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authorAndrii Nakryiko <andrii@kernel.org>2021-08-15 00:05:59 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-08-17 00:45:07 +0200
commit7adfc6c9b315e174cf8743b21b7b691c8766791b (patch)
tree22e614432aca7e0c5eedceb7c4b74c6ce8bb4ef7 /tools/include
parent82e6b1eee6a8875ef4eacfd60711cce6965c6b04 (diff)
downloadlinux-7adfc6c9b315e174cf8743b21b7b691c8766791b.tar.bz2
bpf: Add bpf_get_attach_cookie() BPF helper to access bpf_cookie value
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. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210815070609.987780-7-andrii@kernel.org
Diffstat (limited to 'tools/include')
-rw-r--r--tools/include/uapi/linux/bpf.h16
1 files changed, 16 insertions, 0 deletions
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