linux-kernel - [PATCH 2/7] tracehooks: check PT_PTRACED before reporting the single-step

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Date:	Fri, 18 Dec 2009 02:11:24 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Alexey Dobriyan <adobriyan@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Ananth Mavinakayanahalli <ananth@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org, utrace-devel@...hat.com
Subject: [PATCH 2/7] tracehooks: check PT_PTRACED before reporting the
	single-step

No functional changes, preparation for utrace-ptrace.

tracehook_report_syscall_exit() and tracehook_signal_handler() assume
that only ptrace can set TIF_SINGLESTEP. Currently this is true but we
are going to change this, the stepping logic will be moved into utrace
layer.

Change this code to check PT_PTRACED, ptrace-utrace doesn't set it.

Signed-off-by: Roland McGrath <roland@...hat.com>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---

 include/linux/tracehook.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- V1/include/linux/tracehook.h~2_SIGNAL_HANDLER_CK_PTRACE	2009-12-18 00:38:09.000000000 +0100
+++ V1/include/linux/tracehook.h	2009-12-18 00:45:42.000000000 +0100
@@ -134,7 +134,7 @@ static inline __must_check int tracehook
  */
 static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step)
 {
-	if (step) {
+	if (step && (task_ptrace(current) & PT_PTRACED)) {
 		siginfo_t info;
 		user_single_step_siginfo(current, regs, &info);
 		force_sig_info(SIGTRAP, &info, current);
@@ -386,7 +386,7 @@ static inline void tracehook_signal_hand
 					    const struct k_sigaction *ka,
 					    struct pt_regs *regs, int stepping)
 {
-	if (stepping)
+	if (stepping && (task_ptrace(current) & PT_PTRACED))
 		ptrace_notify(SIGTRAP);
 }
 

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