[src/trunk]: src/sys/arch/x86/x86 Fix a normally harmless race: initialize se...

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

details:   https://anonhg.NetBSD.org/src/rev/7c533204ea54
branches:  trunk
changeset: 454247:7c533204ea54
user:      maxv <maxv%NetBSD.org@localhost>
date:      Thu Sep 12 06:39:47 2019 +0000

description:
Fix a normally harmless race: initialize several global variables only on
cpu0, so we don't get eg cpu1 re-initializing them while cpu0 is using
them.

diffstat:

 sys/arch/x86/x86/identcpu.c |  56 ++++++++++++++++++++++++--------------------
 1 files changed, 31 insertions(+), 25 deletions(-)

diffs (91 lines):

diff -r 7a26aee6c063 -r 7c533204ea54 sys/arch/x86/x86/identcpu.c
--- a/sys/arch/x86/x86/identcpu.c       Thu Sep 12 06:19:47 2019 +0000
+++ b/sys/arch/x86/x86/identcpu.c       Thu Sep 12 06:39:47 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: identcpu.c,v 1.94 2019/09/09 05:36:21 msaitoh Exp $    */
+/*     $NetBSD: identcpu.c,v 1.95 2019/09/12 06:39:47 maxv Exp $       */
 
 /*-
  * Copyright (c) 1999, 2000, 2001, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: identcpu.c,v 1.94 2019/09/09 05:36:21 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: identcpu.c,v 1.95 2019/09/12 06:39:47 maxv Exp $");
 
 #include "opt_xen.h"
 
@@ -837,8 +837,10 @@
        uint32_t miscbytes;
        uint32_t brand[12];
 
-       cpu_vendor = i386_nocpuid_cpus[cputype << 1];
-       cpu_class = i386_nocpuid_cpus[(cputype << 1) + 1];
+       if (ci == &cpu_info_primary) {
+               cpu_vendor = i386_nocpuid_cpus[cputype << 1];
+               cpu_class = i386_nocpuid_cpus[(cputype << 1) + 1];
+       }
 
        if (cpuid_level < 0) {
                /* cpuid instruction not supported */
@@ -859,22 +861,24 @@
        ci->ci_vendor[1] = descs[3];
        ci->ci_vendor[3] = 0;
 
-       if (memcmp(ci->ci_vendor, "GenuineIntel", 12) == 0)
-               cpu_vendor = CPUVENDOR_INTEL;
-       else if (memcmp(ci->ci_vendor,  "AuthenticAMD", 12) == 0)
-               cpu_vendor = CPUVENDOR_AMD;
-       else if (memcmp(ci->ci_vendor,  "CyrixInstead", 12) == 0)
-               cpu_vendor = CPUVENDOR_CYRIX;
-       else if (memcmp(ci->ci_vendor,  "Geode by NSC", 12) == 0)
-               cpu_vendor = CPUVENDOR_CYRIX;
-       else if (memcmp(ci->ci_vendor, "CentaurHauls", 12) == 0)
-               cpu_vendor = CPUVENDOR_IDT;
-       else if (memcmp(ci->ci_vendor, "GenuineTMx86", 12) == 0)
-               cpu_vendor = CPUVENDOR_TRANSMETA;
-       else if (memcmp(ci->ci_vendor, "Vortex86 SoC", 12) == 0)
-               cpu_vendor = CPUVENDOR_VORTEX86;
-       else
-               cpu_vendor = CPUVENDOR_UNKNOWN;
+       if (ci == &cpu_info_primary) {
+               if (memcmp(ci->ci_vendor, "GenuineIntel", 12) == 0)
+                       cpu_vendor = CPUVENDOR_INTEL;
+               else if (memcmp(ci->ci_vendor, "AuthenticAMD", 12) == 0)
+                       cpu_vendor = CPUVENDOR_AMD;
+               else if (memcmp(ci->ci_vendor, "CyrixInstead", 12) == 0)
+                       cpu_vendor = CPUVENDOR_CYRIX;
+               else if (memcmp(ci->ci_vendor, "Geode by NSC", 12) == 0)
+                       cpu_vendor = CPUVENDOR_CYRIX;
+               else if (memcmp(ci->ci_vendor, "CentaurHauls", 12) == 0)
+                       cpu_vendor = CPUVENDOR_IDT;
+               else if (memcmp(ci->ci_vendor, "GenuineTMx86", 12) == 0)
+                       cpu_vendor = CPUVENDOR_TRANSMETA;
+               else if (memcmp(ci->ci_vendor, "Vortex86 SoC", 12) == 0)
+                       cpu_vendor = CPUVENDOR_VORTEX86;
+               else
+                       cpu_vendor = CPUVENDOR_UNKNOWN;
+       }
 
        if (cpuid_level >= 1) {
                x86_cpuid(1, descs);
@@ -883,11 +887,13 @@
                ci->ci_feat_val[1] = descs[2];
                ci->ci_feat_val[0] = descs[3];
 
-               /* Determine family + class. */
-               cpu_class = CPUID_TO_FAMILY(ci->ci_signature)
-                   + (CPUCLASS_386 - 3);
-               if (cpu_class > CPUCLASS_686)
-                       cpu_class = CPUCLASS_686;
+               if (ci == &cpu_info_primary) {
+                       /* Determine family + class. */
+                       cpu_class = CPUID_TO_FAMILY(ci->ci_signature)
+                           + (CPUCLASS_386 - 3);
+                       if (cpu_class > CPUCLASS_686)
+                               cpu_class = CPUCLASS_686;
+               }
 
                /* CLFLUSH line size is next 8 bits */
                if (ci->ci_feat_val[0] & CPUID_CFLUSH)