From: jca <jca@openbsd.org>
Date: Sun, 24 Sep 2023 18:49:29 +0000 (+0000)
Subject: Drop PTE check in pmap_fault_fixup().  Since pmap_enter() doesn't
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=ff9b32b90760849db29e606a8acc9cdc3fe698ec;p=openbsd

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 50ee1ee67cc..3d5d7e2c3a6 100644
--- 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.