Re: toolchain/50866: starting firefox crashes the X server

[Martin Husemann <martin%duskware.de@localhost>]

The following reply was made to PR toolchain/50866; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: christos%NetBSD.org@localhost, joerg%NetBSD.org@localhost
Subject: Re: toolchain/50866: starting firefox crashes the X server
Date: Thu, 3 Mar 2016 08:51:12 +0100

 So there are (at least) two bugs involved in this. I filed PR lib/50887
 about the other one (libc's _clzdi2 is broken when compiled
 with gcc [at least on sparc64]), the other bug is about picking the
 libc version of _clzdi2 over the libgcc* version - this is a difference
 between binutils 2.23 and 2.26.
 
 Here is a gdb session with the X server before crashing it:
 (gdb) break __clzdi2
 Breakpoint 1 at 0xffffffffee00e400: __clzdi2. (2 locations)
 (gdb) break __clzsi2
 Breakpoint 2 at 0xfffffffff6620240: file /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzsi2.c, line 25.
 (gdb) break __clz
 Function "__clz" not defined.
 Make breakpoint pending on future shared library load? (y or [n]) n
 (gdb) break __clzti2
 Breakpoint 3 at 0xffffffffee00e360: __clzti2. (2 locations)
 
 Note the single location in libc for __clzsi2, but two locations (libgcc
 and libc) for the other two.
 
 Now making it crash:
 
 Breakpoint 1, __clzdi2 (a=33)
     at /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzdi2.c:23
 23      {
 (gdb) bt
 #0  __clzdi2 (a=33)
     at /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzdi2.c:23
 #1  0xffffffffeeca4a78 in util_logbase2 (n=<optimized out>)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/auxiliary/util/u_math.h:665
 #2  softpipe_create_sampler_view (pipe=0xffffffffeda76000, 
     resource=0xffffffffeda397a0, templ=0xffffffffffffb110)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/drivers/softpipe/sp_tex_sample.c:3193
 #3  0xffffffffeef01308 in aaline_create_texture (aaline=0xffffffffe7287400)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/auxiliary/draw/draw_pipe_aaline.c:429
 #4  draw_install_aaline_stage (draw=0xffffffffe7388000, 
     pipe=pipe@entry=0xffffffffeda76000)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/auxiliary/draw/draw_pipe_aaline.c:1008
 #5  0xffffffffeecb372c in softpipe_create_context (screen=0xfffffffff4f902c0, 
     priv=<optimized out>)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/drivers/softpipe/sp_context.c:298
 #6  0xffffffffeea9be20 in st_api_create_context (stapi=<optimized out>, 
     smapi=0xfffffffff4f70530, attribs=0xffffffffffffb43c, 
     error=0xffffffffffffb438, shared_stctxi=0x0)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/mesa/state_tracker/st_manager.c:658
 #7  0xffffffffeec8a578 in dri_create_context (api=<optimized out>, 
     visual=0xfffffffff4f71d40, cPriv=0xffffffffedb854c0, 
     major_version=<optimized out>, minor_version=<optimized out>, 
     flags=<optimized out>, notify_reset=false, error=0xffffffffffffb60c, 
     sharedContextPrivate=0x0)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/state_trackers/dri/dri_context.c:112
 #8  0xffffffffee9c74b8 in driCreateContextAttribs (
     screen=screen@entry=0xfffffffff4f70480, api=api@entry=0, 
     config=config@entry=0xfffffffff4f71d40, shared=shared@entry=0x0, 
     num_attribs=num_attribs@entry=0, attribs=attribs@entry=0x0, 
     error=0xffffffffffffb60c, data=0xfffffffff4f21100)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/mesa/drivers/dri/common/dri_util.c:435
 #9  0xffffffffee9c758c in driCreateNewContextForAPI (data=0xfffffffff4f21100, 
     shared=0x0, config=0xfffffffff4f71d40, api=0, screen=0xfffffffff4f70480)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/mesa/drivers/dri/common/dri_util.c:464
 #10 driCreateNewContext (screen=0xfffffffff4f70480, config=0xfffffffff4f71d40, 
     shared=0x0, data=0xfffffffff4f21100)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/mesa/drivers/dri/common/dri_util.c:472
 #11 0x000000000029cdb8 in __glXDRIscreenCreateContext (
     baseScreen=0xfffffffff4f20660, glxConfig=0xfffffffff4f4bd00, 
     baseShareContext=0x0)
     at /ssd/xsrc/external/mit/xorg-server/dist/glx/glxdriswrast.c:296
 #12 0x00000000002a07e4 in DoCreateContext (gcId=<optimized out>, 
     shareList=<optimized out>, config=0xfffffffff4f4bd00, 
     pGlxScreen=0xfffffffff4f20660, isDirect=0 '\000', cl=0xffffffffedb8d928)
     at /ssd/xsrc/external/mit/xorg-server/dist/glx/glxcmds.c:276
 #13 0x00000000002a12e0 in __glXDisp_CreateContext (cl=0xffffffffedb8d928, 
     pc=0xfffffffff4f08038 "\233\003")
     at /ssd/xsrc/external/mit/xorg-server/dist/glx/glxcmds.c:330
 #14 0x000000000029d794 in __glXDispatch (client=0xffffffffedb8d800)
     at /ssd/xsrc/external/mit/xorg-server/dist/glx/glxext.c:558
 #15 0x0000000000161af0 in Dispatch ()
 #16 0x00000000002f3f90 in main ()
 
 And indeed, continuing leads to direct recursion:
 
 #0  __clzdi2 (a=33)
     at /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzdi2.c:23
 #1  0xfffffffff661fb64 in __clzdi2 (a=<optimized out>)
     at /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzdi2.c:27
 #2  0xfffffffff661fb64 in __clzdi2 (a=<optimized out>)
     at /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzdi2.c:27
 #3  0xfffffffff661fb64 in __clzdi2 (a=<optimized out>)
     at /ssd/src/sys/external/bsd/compiler_rt/dist/lib/builtins/clzdi2.c:27
 #4  0xffffffffeeca4a78 in util_logbase2 (n=<optimized out>)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/auxiliary/util/u_math.h:665
 #5  softpipe_create_sampler_view (pipe=0xffffffffeda76000, 
     resource=0xffffffffeda397a0, templ=0xffffffffffffb110)
     at /ssd/xsrc/external/mit/MesaLib/dist/src/gallium/drivers/softpipe/sp_tex_sample.c:3193
 
 
 (but the recursion is part of the other bug).
 
 The question here is: what does binutils 2.26 different to causes libc's
 version of _clzdi2 to be called in the above stack trace.
 
 I can not spot anything obvious: both version of the 
 usr/X11R7/lib/modules/dri/*.so files have 
 
 0000000000000000       F *UND*  0000000000000000              __clzdi2@@GCC_3.4
 
 as reference to the function and 
 
 Dynamic Section:
   NEEDED               libdrm.so.3
   NEEDED               libdrm_radeon.so.0
   NEEDED               libglapi.so.0
   NEEDED               libexpat.so.2
   NEEDED               libstdc++.so.7
   NEEDED               libm.so.0
   NEEDED               libgcc_s.so.1
   NEEDED               libc.so.12
 
 as dependencies. Something about the symbol version? How would I dump version
 details?
 
 Martin