From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 554EB2C15BF for ; Mon, 13 Oct 2025 17:48:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760377701; cv=none; b=PNS6ozL6bfKuhtiCBJtyo9BPZjj1KhJ1gznwfXRR4avxHuc+DlGY3meSTDnNXwG0m51brTWp/NhRJDRxiZH6wUGTUI577SHVqycb9nMnWSUzkTJ49qwO1JxMLZO1WhsCpqjWZKVVlYNgp8bdFUTWo3lc2uHMKu6jTkTjX4os0Xg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760377701; c=relaxed/simple; bh=U0voQM2oYnf6STeO6/rk9aLxKnrO1RiaTGJ/8zUau1w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Aa8e2fOf136ir/BuUh9jcXeR4iori7nEfY9g4uuQiIeri40wZ3C2fPrtRI61ISk8RVPkkMJfrxrHe1xnAkC6W6Q88HDYYViiHfBE1KQs6XOLMsW+Y+NXDm8PpAzPqqwrkrmQMzeowN++mNQBVo8LO/D3Jqi3xdhdBUAaqHA3nGc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=dqog44Hl; arc=none smtp.client-ip=91.218.175.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="dqog44Hl" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1760377696; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GFSgpLJ9oy5bTPXjycAjjR+uiZnaDlBjDtnbne3KHWA=; b=dqog44HlD/xi4SmzgPayoGAyNglOXEbXHUVvDjSrKnNlF3zG9OY+/PnBjRu+tI5R08bv9L 9qo8QWSiIBxn8QVr5br7rI2wp/EfK/WDxBe87TvPgk/V9vehAAux3m0Izgp2PxAQJgot8B Aw2WZP8/zaM7h7tp6DhqHswK/xTC768= From: Tao Chen 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 Subject: [PATCH bpf-next RFC 1/2] perf: Use extern perf_callchain_entry for get_perf_callchain Date: Tue, 14 Oct 2025 01:47:20 +0800 Message-ID: <20251013174721.2681091-2-chen.dylane@linux.dev> In-Reply-To: <20251013174721.2681091-1-chen.dylane@linux.dev> References: <20251013174721.2681091-1-chen.dylane@linux.dev> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT >From bpf stack map, we want to use our own buffers to avoid unnecessary copy, so let us pass it directly. Signed-off-by: Tao Chen --- include/linux/perf_event.h | 5 +++-- kernel/bpf/stackmap.c | 4 ++-- kernel/events/callchain.c | 18 ++++++++++++------ kernel/events/core.c | 2 +- 4 files changed, 18 insertions(+), 11 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index ec9d9602568..ca69ad2723c 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1719,8 +1719,9 @@ 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, u32 init_nr, 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, + u32 init_nr, 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 2e182a3ac4c..e6e40f22826 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, 0, kernel, user, max_depth, + trace = get_perf_callchain(regs, NULL, 0, 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, 0, kernel, user, max_depth, + trace = get_perf_callchain(regs, NULL, 0, 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 6c83ad674d0..fe5d2d58deb 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -217,16 +217,21 @@ static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entr } struct perf_callchain_entry * -get_perf_callchain(struct pt_regs *regs, u32 init_nr, 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, + u32 init_nr, bool kernel, bool user, u32 max_stack, bool crosstask, + bool add_mark) { struct perf_callchain_entry *entry; struct perf_callchain_entry_ctx ctx; int rctx, start_entry_idx; - entry = get_callchain_entry(&rctx); - if (!entry) - return NULL; + if (external_entry) { + entry = external_entry; + } else { + entry = get_callchain_entry(&rctx); + if (!entry) + return NULL; + } ctx.entry = entry; ctx.max_stack = max_stack; @@ -262,7 +267,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, 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 1d354778dcd..08ce44db18f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8204,7 +8204,7 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) if (!kernel && !user) return &__empty_callchain; - callchain = get_perf_callchain(regs, 0, kernel, user, + callchain = get_perf_callchain(regs, NULL, 0, kernel, user, max_stack, crosstask, true); return callchain ?: &__empty_callchain; } -- 2.48.1