ldconfig segfault on RZ/Five was Re: Preparing isar-cip-core for RZ/Five

[Pavel Machek <pavel@denx.de>]

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Hi!

> >> Hmm, seems the issue persists:
> > 
> > :-(. Do you get gcc faulting, too?
> 
> I tried, but installation fails - illegal instruction.

Yeah, ldconfig is needed for installation. But I get a segfaulting gcc
binary.

> >> root@demo:~# ldconfig                                                                        
> >>
> >> [  297.146728] ldconfig[497]: unhandled signal 4 code 0x1 at 0x00000000000380c8 in ldconfig[10000+83000]
> > ...
> >> (gdb) disassemble $pc,+0x10
> >> Dump of assembler code from 0x380c8 to 0x380d8:
> >> => 0x00000000000380c8:  auipc   a2,0x66
> >>    0x00000000000380cc:  addi    a2,a2,2000 # 0x9e898
> >>    0x00000000000380d0:  sd      a0,0(a2)
> > 
> > auipc is something rather simple. a2 = pc + 0x66 << something. Not
> > sure how it could fault. Plus we get "illegal instruction", suggesting
> > it is not some other fault.
> > 
> > Could some kind of self-modifying code be involved? I guess some kind
> > of debugging/watchpoint is not probable.
> 
> No idea - but why should ldconfig be self-modifying?

No idea.

But I do have slightly different results then you (I think; I'm far
from risc-v expert). I did a breakpoint:

Breakpoint 1, 0x00000000000385d4 in ?? ()
(gdb)

Dump of assembler code from 0x385d4 to 0x385f4:
=> 0x00000000000385d4:  lb      zero,81(t1)
   0x00000000000385d8:  andi    a1,a1,25
   0x00000000000385da:  sd      zero,24(sp)
   0x00000000000385dc:  sd      zero,32(sp)

If I do the stepi, it will give the illegal instruction, because,
well, we are in the middle of the auipc instruction:

(gdb) disassemble $pc-0x10,+0x20
Dump of assembler code from 0x385c4 to 0x385e4:
   0x00000000000385c4:  .4byte  0x4881f753
   0x00000000000385c8:  li      a6,0
   0x00000000000385ca:  li      a5,0
   0x00000000000385cc:  addi    a3,a1,920
   0x00000000000385d0:  mv      a2,s8
   0x00000000000385d2:  auipc   a0,0x3f
   0x00000000000385d6:  addi    a0,a0,-1890 # 0x76e70
   0x00000000000385da:  sd      zero,24(sp)
   0x00000000000385dc:  sd      zero,32(sp)
   0x00000000000385de:  sb      t3,20(sp)
   0x00000000000385e2:  sd      s7,40(sp)
End of assembler dump.
(gdb)

Weird. But it explains sigill when executing auipc does not result in
segfault...

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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