mesa3d-dev

[Mesa3d-dev] Unaligned traps in __indirect_glFrustum

[Mike A. H. <mh...@re...>]

I just recently recieved this bug report from an Alpha user.

Description of Problem:

The problem manifests itself in Mesa but this is really g_render.c
trouble so it belongs to X.

Various programs from "Mesa-demos" are consistently getting on Alpha
a number of "unaligned trap" errors.  Like this:

cubemap(16472): unaligned trap at 0000020000590334: 000002000002a03c 27 2
cubemap(16472): unaligned trap at 0000020000590344: 000002000002a044 27 3
cubemap(16472): unaligned trap at 0000020000590348: 000002000002a04c 27 4
cubemap(16472): unaligned trap at 0000020000590350: 000002000002a054 27 5

With Mesa-3.4.1 recompiled for debugging and run from a shell which
forces SIGBUS, instead of a fixup, on an unaligned trap 'gdb' reveals
this:

Starting program: /usr/bin/gears

Program received signal SIGBUS, Bus error.
__indirect_glFrustum (left=-1, right=1, bottom=-1, top=1, zNear=5, zFar=60)
    at g_render.c:2523
2523		__GLX_PUT_DOUBLE(12,right);


Starting program: /usr/bin/bounce

Program received signal SIGBUS, Bus error.
__indirect_glOrtho (left=-8.0000002384185791, right=8.0000002384185791,
    bottom=-6, top=6, zNear=-6, zFar=6) at g_render.c:2590
2590		__GLX_PUT_DOUBLE(12,right);


Starting program: /usr/bin/gamma

Program received signal SIGBUS, Bus error.
__indirect_glOrtho (left=-1, right=1, bottom=-1, top=1, zNear=-1, zFar=1)
    at g_render.c:2590
2590		__GLX_PUT_DOUBLE(12,right);

Starting program: /usr/bin/cubemap
GL_REFLECTION_MAP_ARB mode
keys:
  SPACE - toggle animation
  CURSOR KEYS - rotation
  m - toggle texgen reflection mode

Program received signal SIGBUS, Bus error.
__indirect_glFrustum (left=-2, right=2, bottom=-2, top=2, zNear=6, zFar=20)
    at g_render.c:2523
2523		__GLX_PUT_DOUBLE(12,right);

This is a backtrace for 'bounce'

#0  __indirect_glOrtho (left=-8.0000002384185791, right=8.0000002384185791,
    bottom=-6, top=6, zNear=-6, zFar=6) at g_render.c:2590
#1  0x20000412588 in glOrtho (left=-8.0000002384185791,
    right=8.0000002384185791, bottom=-6, top=6, nearval=-6, farval=6)
    at glapitemp.h:938
#2  0x120001a8c in reshape (width=5889, height=172080) at bounce.c:92
#3  0x200001409f8 in processWindowWorkList (window=0x120105170)
    at glut_event.c:1193
#4  0x20000140cc8 in __glutProcessWindowWorkLists () at glut_event.c:1328
#5  0x20000140d74 in glutMainLoop () at glut_event.c:1349
#6  0x120002240 in main (argc=1, argv=0x11ffff7b8) at bounce.c:218


and this is for 'cubemap'.

#0  __indirect_glFrustum (left=-2, right=2, bottom=-2, top=2, zNear=6,
zFar=20)
    at g_render.c:2523
#1  0x2000040fc08 in glFrustum (left=-2, right=2, bottom=-2, top=2,
nearval=6,
    farval=20) at glapitemp.h:513
#2  0x1200017a8 in reshape (width=300, height=300) at cubemap.c:144
#3  0x200001409f8 in processWindowWorkList (window=0x120104b40)
    at glut_event.c:1193
#4  0x20000140cc8 in __glutProcessWindowWorkLists () at glut_event.c:1328
#5  0x20000140d74 in glutMainLoop () at glut_event.c:1349
#6  0x120001cfc in main (argc=5889, argv=0x2000002a030) at cubemap.c:248

And this is the code in question, from __indirect_glFrustum, after macros
were expanded:

        *((INT16 *) (pc +  0 )) =   52   ;
	*((INT16 *) (pc +  2 )) = 175     ;
	*((FLOAT64 *) (pc +  4 )) =  left  ;
        *((FLOAT64 *) (pc +  12 )) =  right  ;
        *((FLOAT64 *) (pc +  20 )) =  bottom  ;
        *((FLOAT64 *) (pc +  28 )) =  top  ;
        *((FLOAT64 *) (pc +  36 )) =  zNear  ;
        *((FLOAT64 *) (pc +  44 )) =  zFar  ;


Unaligned access can be silent elsewhere but it is a performance drag on
any architecture.

   Michal
   mi...@ha...






----------------------------------------------------------------------
Mike A. Harris                  Shipping/mailing address:
OS Systems Engineer             190 Pittsburgh Ave., Sault Ste. Marie,
Red Hat Inc.                    Ontario, Canada, P6C 5B3
http://www.redhat.com           Phone: (705)949-2136
----------------------------------------------------------------------
Latest XFree86 test RPMS:      ftp://people.redhat.com/mharris/testing

Re: [Mesa3d-dev] Unaligned traps in __indirect_glFrustum

[Brian P. <br...@va...>]

"Mike A. Harris" wrote:
> 
> I just recently recieved this bug report from an Alpha user.
> 
> Description of Problem:
> 
> The problem manifests itself in Mesa but this is really g_render.c
> trouble so it belongs to X.
> 
> Various programs from "Mesa-demos" are consistently getting on Alpha
> a number of "unaligned trap" errors.  Like this:
> 
> cubemap(16472): unaligned trap at 0000020000590334: 000002000002a03c 27 2
> cubemap(16472): unaligned trap at 0000020000590344: 000002000002a044 27 3
> cubemap(16472): unaligned trap at 0000020000590348: 000002000002a04c 27 4
> cubemap(16472): unaligned trap at 0000020000590350: 000002000002a054 27 5
> 
> With Mesa-3.4.1 recompiled for debugging and run from a shell which
> forces SIGBUS, instead of a fixup, on an unaligned trap 'gdb' reveals
> this:
> 
> Starting program: /usr/bin/gears
> 
> Program received signal SIGBUS, Bus error.
> __indirect_glFrustum (left=-1, right=1, bottom=-1, top=1, zNear=5, zFar=60)
>     at g_render.c:2523
> 2523            __GLX_PUT_DOUBLE(12,right);
> 
> Starting program: /usr/bin/bounce
> 
> Program received signal SIGBUS, Bus error.
> __indirect_glOrtho (left=-8.0000002384185791, right=8.0000002384185791,
>     bottom=-6, top=6, zNear=-6, zFar=6) at g_render.c:2590
> 2590            __GLX_PUT_DOUBLE(12,right);
> 
> Starting program: /usr/bin/gamma
> 
> Program received signal SIGBUS, Bus error.
> __indirect_glOrtho (left=-1, right=1, bottom=-1, top=1, zNear=-1, zFar=1)
>     at g_render.c:2590
> 2590            __GLX_PUT_DOUBLE(12,right);
> 
> Starting program: /usr/bin/cubemap
> GL_REFLECTION_MAP_ARB mode
> keys:
>   SPACE - toggle animation
>   CURSOR KEYS - rotation
>   m - toggle texgen reflection mode
> 
> Program received signal SIGBUS, Bus error.
> __indirect_glFrustum (left=-2, right=2, bottom=-2, top=2, zNear=6, zFar=20)
>     at g_render.c:2523
> 2523            __GLX_PUT_DOUBLE(12,right);
> 
> This is a backtrace for 'bounce'
> 
> #0  __indirect_glOrtho (left=-8.0000002384185791, right=8.0000002384185791,
>     bottom=-6, top=6, zNear=-6, zFar=6) at g_render.c:2590
> #1  0x20000412588 in glOrtho (left=-8.0000002384185791,
>     right=8.0000002384185791, bottom=-6, top=6, nearval=-6, farval=6)
>     at glapitemp.h:938
> #2  0x120001a8c in reshape (width=5889, height=172080) at bounce.c:92
> #3  0x200001409f8 in processWindowWorkList (window=0x120105170)
>     at glut_event.c:1193
> #4  0x20000140cc8 in __glutProcessWindowWorkLists () at glut_event.c:1328
> #5  0x20000140d74 in glutMainLoop () at glut_event.c:1349
> #6  0x120002240 in main (argc=1, argv=0x11ffff7b8) at bounce.c:218
> 
> and this is for 'cubemap'.
> 
> #0  __indirect_glFrustum (left=-2, right=2, bottom=-2, top=2, zNear=6,
> zFar=20)
>     at g_render.c:2523
> #1  0x2000040fc08 in glFrustum (left=-2, right=2, bottom=-2, top=2,
> nearval=6,
>     farval=20) at glapitemp.h:513
> #2  0x1200017a8 in reshape (width=300, height=300) at cubemap.c:144
> #3  0x200001409f8 in processWindowWorkList (window=0x120104b40)
>     at glut_event.c:1193
> #4  0x20000140cc8 in __glutProcessWindowWorkLists () at glut_event.c:1328
> #5  0x20000140d74 in glutMainLoop () at glut_event.c:1349
> #6  0x120001cfc in main (argc=5889, argv=0x2000002a030) at cubemap.c:248
> 
> And this is the code in question, from __indirect_glFrustum, after macros
> were expanded:
> 
>         *((INT16 *) (pc +  0 )) =   52   ;
>         *((INT16 *) (pc +  2 )) = 175     ;
>         *((FLOAT64 *) (pc +  4 )) =  left  ;
>         *((FLOAT64 *) (pc +  12 )) =  right  ;
>         *((FLOAT64 *) (pc +  20 )) =  bottom  ;
>         *((FLOAT64 *) (pc +  28 )) =  top  ;
>         *((FLOAT64 *) (pc +  36 )) =  zNear  ;
>         *((FLOAT64 *) (pc +  44 )) =  zFar  ;
> 
> Unaligned access can be silent elsewhere but it is a performance drag on
> any architecture.
> 
>    Michal
>    mi...@ha...
> 


The preprocessor token __GLX_ALIGN64 should fix that.  The
__GLX_PUT_DOUBLE() macro is defined as follows:

#ifdef __GLX_ALIGN64
/*
** This can certainly be done better for a particular machine
** architecture!
*/
#define __GLX_PUT_DOUBLE(offset,a) \
    __GLX_MEM_COPY(pc + offset, &a, 8)
#else
#define __GLX_PUT_DOUBLE(offset,a) \
    *((FLOAT64 *) (pc + offset)) = a
#endif


The following patch should fix this:

Index: Imakefile
===================================================================
RCS file: /cvsroot/dri/xc/xc/lib/GL/glx/Imakefile,v
retrieving revision 1.10
diff -r1.10 Imakefile
89a90,92
> #if defined(AlphaArchitecture)
>      GLX_DEFS = GlxDefines -D__GLX_ALIGN64
> #else
90a94,95
> #endif
> 


-Brian

Re: [Mesa3d-dev] Unaligned traps in __indirect_glFrustum

[Mike A. H. <mh...@re...>]

On Mon, 18 Jun 2001, Brian Paul wrote:

>The preprocessor token __GLX_ALIGN64 should fix that.  The
>__GLX_PUT_DOUBLE() macro is defined as follows:
>
>#ifdef __GLX_ALIGN64
>/*
>** This can certainly be done better for a particular machine
>** architecture!
>*/
>#define __GLX_PUT_DOUBLE(offset,a) \
>    __GLX_MEM_COPY(pc + offset, &a, 8)
>#else
>#define __GLX_PUT_DOUBLE(offset,a) \
>    *((FLOAT64 *) (pc + offset)) = a
>#endif
>
>
>The following patch should fix this:
>
>Index: Imakefile
>===================================================================
>RCS file: /cvsroot/dri/xc/xc/lib/GL/glx/Imakefile,v
>retrieving revision 1.10
>diff -r1.10 Imakefile
>89a90,92
>> #if defined(AlphaArchitecture)
>>      GLX_DEFS = GlxDefines -D__GLX_ALIGN64
>> #else
>90a94,95
>> #endif
>>

Thanks Brian, I'll apply it to my next build.
TTYL


----------------------------------------------------------------------
Mike A. Harris                  Shipping/mailing address:
OS Systems Engineer             190 Pittsburgh Ave., Sault Ste. Marie,
Red Hat Inc.                    Ontario, Canada, P6C 5B3
http://www.redhat.com           Phone: (705)949-2136
----------------------------------------------------------------------
Latest XFree86 test RPMS:      ftp://people.redhat.com/mharris/testing