From nobody Tue Feb 10 01:19:52 2026 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 CBE51319617; Sat, 24 Jan 2026 13:27:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769261260; cv=none; b=n91t57XW6BGeIl1JTqCtxQDczGguyu+UfDo5QtnxXEexPFWcUEOUGbQLZ4Jvfd9zuC6PYPKJ1znXhQ9irF6GEK2+KPlAaKr9QnRBU+fhCNoxbetARNtJAzVUesGjWWJlkvPA2WZQ4gDpZUJ3uL9JgsSQtCwIu8YYFaqIoSAJcF4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769261260; c=relaxed/simple; bh=aph4bN+h6Du3wkXa2Ge6qFDIwoSnf9wzR/wJFGFjJDY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ca3W+M6TCjU/H6lS4T+2jb6ub5w4PK0MmN/E8yELavTnGzkqjmk6wXMX/tR+aV34LhUfTckY1tdaHXhwmtogvKwxXdgsi85OcJWKNh6EQP103D1MX0+iIbvFR85Vtf4sX9U7Atbe1o+EuoqS6P7gk/3sIEd0+nVvOm6asfzmZeg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=KOqKg/7Q; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="KOqKg/7Q" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=hYQKTmNL3usHkDODv+v2CqzvPFVZMn8b05MkXsnAs9M=; b=KOqKg/7QNaR/7oJjP02Urrb9l3 kx1GIWcR4/+mVBZhUtYH4OafAOeGh+SiuqBhRpOp48Xbaf/Yunrf8vNr1Y6+DL6PdW6pBNcm825dY SuYAb8ieOOOGBUjk+KZQgCBxGLuyhCedt6vBobI9K/PQ8tYiDLuuw8adzkgLS/dHQ0SFaRb6xa/jF 2KFt1FFcCaWtNcQkjVYCyHtEvCb/bg6yUhWkum8ZfDaGd/bJefkFSjyFCFDqkCEf86aRSZvkvSYeE qKa42nQSWLYEhThHAcRSrrlN/eq5TmhvEiTorZSrMdu2LmiAAuapzSaNAV0PAThFL49xjalWEp8vG kkePJquA==; Received: from [175.114.83.198] (helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1vjdfh-009OAw-58; Sat, 24 Jan 2026 14:27:26 +0100 From: Changwoo Min To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , kernel-dev@igalia.com, bpf@vger.kernel.org, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Changwoo Min Subject: [PATCH bpf-next v2 1/2] selftests/bpf: Introduce execution context detection helpers Date: Sat, 24 Jan 2026 22:27:05 +0900 Message-ID: <20260124132706.183681-2-changwoo@igalia.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260124132706.183681-1-changwoo@igalia.com> References: <20260124132706.183681-1-changwoo@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Introduce bpf_in_nmi(), bpf_in_hardirq(), bpf_in_serving_softirq(), and bpf_in_task() inline helpers in bpf_experimental.h. These allow BPF programs to query the current execution context with higher granularity than the existing bpf_in_interrupt() helper. While BPF programs can often infer their context from attachment points, subsystems like sched_ext may call the same BPF logic from multiple contexts (e.g., task-to-task wake-ups vs. interrupt-to-task wake-ups). These helpers provide a reliable way for logic to branch based on the current CPU execution state. Implementing these as BPF-native inline helpers wrapping get_preempt_count() allows the compiler and JIT to inline the logic. The implementation accounts for differences in preempt_count layout between standard and PREEMPT_RT kernels. Signed-off-by: Changwoo Min --- .../testing/selftests/bpf/bpf_experimental.h | 38 +++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing= /selftests/bpf/bpf_experimental.h index 68a49b1f77ae..30abdc08366f 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -610,6 +610,8 @@ extern int bpf_cgroup_read_xattr(struct cgroup *cgroup,= const char *name__str, #define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT) #define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT) =20 +#define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT) + extern bool CONFIG_PREEMPT_RT __kconfig __weak; #ifdef bpf_target_x86 extern const int __preempt_count __ksym; @@ -648,4 +650,40 @@ static inline int bpf_in_interrupt(void) (tsk->softirq_disable_cnt & SOFTIRQ_MASK); } =20 +static inline int bpf_in_nmi(void) +{ + return get_preempt_count() & NMI_MASK; +} + +static inline int bpf_in_hardirq(void) +{ + return get_preempt_count() & HARDIRQ_MASK; +} + +static inline int bpf_in_serving_softirq(void) +{ + struct task_struct___preempt_rt *tsk; + int pcnt; + + pcnt =3D get_preempt_count(); + if (!CONFIG_PREEMPT_RT) + return (pcnt & SOFTIRQ_MASK) & SOFTIRQ_OFFSET; + + tsk =3D (void *) bpf_get_current_task_btf(); + return (tsk->softirq_disable_cnt & SOFTIRQ_MASK) & SOFTIRQ_OFFSET; +} + +static inline int bpf_in_task(void) +{ + struct task_struct___preempt_rt *tsk; + int pcnt; + + pcnt =3D get_preempt_count(); + if (!CONFIG_PREEMPT_RT) + return !(pcnt & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)); + + tsk =3D (void *) bpf_get_current_task_btf(); + return !((pcnt & (NMI_MASK | HARDIRQ_MASK)) | + ((tsk->softirq_disable_cnt & SOFTIRQ_MASK) & SOFTIRQ_OFFSET)); +} #endif --=20 2.52.0