[libunwind] libunwind segv with gcc 2.96 programs run on Redhat EL 3 with GLIBC 2.3.2

[Harrow, Jerry]

My project has been using libunwind to trace the stack at event points within a process.  When testing with the new Redhat EL V3 on Itanium (glibc 2.3.2)  we started to see a segv from libunwind when attempting to unwind through main().    I downloaded and built the latest libunwind 0.96, but the behavior is the same.  I tracked it down to the following case:

 

If the main program has been built on RH AS 2.1 (with gcc 2.96), and we attempt to unwind past main() we get a segv.   It appears that the end of the callstack is not detected.  If I rebuild the main program on RH it works fine.  Strangely, it also works fine if I set LD_ASSUME_KERNEL=2.4.1 which forces the use the /lib/libc.so.6.1 for linuxthreads instead of the default /lib/tls/libc.so.6.1 which is built to work with the new NPTL threads library.

 

Is there any known incompatibility that would cause this?  I’d be glad to try to help resolve this anyway I can.   I am using the attached example bt.c.   Below is as much info as I could capture using the debugger. 

 

Thanks.

 

-Jer

 

 

-- On RH AS 2.1 --

> gcc bt.c -o bt -I$VT/lib/libunwind/libunwind-0.96/$VTARCH/include -L$VT/lib/libunwind/libunwind-0.96/$VTARCH/lib -lunwind –g

 

-- On RH EL 3 --

> gdb bt

(gdb) r

Starting program: /var/users/harrow/bt

ip = 0x4000000000000c10, sp = 0x60000fffffffb200

ip = 0x4000000000000c60, sp = 0x60000fffffffb200

ip = 0x4000000000000cb0, sp = 0x60000fffffffb200

ip = 0x20000000000fe7d0, sp = 0x60000fffffffb200

ip = 0x40000000000008e0, sp = 0x60000fffffffb630

 

Program received signal SIGSEGV, Segmentation fault.

update_frame_state (c=0x60000fffffff97a0) at unwind_i.h:119

119     unwind_i.h: No such file or directory.

        in unwind_i.h

(gdb) where

#0  update_frame_state (c=0x60000fffffff97a0) at unwind_i.h:119

#1  0x200000000007c0e0 in _ULia64_step (cursor=0x60000fffffff97b0) at Gstep-ia64.c:341

#2  0x4000000000000ae0 in show_backtrace () at bt.c:19

#3  0x4000000000000c10 in parent2 () at bt.c:31

#4  0x4000000000000c60 in parent1 () at bt.c:35

#5  0x4000000000000cb0 in main () at bt.c:39

#6  0x20000000000fe7d0 in __libc_start_main () from /lib/tls/libc.so.6.1

(gdb)

(gdb) set environ LD_ASSUME_KERNEL=2.4.1

(gdb) break show_backtrace

Breakpoint 1 at 0x4000000000000a62: file bt.c, line 15.

(gdb) r

Starting program: /var/users/harrow/bt

 

Breakpoint 1, show_backtrace () at bt.c:15

15        unw_getcontext(&uc);

(gdb) where

#0  show_backtrace () at bt.c:15

#1  0x4000000000000c10 in parent2 () at bt.c:31

#2  0x4000000000000c60 in parent1 () at bt.c:35

#3  0x4000000000000cb0 in main () at bt.c:39

#4  0x20000000000ff280 in __libc_start_main () from /lib/libc.so.6.1

#5  0x40000000000008e0 in _start ()

(gdb) c

Continuing.

ip = 0x4000000000000c10, sp = 0x60000fffffffb600

ip = 0x4000000000000c60, sp = 0x60000fffffffb600

ip = 0x4000000000000cb0, sp = 0x60000fffffffb600

ip = 0x20000000000ff280, sp = 0x60000fffffffb600

ip = 0x40000000000008e0, sp = 0x60000fffffffb600

 

Program exited normally.

(gdb)

 

 

 

 

Jerry J. Harrow, Jr.	Hewlett-Packard Company 110 Spit Brook Rd Nashua, NH 03062-2698 USA
address@hidden Telephone: 603.884.2193

 

 

bt.c
Description: bt.c