amd64/59650: passing float parameters in non-main threads bus errors

[Adriaan de Groot]

The following reply was made to PR amd64/59650; it has been noted by GNATS.

From: Adriaan de Groot <adridg at cs.kun.nl>
To: freebsd-gnats-submit at FreeBSD.org
Cc:  
Subject: Re: amd64/59650: passing float parameters in non-main threads bus errors
Date: Wed, 26 Nov 2003 14:23:10 +0100

 Some further debugging shows that it's not even sprintf() of va_start() 
 specific, but just passing float / double arguments to a varargs function in 
 a non-main thread of control triggers bus errors already:
 
 /*
 ** Demonstration program that float parameters to
 ** varargs functions in non-main threads of
 ** control on amd64 does not work properly.
 */
 
 #include <stdio.h>
 #include <pthread.h>
 #include <stdarg.h>
 
 
 /*
 ** This is a varargs function to which we will attempt to pass
 ** a float value in the ... .
 */
 
 int PrintF(int fd, const char *fmt, int i, ...)
 {
         int ret = 2;
         fprintf(stderr,"[%lx]B %d\n",(long)pthread_self(),fd);
         return ret;
 }
 
 
 /*
 ** Demonstration function. Expected output is something like
 **
 ** [504000]B 0
 ** [504000]B 1
 ** [504000]B 2
 ** [504000]B 3
 **
 ** From the 4 calls to PrintF(). This bus errors in the third
 ** call when not in the main thread of control.
 */
 
 void *threadfunc(void *p)
 {
         PrintF(0,"hello",0,0);
         PrintF(1,"hello",0,6);
         PrintF(2,"hello",1,0.00028376223); /* arg4 is a float */
         PrintF(3,"hello",0.00028376223,6); /* arg3 converts to int here */
         return p;
 }
 
 int main(int argc, char **argv)
 {
         pthread_t tid;
 
         threadfunc(NULL);
         pthread_create(&tid,NULL,threadfunc,NULL);
         sleep(4);
         threadfunc(NULL);
 
         return 0;
 }
 
 Now, either I'm doing something totally moronic with threads (and the ogg123 
 port is too) or the argument passing is seriously broken. I might be 
 compiling it wrong, though:
 
 beans.ebn.kun.nl$gcc -o threadtest -g v.c -lc_r && ./threadtest
 [504000]B 0
 [504000]B 1
 [504000]B 2
 [504000]B 3
 [504800]B 0
 [504800]B 1
 Bus error (core dumped)
 
 The machine has been updated in -CURRENT since the original bug report:
 
 FreeBSD beans.ebn.kun.nl 5.2-BETA FreeBSD 5.2-BETA #2: Sun Nov 23 19:48:43 CET 
 2003     root at beans.ebn.kun.nl:/usr/obj/mnt/sys/CURRENT/src/sys/BEANS  amd64
 
 
 -- 
 pub  1024D/FEA2A3FE 2002-06-18 Adriaan de Groot <groot at kde.org>
             If the door is ajar, can we fill it with door-jamb?