Re: Native build failure...

[Johnny Billquist <bqt%softjar.se@localhost>]

Michael L. Hitch wrote:
> On Mon, 26 Jul 2010, Matt Thomas wrote:
>
> > > > > > > If I read things right, it's one of these two lines wich cause 
> > > > > > > the segfault though:
> > > > > > >    ce1:       c8 50 ad d8     bisl2 r0,0xffffffd8(fp)
> > > > > > >    ce5:       e8 a6 0d 05     blbs 0xd(r6),cee <update_file+0x428>
> > > ...
> > > > > > blbs uses a longword access so if r6+0xd is at 0xffd..0xfff and 
> > > > > > the page following isn't mapped you will get a segfault.
> > > > > Yes, but my first guess is that it would be the bisl2 instruction. 
> > > > > The address (if my conversions are right) would point to pc 
> > > > > pointing at the blbs after the trap, and I assume the pc have been 
> > > > > updated at that point?
> > > > > But I might be totally messing up my address calculations as well...
> > >
> > >  I think Matt want's the VA that caused the fault, which would likely
> > > be the contents of R6 + 0xd.  I have a rather vague memory of 
> > > something similar where the target address of the blbs was indexed 
> > > with a non-multiple-of-four offset which caused a memory fault.  The 
> > > same rather vague memory seems to recall that Matt came up with a 
> > > code generation change that did the blbs differently if the indexed 
> > > offset was not a multiple of 4.  A -g build could hide the problem by 
> > > re-arranging the code such that the test is done differently, or the 
> > > data re-arranged so that the 4 bytes at (r6) are valid.
> >
> > But that was for extzv and inszv but not blb[sc].  Basically for 
> > unaligned displacements, use bb[sc] instead.  Shouldn't be that hard 
> > to code up.
>
>   The memory may be vague, but searching my mail finds what I remember, 
> and it was blbs:
>
> http://mail-index.NetBSD.org/port-vax/2009/05/28/msg000691.html
>
>   I don't know if there was any followup to that message though.

Interesting. And that might be relevant...

Anyway, after some more fiddling, I managed to get gdb to give a lot 
more useful information...

(gdb) core nbgmake.core
Reading symbols from /usr/lib/libc.so.12...done.
Breakpoint 1 at 0x7f78a51d
Breakpoint 2 at 0x7f79efa5
Loaded symbols for /usr/lib/libc.so.12
Reading symbols from /usr/libexec/ld.elf_so...done.
Loaded symbols for /usr/libexec/ld.elf_so
Core was generated by `nbgmake'.
Program terminated with signal 11, Segmentation fault.
#0  update_file (file=0x7f44b6a0, depth=18, 2135209632, 18)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:464
464           if (! d->ignore_mtime)
(gdb) bt
#0  update_file (file=0x7f44b6a0, depth=18, 2135209632, 18)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:464
#1  0x0002150a in check_dep (file=<value optimized out>, depth=18,
    this_mtime=1279970249,
    must_make_ptr=0x7fff9bac, 2135209632, 17, 1279970249, 0, 2147457964)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#2  0x00020b8d in update_file (file=0x7f59ff10, depth=16, 2136604432, 16)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#3  0x0002150a in check_dep (file=<value optimized out>, depth=16,
    this_mtime=1279970274,
    must_make_ptr=0x7fff9c5c, 2136604432, 15, 1279970274, 0, 2147458140)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#4  0x00020b8d in update_file (file=0x7f570240, depth=14, 2136408640, 14)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#5  0x0002150a in check_dep (file=<value optimized out>, depth=14,
    this_mtime=1279970283,
    must_make_ptr=0x7fff9d0c, 2136408640, 13, 1279970283, 0, 2147458316)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#6  0x00020b8d in update_file (file=0x7f570290, depth=12, 2136408720, 12)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#7  0x0002150a in check_dep (file=<value optimized out>, depth=12,
    this_mtime=1279970284,
    must_make_ptr=0x7fff9dbc, 2136408720, 11, 1279970284, 0, 2147458492)
---Type <return> to continue, or q <return> to quit---
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#8  0x00020b8d in update_file (file=0x7f5702e0, depth=10, 2136408800, 10)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#9  0x0002150a in check_dep (file=<value optimized out>, depth=10,
    this_mtime=1279970310,
    must_make_ptr=0x7fff9e6c, 2136408800, 9, 1279970310, 0, 2147458668)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#10 0x00020b8d in update_file (file=0x7f570330, depth=8, 2136408880, 8)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#11 0x0002150a in check_dep (file=<value optimized out>, depth=8,
    this_mtime=1, must_make_ptr=0x7fff9f1c, 2136408880, 7, 1, 0, 
2147458844)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#12 0x00020b8d in update_file (file=0x7f59fdd0, depth=6, 2136604112, 6)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#13 0x0002150a in check_dep (file=<value optimized out>, depth=6,
    this_mtime=1, must_make_ptr=0x7fff9fcc, 2136604112, 5, 1, 0, 
2147459020)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#14 0x00020b8d in update_file (file=0x7f59fd30, depth=4, 2136603952, 4)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#15 0x0002150a in check_dep (file=<value optimized out>, depth=4,
    this_mtime=1, must_make_ptr=0x7fffa07c, 2136603952, 3, 1, 0, 
2147459196)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#16 0x00020b8d in update_file (file=0x7f4ddbf0, depth=2, 2135809008, 2)
---Type <return> to continue, or q <return> to quit---
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#17 0x0002150a in check_dep (file=<value optimized out>, depth=2,
    this_mtime=1, must_make_ptr=0x7fffa12c, 2135809008, 1, 1, 0, 
2147459372)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:857
#18 0x00020b8d in update_file (file=0x7f5221a0, depth=0, 2136088992, 0)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:463
#19 0x00021858 in update_goal_chain (goals=0x7f4015a0,
    makefiles=0, 2136015744, 0)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/remake.c:157
#20 0x0001c5b5 in main (argc=91, argv=0x7fffd284,
    envp=0x7fffd3f4, 91, 2147472004, 2147472372)
    at /usr/src/tools/gmake/../../gnu/dist/gmake/main.c:1946
(gdb) print/x $r6
$2 = 0x7f5ffff0
(gdb)

Anything else I can do that will help?

        Johnny

--
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol