From: Iain Buclaw <ibuclaw@gdcproject.org>
Date: Tue, 7 Nov 2023 13:04:07 +0000 (+0100)
Subject: libphobos: Fix regression d21 loops in getCpuInfo0B in Solaris/x86 kernel zone
X-Git-Tag: releases/gcc-13.3.0~773
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b25c1295d4e84af681f4b1f4af2ad37cd270da3;p=thirdparty%2Fgcc.git

libphobos: Fix regression d21 loops in getCpuInfo0B in Solaris/x86 kernel zone

This function assumes that cpuid would return "invalid domain" when a
sub-leaf index greater than what's supported is requested.  This turned
out not to always be the case when running on some virtual machines.

As the loop only does anything for levels 0 and 1, make that a hard
limit for number of times the loop is ran.

    PR d/112408

libphobos/ChangeLog:

	* libdruntime/core/cpuid.d (getCpuInfo0B): Limit number of times loop
	runs.
---

diff --git a/libphobos/libdruntime/core/cpuid.d b/libphobos/libdruntime/core/cpuid.d
index b79bd1df9c48..9c5735728b52 100644
--- a/libphobos/libdruntime/core/cpuid.d
+++ b/libphobos/libdruntime/core/cpuid.d
@@ -666,10 +666,12 @@ void getAMDcacheinfo()
 // to determine number of processors.
 void getCpuInfo0B()
 {
-    int level=0;
     int threadsPerCore;
     uint a, b, c, d;
-    do {
+    // I'm not sure about this. The docs state that there
+    // are 2 hyperthreads per core if HT is factory enabled.
+    for (int level = 0; level < 2; level++)
+    {
         version (GNU_OR_LDC) asm pure nothrow @nogc {
             "cpuid" : "=a" (a), "=b" (b), "=c" (c), "=d" (d) : "a" (0x0B), "c" (level);
         } else asm pure nothrow @nogc {
@@ -681,19 +683,20 @@ void getCpuInfo0B()
             mov c, ECX;
             mov d, EDX;
         }
-        if (b!=0) {
-           // I'm not sure about this. The docs state that there
-           // are 2 hyperthreads per core if HT is factory enabled.
-            if (level==0)
+        if (b != 0)
+        {
+            if (level == 0)
                 threadsPerCore = b & 0xFFFF;
-            else if (level==1) {
+            else if (level == 1)
+            {
                 cpuFeatures.maxThreads = b & 0xFFFF;
                 cpuFeatures.maxCores = cpuFeatures.maxThreads / threadsPerCore;
             }
-
         }
-        ++level;
-    } while (a!=0 || b!=0);
+        // Got "invalid domain" returned from cpuid
+        if (a == 0 && b == 0)
+            break;
+    }
 }
 
 void cpuidX86()