Author: gber Date: Tue Jun 4 09:21:18 2013 New Revision: 251370 URL: http://svnweb.freebsd.org/changeset/base/251370
Log: Implement pmap_copy() for ARMv6/v7. Copy the given range of mappings from the source map to the destination map, thereby reducing the number of VM faults on fork. Submitted by: Zbigniew Bodek <[email protected]> Sponsored by: The FreeBSD Foundation, Semihalf Modified: head/sys/arm/arm/pmap-v6.c Modified: head/sys/arm/arm/pmap-v6.c ============================================================================== --- head/sys/arm/arm/pmap-v6.c Tue Jun 4 07:37:06 2013 (r251369) +++ head/sys/arm/arm/pmap-v6.c Tue Jun 4 09:21:18 2013 (r251370) @@ -2966,6 +2966,126 @@ 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 l2_bucket *l2b_src, *l2b_dst; + struct pv_entry *pve; + vm_offset_t addr; + vm_offset_t end_addr; + vm_offset_t next_bucket; + u_int flags; + boolean_t l2b_alloc; + + CTR4(KTR_PMAP, "%s: VA = 0x%08x, len = 0x%08x. Will %s\n", __func__, + src_addr, len, (dst_addr != src_addr) ? "exit" : "copy"); + + if (dst_addr != src_addr) + return; + + rw_wlock(&pvh_global_lock); + if (dst_pmap < src_pmap) { + PMAP_LOCK(dst_pmap); + PMAP_LOCK(src_pmap); + } else { + PMAP_LOCK(src_pmap); + PMAP_LOCK(dst_pmap); + } + + end_addr = src_addr + len; + addr = src_addr; + /* + * Iterate through all used l2_buckets in a given range. + */ + while (addr < end_addr) { + pt_entry_t *src_ptep, *dst_ptep; + pt_entry_t src_pte; + + next_bucket = L2_NEXT_BUCKET(addr); + /* + * If the next bucket VA is out of the + * copy range then set it to end_addr in order + * to copy all mappings until the given limit. + */ + if (next_bucket > end_addr) + next_bucket = end_addr; + + l2b_src = pmap_get_l2_bucket(src_pmap, addr); + if (l2b_src == NULL) { + addr = next_bucket; + continue; + } + src_ptep = &l2b_src->l2b_kva[l2pte_index(addr)]; + + while (addr < next_bucket) { + vm_page_t srcmpte; + + src_pte = *src_ptep; + srcmpte = PHYS_TO_VM_PAGE(l2pte_pa(src_pte)); + /* + * We only virtual copy managed pages + */ + if (srcmpte && (srcmpte->oflags & VPO_UNMANAGED) == 0) { + l2b_alloc = FALSE; + l2b_dst = pmap_get_l2_bucket(dst_pmap, addr); + /* + * Check if the allocation of another + * l2_bucket is necessary. + */ + if (l2b_dst == NULL) { + l2b_dst = pmap_alloc_l2_bucket(dst_pmap, + addr); + l2b_alloc = TRUE; + } + if (l2b_dst == NULL) + goto out; + + dst_ptep = &l2b_dst->l2b_kva[l2pte_index(addr)]; + + if (*dst_ptep == 0 && + (pve = pmap_get_pv_entry(dst_pmap, TRUE))) { + /* + * Check whether the source mapping is + * writable and set the proper flag + * for a copied mapping so that right + * permissions could be set on the + * access fault. + */ + flags = 0; + if ((src_pte & L2_APX) == 0) + flags = PVF_WRITE; + pmap_enter_pv(srcmpte, pve, dst_pmap, + addr, flags); + /* + * Clear the modified and + * accessed (referenced) flags + * and don't set the wired flag + * during the copy. + */ + *dst_ptep = src_pte; + *dst_ptep &= ~L2_S_REF; + *dst_ptep |= L2_APX; + /* + * Update stats + */ + l2b_dst->l2b_occupancy++; + dst_pmap->pm_stats.resident_count++; + } else { + /* + * If the l2_bucket was acquired as + * a result of allocation then free it. + */ + if (l2b_alloc) + pmap_free_l2_bucket(dst_pmap, + l2b_dst, 1); + goto out; + } + } + addr += PAGE_SIZE; + src_ptep++; + } + } +out: + rw_wunlock(&pvh_global_lock); + PMAP_UNLOCK(src_pmap); + PMAP_UNLOCK(dst_pmap); } _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
