From: Menglong Dong <menglong8.dong@gmail.com>
To: jolsa@kernel.org
Cc: kpsingh@kernel.org, mattbobrowski@google.com, song@kernel.org,
ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev,
john.fastabend@gmail.com, sdf@fomichev.me, haoluo@google.com,
rostedt@goodmis.org, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: [PATCH bpf-next] bpf: remove is_return in struct bpf_session_run_ctx
Date: Mon, 22 Sep 2025 17:57:05 +0800 [thread overview]
Message-ID: <20250922095705.252519-1-dongml2@chinatelecom.cn> (raw)
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 <dongml2@chinatelecom.cn>
---
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
next reply other threads:[~2025-09-22 9:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-22 9:57 Menglong Dong [this message]
2025-09-22 14:08 ` [PATCH bpf-next] bpf: remove is_return in struct bpf_session_run_ctx Song Liu
2025-09-22 14:10 ` Menglong Dong
2025-09-23 19:23 ` Alexei Starovoitov
2025-09-24 2:03 ` menglong.dong
2025-09-23 7:52 ` kernel test robot
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