[src/trunk]: src/sys/arch/x86/x86 Remove the D bit as part of the hotpatch cl...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/702aebf08616
branches:  trunk
changeset: 971721:702aebf08616
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sat May 02 16:25:47 2020 +0000

description:
Remove the D bit as part of the hotpatch cleanup procedure.

diffstat:

 sys/arch/x86/x86/patch.c |  48 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 46 insertions(+), 2 deletions(-)

diffs (83 lines):

diff -r 8b946ae82281 -r 702aebf08616 sys/arch/x86/x86/patch.c
--- a/sys/arch/x86/x86/patch.c  Sat May 02 14:31:13 2020 +0000
+++ b/sys/arch/x86/x86/patch.c  Sat May 02 16:25:47 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: patch.c,v 1.47 2020/05/02 11:37:17 maxv Exp $  */
+/*     $NetBSD: patch.c,v 1.48 2020/05/02 16:25:47 maxv Exp $  */
 
 /*-
  * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: patch.c,v 1.47 2020/05/02 11:37:17 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: patch.c,v 1.48 2020/05/02 16:25:47 maxv Exp $");
 
 #include "opt_lockdebug.h"
 #ifdef i386
@@ -49,6 +49,9 @@
 #include <machine/specialreg.h>
 #include <machine/frameasm.h>
 
+#include <uvm/uvm.h>
+#include <machine/pmap.h>
+
 #include <x86/cpuvar.h>
 #include <x86/cputypes.h>
 
@@ -256,6 +259,45 @@
        return 0;
 }
 
+#ifdef __x86_64__
+/*
+ * The CPU added the D bit on the text pages while we were writing to them.
+ * Remove that bit. Kinda annoying, but we can't avoid it.
+ */
+static void
+remove_d_bit(void)
+{
+       extern struct bootspace bootspace;
+       pt_entry_t pte;
+       vaddr_t va;
+       size_t i, n;
+
+       for (i = 0; i < BTSPACE_NSEGS; i++) {
+               if (bootspace.segs[i].type != BTSEG_TEXT)
+                       continue;
+               va = bootspace.segs[i].va;
+               n = 0;
+               while (n < bootspace.segs[i].sz) {
+                       if (L2_BASE[pl2_i(va)] & PTE_PS) {
+                               pte = L2_BASE[pl2_i(va)] & ~PTE_D;
+                               pmap_pte_set(&L2_BASE[pl2_i(va)], pte);
+                               n += NBPD_L2;
+                               va += NBPD_L2;
+                       } else {
+                               pte = L1_BASE[pl1_i(va)] & ~PTE_D;
+                               pmap_pte_set(&L1_BASE[pl1_i(va)], pte);
+                               n += NBPD_L1;
+                               va += NBPD_L1;
+                       }
+               }
+       }
+
+       tlbflushg();
+}
+#else
+#define remove_d_bit() __nothing
+#endif
+
 /*
  * Interrupts disabled here. Called from ASM only, prototype not public.
  */
@@ -266,6 +308,8 @@
        if (retval != 0) {
                panic("x86_hotpatch_apply failed");
        }
+
+       remove_d_bit();
 }
 
 /* -------------------------------------------------------------------------- */