Re: [patch] Fix oddity in personality routine

On Wed, Dec 02, 2009 at 09:34:33AM +0000, Andrew Haley wrote:
> Jack Howarth wrote:
> > On Tue, Dec 01, 2009 at 05:24:29PM +0000, Andrew Haley wrote:
> >> Jack Howarth wrote:
> >>> On Tue, Dec 01, 2009 at 09:29:36AM +0000, Andrew Haley wrote:
> >>>> Jack Howarth wrote:
> >>>>
> >>>>> (gdb) 
> >>>>> 54	  (*real_main) (args);
> >>>>> (gdb) 
> >>>>>
> >>>>> Program received signal EXC_BAD_ACCESS, Could not access memory.
> >>>>> Reason: KERN_PROTECTION_FAILURE at address: 0x0000000103f05db0
> >>>>> 0x0000000103f05db0 in ?? () at RowSetEvent.java:51
> >>>>> 51	RowSetEvent.java: No such file or directory.
> >>>>> 	in RowSetEvent.java
> >>>>> (gdb) 
> >>>>>
> >>>>> A backtrace only shows...
> >>>>>
> >>>>> (gdb) bt
> >>>>> #0  0x0000000103f05db0 in ?? () at RowSetEvent.java:51
> >>>>> #1  0x00000001000485be in gnu::java::lang::MainThread::call_main (this=0x104875dc0) at ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc:54
> >>>>> Previous frame inner to this frame (gdb could not unwind past this frame)
> >>>>>
> >>>>> Let me know if you have any suggestions for debugging this further.
> >>>> Disassemble the first 10 or so instructions at the instruction where the
> >>>> EXC_BAD_ACCESS occurs.  I think this is a libffi bug.
> >>>>
> >>>> Andrew.
> >>> Andrew,
> >>>    So just to clarify, for the instance of...
> >>>
> >>> -------------------
> >>>
> >>> (gdb) 
> >>> 0x00000001004168df in _ZN4java4lang7reflect8Modifier8isPublicEJbi (mod=9) at Modifier.java:258
> >>> 258	    return (mod & PUBLIC) != 0;
> >>> (gdb) 
> >>> gnu::java::lang::MainThread::call_main (this=0x104875dc0) at ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc:46
> >>> 46	    msg =  "`main' must be public";
> >>> (gdb) 
> >>> 45	  else if (! ::java::lang::reflect::Modifier::isPublic(meth->accflags))
> >>> (gdb) 
> >>> 54	  (*real_main) (args);
> >>> (gdb) 
> >>>
> >>> Program received signal EXC_BAD_ACCESS, Could not access memory.
> >>> Reason: KERN_PROTECTION_FAILURE at address: 0x0000000103f05db0
> >>> 0x0000000103f05db0 in ?? () at RowSetEvent.java:51
> >>> 51	RowSetEvent.java: No such file or directory.
> >>> 	in RowSetEvent.java
> >>> (gdb) 
> >>>
> >>> A backtrace only shows...
> >>>
> >>> (gdb) bt
> >>> #0  0x0000000103f05db0 in ?? () at RowSetEvent.java:51
> >>> #1  0x00000001000485be in gnu::java::lang::MainThread::call_main (this=0x104875dc0) at ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc:54
> >>> Previous frame inner to this frame (gdb could not unwind past this frame)
> >>>
> >>> -----------------
> >>>
> >>> I want to disassemble from 0x00000001000485be, right?
> >> 0x0000000103f05db0, where the fault happens.  I think it's a libffi stub,
> >> and I think its page permissions are not correctly set.
> >>
> >> But let's see.
> >>
> >> What I would do is, at
> >>
> >>> 54	  (*real_main) (args);
> >> disassemble the call instruction, it's probably  call ($rax)  or somesuch.
> >> look in $rax with
> >>
> >> p $rax
> >>
> >> and disassemble from the address that's in there.
> >>
> >> Andrew.
> > 
> > Andrew,
> >    I can't disassemble 0x0000000103f05db0...
> > 
> > (gdb) disassemble 0x0000000103f05db0
> > No function contains specified address.
> 
> x/10i 0x0000000103f05db0
> 
> Andrew.

Andrew,
   Okay, I see...

gdb /sw/lib/gcc4.5/libexec/gcc/x86_64-apple-darwin9.8.0/4.5.0/ecj1
...
gdb) break ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc:46
Breakpoint 1 at 0x20c49ba4b0a5ab: file ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc, line 46.
(gdb) r testme.java -fbootclasspath=/sw/share/java/ecj/ecj.jar:./:/sw/lib/gcc4.5/share/java/libgcj-4.5.0.jar -fsource=1.5 -ftarget=1.5 -fzip-dependency /var/folders/1C/1CdoNxmNFHyOIjNBLNuJh++++TM/-Tmp-//ccQOWl1c.zip -fzip-target /var/folders/1C/1CdoNxmNFHyOIjNBLNuJh++++TM/-Tmp-//cc4p4DHj.jar
Starting program: /sw/lib/gcc4.5/libexec/gcc/x86_64-apple-darwin9.8.0/4.5.0/ecj1 testme.java -fbootclasspath=/sw/share/java/ecj/ecj.jar:./:/sw/lib/gcc4.5/share/java/libgcj-4.5.0.jar -fsource=1.5 -ftarget=1.5 -fzip-dependency /var/folders/1C/1CdoNxmNFHyOIjNBLNuJh++++TM/-Tmp-//ccQOWl1c.zip -fzip-target /var/folders/1C/1CdoNxmNFHyOIjNBLNuJh++++TM/-Tmp-//cc4p4DHj.jar
warning: posix_spawn failed, trying execvp, error: 86
Reading symbols for shared libraries +++++.. done
Breakpoint 1 at 0x1000485ab: file ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc, line 46.

Breakpoint 1, gnu::java::lang::MainThread::call_main (this=0x104875dc0) at ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc:46
46	    msg =  "`main' must be public";
(gdb) s
Current language:  auto; currently c++
45	  else if (! ::java::lang::reflect::Modifier::isPublic(meth->accflags))
(gdb) s
54	  (*real_main) (args);
(gdb) x/10i 0x0000000103f05db0
0x103f05db0:	mov    $0x1009814e8,%r11
0x103f05dba:	mov    $0x103f05db0,%r10
0x103f05dc4:	clc    
0x103f05dc5:	rex.WB jmpq   *%r11
0x103f05dc8:	add    %bl,-0x10(%rsi)
0x103f05dcb:	add    (%rcx),%eax
0x103f05dcd:	add    %al,(%rax)
0x103f05dcf:	add    %ah,%al
0x103f05dd1:	(bad)  
0x103f05dd2:	cwtl   
(gdb) bt
#0  gnu::java::lang::MainThread::call_main (this=0x104875dc0) at ../../../gcc-4.5-20091128/libjava/gnu/java/lang/natMainThread.cc:54
#1  0x0000000104875dc0 in ?? () at ClassHelper.java:106
#2  0x0000000104875f00 in ?? () at ClassHelper.java:106
#3  0x000000010493e980 in ?? () at ClassHelper.java:106
#4  0x00000001000b1b74 in _ZN3gnu4java4lang10MainThread3runEJvv (this=0x104875dc0) at MainThread.java:106
Previous frame inner to this frame (gdb could not unwind past this frame)
(gdb) p $rax
$1 = 1

(gdb) s

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x0000000103f05db0
0x0000000103f05db0 in ?? () at ClassHelper.java:106
106	ClassHelper.java: No such file or directory.
	in ClassHelper.java

What do you make of the bad assembly at 0x103f05dd1?
                       Jack