[src/trunk]: src/sys/arch/xen/x86 Map the kernel text, rodata and data+bss in...

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

details:   https://anonhg.NetBSD.org/src/rev/4781a3bfa7c2
branches:  trunk
changeset: 346778:4781a3bfa7c2
user:      maxv <maxv%NetBSD.org@localhost>
date:      Tue Aug 02 14:21:53 2016 +0000

description:
Map the kernel text, rodata and data+bss independently on Xen, with
respectively RX, R and RW.

diffstat:

 sys/arch/xen/x86/x86_xpmap.c |  33 +++++++++++++++++++++++++--------
 1 files changed, 25 insertions(+), 8 deletions(-)

diffs (77 lines):

diff -r ec8ab933d504 -r 4781a3bfa7c2 sys/arch/xen/x86/x86_xpmap.c
--- a/sys/arch/xen/x86/x86_xpmap.c      Tue Aug 02 14:03:34 2016 +0000
+++ b/sys/arch/xen/x86/x86_xpmap.c      Tue Aug 02 14:21:53 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: x86_xpmap.c,v 1.56 2016/08/02 13:29:35 maxv Exp $      */
+/*     $NetBSD: x86_xpmap.c,v 1.57 2016/08/02 14:21:53 maxv Exp $      */
 
 /*
  * Copyright (c) 2006 Mathieu Ropert <mro%adviseo.fr@localhost>
@@ -69,7 +69,7 @@
 
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: x86_xpmap.c,v 1.56 2016/08/02 13:29:35 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: x86_xpmap.c,v 1.57 2016/08/02 14:21:53 maxv Exp $");
 
 #include "opt_xen.h"
 #include "opt_ddb.h"
@@ -730,15 +730,24 @@
        pd_entry_t *pdtpe, *pde, *pte;
        pd_entry_t *bt_pgd;
        paddr_t addr;
-       vaddr_t page, avail, text_end, map_end;
+       vaddr_t page, avail, map_end;
        int i;
+       extern char __rodata_start;
        extern char __data_start;
+       extern char __kernel_end;
        extern char *early_zerop; /* from pmap.c */
+       pt_entry_t pg_nx;
+       u_int descs[4];
 
        __PRINTK(("xen_bootstrap_tables(%#" PRIxVADDR ", %#" PRIxVADDR ","
            " %d, %d)\n",
            old_pgd, new_pgd, old_count, new_count));
-       text_end = ((vaddr_t)&__data_start) & ~PAGE_MASK;
+
+       /*
+        * Set the NX/XD bit, if available. descs[3] = %edx.
+        */
+       x86_cpuid(0x80000001, descs);
+       pg_nx = (descs[3] & CPUID_NOX) ? PG_NX : 0;
 
        /*
         * size of R/W area after kernel text:
@@ -776,8 +785,7 @@
        }
 #endif /* DOM0OPS */
 
-       __PRINTK(("xen_bootstrap_tables text_end 0x%lx map_end 0x%lx\n",
-           text_end, map_end));
+       __PRINTK(("xen_bootstrap_tables map_end 0x%lx\n", map_end));
        __PRINTK(("console %#lx ", xen_start_info.console_mfn));
        __PRINTK(("xenstore %#" PRIx32 "\n", xen_start_info.store_mfn));
 
@@ -907,10 +915,19 @@
                                    IOM_BEGIN + (page - (vaddr_t)atdevbase);
                        }
 #endif
+
                        pte[pl1_pi(page)] |= PG_k | PG_V;
-                       if (page < text_end) {
-                               /* map kernel text RO */
+                       if (page < (vaddr_t)&__rodata_start) {
+                               /* Map kernel text RX. */
                                pte[pl1_pi(page)] |= PG_RO;
+                       } else if (page >= (vaddr_t)&__rodata_start &&
+                           page < (vaddr_t)&__data_start) {
+                               /* Map the kernel rodata R. */
+                               pte[pl1_pi(page)] |= PG_RO | pg_nx;
+                       } else if (page >= (vaddr_t)&__data_start &&
+                           page < (vaddr_t)&__kernel_end) {
+                               /* Map the kernel data+bss RW. */
+                               pte[pl1_pi(page)] |= PG_RW | pg_nx;
                        } else if (page >= old_pgd &&
                            page < old_pgd + (old_count * PAGE_SIZE)) {
                                /* map old page tables RO */