Re: Ptrace broken since 2.4.0-test8pre4?...

From: Roderich Schupp (rsch@ExperTeam.de)
Date: Wed Sep 20 2000 - 20:14:00 EST


Yuri Pudgorodsky <yur@asplinux.ru> said:
> Beeing an active user mode linux user :-) I can say that since
> 2.4.0-test8 (host kernel) I cannot run uml-linux successfully.

"Andi Kleen" <ak@suse.de> said:
> The following patch added in 2.4.0test8-pre4 breaks ups (an
> alternative source level debugger that does not use gdb):

The ptrace change in test8 also breaks ltrace - the ltraced child
gets SEGV (on the first PTRACE_SINGLESTEP):

$ strace ltrace ls
...
ptrace(PTRACE_PEEKTEXT, 30364, 0x80490bc, [0x330825cc]) = 0
ptrace(PTRACE_POKETEXT, 30364, 0x80490bc, 0x330825ff) = 0
ptrace(PTRACE_POKEUSER, 30364, 4*EIP, 0x80490bc) = 0
ptrace(PTRACE_SINGLESTEP, 30364, 0, SIG_0) = 0
--- SIGCHLD (Child exited) ---
wait4(-1, [WIFSIGNALED(s) && WTERMSIG(s) == SIGSEGV], 0, NULL) = 30364
write(2, " <unfinished ...>\n", 18 <unfinished ...>
) = 18
write(2, "+++ killed by SIGSEGV +++", 25+++ killed by SIGSEGV +++) = 25
write(2, "\n", 1
) = 1
_exit(0) = ?

If I back out the change to linux/arch/i386/kernel/ptrace.c
ltrace works as expected.

Cheers, Roderich

-- 
WHAT? I thought these were stuffed peppers.  Honey, what the heck
       IS this??  Whatever it is, I'm not eating it!
                               -- Calvin & Hobbes

Roderich Schupp mailto:rsch@ExperTeam.de ExperTeam GmbH http://www.experteam.de/ Munich, Germany

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