From: Tao Chen <chen.dylane@linux.dev>
To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
namhyung@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@kernel.org,
irogers@google.com, adrian.hunter@intel.com,
kan.liang@linux.intel.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, kpsingh@kernel.org, sdf@fomichev.me,
haoluo@google.com
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org, Tao Chen <chen.dylane@linux.dev>
Subject: [RFC PATCH bpf-next v2 1/2] perf: Use extern perf_callchain_entry for get_perf_callchain
Date: Tue, 14 Oct 2025 18:01:27 +0800 [thread overview]
Message-ID: <20251014100128.2721104-2-chen.dylane@linux.dev> (raw)
In-Reply-To: <20251014100128.2721104-1-chen.dylane@linux.dev>
From bpf stack map, we want to use our own buffers to avoid unnecessary
copy, so let us pass it directly. BPF will use this in the next patch.
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
include/linux/perf_event.h | 4 ++--
kernel/bpf/stackmap.c | 4 ++--
kernel/events/callchain.c | 13 +++++++++----
kernel/events/core.c | 2 +-
4 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index fd1d91017b9..b144da7d803 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1719,8 +1719,8 @@ DECLARE_PER_CPU(struct perf_callchain_entry, perf_callchain_entry);
extern void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs);
extern void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs);
extern struct perf_callchain_entry *
-get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
- u32 max_stack, bool crosstask, bool add_mark);
+get_perf_callchain(struct pt_regs *regs, struct perf_callchain_entry *external_entry,
+ bool kernel, bool user, u32 max_stack, bool crosstask, bool add_mark);
extern int get_callchain_buffers(int max_stack);
extern void put_callchain_buffers(void);
extern struct perf_callchain_entry *get_callchain_entry(int *rctx);
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 4d53cdd1374..94e46b7f340 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -314,7 +314,7 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
if (max_depth > sysctl_perf_event_max_stack)
max_depth = sysctl_perf_event_max_stack;
- trace = get_perf_callchain(regs, kernel, user, max_depth,
+ trace = get_perf_callchain(regs, NULL, kernel, user, max_depth,
false, false);
if (unlikely(!trace))
@@ -451,7 +451,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
else if (kernel && task)
trace = get_callchain_entry_for_task(task, max_depth);
else
- trace = get_perf_callchain(regs, kernel, user, max_depth,
+ trace = get_perf_callchain(regs, NULL, kernel, user, max_depth,
crosstask, false);
if (unlikely(!trace) || trace->nr < skip) {
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 808c0d7a31f..851e8f9d026 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -217,8 +217,8 @@ static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entr
}
struct perf_callchain_entry *
-get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
- u32 max_stack, bool crosstask, bool add_mark)
+get_perf_callchain(struct pt_regs *regs, struct perf_callchain_entry *external_entry,
+ bool kernel, bool user, u32 max_stack, bool crosstask, bool add_mark)
{
struct perf_callchain_entry *entry;
struct perf_callchain_entry_ctx ctx;
@@ -228,7 +228,11 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
if (crosstask && user && !kernel)
return NULL;
- entry = get_callchain_entry(&rctx);
+ if (external_entry)
+ entry = external_entry;
+ else
+ entry = get_callchain_entry(&rctx);
+
if (!entry)
return NULL;
@@ -260,7 +264,8 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
}
exit_put:
- put_callchain_entry(rctx);
+ if (!external_entry)
+ put_callchain_entry(rctx);
return entry;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7541f6f85fc..5d8e146003a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8217,7 +8217,7 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
if (!kernel && !user)
return &__empty_callchain;
- callchain = get_perf_callchain(regs, kernel, user,
+ callchain = get_perf_callchain(regs, NULL, kernel, user,
max_stack, crosstask, true);
return callchain ?: &__empty_callchain;
}
--
2.48.1
next prev parent reply other threads:[~2025-10-14 10:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-14 10:01 [RFC PATCH bpf-next v2 0/2] Pass external callchain entry to get_perf_callchain Tao Chen
2025-10-14 10:01 ` Tao Chen [this message]
2025-10-14 10:01 ` [RFC PATCH bpf-next v2 2/2] bpf: " Tao Chen
2025-10-14 12:14 ` Jiri Olsa
2025-10-14 12:34 ` Tao Chen
2025-10-14 15:02 ` Alexei Starovoitov
2025-10-16 20:39 ` Andrii Nakryiko
2025-10-18 7:51 ` Tao Chen
2025-10-21 16:37 ` Andrii Nakryiko
2025-10-23 6:11 ` Tao Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20251014100128.2721104-2-chen.dylane@linux.dev \
--to=chen.dylane@linux.dev \
--cc=acme@kernel.org \
--cc=adrian.hunter@intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=haoluo@google.com \
--cc=irogers@google.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kan.liang@linux.intel.com \
--cc=kpsingh@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=martin.lau@linux.dev \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=sdf@fomichev.me \
--cc=song@kernel.org \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).