bk commit into 5.0 tree (msvensson:1.2447) BUG#21765

[msvensson]

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ChangeSet@stripped, 2007-04-11 22:07:24+02:00, msvensson@stripped +1 -0
  Bug#21765 Illegal Instruction crash on pre-pentium when using YASSL
   - Import patch with different method of detecting if machine has
     cpuid instruction

  extra/yassl/taocrypt/src/misc.cpp@stripped, 2007-04-11 19:34:46+02:00,
msvensson@stripped +21 -16
    Import patch yassl.diff

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	msvensson
# Host:	pilot.blaudden
# Root:	/home/msvensson/mysql/yassl_import/my50-yassl_import

--- 1.20/extra/yassl/taocrypt/src/misc.cpp	2007-02-27 12:05:13 +01:00
+++ 1.21/extra/yassl/taocrypt/src/misc.cpp	2007-04-11 19:34:46 +02:00
@@ -192,27 +192,32 @@ bool HaveCpuId()
     }
     return true;
 #else
-    typedef void (*SigHandler)(int);
-
-    SigHandler oldHandler = signal(SIGILL, SigIllHandler);
-    if (oldHandler == SIG_ERR)
-        return false;
-
-    bool result = true;
-    if (setjmp(s_env))
-        result = false;
-    else 
+    word32 eax, ebx;
         __asm__ __volatile
         (
-            // save ebx in case -fPIC is being used
-            "push %%ebx; mov $0, %%eax; cpuid; pop %%ebx"
-            : 
+        /* Put EFLAGS in eax and ebx */
+        "pushf;"
+        "pushf;"
+        "pop %0;"
+        "movl %0,%1;"
+
+        /* Flip the cpuid bit and store back in EFLAGS */
+        "xorl $0x200000,%0;"
+        "push %0;"
+        "popf;"
+
+        /* Read EFLAGS again */
+        "pushf;"
+        "pop %0;"
+        "popf"
+        : "=r" (eax), "=r" (ebx)
             :
-            : "%eax", "%ecx", "%edx" 
+        : "cc"
         );
 
-    signal(SIGILL, oldHandler);
-    return result;
+    if (eax == ebx)
+        return false;
+    return true;
 #endif
 }