[PATCH bpf-next] bpf: remove is_return in struct bpf_session_run_ctx
From: Menglong Dong <hidden>
Date: 2025-09-22 09:57:14
Also in:
bpf, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [security & lsm] (security audit and enforcement using bpf), bpf [tracing], the rest, tracing · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, KP Singh, Matt Bobrowski, Song Liu, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
The "data" in struct bpf_session_run_ctx is always 8-bytes aligned. Therefore, we can store the "is_return" to the last bit of the "data", which can make bpf_session_run_ctx 8-bytes aligned and save memory. Signed-off-by: Menglong Dong <redacted> --- kernel/trace/bpf_trace.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f2360579658e..b6a34aa039f6 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c@@ -2269,7 +2269,6 @@ fs_initcall(bpf_event_init); struct bpf_session_run_ctx { struct bpf_run_ctx run_ctx; - bool is_return; void *data; };
@@ -2535,8 +2534,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link, { struct bpf_kprobe_multi_run_ctx run_ctx = { .session_ctx = { - .is_return = is_return, - .data = data, + .data = (void *)((unsigned long)data | !!is_return), }, .link = link, .entry_ip = entry_ip,
@@ -3058,8 +3056,7 @@ static int uprobe_prog_run(struct bpf_uprobe *uprobe, struct bpf_uprobe_multi_link *link = uprobe->link; struct bpf_uprobe_multi_run_ctx run_ctx = { .session_ctx = { - .is_return = is_return, - .data = data, + .data = (void *)((unsigned long)data | !!is_return), }, .entry_ip = entry_ip, .uprobe = uprobe,
@@ -3316,7 +3313,7 @@ __bpf_kfunc bool bpf_session_is_return(void) struct bpf_session_run_ctx *session_ctx; session_ctx = container_of(current->bpf_ctx, struct bpf_session_run_ctx, run_ctx); - return session_ctx->is_return; + return (unsigned long)session_ctx->data & 1; } __bpf_kfunc __u64 *bpf_session_cookie(void)
@@ -3324,7 +3321,7 @@ __bpf_kfunc __u64 *bpf_session_cookie(void) struct bpf_session_run_ctx *session_ctx; session_ctx = container_of(current->bpf_ctx, struct bpf_session_run_ctx, run_ctx); - return session_ctx->data; + return (__u64 *)((unsigned long)session_ctx->data & ~1); } __bpf_kfunc_end_defs();
--
2.51.0