[src/trunk]: src/sys/kern Introduce fixes for ptrace(2)

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

details:   https://anonhg.NetBSD.org/src/rev/850e84b7816f
branches:  trunk
changeset: 450993:850e84b7816f
user:      kamil <kamil%NetBSD.org@localhost>
date:      Thu May 02 22:23:49 2019 +0000

description:
Introduce fixes for ptrace(2)

Stop disabling LWP create and exit events for PT_SYSCALL tracing.
PT_SYSCALL disabled EXEC reporting for legacy reasons, there is no need
to repeat it for LWP and CHLD events.

Pass full siginfo from trapsignal events (SEGV, BUS, ILL, TRAP, FPE).
This adds missing information about signals like fault address.

Set ps_lwp always.

Before passing siginfo to userland through p_sigctx.ps_info, make sure
that it was zeroed for unused bytes. LWP and CHLD events do not set si_addr
and si_trap, these pieces of information are passed for crashes (like
software breakpoint).

LLDB crash reporting works now correctly:

(lldb) r
Process 552 launched: '/tmp/a.out' (x86_64)
Process 552 stopped
* thread #1, stop reason = signal SIGSEGV: invalid address (fault address: 0x123456)

diffstat:

 sys/kern/kern_lwp.c |   6 +++---
 sys/kern/kern_sig.c |  16 ++++++++++++----
 sys/kern/sys_lwp.c  |  10 +++++-----
 3 files changed, 20 insertions(+), 12 deletions(-)

diffs (105 lines):

diff -r 876cbe62e6cb -r 850e84b7816f sys/kern/kern_lwp.c
--- a/sys/kern/kern_lwp.c       Thu May 02 21:33:12 2019 +0000
+++ b/sys/kern/kern_lwp.c       Thu May 02 22:23:49 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_lwp.c,v 1.198 2019/05/01 21:57:34 kamil Exp $     */
+/*     $NetBSD: kern_lwp.c,v 1.199 2019/05/02 22:23:49 kamil Exp $     */
 
 /*-
  * Copyright (c) 2001, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -211,7 +211,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.198 2019/05/01 21:57:34 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.199 2019/05/02 22:23:49 kamil Exp $");
 
 #include "opt_ddb.h"
 #include "opt_lockdebug.h"
@@ -1079,7 +1079,7 @@
         */
        mutex_enter(proc_lock);
 
-       if ((p->p_slflag & (PSL_TRACED|PSL_TRACELWP_EXIT|PSL_SYSCALL)) ==
+       if ((p->p_slflag & (PSL_TRACED|PSL_TRACELWP_EXIT)) ==
            (PSL_TRACED|PSL_TRACELWP_EXIT)) {
                mutex_enter(p->p_lock);
                p->p_lwp_exited = l->l_lid;
diff -r 876cbe62e6cb -r 850e84b7816f sys/kern/kern_sig.c
--- a/sys/kern/kern_sig.c       Thu May 02 21:33:12 2019 +0000
+++ b/sys/kern/kern_sig.c       Thu May 02 22:23:49 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_sig.c,v 1.355 2019/05/01 21:52:35 kamil Exp $     */
+/*     $NetBSD: kern_sig.c,v 1.356 2019/05/02 22:23:49 kamil Exp $     */
 
 /*-
  * Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.355 2019/05/01 21:52:35 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.356 2019/05/02 22:23:49 kamil Exp $");
 
 #include "opt_ptrace.h"
 #include "opt_dtrace.h"
@@ -913,8 +913,14 @@
        mutex_enter(p->p_lock);
 
        if (ISSET(p->p_slflag, PSL_TRACED) &&
-           !(p->p_pptr == p->p_opptr && ISSET(p->p_lflag, PL_PPWAIT))) {
-               eventswitch(signo, ksi->ksi_code);
+           !(p->p_pptr == p->p_opptr && ISSET(p->p_lflag, PL_PPWAIT)) &&
+           p->p_xsig != SIGKILL &&
+           !sigismember(&p->p_sigpend.sp_set, SIGKILL)) {
+               p->p_xsig = signo;
+               p->p_sigctx.ps_faked = true;
+               p->p_sigctx.ps_lwp = ksi->ksi_lid;
+               p->p_sigctx.ps_info = ksi->ksi_info;
+               sigswitch(0, signo, false);
                // XXX ktrpoint(KTR_PSIG)
                mutex_exit(p->p_lock);
                return;
@@ -1556,6 +1562,8 @@
 
        p->p_xsig = signo;
        p->p_sigctx.ps_faked = true;
+       p->p_sigctx.ps_lwp = l->l_lid;
+       memset(&p->p_sigctx.ps_info, 0, sizeof(p->p_sigctx.ps_info));
        p->p_sigctx.ps_info._signo = signo;
        p->p_sigctx.ps_info._code = code;
 
diff -r 876cbe62e6cb -r 850e84b7816f sys/kern/sys_lwp.c
--- a/sys/kern/sys_lwp.c        Thu May 02 21:33:12 2019 +0000
+++ b/sys/kern/sys_lwp.c        Thu May 02 22:23:49 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_lwp.c,v 1.65 2019/05/01 22:55:55 kamil Exp $       */
+/*     $NetBSD: sys_lwp.c,v 1.66 2019/05/02 22:23:49 kamil Exp $       */
 
 /*-
  * Copyright (c) 2001, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_lwp.c,v 1.65 2019/05/01 22:55:55 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_lwp.c,v 1.66 2019/05/02 22:23:49 kamil Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -78,12 +78,12 @@
        (p->p_emul->e_startlwp)(arg);
 
        /* If the process is traced, report lwp creation to a debugger */
-       if ((p->p_slflag & (PSL_TRACED|PSL_TRACELWP_CREATE|PSL_SYSCALL)) ==
+       if ((p->p_slflag & (PSL_TRACED|PSL_TRACELWP_CREATE)) ==
            (PSL_TRACED|PSL_TRACELWP_CREATE)) {
                /* Paranoid check */
                mutex_enter(proc_lock);
-               if ((p->p_slflag & (PSL_TRACED|PSL_TRACELWP_CREATE|PSL_SYSCALL)) !=
-                   (PSL_TRACED|PSL_TRACELWP_CREATE)) {
+               if ((p->p_slflag & (PSL_TRACED|PSL_TRACELWP_CREATE)) !=
+                   (PSL_TRACED|PSL_TRACELWP_CREATE)) { 
                        mutex_exit(proc_lock);
                        return;
                }