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From: Alexei Starovoitov <ast@fb.com>
To: <davem@davemloft.net>
Cc: <daniel@iogearbox.net>, <torvalds@linux-foundation.org>,
	<peterz@infradead.org>, <rostedt@goodmis.org>,
	<netdev@vger.kernel.org>, <kernel-team@fb.com>,
	<linux-api@vger.kernel.org>
Subject: [PATCH v3 bpf-next 06/10] tracepoint: compute num_args at build time
Date: Thu, 22 Mar 2018 11:01:53 -0700	[thread overview]
Message-ID: <20180322180157.742725-7-ast@fb.com> (raw)
In-Reply-To: <20180322180157.742725-1-ast@fb.com>

From: Alexei Starovoitov <ast@kernel.org>

add fancy macro to compute number of arguments passed into tracepoint
at compile time and store it as part of 'struct tracepoint'.
The number is necessary to check safety of bpf program access that
is coming in subsequent patch.

for_each_tracepoint_range() api has no users inside the kernel.
Make it more useful with ability to stop for_each() loop depending
via callback return value.
In such form it's used in subsequent patch.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/linux/tracepoint-defs.h |  1 +
 include/linux/tracepoint.h      | 28 +++++++++++++++++++---------
 include/trace/define_trace.h    | 14 +++++++-------
 kernel/tracepoint.c             | 27 ++++++++++++++++-----------
 4 files changed, 43 insertions(+), 27 deletions(-)

diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
index 64ed7064f1fa..39a283c61c51 100644
--- a/include/linux/tracepoint-defs.h
+++ b/include/linux/tracepoint-defs.h
@@ -33,6 +33,7 @@ struct tracepoint {
 	int (*regfunc)(void);
 	void (*unregfunc)(void);
 	struct tracepoint_func __rcu *funcs;
+	u32 num_args;
 };
 
 #endif
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index c94f466d57ef..2194e7c31484 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -40,9 +40,19 @@ tracepoint_probe_register_prio(struct tracepoint *tp, void *probe, void *data,
 			       int prio);
 extern int
 tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data);
-extern void
-for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
-		void *priv);
+
+#ifdef CONFIG_TRACEPOINTS
+void *
+for_each_kernel_tracepoint(void *(*fct)(struct tracepoint *tp, void *priv),
+			   void *priv);
+#else
+static inline void *
+for_each_kernel_tracepoint(void *(*fct)(struct tracepoint *tp, void *priv),
+			   void *priv)
+{
+	return NULL;
+}
+#endif
 
 #ifdef CONFIG_MODULES
 struct tp_module {
@@ -230,18 +240,18 @@ extern void syscall_unregfunc(void);
  * structures, so we create an array of pointers that will be used for iteration
  * on the tracepoints.
  */
-#define DEFINE_TRACE_FN(name, reg, unreg)				 \
+#define DEFINE_TRACE_FN(name, reg, unreg, num_args)			 \
 	static const char __tpstrtab_##name[]				 \
 	__attribute__((section("__tracepoints_strings"))) = #name;	 \
 	struct tracepoint __tracepoint_##name				 \
 	__attribute__((section("__tracepoints"))) =			 \
-		{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
+		{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL, num_args };\
 	static struct tracepoint * const __tracepoint_ptr_##name __used	 \
 	__attribute__((section("__tracepoints_ptrs"))) =		 \
 		&__tracepoint_##name;
 
-#define DEFINE_TRACE(name)						\
-	DEFINE_TRACE_FN(name, NULL, NULL);
+#define DEFINE_TRACE(name, num_args)					\
+	DEFINE_TRACE_FN(name, NULL, NULL, num_args);
 
 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\
 	EXPORT_SYMBOL_GPL(__tracepoint_##name)
@@ -275,8 +285,8 @@ extern void syscall_unregfunc(void);
 		return false;						\
 	}
 
-#define DEFINE_TRACE_FN(name, reg, unreg)
-#define DEFINE_TRACE(name)
+#define DEFINE_TRACE_FN(name, reg, unreg, num_args)
+#define DEFINE_TRACE(name, num_args)
 #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
 #define EXPORT_TRACEPOINT_SYMBOL(name)
 
diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
index d9e3d4aa3f6e..96b22ace9ae7 100644
--- a/include/trace/define_trace.h
+++ b/include/trace/define_trace.h
@@ -25,7 +25,7 @@
 
 #undef TRACE_EVENT
 #define TRACE_EVENT(name, proto, args, tstruct, assign, print)	\
-	DEFINE_TRACE(name)
+	DEFINE_TRACE(name, COUNT_ARGS(args))
 
 #undef TRACE_EVENT_CONDITION
 #define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \
@@ -39,24 +39,24 @@
 #undef TRACE_EVENT_FN
 #define TRACE_EVENT_FN(name, proto, args, tstruct,		\
 		assign, print, reg, unreg)			\
-	DEFINE_TRACE_FN(name, reg, unreg)
+	DEFINE_TRACE_FN(name, reg, unreg, COUNT_ARGS(args))
 
 #undef TRACE_EVENT_FN_COND
 #define TRACE_EVENT_FN_COND(name, proto, args, cond, tstruct,		\
 		assign, print, reg, unreg)			\
-	DEFINE_TRACE_FN(name, reg, unreg)
+	DEFINE_TRACE_FN(name, reg, unreg, COUNT_ARGS(args))
 
 #undef DEFINE_EVENT
 #define DEFINE_EVENT(template, name, proto, args) \
-	DEFINE_TRACE(name)
+	DEFINE_TRACE(name, COUNT_ARGS(args))
 
 #undef DEFINE_EVENT_FN
 #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg) \
-	DEFINE_TRACE_FN(name, reg, unreg)
+	DEFINE_TRACE_FN(name, reg, unreg, COUNT_ARGS(args))
 
 #undef DEFINE_EVENT_PRINT
 #define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
-	DEFINE_TRACE(name)
+	DEFINE_TRACE(name, COUNT_ARGS(args))
 
 #undef DEFINE_EVENT_CONDITION
 #define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \
@@ -64,7 +64,7 @@
 
 #undef DECLARE_TRACE
 #define DECLARE_TRACE(name, proto, args)	\
-	DEFINE_TRACE(name)
+	DEFINE_TRACE(name, COUNT_ARGS(args))
 
 #undef TRACE_INCLUDE
 #undef __TRACE_INCLUDE
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 671b13457387..3f2dc5738c2b 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -502,17 +502,22 @@ static __init int init_tracepoints(void)
 __initcall(init_tracepoints);
 #endif /* CONFIG_MODULES */
 
-static void for_each_tracepoint_range(struct tracepoint * const *begin,
-		struct tracepoint * const *end,
-		void (*fct)(struct tracepoint *tp, void *priv),
-		void *priv)
+static void *for_each_tracepoint_range(struct tracepoint * const *begin,
+				       struct tracepoint * const *end,
+				       void *(*fct)(struct tracepoint *tp, void *priv),
+				       void *priv)
 {
 	struct tracepoint * const *iter;
+	void *ret;
 
 	if (!begin)
-		return;
-	for (iter = begin; iter < end; iter++)
-		fct(*iter, priv);
+		return NULL;
+	for (iter = begin; iter < end; iter++) {
+		ret = fct(*iter, priv);
+		if (ret)
+			return ret;
+	}
+	return NULL;
 }
 
 /**
@@ -520,11 +525,11 @@ static void for_each_tracepoint_range(struct tracepoint * const *begin,
  * @fct: callback
  * @priv: private data
  */
-void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
-		void *priv)
+void *for_each_kernel_tracepoint(void *(*fct)(struct tracepoint *tp, void *priv),
+				 void *priv)
 {
-	for_each_tracepoint_range(__start___tracepoints_ptrs,
-		__stop___tracepoints_ptrs, fct, priv);
+	return for_each_tracepoint_range(__start___tracepoints_ptrs,
+					 __stop___tracepoints_ptrs, fct, priv);
 }
 EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
 
-- 
2.9.5

  parent reply	other threads:[~2018-03-22 18:02 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-22 18:01 [PATCH v3 bpf-next 00/10] bpf, tracing: introduce bpf raw tracepoints Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 01/10] treewide: remove struct-pass-by-value from tracepoints arguments Alexei Starovoitov
2018-03-22 18:11   ` Steven Rostedt
2018-03-22 19:31     ` Alexei Starovoitov
2018-03-22 20:19       ` Linus Torvalds
2018-03-22 20:48       ` Steven Rostedt
2018-03-22 20:52         ` Linus Torvalds
2018-03-22 22:52           ` Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 02/10] net/mediatek: disambiguate mt76 vs mt7601u trace events Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 03/10] net/mac802154: disambiguate mac80215 vs mac802154 " Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 04/10] net/wireless/iwlwifi: fix iwlwifi_dev_ucode_error tracepoint Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 05/10] macro: introduce COUNT_ARGS() macro Alexei Starovoitov
2018-03-22 18:01 ` Alexei Starovoitov [this message]
2018-03-22 18:01 ` [PATCH v3 bpf-next 07/10] bpf: introduce BPF_RAW_TRACEPOINT Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 08/10] libbpf: add bpf_raw_tracepoint_open helper Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 09/10] samples/bpf: raw tracepoint test Alexei Starovoitov
2018-03-22 18:01 ` [PATCH v3 bpf-next 10/10] selftests/bpf: test for bpf_get_stackid() from raw tracepoints Alexei Starovoitov

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