[lttng-dev] [PATCH lttng-modules 1/3] Fix: signal: Distinguish between kernel_siginfo and siginfo (v4.20)

[Michael Jeanson]

See upstream commit :

  commit ae7795bc6187a15ec51cf258abae656a625f9980
  Author: Eric W. Biederman <ebiederm at xmission.com>
  Date:   Tue Sep 25 11:27:20 2018 +0200

    signal: Distinguish between kernel_siginfo and siginfo

    Linus recently observed that if we did not worry about the padding
    member in struct siginfo it is only about 48 bytes, and 48 bytes is
    much nicer than 128 bytes for allocating on the stack and copying
    around in the kernel.

    The obvious thing of only adding the padding when userspace is
    including siginfo.h won't work as there are sigframe definitions in
    the kernel that embed struct siginfo.

    So split siginfo in two; kernel_siginfo and siginfo.  Keeping the
    traditional name for the userspace definition.  While the version that
    is used internally to the kernel and ultimately will not be padded to
    128 bytes is called kernel_siginfo.

    The definition of struct kernel_siginfo I have put in include/signal_types.h

    A set of buildtime checks has been added to verify the two structures have
    the same field offsets.

    To make it easy to verify the change kernel_siginfo retains the same
    size as siginfo.  The reduction in size comes in a following change.

Signed-off-by: Michael Jeanson <mjeanson at efficios.com>
---
 instrumentation/events/lttng-module/signal.h | 41 ++++++++++++++++++--
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/instrumentation/events/lttng-module/signal.h b/instrumentation/events/lttng-module/signal.h
index 68045ce..6c484ba 100644
--- a/instrumentation/events/lttng-module/signal.h
+++ b/instrumentation/events/lttng-module/signal.h
@@ -36,21 +36,24 @@
  * SEND_SIG_NOINFO means that si_code is SI_USER, and SEND_SIG_PRIV
  * means that si_code is SI_KERNEL.
  */
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,4,0))
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,20,0))
 LTTNG_TRACEPOINT_EVENT(signal_generate,
 
-	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task),
+	TP_PROTO(int sig, struct kernel_siginfo *info, struct task_struct *task,
+			int group, int result),
 
-	TP_ARGS(sig, info, task),
+	TP_ARGS(sig, info, task, group, result),
 
 	TP_FIELDS(
 		ctf_integer(int, sig, sig)
 		LTTNG_FIELDS_SIGINFO(info)
 		ctf_array_text(char, comm, task->comm, TASK_COMM_LEN)
 		ctf_integer(pid_t, pid, task->pid)
+		ctf_integer(int, group, group)
+		ctf_integer(int, result, result)
 	)
 )
-#else
+#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(3,4,0))
 LTTNG_TRACEPOINT_EVENT(signal_generate,
 
 	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task,
@@ -67,6 +70,20 @@ LTTNG_TRACEPOINT_EVENT(signal_generate,
 		ctf_integer(int, result, result)
 	)
 )
+#else
+LTTNG_TRACEPOINT_EVENT(signal_generate,
+
+	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task),
+
+	TP_ARGS(sig, info, task),
+
+	TP_FIELDS(
+		ctf_integer(int, sig, sig)
+		LTTNG_FIELDS_SIGINFO(info)
+		ctf_array_text(char, comm, task->comm, TASK_COMM_LEN)
+		ctf_integer(pid_t, pid, task->pid)
+	)
+)
 #endif
 
 /**
@@ -83,6 +100,21 @@ LTTNG_TRACEPOINT_EVENT(signal_generate,
  * This means, this can show which signals are actually delivered, but
  * matching generated signals and delivered signals may not be correct.
  */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,20,0))
+LTTNG_TRACEPOINT_EVENT(signal_deliver,
+
+	TP_PROTO(int sig, struct kernel_siginfo *info, struct k_sigaction *ka),
+
+	TP_ARGS(sig, info, ka),
+
+	TP_FIELDS(
+		ctf_integer(int, sig, sig)
+		LTTNG_FIELDS_SIGINFO(info)
+		ctf_integer(unsigned long, sa_handler, (unsigned long) ka->sa.sa_handler)
+		ctf_integer(unsigned long, sa_flags, ka->sa.sa_flags)
+	)
+)
+#else
 LTTNG_TRACEPOINT_EVENT(signal_deliver,
 
 	TP_PROTO(int sig, struct siginfo *info, struct k_sigaction *ka),
@@ -96,6 +128,7 @@ LTTNG_TRACEPOINT_EVENT(signal_deliver,
 		ctf_integer(unsigned long, sa_flags, ka->sa.sa_flags)
 	)
 )
+#endif
 
 #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,4,0))
 LTTNG_TRACEPOINT_EVENT_CLASS(signal_queue_overflow,
-- 
2.17.1