Drop PTE check in pmap_fault_fixup(). Since pmap_enter() doesn't

add PTE's for pages that haven't been accessed yet, the check would
skip the fixup on such pages and force us to go through uvm_fault()
just for the sake of MOD/REF bit emulation.  Since we already check
the PTE descriptor, dropping the check should be safe.  Doing so
gives us a nice 10% performance gain when building a kernel.

Original commit for arch/arm64/arm64/pmap.c:
date: 2021/05/16 17:41:30;  author: kettenis;  state: Exp;  lines: +1 -8;  commitid: yBzyZzIKRLyAkuDY;

ok drahn@ kettenis@

diff --git a/sys/arch/riscv64/riscv64/pmap.c b/sys/arch/riscv64/riscv64/pmap.c
index 50ee1ee..3d5d7e2 100644 (file)
--- a/sys/arch/riscv64/riscv64/pmap.c
+++ b/sys/arch/riscv64/riscv64/pmap.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: pmap.c,v 1.34 2023/09/18 17:01:41 jca Exp $   */
+/*     $OpenBSD: pmap.c,v 1.35 2023/09/24 18:49:29 jca Exp $   */
 
 /*
  * Copyright (c) 2019-2020 Brian Bamsch <bbamsch@google.com>
@@ -1679,13 +1679,6 @@ pmap_fault_fixup(pmap_t pm, vaddr_t va, vm_prot_t ftype)
        if (pg == NULL)
                goto done;
 
-       /*
-        * Check based on fault type for mod/ref emulation.
-        * if L3 entry is zero, it is not a possible fixup
-        */
-       if (*pl3 == 0)
-               goto done;
-
        /*
         * Check the fault types to find out if we were doing
         * any mod/ref emulation and fixup the PTE if we were.