From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E05A7212552 for ; Wed, 17 Dec 2025 23:36:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766014591; cv=none; b=trY2pwFFubfVEoppIILMVYHGhnd8lS1Ofw30Q1N+vasB54+2hJSNgh2UGaeEvVnTPhUrkTSoYvzhl4GZTrQJEsFAywXQdv6MJLtGEIAOspKfygXk1RhybbY8HuzZp8hy7JmVDgPTrfNB8DicIXICj9QqdLraNZx2MV6VthkQHmE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766014591; c=relaxed/simple; bh=rKOV9zyJXMZ/yYe4aPWF7ZuJKQBqItGT2/94wCSdR2A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Oj1QK9uDoOkA0JGOqMuM5Z7rxADHfAmcHQiUbvpZtyFS5d5J1RE3Sa9B+cLHqGRM5X+sPU3MAuFC6h/vWSg6SB+pkjLKFU099CgPc7Oc73fNYYCcPDAsF/sOJgRVlE85zfB/EhRrHGpQ07STXjT9ksAjakBmHZy/EH5hUD6U+uY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dK+/WRSo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dK+/WRSo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 502DDC4CEF5; Wed, 17 Dec 2025 23:36:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766014590; bh=rKOV9zyJXMZ/yYe4aPWF7ZuJKQBqItGT2/94wCSdR2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dK+/WRSon+1IxN7pti+DVU7EN3TiR1yV7yXoF1USYuDut10TSbRzSf2W5h06Eo/Ai rBO4SfCst9uQzK7v6n7teJGJMPztkRVbFlXsrE3w+YWnQbroWf0ytNEFxp/wzc+XTC a9IhwGUYcYrb3t4llzE5iFrrmijREUmOXbosCOGS+mnheXRUnCWemPNr6NnGCRnJoB CEbd8nxpK/vclmMW8miy+jklY572I7NyxdB3efg9mD6XdbHi5BZJMyKuXBsbyl+5Cy 7c9cd6Y1aoZuI8CvjsYH5n0bYgO2xw/Tm72IzGosU8i4D0wA0u05uDCOVSo1LuzQq2 VT8onJCcxrEPg== From: Puranjay Mohan To: bpf@vger.kernel.org Cc: Puranjay Mohan , Puranjay Mohan , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , kernel-team@meta.com, Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org Subject: [PATCH bpf-next v2 1/2] bpf: move recursion detection logic to helpers Date: Wed, 17 Dec 2025 15:35:56 -0800 Message-ID: <20251217233608.2374187-2-puranjay@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251217233608.2374187-1-puranjay@kernel.org> References: <20251217233608.2374187-1-puranjay@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit BPF programs detect recursion by doing atomic inc/dec on a per-cpu active counter from the trampoline. Create two helpers for operations on this active counter, this makes it easy to changes the recursion detection logic in future. This change makes no functional changes. Signed-off-by: Puranjay Mohan --- include/linux/bpf.h | 10 ++++++++++ kernel/bpf/trampoline.c | 8 ++++---- kernel/trace/bpf_trace.c | 4 ++-- 3 files changed, 16 insertions(+), 6 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index bb3847caeae1..2da986136d26 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2004,6 +2004,16 @@ struct bpf_struct_ops_common_value { enum bpf_struct_ops_state state; }; +static inline bool bpf_prog_get_recursion_context(struct bpf_prog *prog) +{ + return this_cpu_inc_return(*(prog->active)) == 1; +} + +static inline void bpf_prog_put_recursion_context(struct bpf_prog *prog) +{ + this_cpu_dec(*(prog->active)); +} + #if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL) /* This macro helps developer to register a struct_ops type and generate * type information correctly. Developers should use this macro to register diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 976d89011b15..2a125d063e62 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -949,7 +949,7 @@ static u64 notrace __bpf_prog_enter_recur(struct bpf_prog *prog, struct bpf_tram run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); - if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { + if (unlikely(!bpf_prog_get_recursion_context(prog))) { bpf_prog_inc_misses_counter(prog); if (prog->aux->recursion_detected) prog->aux->recursion_detected(prog); @@ -993,7 +993,7 @@ static void notrace __bpf_prog_exit_recur(struct bpf_prog *prog, u64 start, bpf_reset_run_ctx(run_ctx->saved_run_ctx); update_prog_stats(prog, start); - this_cpu_dec(*(prog->active)); + bpf_prog_put_recursion_context(prog); rcu_read_unlock_migrate(); } @@ -1029,7 +1029,7 @@ u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); - if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { + if (unlikely(!bpf_prog_get_recursion_context(prog))) { bpf_prog_inc_misses_counter(prog); if (prog->aux->recursion_detected) prog->aux->recursion_detected(prog); @@ -1044,7 +1044,7 @@ void notrace __bpf_prog_exit_sleepable_recur(struct bpf_prog *prog, u64 start, bpf_reset_run_ctx(run_ctx->saved_run_ctx); update_prog_stats(prog, start); - this_cpu_dec(*(prog->active)); + bpf_prog_put_recursion_context(prog); migrate_enable(); rcu_read_unlock_trace(); } diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index fe28d86f7c35..6e076485bf70 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2063,7 +2063,7 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args) struct bpf_trace_run_ctx run_ctx; cant_sleep(); - if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { + if (unlikely(!bpf_prog_get_recursion_context(prog))) { bpf_prog_inc_misses_counter(prog); goto out; } @@ -2077,7 +2077,7 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args) bpf_reset_run_ctx(old_run_ctx); out: - this_cpu_dec(*(prog->active)); + bpf_prog_put_recursion_context(prog); } #define UNPACK(...) __VA_ARGS__ -- 2.47.3