On 11/25, Ananth N Mavinakayanahalli wrote:
>
> I ran the ptrace-tests testsuite [1] on powerpc on the vanilla ptrace
> and then with ptrace/utrace. The results for ptrace/utrace look better
> :-)
Great! thanks a lot Ananth for doing this.
ptrace-utrace still fails 2 tests,
> FAIL: syscall-reset
I'll take a look later. Since unpatched kernel fails this test too
I am not going to worry right now. I think this is ppc specific, x86
passes this test.
> step-fork: step-fork.c:56: handler_fail: Assertion `0' failed.
> /bin/sh: line 5: 24803 Aborted ${dir}$tst
> FAIL: step-fork
This is expected. Should be fixed by
ptrace-copy_process-should-disable-stepping.patch
in -mm tree. (I am attaching this patch below just in case)
I din't mention this patch in this series because this bug
is "ortogonal" to utrace/ptrace.
Oleg.
------------------------------------------------------
If the tracee calls fork() after PTRACE_SINGLESTEP, the forked child
starts with TIF_SINGLESTEP/X86_EFLAGS_TF bits copied from ptraced parent.
This is not right, especially when the new child is not auto-attaced: in
this case it is killed by SIGTRAP.
Change copy_process() to call user_disable_single_step(). Tested on x86.
Test-case:
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <assert.h>
int main(void)
{
int pid, status;
if (!(pid = fork())) {
assert(ptrace(PTRACE_TRACEME) == 0);
kill(getpid(), SIGSTOP);
if (!fork()) {
/* kernel bug: this child will be killed by
SIGTRAP */
printf("Hello world\n");
return 43;
}
wait(&status);
return WEXITSTATUS(status);
}
for (;;) {
assert(pid == wait(&status));
if (WIFEXITED(status))
break;
assert(ptrace(PTRACE_SINGLESTEP, pid, 0,0) == 0);
}
assert(WEXITSTATUS(status) == 43);
return 0;
}
Signed-off-by: Oleg Nesterov <o...@redhat.com>
Acked-by: Roland McGrath <rol...@redhat.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---
diff -puN kernel/fork.c~ptrace-copy_process-should-disable-stepping
kernel/fork.c
--- a/kernel/fork.c~ptrace-copy_process-should-disable-stepping
+++ a/kernel/fork.c
@@ -1203,9 +1203,10 @@ static struct task_struct *copy_process(
p->sas_ss_sp = p->sas_ss_size = 0;
/*
- * Syscall tracing should be turned off in the child regardless
- * of CLONE_PTRACE.
+ * Syscall tracing and stepping should be turned off in the
+ * child regardless of CLONE_PTRACE.
*/
+ user_disable_single_step(p);
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
