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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Clark Williams <williams@redhat.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>
Subject: [PATCH 13/24] perf: Make perf_event_output() propagate the output() return
Date: Mon, 21 Jan 2019 20:56:55 -0300	[thread overview]
Message-ID: <20190121235706.20005-14-acme@kernel.org> (raw)
In-Reply-To: <20190121235706.20005-1-acme@kernel.org>

From: Arnaldo Carvalho de Melo <acme@redhat.com>

For the original mode of operation it isn't needed, since we report back
errors via PERF_RECORD_LOST records in the ring buffer, but for use in
bpf_perf_event_output() it is convenient to return the errors, basically
-ENOSPC.

Currently bpf_perf_event_output() returns an error indication, the last
thing it does, which is to push it to the ring buffer is that can fail
and if so, this failure won't be reported back to its users, fix it.

Reported-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/r/20190118150938.GN5823@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 include/linux/perf_event.h                       |  6 +++---
 kernel/events/core.c                             | 11 +++++++----
 kernel/trace/bpf_trace.c                         |  3 +--
 tools/perf/examples/bpf/augmented_raw_syscalls.c |  4 ++--
 tools/perf/examples/bpf/augmented_syscalls.c     | 14 +++++++-------
 tools/perf/examples/bpf/etcsnoop.c               | 10 +++++-----
 6 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f8ec36197718..4eb88065a9b5 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -978,9 +978,9 @@ extern void perf_event_output_forward(struct perf_event *event,
 extern void perf_event_output_backward(struct perf_event *event,
 				       struct perf_sample_data *data,
 				       struct pt_regs *regs);
-extern void perf_event_output(struct perf_event *event,
-			      struct perf_sample_data *data,
-			      struct pt_regs *regs);
+extern int perf_event_output(struct perf_event *event,
+			     struct perf_sample_data *data,
+			     struct pt_regs *regs);
 
 static inline bool
 is_default_overflow_handler(struct perf_event *event)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index fbe59b793b36..bc525cd1615c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6489,7 +6489,7 @@ void perf_prepare_sample(struct perf_event_header *header,
 		data->phys_addr = perf_virt_to_phys(data->addr);
 }
 
-static __always_inline void
+static __always_inline int
 __perf_event_output(struct perf_event *event,
 		    struct perf_sample_data *data,
 		    struct pt_regs *regs,
@@ -6499,13 +6499,15 @@ __perf_event_output(struct perf_event *event,
 {
 	struct perf_output_handle handle;
 	struct perf_event_header header;
+	int err;
 
 	/* protect the callchain buffers */
 	rcu_read_lock();
 
 	perf_prepare_sample(&header, data, event, regs);
 
-	if (output_begin(&handle, event, header.size))
+	err = output_begin(&handle, event, header.size);
+	if (err)
 		goto exit;
 
 	perf_output_sample(&handle, &header, data, event);
@@ -6514,6 +6516,7 @@ __perf_event_output(struct perf_event *event,
 
 exit:
 	rcu_read_unlock();
+	return err;
 }
 
 void
@@ -6532,12 +6535,12 @@ perf_event_output_backward(struct perf_event *event,
 	__perf_event_output(event, data, regs, perf_output_begin_backward);
 }
 
-void
+int
 perf_event_output(struct perf_event *event,
 		  struct perf_sample_data *data,
 		  struct pt_regs *regs)
 {
-	__perf_event_output(event, data, regs, perf_output_begin);
+	return __perf_event_output(event, data, regs, perf_output_begin);
 }
 
 /*
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 8b068adb9da1..088c2032ceaf 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -431,8 +431,7 @@ __bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
 	if (unlikely(event->oncpu != cpu))
 		return -EOPNOTSUPP;
 
-	perf_event_output(event, sd, regs);
-	return 0;
+	return perf_event_output(event, sd, regs);
 }
 
 BPF_CALL_5(bpf_perf_event_output, struct pt_regs *, regs, struct bpf_map *, map,
diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
index 53c233370fae..9e9d4c66e53c 100644
--- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
@@ -141,8 +141,8 @@ int sys_enter(struct syscall_enter_args *args)
 		len = sizeof(augmented_args.args);
 	}
 
-	perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, &augmented_args, len);
-	return 0;
+	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */
+	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, &augmented_args, len);
 }
 
 SEC("raw_syscalls:sys_exit")
diff --git a/tools/perf/examples/bpf/augmented_syscalls.c b/tools/perf/examples/bpf/augmented_syscalls.c
index 2ae44813ef2d..b7dba114e36c 100644
--- a/tools/perf/examples/bpf/augmented_syscalls.c
+++ b/tools/perf/examples/bpf/augmented_syscalls.c
@@ -55,9 +55,9 @@ int syscall_enter(syscall)(struct syscall_enter_##syscall##_args *args)				\
 		len -= sizeof(augmented_args.filename.value) - augmented_args.filename.size;	\
 		len &= sizeof(augmented_args.filename.value) - 1;				\
 	}											\
-	perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, 			\
-			  &augmented_args, len);						\
-	return 0;										\
+	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */	\
+	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, 		\
+				 &augmented_args, len);						\
 }												\
 int syscall_exit(syscall)(struct syscall_exit_args *args)					\
 {												\
@@ -125,10 +125,10 @@ int syscall_enter(syscall)(struct syscall_enter_##syscall##_args *args)				\
 /*		addrlen = augmented_args.args.addrlen;				     */		\
 /*										     */		\
 	probe_read(&augmented_args.addr, addrlen, args->addr_ptr); 				\
-	perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, 			\
-			  &augmented_args, 							\
-			  sizeof(augmented_args) - sizeof(augmented_args.addr) + addrlen);	\
-	return 0;										\
+	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */	\
+	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, 		\
+				 &augmented_args, 						\
+				sizeof(augmented_args) - sizeof(augmented_args.addr) + addrlen);\
 }												\
 int syscall_exit(syscall)(struct syscall_exit_args *args)					\
 {												\
diff --git a/tools/perf/examples/bpf/etcsnoop.c b/tools/perf/examples/bpf/etcsnoop.c
index b59e8812ee8c..550e69c2e8d1 100644
--- a/tools/perf/examples/bpf/etcsnoop.c
+++ b/tools/perf/examples/bpf/etcsnoop.c
@@ -49,11 +49,11 @@ int syscall_enter(syscall)(struct syscall_enter_##syscall##_args *args)				\
 						      args->filename_ptr); 			\
 	if (__builtin_memcmp(augmented_args.filename.value, etc, 4) != 0)			\
 		return 0;									\
-	perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, 			\
-			  &augmented_args, 							\
-			  (sizeof(augmented_args) - sizeof(augmented_args.filename.value) +	\
-			   augmented_args.filename.size));					\
-	return 0;										\
+	/* If perf_event_output fails, return non-zero so that it gets recorded unaugmented */	\
+	return perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, 		\
+				 &augmented_args,						\
+				 (sizeof(augmented_args) - sizeof(augmented_args.filename.value) + \
+				 augmented_args.filename.size));				\
 }
 
 struct syscall_enter_openat_args {
-- 
2.20.1


  parent reply	other threads:[~2019-01-21 23:58 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-21 23:56 [GIT PULL 00/24] perf/core improvements and fixes Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 01/24] perf tools: Replace automatic const char[] variables by statics Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 02/24] perf session: Rearrange perf_session__process_events function Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 03/24] perf session: Get rid of file_size variable Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 04/24] perf session: Add reader object Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 05/24] perf session: Add 'data_size' member to " Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 06/24] perf session: Add 'data_offset' " Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 07/24] perf session: Add reader__process_events function Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 08/24] perf: Remove duplicated workqueue.h include from perf_event.h Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 09/24] perf tools: Remove duplicate headers Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 10/24] perf report: Display arch specific diagnostic counter sets, starting with s390 Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 11/24] perf report: Display names in s390 diagnostic counter sets Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 12/24] perf report: Dump s390 counter set data to file Arnaldo Carvalho de Melo
2019-01-21 23:56 ` Arnaldo Carvalho de Melo [this message]
2019-01-21 23:56 ` [PATCH 14/24] perf, bpf: Introduce PERF_RECORD_KSYMBOL Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 15/24] tools headers uapi: Sync tools/include/uapi/linux/perf_event.h Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 16/24] perf, bpf: Introduce PERF_RECORD_BPF_EVENT Arnaldo Carvalho de Melo
2019-01-21 23:56 ` [PATCH 17/24] tools headers uapi: Sync tools/include/uapi/linux/perf_event.h Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 18/24] perf tools: Handle PERF_RECORD_KSYMBOL Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 19/24] perf tools: Handle PERF_RECORD_BPF_EVENT Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 20/24] perf tools: Synthesize PERF_RECORD_* for loaded BPF programs Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 21/24] perf top: Synthesize BPF events for pre-existing " Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 22/24] bpf: Add module name [bpf] to ksymbols for bpf programs Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 23/24] perf python: Remove -fstack-clash-protection when building with some clang versions Arnaldo Carvalho de Melo
2019-01-21 23:57 ` [PATCH 24/24] perf utils: Move perf_config using routines from color.c to separate object Arnaldo Carvalho de Melo
2019-01-22 10:07 ` [GIT PULL 00/24] perf/core improvements and fixes Ingo Molnar

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