Date: Mon, 1 Jul 2019 22:00:42 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r349585 - head/sys/amd64/amd64 Message-ID: <201907012200.x61M0hiN035637@repo.freebsd.org>
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Author: alc Date: Mon Jul 1 22:00:42 2019 New Revision: 349585 URL: https://svnweb.freebsd.org/changeset/base/349585 Log: Tidy up pmap_copy(). Notably, deindent the innermost loop by making a simple change to the control flow. Replace an unnecessary test by a KASSERT. Add a comment explaining an obscure test. Reviewed by: kib, markj MFC after: 3 weeks Differential Revision: https://reviews.freebsd.org/D20812 Modified: head/sys/amd64/amd64/pmap.c Modified: head/sys/amd64/amd64/pmap.c ============================================================================== --- head/sys/amd64/amd64/pmap.c Mon Jul 1 21:50:53 2019 (r349584) +++ head/sys/amd64/amd64/pmap.c Mon Jul 1 22:00:42 2019 (r349585) @@ -6345,18 +6345,18 @@ pmap_unwire(pmap_t pmap, vm_offset_t sva, vm_offset_t * * This routine is only advisory and need not do anything. */ - void pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len, vm_offset_t src_addr) { struct rwlock *lock; struct spglist free; - vm_offset_t addr; - vm_offset_t end_addr = src_addr + len; - vm_offset_t va_next; + pml4_entry_t *pml4e; + pdp_entry_t *pdpe; + pd_entry_t *pde, srcptepaddr; + pt_entry_t *dst_pte, PG_A, PG_M, PG_V, ptetemp, *src_pte; + vm_offset_t addr, end_addr, va_next; vm_page_t dst_pdpg, dstmpte, srcmpte; - pt_entry_t PG_A, PG_M, PG_V; if (dst_addr != src_addr) return; @@ -6375,6 +6375,7 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_ if (pmap_emulate_ad_bits(dst_pmap)) return; + end_addr = src_addr + len; lock = NULL; if (dst_pmap < src_pmap) { PMAP_LOCK(dst_pmap); @@ -6389,11 +6390,6 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_ PG_V = pmap_valid_bit(dst_pmap); for (addr = src_addr; addr < end_addr; addr = va_next) { - pt_entry_t *src_pte, *dst_pte; - pml4_entry_t *pml4e; - pdp_entry_t *pdpe; - pd_entry_t srcptepaddr, *pde; - KASSERT(addr < UPT_MIN_ADDRESS, ("pmap_copy: invalid to pmap_copy page tables")); @@ -6435,7 +6431,8 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_ pmap_pv_insert_pde(dst_pmap, addr, srcptepaddr, PMAP_ENTER_NORECLAIM, &lock))) { *pde = srcptepaddr & ~PG_W; - pmap_resident_count_inc(dst_pmap, NBPDR / PAGE_SIZE); + pmap_resident_count_inc(dst_pmap, NBPDR / + PAGE_SIZE); atomic_add_long(&pmap_pde_mappings, 1); } else dst_pdpg->wire_count--; @@ -6453,58 +6450,54 @@ pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_ src_pte = (pt_entry_t *)PHYS_TO_DMAP(srcptepaddr); src_pte = &src_pte[pmap_pte_index(addr)]; dstmpte = NULL; - while (addr < va_next) { - pt_entry_t ptetemp; + for (; addr < va_next; addr += PAGE_SIZE, src_pte++) { ptetemp = *src_pte; + /* - * we only virtual copy managed pages + * We only virtual copy managed pages. */ - if ((ptetemp & PG_MANAGED) != 0) { - if (dstmpte != NULL && - dstmpte->pindex == pmap_pde_pindex(addr)) - dstmpte->wire_count++; - else if ((dstmpte = pmap_allocpte(dst_pmap, - addr, NULL)) == NULL) - goto out; - dst_pte = (pt_entry_t *) - PHYS_TO_DMAP(VM_PAGE_TO_PHYS(dstmpte)); - dst_pte = &dst_pte[pmap_pte_index(addr)]; - if (*dst_pte == 0 && - pmap_try_insert_pv_entry(dst_pmap, addr, - PHYS_TO_VM_PAGE(ptetemp & PG_FRAME), - &lock)) { + if ((ptetemp & PG_MANAGED) == 0) + continue; + + if (dstmpte != NULL) { + KASSERT(dstmpte->pindex == + pmap_pde_pindex(addr), + ("dstmpte pindex/addr mismatch")); + dstmpte->wire_count++; + } else if ((dstmpte = pmap_allocpte(dst_pmap, addr, + NULL)) == NULL) + goto out; + dst_pte = (pt_entry_t *) + PHYS_TO_DMAP(VM_PAGE_TO_PHYS(dstmpte)); + dst_pte = &dst_pte[pmap_pte_index(addr)]; + if (*dst_pte == 0 && + pmap_try_insert_pv_entry(dst_pmap, addr, + PHYS_TO_VM_PAGE(ptetemp & PG_FRAME), &lock)) { + /* + * Clear the wired, modified, and accessed + * (referenced) bits during the copy. + */ + *dst_pte = ptetemp & ~(PG_W | PG_M | PG_A); + pmap_resident_count_inc(dst_pmap, 1); + } else { + SLIST_INIT(&free); + if (pmap_unwire_ptp(dst_pmap, addr, dstmpte, + &free)) { /* - * Clear the wired, modified, and - * accessed (referenced) bits - * during the copy. + * Although "addr" is not mapped, + * paging-structure caches could + * nonetheless have entries that refer + * to the freed page table pages. + * Invalidate those entries. */ - *dst_pte = ptetemp & ~(PG_W | PG_M | - PG_A); - pmap_resident_count_inc(dst_pmap, 1); - } else { - SLIST_INIT(&free); - if (pmap_unwire_ptp(dst_pmap, addr, - dstmpte, &free)) { - /* - * Although "addr" is not - * mapped, paging-structure - * caches could nonetheless - * have entries that refer to - * the freed page table pages. - * Invalidate those entries. - */ - pmap_invalidate_page(dst_pmap, - addr); - vm_page_free_pages_toq(&free, - true); - } - goto out; + pmap_invalidate_page(dst_pmap, addr); + vm_page_free_pages_toq(&free, true); } - if (dstmpte->wire_count >= srcmpte->wire_count) - break; + goto out; } - addr += PAGE_SIZE; - src_pte++; + /* Have we copied all of the valid mappings? */ + if (dstmpte->wire_count >= srcmpte->wire_count) + break; } } out:
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