netdev - [RFC 1/6] perf: Add new type PERF_TYPE

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Message-ID: <20171108181721.3354137-3-songliubraving@fb.com>
Date:   Wed, 8 Nov 2017 10:17:15 -0800
From:   Song Liu <songliubraving@...com>
To:     <peterz@...radead.org>, <rostedt@...dmis.org>, <mingo@...hat.com>,
        <davem@...emloft.net>, <netdev@...r.kernel.org>, <ast@...nel.org>,
        <daniel@...earbox.net>
CC:     <kernel-team@...com>, Song Liu <songliubraving@...com>
Subject: [RFC 1/6] perf: Add new type PERF_TYPE_PROBE

A new perf type PERF_TYPE_PROBE is added to allow creating [k,u]probe
with perf_event_open. These [k,u]probe are associated with the file
decriptor created by perf_event_open, thus are easy to clean when
the file descriptor is destroyed.

Struct probe_desc and two flags, is_uprobe and is_return, are added
to describe the probe being created with perf_event_open.

Note: We use type __u64 for pointer probe_desc instead of __aligned_u64.
The reason here is to avoid changing the size of struct perf_event_attr,
and breaking new-kernel-old-utility scenario. To avoid alignment problem
with the pointer, we will (in the following patches) copy probe_desc to
__aligned_u64 before using it as pointer.

Signed-off-by: Song Liu <songliubraving@...com>
Reviewed-by: Yonghong Song <yhs@...com>
Reviewed-by: Josef Bacik <jbacik@...com>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
 include/uapi/linux/perf_event.h | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 362493a..cc42d59 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -33,6 +33,7 @@ enum perf_type_id {
 	PERF_TYPE_HW_CACHE			= 3,
 	PERF_TYPE_RAW				= 4,
 	PERF_TYPE_BREAKPOINT			= 5,
+	PERF_TYPE_PROBE				= 6,
 
 	PERF_TYPE_MAX,				/* non-ABI */
 };
@@ -299,6 +300,29 @@ enum perf_event_read_format {
 #define PERF_ATTR_SIZE_VER4	104	/* add: sample_regs_intr */
 #define PERF_ATTR_SIZE_VER5	112	/* add: aux_watermark */
 
+#define MAX_PROBE_FUNC_NAME_LEN	64
+/*
+ * Describe a kprobe or uprobe for PERF_TYPE_PROBE.
+ * perf_event_attr.probe_desc will point to this structure. is_uprobe
+ * and is_return are used to differentiate different types of probe
+ * (k/u, probe/retprobe).
+ *
+ * The two unions should be used as follows:
+ * For uprobe: use path and offset;
+ * For kprobe: if func is empty, use addr
+ *             if func is not emtpy, use func and offset
+ */
+struct probe_desc {
+	union {
+		__aligned_u64	func;
+		__aligned_u64	path;
+	};
+	union {
+		__aligned_u64	addr;
+		__u64		offset;
+	};
+};
+
 /*
  * Hardware event_id to monitor via a performance monitoring event:
  *
@@ -320,7 +344,10 @@ struct perf_event_attr {
 	/*
 	 * Type specific configuration information.
 	 */
-	__u64			config;
+	union {
+		__u64		config;
+		__u64		probe_desc; /* ptr to struct probe_desc */
+	};
 
 	union {
 		__u64		sample_period;
@@ -370,7 +397,11 @@ struct perf_event_attr {
 				context_switch :  1, /* context switch data */
 				write_backward :  1, /* Write ring buffer from end to beginning */
 				namespaces     :  1, /* include namespaces data */
-				__reserved_1   : 35;
+
+				/* For PERF_TYPE_PROBE */
+				is_uprobe      :  1, /* 0: kprobe, 1: uprobe */
+				is_return      :  1, /* 0: probe, 1: retprobe */
+				__reserved_1   : 33;
 
 	union {
 		__u32		wakeup_events;	  /* wakeup every n events */
-- 
2.9.5