From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) (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 BAFA73451AF for ; Mon, 25 May 2026 22:40:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779748811; cv=none; b=A4EnYNb55zxao9lsdu072gFCjBHZPQioG+BMk/Bm7jAn7WroKpnh0Imdk6aZxCj2o86lwbCpWCuxDgAT1T3n9YGhtpBjVV4X8hIWE09vGMQKVbr3Pwz6SnVbLqn2u5MlPm2RWapBOnk2aPaGgIgG1VFKa9gtIVfd+AV4TQoL1m0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779748811; c=relaxed/simple; bh=Jr9lcIbXLq4LE+XYFj8sp3KUpS6T1W/u6KkSV5Q3PFs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=StJfRADtXca53Xq9PhZnsaoCV4qlcLHyZVU1B/egegbbcW8YhIOQLQbyURXPRr1DZLBBVpRRSGuT4jeScKoPmBGvEU+Gw1LwtYHiXQpLXKefo46uB4l7qvaSE8jeGbLbqZMpEgnkIHvvsqmwFB72RPMEEeXV1w+flqDFJSmBA9w= 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=qSP7oJYM; arc=none smtp.client-ip=95.215.58.172 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="qSP7oJYM" 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=1779748807; 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=GVrvzy9clah8EtD+v/2ouiX/NekgcIxxRRED2Tw7R3w=; b=qSP7oJYM64isI/RnAp8IUkaDX0elXGA5tQCQJUsP1ZwSwwMsIx45Qvi0arEURyvepEuuS4 mZHnd2VO/7lhE4i3hgi6CKehhgmAqvyHqzEpKAN1yb7qmfzEBZQy8yQCsOxdKW/UzMqY1V VN9tFQazhsZdsrXZR4pcdxr5DJ5kU+Q= From: Ihor Solodrai To: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Kumar Kartikeya Dwivedi Cc: Puranjay Mohan , Shakeel Butt , Mykyta Yatsenko , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: [PATCH bpf-next v7 1/3] bpf: Factor out stack_map build ID helpers Date: Mon, 25 May 2026 15:39:46 -0700 Message-ID: <20260525223948.1920986-2-ihor.solodrai@linux.dev> In-Reply-To: <20260525223948.1920986-1-ihor.solodrai@linux.dev> References: <20260525223948.1920986-1-ihor.solodrai@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Factor out helpers from stack_map_get_build_id_offset() in preparation for adding a sleepable build ID resolution path: stack_map_build_id_set_ip(), stack_map_build_id_offset(), and stack_map_build_id_set_valid(). While here, refactor stack_map_get_build_id_offset(): * use continue-driven control flow in the main loop and remove build_id_valid label * update prev_vma and prev_build_id on the fall-back-to-IP branch so the cache reflects the actual VMA seen on the previous IP [1] * guard fetch_build_id() with vma_is_anonymous() [2] to skip parse attempts that would otherwise fail the ELF magic check [1] https://lore.kernel.org/bpf/CAEf4Bzac9uWWqBvzH0iFzKvJcq3vxscZ3pKm0sUHmN-F-z9wVQ@mail.gmail.com/ [2] https://lore.kernel.org/bpf/226398c1ff3f2b686c0aeb010408d85fb15df13f9ff60a045bee31e79b9e41e9@mail.kernel.org/ Acked-by: Mykyta Yatsenko Signed-off-by: Ihor Solodrai --- kernel/bpf/stackmap.c | 57 ++++++++++++++++++++++++++++++------------- 1 file changed, 40 insertions(+), 17 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index da3d328f5c15..e23be7d44503 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -152,6 +152,28 @@ static int fetch_build_id(struct vm_area_struct *vma, unsigned char *build_id, b : build_id_parse_nofault(vma, build_id, NULL); } +static inline void stack_map_build_id_set_ip(struct bpf_stack_build_id *id) +{ + id->status = BPF_STACK_BUILD_ID_IP; + memset(id->build_id, 0, BUILD_ID_SIZE_MAX); +} + +static inline u64 stack_map_build_id_offset(unsigned long vm_pgoff, + unsigned long vm_start, u64 ip) +{ + return (vm_pgoff << PAGE_SHIFT) + ip - vm_start; +} + +static inline void stack_map_build_id_set_valid(struct bpf_stack_build_id *id, + u64 offset, + const unsigned char *build_id) +{ + id->status = BPF_STACK_BUILD_ID_VALID; + id->offset = offset; + if (id->build_id != build_id) + memcpy(id->build_id, build_id, BUILD_ID_SIZE_MAX); +} + /* * Expects all id_offs[i].ip values to be set to correct initial IPs. * They will be subsequently: @@ -165,44 +187,45 @@ static int fetch_build_id(struct vm_area_struct *vma, unsigned char *build_id, b static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, u32 trace_nr, bool user, bool may_fault) { - int i; struct mmap_unlock_irq_work *work = NULL; bool irq_work_busy = bpf_mmap_unlock_get_irq_work(&work); + bool has_user_ctx = user && current && current->mm; struct vm_area_struct *vma, *prev_vma = NULL; - const char *prev_build_id; + const unsigned char *prev_build_id = NULL; + int i; /* If the irq_work is in use, fall back to report ips. Same * fallback is used for kernel stack (!user) on a stackmap with * build_id. */ - if (!user || !current || !current->mm || irq_work_busy || - !mmap_read_trylock(current->mm)) { + if (!has_user_ctx || irq_work_busy || !mmap_read_trylock(current->mm)) { /* cannot access current->mm, fall back to ips */ - for (i = 0; i < trace_nr; i++) { - id_offs[i].status = BPF_STACK_BUILD_ID_IP; - memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); - } + for (i = 0; i < trace_nr; i++) + stack_map_build_id_set_ip(&id_offs[i]); return; } for (i = 0; i < trace_nr; i++) { u64 ip = READ_ONCE(id_offs[i].ip); + u64 offset; - if (range_in_vma(prev_vma, ip, ip)) { + if (prev_build_id && range_in_vma(prev_vma, ip, ip)) { vma = prev_vma; - memcpy(id_offs[i].build_id, prev_build_id, BUILD_ID_SIZE_MAX); - goto build_id_valid; + offset = stack_map_build_id_offset(vma->vm_pgoff, vma->vm_start, ip); + stack_map_build_id_set_valid(&id_offs[i], offset, prev_build_id); + continue; } vma = find_vma(current->mm, ip); - if (!vma || fetch_build_id(vma, id_offs[i].build_id, may_fault)) { + if (!vma || vma_is_anonymous(vma) || + fetch_build_id(vma, id_offs[i].build_id, may_fault)) { /* per entry fall back to ips */ - id_offs[i].status = BPF_STACK_BUILD_ID_IP; - memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); + stack_map_build_id_set_ip(&id_offs[i]); + prev_vma = vma; + prev_build_id = NULL; continue; } -build_id_valid: - id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ip - vma->vm_start; - id_offs[i].status = BPF_STACK_BUILD_ID_VALID; + offset = stack_map_build_id_offset(vma->vm_pgoff, vma->vm_start, ip); + stack_map_build_id_set_valid(&id_offs[i], offset, id_offs[i].build_id); prev_vma = vma; prev_build_id = id_offs[i].build_id; } -- 2.54.0