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Date:      Tue, 27 Sep 2011 13:17:02 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r225791 - head/sys/kern
Message-ID:  <201109271317.p8RDH2lY024248@svn.freebsd.org>
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Author: kib
Date: Tue Sep 27 13:17:02 2011
New Revision: 225791
URL: http://svn.freebsd.org/changeset/base/225791

Log:
  Do not deliver SIGTRAP on exec as the normal signal, use ptracestop() on
  syscall exit path. Otherwise, if SIGTRAP is ignored, that tdsendsignal()
  do not want to deliver the signal, and debugger never get a notification
  of exec.
  
  Found and tested by:	Anton Yuzhaninov <citrin citrin ru>
  Discussed with:	jhb
  MFC after:	2 weeks

Modified:
  head/sys/kern/kern_exec.c
  head/sys/kern/subr_syscall.c

Modified: head/sys/kern/kern_exec.c
==============================================================================
--- head/sys/kern/kern_exec.c	Tue Sep 27 12:14:43 2011	(r225790)
+++ head/sys/kern/kern_exec.c	Tue Sep 27 13:17:02 2011	(r225791)
@@ -777,16 +777,6 @@ interpret:
 	KNOTE_LOCKED(&p->p_klist, NOTE_EXEC);
 	p->p_flag &= ~P_INEXEC;
 
-	/*
-	 * If tracing the process, trap to the debugger so that
-	 * breakpoints can be set before the program executes.  We
-	 * have to use tdsignal() to deliver the signal to the current
-	 * thread since any other threads in this process will exit if
-	 * execve() succeeds.
-	 */
-	if (p->p_flag & P_TRACED)
-		tdsignal(td, SIGTRAP);
-
 	/* clear "fork but no exec" flag, as we _are_ execing */
 	p->p_acflag &= ~AFORK;
 

Modified: head/sys/kern/subr_syscall.c
==============================================================================
--- head/sys/kern/subr_syscall.c	Tue Sep 27 12:14:43 2011	(r225790)
+++ head/sys/kern/subr_syscall.c	Tue Sep 27 13:17:02 2011	(r225791)
@@ -204,9 +204,17 @@ syscallret(struct thread *td, int error,
 	 * is not the case, this code will need to be revisited.
 	 */
 	STOPEVENT(p, S_SCX, sa->code);
-	PTRACESTOP_SC(p, td, S_PT_SCX);
 	if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
 		PROC_LOCK(p);
+		/*
+		 * If tracing the execed process, trap to the debugger
+		 * so that breakpoints can be set before the program
+		 * executes.  If debugger requested tracing of syscall
+		 * returns, do it now too.
+		 */
+		if (traced && ((td->td_dbgflags & TDB_EXEC) != 0 ||
+		    (p->p_stops & S_PT_SCX) != 0))
+			ptracestop(td, SIGTRAP);
 		td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
 		PROC_UNLOCK(p);
 	}

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