:
amap = ufi.entry->aref.ar_amap;
uobj = ufi.entry->object.uvm_obj;
- /*
- * map in the backpages and frontpages we found in the amap in hopes
- * of preventing future faults. we also init the pages[] array as
- * we go.
- */
- currva = flt.startva;
- shadowed = FALSE;
- for (lcv = 0 ; lcv < flt.npages ; lcv++, currva += PAGE_SIZE) {
- /*
- * dont play with VAs that are already mapped
- * except for center)
- */
- if (lcv != flt.centeridx &&
- pmap_extract(ufi.orig_map->pmap, currva, &pa)) {
- pages[lcv] = PGO_DONTCARE;
- continue;
- }
-
- /* unmapped or center page. check if any anon at this level.
*/
- if (amap == NULL || anons[lcv] == NULL) {
- pages[lcv] = NULL;
- continue;
- }
-
- /* check for present page and map if possible. re-activate
it. */
- pages[lcv] = PGO_DONTCARE;
- if (lcv == flt.centeridx) { /* save center for later! */
- shadowed = TRUE;
- continue;
- }
- anon = anons[lcv];
- if (anon->an_page &&
- (anon->an_page->pg_flags & (PG_RELEASED|PG_BUSY)) == 0) {
- uvm_lock_pageq();
- uvm_pageactivate(anon->an_page); /* reactivate */
- uvm_unlock_pageq();
- uvmexp.fltnamap++;
-
- /*
- * Since this isn't the page that's actually faulting,
- * ignore pmap_enter() failures; it's not critical
- * that we enter these right now.
- */
- (void) pmap_enter(ufi.orig_map->pmap, currva,
- VM_PAGE_TO_PHYS(anon->an_page) | flt.pa_flags,
- (anon->an_ref > 1) ?
- (flt.enter_prot & ~PROT_WRITE) : flt.enter_prot,
- PMAP_CANFAIL |
- (VM_MAPENT_ISWIRED(ufi.entry) ? PMAP_WIRED : 0));
- }
- }
- if (flt.npages > 1)
- pmap_update(ufi.orig_map->pmap);
-
/* (shadowed == TRUE) if there is an anon at the faulting address */
+ shadowed = uvm_fault_upper_lookup(&ufi, &flt, anons, pages);
+
/*
* if the desired page is not shadowed by the amap and we have a
* backing object, then we check to see if the backing object would
