arm/181722: gdb on ARM unable to sensibly debug core file from assert(3)

[Peter Jeremy]

>Number:         181722
>Category:       arm
>Synopsis:       gdb on ARM unable to sensibly debug core file from assert(3)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-arm
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Sep 01 11:00:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Peter Jeremy
>Release:        FreeBSD 10.0-CURRENT arm
>Organization:
n/a
>Environment:
System: FreeBSD rpi1.rulingia.com 10.0-CURRENT FreeBSD 10.0-CURRENT #0: Mon Jul  8 19:45:57 UTC 2013     root at rpi1.rulingia.com:/usr/obj/usr/src/sys/RPI-PJ  arm

>Description:
	Whilst trying to build head r254986 with clang on my Raspberry Pi,
	I consistently get an assertion failure and core file.  Attempting
	to examine the core file with gdb gives a truncated backtrace (see
	below).  If clang is run under gdb, setting a breakpoint at
	__assert, correct backtraces are shown.

root at rpi1:/a # gdb /a/obj/usr/src/tmp/usr/bin/cc cc.core 
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "armv6-marcel-freebsd"...
Core was generated by `cc'.
Program terminated with signal 6, Aborted.
#0  0x01f92094 in kill ()
(gdb) where
#0  0x01f92094 in kill ()
#1  0x01f92038 in raise ()
#2  0x01f901a0 in abort ()
#3  0x01f7b55c in __assert ()
#4  0x01f7b55c in __assert ()
(gdb) 
...
(gdb) up
#4  0x01f7b55c in __assert ()
(gdb) info regi
r0             0x0      0
r1             0x0      0
r2             0x0      0
r3             0xffffffdf       -33
r4             0x0      0
r5             0xbfffcb74       -1073755276
r6             0x3      3
r7             0x57     87
r8             0x228152b8       578900664
r9             0x2284fb00       579140352
r10            0x22876000       579297280
r11            0xbfffcba8       -1073755224
r12            0xbfffcb94       -1073755244
sp             *value not available*
lr             0x1f7b55c        33011036
pc             0x1f7b55c        33011036
fps            0x0      0
cpsr           0x80000010       -2147483632
(gdb) disas 0x1f7b55c
Dump of assembler code for function $d:
0x01f7b55c <$d+0>:      eorseq  r8, r11, #12845056      ; 0xc40000
0x01f7b560 <$d+4>:      eorseq  r3, r10, #16515072      ; 0xfc0000
0x01f7b564 <$d+8>:      eorseq  r3, r10, #655360        ; 0xa0000
End of assembler dump.
(gdb) disas __assert
Dump of assembler code for function __assert:
0x01f7b4fc <__assert+0>:        mov     r12, sp
0x01f7b500 <__assert+4>:        push    {r11, r12, lr, pc}
0x01f7b504 <__assert+8>:        sub     r11, r12, #4    ; 0x4
0x01f7b508 <__assert+12>:       sub     sp, sp, #8      ; 0x8
0x01f7b50c <__assert+16>:       mov     lr, r1
0x01f7b510 <__assert+20>:       mov     r4, r3
0x01f7b514 <__assert+24>:       subs    r12, r0, #0     ; 0x0
0x01f7b518 <__assert+28>:       bne     0x1f7b53c <__assert+64>
0x01f7b51c <__assert+32>:       ldr     r3, [pc, #56]   ; 0x1f7b55c <$d>
0x01f7b520 <__assert+36>:       ldr     r0, [r3]
0x01f7b524 <__assert+40>:       str     r2, [sp]
0x01f7b528 <__assert+44>:       ldr     r1, [pc, #48]   ; 0x1f7b560 <$d+4>
0x01f7b52c <__assert+48>:       mov     r2, r4
0x01f7b530 <__assert+52>:       mov     r3, lr
0x01f7b534 <__assert+56>:       bl      0x1f7b6c0 <fprintf>
0x01f7b538 <__assert+60>:       b       0x1f7b558 <__assert+92>
0x01f7b53c <__assert+64>:       ldr     r3, [pc, #24]   ; 0x1f7b55c <$d>
0x01f7b540 <__assert+68>:       ldr     r0, [r3]
0x01f7b544 <__assert+72>:       stm     sp, {r1, r2}
0x01f7b548 <__assert+76>:       ldr     r1, [pc, #20]   ; 0x1f7b564 <$d+8>
0x01f7b54c <__assert+80>:       mov     r2, r4
0x01f7b550 <__assert+84>:       mov     r3, r12
0x01f7b554 <__assert+88>:       bl      0x1f7b6c0 <fprintf>
0x01f7b558 <__assert+92>:       bl      0x1f90104 <abort>
End of assembler dump.
(gdb) x/20x $r12
0xbfffcb94:     Cannot access memory at address 0xbfffcb94
(gdb) 

>How-To-Repeat:

	$ cat <<E*O*F > /tmp/test.i
extern void __stack_chk_fail (void);

void
__attribute__((visibility ("hidden")))
__stack_chk_fail_local (void)
{
  __stack_chk_fail ();
}
E*O*F
	$ clang -cc1 -triple armv6--freebsd10.0-gnueabi -S -disable-free -main-file-name ssp-local.c -mrelocation-model pic -pic-level 2 -mdisable-fp-elim -mconstructor-aliases -target-abi aapcs-linux -target-cpu arm1136jf-s -msoft-float -mfloat-abi soft -target-feature +soft-float -target-feature +soft-float-abi -target-feature -neon -g -coverage-file /tmp/test.s -O2 -std=gnu99 -fno-dwarf-directory-asm -fdebug-compilation-dir /usr/obj/usr/src/gnu/lib/libssp/libssp_nonshared -ferror-limit 19 -fmessage-length 168 -fvisibility hidden -mstackrealign -fno-signed-char -fobjc-runtime=gnustep -fobjc-default-synthesize-properties -fdiagnostics-show-option -fcolor-diagnostics -backend-option -vectorize-loops -o /tmp/test.s -x c /tmp/test.i
	$ gdb clang clang.core
	(gdb) where

>Fix:
	Unknown.


>Release-Note:
>Audit-Trail:
>Unformatted: