[src/trunk]: src Fix and enable traceme_signal_nohandler2 in ATF ptrace(2) tests

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/716528d7e1ef
branches:  trunk
changeset: 322854:716528d7e1ef
user:      kamil <kamil%NetBSD.org@localhost>
date:      Sun May 20 03:51:31 2018 +0000

description:
Fix and enable traceme_signal_nohandler2 in ATF ptrace(2) tests

traceme_signal_nohandler2 checks emitting SIGSTOP to a traced process
with the PT_CONTINUE operation.

The expected behavior is to simulate a behavior of receiving SIGSTOP,
generating SIGCHLD to its parent (in this case the debugger) and ability
to call wait(2)-like function receiving the stopped child event.

The previous behavior was unstopping the process and it has been adjusted
in the kernel code.

FreeBSD keeps unstopping a process for emitting SIGSTOP.
Linux handles this scenario in the same way as NetBSD now.

While there, implement the missing bits in the userland ATF test for
traceme_signal_nohandler2: receiving and validating 2nd SIGSTOP event and
continuing the process, followed by its normal termination.

Sponsored by <The NetBSD Foundation>

diffstat:

 sys/kern/sys_ptrace_common.c       |  15 ++++++++++++---
 tests/lib/libc/sys/t_ptrace_wait.c |  33 +++++++++++++++++++++++++++++----
 2 files changed, 41 insertions(+), 7 deletions(-)

diffs (111 lines):

diff -r 21a2687c9659 -r 716528d7e1ef sys/kern/sys_ptrace_common.c
--- a/sys/kern/sys_ptrace_common.c      Sun May 20 03:09:02 2018 +0000
+++ b/sys/kern/sys_ptrace_common.c      Sun May 20 03:51:31 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_ptrace_common.c,v 1.40 2018/05/01 16:37:23 kamil Exp $     */
+/*     $NetBSD: sys_ptrace_common.c,v 1.41 2018/05/20 03:51:31 kamil Exp $     */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -118,7 +118,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.40 2018/05/01 16:37:23 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.41 2018/05/20 03:51:31 kamil Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ptrace.h"
@@ -865,7 +865,16 @@
                 * an LWP runs to see it.
                 */
                t->p_xsig = signo;
-               if (resume_all)
+
+               /*
+                * signo > 0 check precents a potential panic, as
+                * sigismember(&...,0) is invalid check and signo
+                * can be equal to 0 as a special case of no-signal.
+                */
+               if (signo > 0 && sigismember(&stopsigmask, signo)) {
+                       t->p_waited = 0;
+                       child_psignal(t, 0);
+               } else if (resume_all)
                        proc_unstop(t);
                else
                        lwp_unstop(lt);
diff -r 21a2687c9659 -r 716528d7e1ef tests/lib/libc/sys/t_ptrace_wait.c
--- a/tests/lib/libc/sys/t_ptrace_wait.c        Sun May 20 03:09:02 2018 +0000
+++ b/tests/lib/libc/sys/t_ptrace_wait.c        Sun May 20 03:51:31 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: t_ptrace_wait.c,v 1.47 2018/05/19 05:25:21 kamil Exp $ */
+/*     $NetBSD: t_ptrace_wait.c,v 1.48 2018/05/20 03:51:31 kamil Exp $ */
 
 /*-
  * Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: t_ptrace_wait.c,v 1.47 2018/05/19 05:25:21 kamil Exp $");
+__RCSID("$NetBSD: t_ptrace_wait.c,v 1.48 2018/05/20 03:51:31 kamil Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -299,6 +299,7 @@
 
                switch (sigsent) {
                case SIGCONT:
+               case SIGSTOP:
                        _exit(exitval);
                default:
                        /* NOTREACHED */
@@ -332,6 +333,30 @@
        TWAIT_REQUIRE_SUCCESS(wpid = TWAIT_GENERIC(child, &status, 0), child);
 
        switch (sigsent) {
+       case SIGSTOP:
+               validate_status_stopped(status, sigsent);
+               DPRINTF("Before calling ptrace(2) with PT_GET_SIGINFO for "
+                       "child\n");
+               SYSCALL_REQUIRE(ptrace(PT_GET_SIGINFO, child, &info,
+                                      sizeof(info)) != -1);
+
+               DPRINTF("Signal traced to lwpid=%d\n", info.psi_lwpid);
+               DPRINTF("Signal properties: si_signo=%#x si_code=%#x "
+                       "si_errno=%#x\n",
+                       info.psi_siginfo.si_signo, info.psi_siginfo.si_code,
+                       info.psi_siginfo.si_errno);
+
+               ATF_REQUIRE_EQ(info.psi_siginfo.si_signo, sigval);
+               ATF_REQUIRE_EQ(info.psi_siginfo.si_code, SI_LWP);
+
+               DPRINTF("Before resuming the child process where it left off "
+                       "and with signal %s to be sent\n", strsignal(sigsent));
+               SYSCALL_REQUIRE(ptrace(PT_CONTINUE, child, (void *)1, 0) != -1);
+
+               DPRINTF("Before calling %s() for the child\n", TWAIT_FNAME);
+               TWAIT_REQUIRE_SUCCESS(wpid = TWAIT_GENERIC(child, &status, 0),
+                                     child);
+               /* FALLTHROUGH */
        case SIGCONT:
                validate_status_exited(status, exitval);
                break;
@@ -360,7 +385,7 @@
 }
 
 TRACEME_SIGNAL_NOHANDLER(traceme_signal_nohandler1, SIGKILL) /* non-maskable */
-//TRACEME_SIGNAL_NOHANDLER(traceme_signal_nohandler2, SIGSTOP) /* non-maskable */
+TRACEME_SIGNAL_NOHANDLER(traceme_signal_nohandler2, SIGSTOP) /* non-maskable */
 TRACEME_SIGNAL_NOHANDLER(traceme_signal_nohandler3, SIGABRT) /* abort trap */
 TRACEME_SIGNAL_NOHANDLER(traceme_signal_nohandler4, SIGHUP)  /* hangup */
 TRACEME_SIGNAL_NOHANDLER(traceme_signal_nohandler5, SIGCONT) /* continued? */
@@ -7113,7 +7138,7 @@
        ATF_TP_ADD_TC(tp, traceme_sighandler_catch3);
 
        ATF_TP_ADD_TC(tp, traceme_signal_nohandler1);
-//     ATF_TP_ADD_TC(tp, traceme_signal_nohandler2); // not yet
+       ATF_TP_ADD_TC(tp, traceme_signal_nohandler2);
        ATF_TP_ADD_TC(tp, traceme_signal_nohandler3);
        ATF_TP_ADD_TC(tp, traceme_signal_nohandler4);
        ATF_TP_ADD_TC(tp, traceme_signal_nohandler5);