> Date: Fri, 13 Nov 2020 08:19:03 -0300
> From: Martin Pieuchot <[email protected]>
>
> 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?
ok kettenis@
> 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
>
>
