From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>,
Peter Zijlstra <peterz@infradead.org>, Yonghong Song <yhs@fb.com>
Subject: [PATCH v5 bpf-next 06/16] bpf: add bpf_get_attach_cookie() BPF helper to access bpf_cookie value
Date: Sun, 15 Aug 2021 00:05:59 -0700 [thread overview]
Message-ID: <20210815070609.987780-7-andrii@kernel.org> (raw)
In-Reply-To: <20210815070609.987780-1-andrii@kernel.org>
Add new BPF helper, bpf_get_attach_cookie(), which can be used by BPF programs
to get access to a user-provided bpf_cookie value, specified during BPF
program attachment (BPF link creation) time.
Naming is hard, though. With the concept being named "BPF cookie", I've
considered calling the helper:
- bpf_get_cookie() -- seems too unspecific and easily mistaken with socket
cookie;
- bpf_get_bpf_cookie() -- too much tautology;
- bpf_get_link_cookie() -- would be ok, but while we create a BPF link to
attach BPF program to BPF hook, it's still an "attachment" and the
bpf_cookie is associated with BPF program attachment to a hook, not a BPF
link itself. Technically, we could support bpf_cookie with old-style
cgroup programs.So I ultimately rejected it in favor of
bpf_get_attach_cookie().
Currently all perf_event-backed BPF program types support
bpf_get_attach_cookie() helper. Follow-up patches will add support for
fentry/fexit programs as well.
While at it, mark bpf_tracing_func_proto() as static to make it obvious that
it's only used from within the kernel/trace/bpf_trace.c.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
include/linux/bpf.h | 3 ---
include/uapi/linux/bpf.h | 16 ++++++++++++++++
kernel/trace/bpf_trace.c | 35 +++++++++++++++++++++++++++++++++-
tools/include/uapi/linux/bpf.h | 16 ++++++++++++++++
4 files changed, 66 insertions(+), 4 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 83c3cc5e90df..f4c16f19f83e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2102,9 +2102,6 @@ extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;
extern const struct bpf_func_proto bpf_sk_setsockopt_proto;
extern const struct bpf_func_proto bpf_sk_getsockopt_proto;
-const struct bpf_func_proto *bpf_tracing_func_proto(
- enum bpf_func_id func_id, const struct bpf_prog *prog);
-
const struct bpf_func_proto *tracing_prog_func_proto(
enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 63ee482d50e1..c4f7892edb2b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4856,6 +4856,21 @@ union bpf_attr {
* Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
+ *
+ * u64 bpf_get_attach_cookie(void *ctx)
+ * Description
+ * Get bpf_cookie value provided (optionally) during the program
+ * attachment. It might be different for each individual
+ * attachment, even if BPF program itself is the same.
+ * Expects BPF program context *ctx* as a first argument.
+ *
+ * Supported for the following program types:
+ * - kprobe/uprobe;
+ * - tracepoint;
+ * - perf_event.
+ * Return
+ * Value specified by user at BPF link creation/attachment time
+ * or 0, if it was not specified.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5032,6 +5047,7 @@ union bpf_attr {
FN(timer_start), \
FN(timer_cancel), \
FN(get_func_ip), \
+ FN(get_attach_cookie), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 57879d28f824..cbc73c08c4a4 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -975,7 +975,34 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
.arg1_type = ARG_PTR_TO_CTX,
};
-const struct bpf_func_proto *
+BPF_CALL_1(bpf_get_attach_cookie_trace, void *, ctx)
+{
+ struct bpf_trace_run_ctx *run_ctx;
+
+ run_ctx = container_of(current->bpf_ctx, struct bpf_trace_run_ctx, run_ctx);
+ return run_ctx->bpf_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_trace = {
+ .func = bpf_get_attach_cookie_trace,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_1(bpf_get_attach_cookie_pe, struct bpf_perf_event_data_kern *, ctx)
+{
+ return ctx->event->bpf_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_attach_cookie_proto_pe = {
+ .func = bpf_get_attach_cookie_pe,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+static const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
@@ -1109,6 +1136,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
#endif
case BPF_FUNC_get_func_ip:
return &bpf_get_func_ip_proto_kprobe;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -1219,6 +1248,8 @@ tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_stackid_proto_tp;
case BPF_FUNC_get_stack:
return &bpf_get_stack_proto_tp;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_trace;
default:
return bpf_tracing_func_proto(func_id, prog);
}
@@ -1326,6 +1357,8 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_perf_prog_read_value_proto;
case BPF_FUNC_read_branch_records:
return &bpf_read_branch_records_proto;
+ case BPF_FUNC_get_attach_cookie:
+ return &bpf_get_attach_cookie_proto_pe;
default:
return bpf_tracing_func_proto(func_id, prog);
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 63ee482d50e1..c4f7892edb2b 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4856,6 +4856,21 @@ union bpf_attr {
* Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
+ *
+ * u64 bpf_get_attach_cookie(void *ctx)
+ * Description
+ * Get bpf_cookie value provided (optionally) during the program
+ * attachment. It might be different for each individual
+ * attachment, even if BPF program itself is the same.
+ * Expects BPF program context *ctx* as a first argument.
+ *
+ * Supported for the following program types:
+ * - kprobe/uprobe;
+ * - tracepoint;
+ * - perf_event.
+ * Return
+ * Value specified by user at BPF link creation/attachment time
+ * or 0, if it was not specified.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5032,6 +5047,7 @@ union bpf_attr {
FN(timer_start), \
FN(timer_cancel), \
FN(get_func_ip), \
+ FN(get_attach_cookie), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.30.2
next prev parent reply other threads:[~2021-08-15 7:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-15 7:05 [PATCH v5 bpf-next 00/16] BPF perf link and user-provided bpf_cookie Andrii Nakryiko
2021-08-15 7:05 ` [PATCH v5 bpf-next 01/16] bpf: refactor BPF_PROG_RUN into a function Andrii Nakryiko
2021-08-15 7:05 ` [PATCH v5 bpf-next 02/16] bpf: refactor BPF_PROG_RUN_ARRAY family of macros into functions Andrii Nakryiko
2021-08-15 7:05 ` [PATCH v5 bpf-next 03/16] bpf: refactor perf_event_set_bpf_prog() to use struct bpf_prog input Andrii Nakryiko
2021-08-15 7:05 ` [PATCH v5 bpf-next 04/16] bpf: implement minimal BPF perf link Andrii Nakryiko
2021-08-15 7:05 ` [PATCH v5 bpf-next 05/16] bpf: allow to specify user-provided bpf_cookie for BPF perf links Andrii Nakryiko
2021-08-16 11:46 ` Peter Zijlstra
2021-08-15 7:05 ` Andrii Nakryiko [this message]
2021-08-15 7:06 ` [PATCH v5 bpf-next 07/16] libbpf: re-build libbpf.so when libbpf.map changes Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 08/16] libbpf: remove unused bpf_link's destroy operation, but add dealloc Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 09/16] libbpf: use BPF perf link when supported by kernel Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 10/16] libbpf: add bpf_cookie support to bpf_link_create() API Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 11/16] libbpf: add bpf_cookie to perf_event, kprobe, uprobe, and tp attach APIs Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 12/16] selftests/bpf: test low-level perf BPF link API Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 13/16] selftests/bpf: extract uprobe-related helpers into trace_helpers.{c,h} Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 14/16] selftests/bpf: add bpf_cookie selftests for high-level APIs Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 15/16] libbpf: add uprobe ref counter offset support for USDT semaphores Andrii Nakryiko
2021-08-15 7:06 ` [PATCH v5 bpf-next 16/16] selftests/bpf: add ref_ctr_offset selftests Andrii Nakryiko
2021-08-16 23:10 ` [PATCH v5 bpf-next 00/16] BPF perf link and user-provided bpf_cookie patchwork-bot+netdevbpf
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