From: Kris Van Hees <kris.van.hees@oracle.com>
To: netdev@vger.kernel.org, bpf@vger.kernel.org,
dtrace-devel@oss.oracle.com, linux-kernel@vger.kernel.org
Cc: rostedt@goodmis.org, mhiramat@kernel.org, acme@kernel.org,
ast@kernel.org, daniel@iogearbox.net
Subject: [RFC PATCH 10/11] bpf: add bpf_buffer_reserve and bpf_buffer_commit
Date: Tue, 21 May 2019 20:39:59 +0000 (UTC) [thread overview]
Message-ID: <201905212039.x4LKdxnH023514@aserv0121.oracle.com> (raw)
In-Reply-To: <201905202347.x4KNl0cs030532@aserv0121.oracle.com> <helpers>
Add two helpers that are primarily used in combination with the
writable-buffer support. The bpf_buffer_reserve() helper sets aside
a chunk of buffer space that can be written to, and once all data
has been written, the bpf_buffer_commit() helper is used to make the
data in the ring buffer visible to userspace.
Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Nick Alcock <nick.alcock@oracle.com>
---
include/uapi/linux/bpf.h | 39 ++++++++++++++++++++++-
kernel/bpf/verifier.c | 6 +++-
tools/include/uapi/linux/bpf.h | 39 ++++++++++++++++++++++-
tools/testing/selftests/bpf/bpf_helpers.h | 4 +++
4 files changed, 85 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7bcb707539d1..2b7772aa00b6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2681,6 +2681,41 @@ union bpf_attr {
* the implementing program type.
* Return
* 0 on success, or a negative error in case of failure.
+ *
+ * int bpf_buffer_reserve(void *ctx, int id, struct bpf_map *map, int size)
+ * Description
+ * Reserve *size* bytes in the output buffer for the special BPF
+ * BPF perf event referenced by *map*, a BPF map of type
+ * **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The perf event must have
+ * the attributes: **PERF_SAMPLE_RAW** as **sample_type**,
+ * **PERF_TYPE_SOFTWARE** as **type**, and
+ * **PERF_COUNT_SW_BPF_OUTPUT** as **config**. The reserved space
+ * will be available as the writable buffer identified with
+ * numeric ID **id** in the context.
+ *
+ * The amount of reserved bytes cannot exceed the page size.
+ * The chunk of buffer space will be reserved within a single
+ * page, and if this results in unused space at the end of the
+ * previous page in the ring-buffer, that unsused space will be
+ * filled with zeros.
+ * Return
+ * 0 on success, or a negative error in case of failure.
+ *
+ * int bpf_buffer_commit(void *ctx, int id, struct bpf_map *map)
+ * Description
+ * FInalize the previously reserved space in the output buffer
+ * for the special BPF perf event referenced by *map*, a BPF map
+ * of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The perf event must
+ * have the attributes: **PERF_SAMPLE_RAW** as **sample_type**,
+ * **PERF_TYPE_SOFTWARE** as **type**, and
+ * **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * The writable buffer identified with numeric ID **id** in the
+ * context will be invalidated, and can no longer be used to
+ * write data to until a new **bpf_buffer_reserve**\ () has been
+ * invoked.
+ * Return
+ * 0 on success, or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2792,7 +2827,9 @@ union bpf_attr {
FN(strtoul), \
FN(sk_storage_get), \
FN(sk_storage_delete), \
- FN(finalize_context),
+ FN(finalize_context), \
+ FN(buffer_reserve), \
+ FN(buffer_commit),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 90ae04b4d5c7..ff73ed743a58 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2763,7 +2763,9 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
if (func_id != BPF_FUNC_perf_event_read &&
func_id != BPF_FUNC_perf_event_output &&
- func_id != BPF_FUNC_perf_event_read_value)
+ func_id != BPF_FUNC_perf_event_read_value &&
+ func_id != BPF_FUNC_buffer_reserve &&
+ func_id != BPF_FUNC_buffer_commit)
goto error;
break;
case BPF_MAP_TYPE_STACK_TRACE:
@@ -2848,6 +2850,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
case BPF_FUNC_perf_event_read:
case BPF_FUNC_perf_event_output:
case BPF_FUNC_perf_event_read_value:
+ case BPF_FUNC_buffer_reserve:
+ case BPF_FUNC_buffer_commit:
if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
goto error;
break;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 7bcb707539d1..2b7772aa00b6 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -2681,6 +2681,41 @@ union bpf_attr {
* the implementing program type.
* Return
* 0 on success, or a negative error in case of failure.
+ *
+ * int bpf_buffer_reserve(void *ctx, int id, struct bpf_map *map, int size)
+ * Description
+ * Reserve *size* bytes in the output buffer for the special BPF
+ * BPF perf event referenced by *map*, a BPF map of type
+ * **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The perf event must have
+ * the attributes: **PERF_SAMPLE_RAW** as **sample_type**,
+ * **PERF_TYPE_SOFTWARE** as **type**, and
+ * **PERF_COUNT_SW_BPF_OUTPUT** as **config**. The reserved space
+ * will be available as the writable buffer identified with
+ * numeric ID **id** in the context.
+ *
+ * The amount of reserved bytes cannot exceed the page size.
+ * The chunk of buffer space will be reserved within a single
+ * page, and if this results in unused space at the end of the
+ * previous page in the ring-buffer, that unsused space will be
+ * filled with zeros.
+ * Return
+ * 0 on success, or a negative error in case of failure.
+ *
+ * int bpf_buffer_commit(void *ctx, int id, struct bpf_map *map)
+ * Description
+ * FInalize the previously reserved space in the output buffer
+ * for the special BPF perf event referenced by *map*, a BPF map
+ * of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The perf event must
+ * have the attributes: **PERF_SAMPLE_RAW** as **sample_type**,
+ * **PERF_TYPE_SOFTWARE** as **type**, and
+ * **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * The writable buffer identified with numeric ID **id** in the
+ * context will be invalidated, and can no longer be used to
+ * write data to until a new **bpf_buffer_reserve**\ () has been
+ * invoked.
+ * Return
+ * 0 on success, or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2792,7 +2827,9 @@ union bpf_attr {
FN(strtoul), \
FN(sk_storage_get), \
FN(sk_storage_delete), \
- FN(finalize_context),
+ FN(finalize_context), \
+ FN(buffer_reserve), \
+ FN(buffer_commit),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index d98a62b3b56c..72af8157d4db 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -218,6 +218,10 @@ static int (*bpf_sk_storage_delete)(void *map, struct bpf_sock *sk) =
(void *)BPF_FUNC_sk_storage_delete;
static int (*bpf_finalize_context)(void *ctx, void *map) =
(void *) BPF_FUNC_finalize_context;
+static int (*bpf_buffer_reserve)(void *ctx, int id, void *map, int size) =
+ (void *) BPF_FUNC_buffer_reserve;
+static int (*bpf_buffer_commit)(void *ctx, int id, void *map) =
+ (void *) BPF_FUNC_buffer_commit;
/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions
--
2.20.1
next prev parent reply other threads:[~2019-05-21 20:41 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 23:47 [RFC PATCH 00/11] bpf, trace, dtrace: DTrace BPF program type implementation and sample use Kris Van Hees
2019-05-21 17:56 ` Alexei Starovoitov
2019-05-21 18:41 ` Kris Van Hees
2019-05-21 20:55 ` Alexei Starovoitov
2019-05-21 21:36 ` Steven Rostedt
2019-05-21 21:43 ` Alexei Starovoitov
2019-05-21 21:48 ` Steven Rostedt
2019-05-22 5:23 ` Kris Van Hees
2019-05-22 20:53 ` Alexei Starovoitov
2019-05-23 5:46 ` Kris Van Hees
2019-05-23 21:13 ` Alexei Starovoitov
2019-05-23 23:02 ` Steven Rostedt
2019-05-24 0:31 ` Alexei Starovoitov
2019-05-24 1:57 ` Steven Rostedt
2019-05-24 2:08 ` Alexei Starovoitov
2019-05-24 2:40 ` Steven Rostedt
2019-05-24 5:26 ` Kris Van Hees
2019-05-24 5:10 ` Kris Van Hees
2019-05-24 4:05 ` Kris Van Hees
2019-05-24 13:28 ` Steven Rostedt
2019-05-21 21:36 ` Kris Van Hees
2019-05-21 23:26 ` Alexei Starovoitov
2019-05-22 4:12 ` Kris Van Hees
2019-05-22 20:16 ` Alexei Starovoitov
2019-05-23 5:16 ` Kris Van Hees
2019-05-23 20:28 ` Alexei Starovoitov
2019-05-30 16:15 ` Kris Van Hees
2019-05-31 15:25 ` Chris Mason
2019-06-06 20:58 ` Kris Van Hees
2019-06-18 1:25 ` Kris Van Hees
2019-06-18 1:32 ` Alexei Starovoitov
2019-06-18 1:54 ` Kris Van Hees
2019-06-18 3:01 ` Alexei Starovoitov
2019-06-18 3:19 ` Kris Van Hees
2019-05-22 14:25 ` Peter Zijlstra
2019-05-22 18:22 ` Kris Van Hees
2019-05-22 19:55 ` Alexei Starovoitov
2019-05-22 20:20 ` David Miller
2019-05-23 5:19 ` Kris Van Hees
2019-05-24 7:27 ` Peter Zijlstra
2019-05-21 20:39 ` [RFC PATCH 01/11] bpf: context casting for tail call Kris Van Hees
2019-05-21 20:39 ` [RFC PATCH 02/11] bpf: add BPF_PROG_TYPE_DTRACE Kris Van Hees
2019-05-21 20:39 ` [RFC PATCH 03/11] bpf: export proto for bpf_perf_event_output helper Kris Van Hees
[not found] ` <facilities>
2019-05-21 20:39 ` [RFC PATCH 04/11] trace: initial implementation of DTrace based on kernel Kris Van Hees
2019-05-21 20:39 ` [RFC PATCH 05/11] trace: update Kconfig and Makefile to include DTrace Kris Van Hees
[not found] ` <features>
2019-05-21 20:39 ` [RFC PATCH 06/11] dtrace: tiny userspace tool to exercise DTrace support Kris Van Hees
2019-05-21 20:39 ` [RFC PATCH 07/11] bpf: implement writable buffers in contexts Kris Van Hees
2019-05-21 20:39 ` [RFC PATCH 08/11] perf: add perf_output_begin_forward_in_page Kris Van Hees
[not found] ` <the>
[not found] ` <context>
2019-05-21 20:39 ` [RFC PATCH 09/11] bpf: mark helpers explicitly whether they may change Kris Van Hees
[not found] ` <helpers>
2019-05-21 20:39 ` Kris Van Hees [this message]
2019-05-21 20:40 ` [RFC PATCH 11/11] dtrace: make use of writable buffers in BPF Kris Van Hees
2019-05-21 20:48 ` [RFC PATCH 00/11] bpf, trace, dtrace: DTrace BPF program type implementation and sample use Kris Van Hees
2019-05-21 20:54 ` Steven Rostedt
2019-05-21 20:56 ` Alexei Starovoitov
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