Re: Stuck CLOSED sockets / sshd / zombies...
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On Tue, Apr 08, 2014 at 04:33:03PM +0100, Karl Pielorz wrote:
>=20
>=20
> --On 08 April 2014 09:36 -0400 John Baldwin <jhb@freebsd.org> wrote:
>=20
> > Humm, it needs to build new ones with debug symbols. If it doesn't,
> > you'll need to do 'make clean' before the other makes. I think you
> > should be fine to do that (make clean then the command above) for those
> > directories and restart gdb without having to restart your sshd. Please
> > also add '/usr/src/libexec/rtld-elf' to the list of directories where y=
ou
> > do this. Then do 'detach' in gdb, exit gdb and restart it.
>=20
> Ok, it hit an issue with libc (complained it couldn't find yp.h - but I=
=20
> fixed that) and it compiled up OK then. The rest all recompiled / install=
ed=20
> OK, and I included the rtld-elf code.
>=20
> > Hmmm, that is useful even though the debug symbols aren't there. Please
> > do the rebuilds I asked for above and re-attach gdb and get 'bt' again.
>=20
> Ok, that now nets:
>=20
> "
> ...
> [Switching to LWP 100218]
> 0x00000008038ea89c in __error () from /lib/libthr.so.3
> (gdb) bt
> #0 0x00000008038ea89c in __error () from /lib/libthr.so.3
> #1 0x00000008038e104f in __thr_rwlock_rdlock (rwlock=3D0x803af9480,=20
> flags=3D<value optimized out>, tsp=3D<value optimized out>)
> at /usr/src/lib/libthr/thread/thr_umtx.c:277
> #2 0x00000008038e821c in _thr_rtld_rlock_acquire (lock=3D0x803af9480) at=
=20
> atomic.h:143
> #3 0x000000080064f9a2 in rlock_acquire (lock=3D0x80085fe00,=20
> lockstate=3D0x7fffffffba68) at /usr/src/libexec/rtld-elf/rtld_lock.c:197
> #4 0x00000008006498c9 in _rtld_bind (obj=3D0x800662000, reloff=3D13008) =
at=20
> /usr/src/libexec/rtld-elf/rtld.c:675
> #5 0x00000008006470cd in _rtld_bind_start () at=20
> /usr/src/libexec/rtld-elf/amd64/rtld_start.S:99
> #6 0x0000000000000246 in ?? ()
> #7 0x0000000000000000 in ?? ()
> "
The following patch might allow to see the backtrace beyond the binder
entry point. You might also have better luck with the gdb from ports.
diff --git a/libexec/rtld-elf/amd64/rtld_start.S b/libexec/rtld-elf/amd64/r=
tld_start.S
index da3d156..54ef468 100644
--- a/libexec/rtld-elf/amd64/rtld_start.S
+++ b/libexec/rtld-elf/amd64/rtld_start.S
@@ -79,17 +79,39 @@
.globl _rtld_bind_start
.type _rtld_bind_start,@function
_rtld_bind_start:
+ .cfi_startproc
+ .cfi_adjust_cfa_offset 16
subq $8,%rsp
+ .cfi_adjust_cfa_offset 8
pushfq # Save rflags
+ .cfi_adjust_cfa_offset 8
pushq %rax # Save %rax
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %rax,-24
pushq %rdx # Save %rdx
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %rdx,-32
pushq %rcx # Save %rcx
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %rcx,-40
pushq %rsi # Save %rsi
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %rsi,-48
pushq %rdi # Save %rdi
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %rdi,-56
pushq %r8 # Save %r8
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %r8,-64
pushq %r9 # Save %r9
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %r9,-72
pushq %r10 # Save %r10
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %r10,-80
pushq %r11 # Save %r11
+ .cfi_adjust_cfa_offset 8
+ .cfi_offset %r11,-88
=20
movq 0x58(%rsp),%rdi # Fetch obj argument
movq 0x60(%rsp),%rsi # Fetch reloff argument
@@ -101,16 +123,37 @@ _rtld_bind_start:
=20
movq %rax,0x60(%rsp) # Store target over reloff argument
popq %r11 # Restore %r11
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %r11
popq %r10 # Restore %r10
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %r10
popq %r9 # Restore %r9
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %r9
popq %r8 # Restore %r8
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %r8
popq %rdi # Restore %rdi
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %rdi
popq %rsi # Restore %rsi
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %rsi
popq %rcx # Restore %rcx
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %rcx
popq %rdx # Restore %rdx
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %rdx
popq %rax # Restore %rax
+ .cfi_adjust_cfa_offset -8
+ .cfi_restore %rax
popfq # Restore rflags
+ .cfi_adjust_cfa_offset -8
leaq 16(%rsp),%rsp # Discard spare, obj, do not change rflags
ret # "Return" to target address
+ .cfi_endproc
+ .size _rtld_bind_start, . - _rtld_bind_start
=20
.section .note.GNU-stack,"",%progbits
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