From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 C98143CE489 for ; Fri, 3 Jul 2026 10:32:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783074762; cv=none; b=TwpB/QiLxoowJxfxJ5JWR4YQQtPRCWa7xyyWCepGIBcWbjaMiV7wkVn+FypU4TkFHEmWSvbX3jbtSISAar1cX1e85jPK2yO7PCnIX8E1p+99DjRXXLGRDNidwgxG479tTdJiPgbrl+lcxSB674LwugshxA46gUX2iSu/I7P1Xgc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783074762; c=relaxed/simple; bh=/fB9IuqJiHVmLzD2u0IUiNqOXeUaq6qqQVFfCt3/g+4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pSd99V/4hdUBCtb25fPvvgmjXm+9lJWt+73hKx4GHtsZ6/Y+RYvfuRUMLhAkkuXrZnqSeyVdIxoEBg+WFLbIkeWzorETpfzRNXzEj5rcYJJroKRhuDroCDfwYkrI+5Cm894Eo1+72yVJjjrY7acG1YKnYdM5nf0aw4Y7T1RFBtI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=gdzVP03Y; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gdzVP03Y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783074759; 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=SZbbfONgwHJc3tfkOgFaKYw/dvTQBrDTf1r8+XH/UuM=; b=gdzVP03Y/Kw40oMTRluWC7ZjWNi4dXhFMLNqwpxPxPCWcKsRw4rbAdEkbjP0NWkIq3osf/ VJfEcyURGi5F823qKOrzzoKv7ed9YtBAdpyyiVJe9EbcKMrMBIn+tNrOou9oboPvBYQenN o8F8BEZbCPaROMpbkSvpP95+rTGuocE= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-500-Mlvsze9XN_apOpQOv0nMNw-1; Fri, 03 Jul 2026 06:32:34 -0400 X-MC-Unique: Mlvsze9XN_apOpQOv0nMNw-1 X-Mimecast-MFC-AGG-ID: Mlvsze9XN_apOpQOv0nMNw_1783074752 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1DD8D1945CBE; Fri, 3 Jul 2026 10:32:32 +0000 (UTC) Received: from vmalik-fedora.redhat.com (unknown [10.44.34.72]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3B50A1956095; Fri, 3 Jul 2026 10:32:25 +0000 (UTC) From: Viktor Malik To: linux-perf-users@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Viktor Malik , Howard Chu , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Michael Petlan , stable@vger.kernel.org Subject: [PATCH v2 1/2] perf trace: Factor out BPF loop body Date: Fri, 3 Jul 2026 12:32:14 +0200 Message-ID: <20fc67aa2550ca5aff52b3a9a207f2e07f8e0b1d.1783070132.git.vmalik@redhat.com> In-Reply-To: References: 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-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 The BPF program in augmented_raw_syscalls uses a for loop to iterate all syscall arguments. The loop body is quite complex and often poses problems for the BPF verifier. As a preparation step for addressing this issue, factor out the loop body into a separate function. Signed-off-by: Viktor Malik Cc: stable@vger.kernel.org --- .../bpf_skel/augmented_raw_syscalls.bpf.c | 127 ++++++++++-------- 1 file changed, 72 insertions(+), 55 deletions(-) diff --git a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c index 2a6e61864ee0..cbdd5ce19a2f 100644 --- a/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c +++ b/tools/perf/util/bpf_skel/augmented_raw_syscalls.bpf.c @@ -429,15 +429,79 @@ static bool pid_filter__has(struct pids_filtered *pids, pid_t pid) return bpf_map_lookup_elem(pids, &pid) != NULL; } +/* + * Determine what type of argument and how many bytes to read from user space, using the + * value in the beauty_map. This is the relation of parameter type and its corresponding + * value in the beauty map, and how many bytes we read eventually: + * + * string: 1 -> size of string + * struct: size of struct -> size of struct + * buffer: -1 * (index of paired len) -> value of paired len (maximum: TRACE_AUG_MAX_BUF) + */ +static inline int augment_arg(struct syscall_enter_args *args, int i, + unsigned int *beauty_map, void *payload_offset) +{ + int index, value_size = sizeof(struct augmented_arg) - offsetof(struct augmented_arg, value); + s64 aug_size, size; + bool augmented; + void *arg; + + arg = (void *)args->args[i]; + augmented = false; + size = beauty_map[i]; + aug_size = size; /* size of the augmented data read from user space */ + + if (size == 0 || arg == NULL) + return 0; + + if (size == 1) { /* string */ + aug_size = bpf_probe_read_user_str(((struct augmented_arg *)payload_offset)->value, value_size, arg); + /* minimum of 0 to pass the verifier */ + if (aug_size < 0) + aug_size = 0; + + augmented = true; + } else if (size > 0 && size <= value_size) { /* struct */ + if (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)->value, size, arg)) + augmented = true; + } else if ((int)size < 0 && size >= -6) { /* buffer */ + index = -(size + 1); + barrier_var(index); // Prevent clang (noticed with v18) from removing the &= 7 trick. + index &= 7; // Satisfy the bounds checking with the verifier in some kernels. + aug_size = args->args[index] > TRACE_AUG_MAX_BUF ? TRACE_AUG_MAX_BUF : args->args[index]; + + if (aug_size > 0) { + if (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)->value, aug_size, arg)) + augmented = true; + } + } + + /* Augmented data size is limited to sizeof(augmented_arg->unnamed union with value field) */ + if (aug_size > value_size) + aug_size = value_size; + + /* write data to payload */ + if (augmented) { + int written = offsetof(struct augmented_arg, value) + aug_size; + + if (written < 0 || written > sizeof(struct augmented_arg)) + return -1; + + ((struct augmented_arg *)payload_offset)->size = aug_size; + return written; + } + + return 0; +} + static int augment_sys_enter(void *ctx, struct syscall_enter_args *args) { - bool augmented, do_output = false; - int zero = 0, index, value_size = sizeof(struct augmented_arg) - offsetof(struct augmented_arg, value); + bool do_output = false; + int zero = 0, written; u64 output = 0; /* has to be u64, otherwise it won't pass the verifier */ - s64 aug_size, size; unsigned int nr, *beauty_map; struct beauty_payload_enter *payload; - void *arg, *payload_offset; + void *payload_offset; /* fall back to do predefined tail call */ if (args == NULL) @@ -457,58 +521,11 @@ static int augment_sys_enter(void *ctx, struct syscall_enter_args *args) /* copy the sys_enter header, which has the syscall_nr */ __builtin_memcpy(&payload->args, args, sizeof(struct syscall_enter_args)); - /* - * Determine what type of argument and how many bytes to read from user space, using the - * value in the beauty_map. This is the relation of parameter type and its corresponding - * value in the beauty map, and how many bytes we read eventually: - * - * string: 1 -> size of string - * struct: size of struct -> size of struct - * buffer: -1 * (index of paired len) -> value of paired len (maximum: TRACE_AUG_MAX_BUF) - */ for (int i = 0; i < 6; i++) { - arg = (void *)args->args[i]; - augmented = false; - size = beauty_map[i]; - aug_size = size; /* size of the augmented data read from user space */ - - if (size == 0 || arg == NULL) - continue; - - if (size == 1) { /* string */ - aug_size = bpf_probe_read_user_str(((struct augmented_arg *)payload_offset)->value, value_size, arg); - /* minimum of 0 to pass the verifier */ - if (aug_size < 0) - aug_size = 0; - - augmented = true; - } else if (size > 0 && size <= value_size) { /* struct */ - if (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)->value, size, arg)) - augmented = true; - } else if ((int)size < 0 && size >= -6) { /* buffer */ - index = -(size + 1); - barrier_var(index); // Prevent clang (noticed with v18) from removing the &= 7 trick. - index &= 7; // Satisfy the bounds checking with the verifier in some kernels. - aug_size = args->args[index] > TRACE_AUG_MAX_BUF ? TRACE_AUG_MAX_BUF : args->args[index]; - - if (aug_size > 0) { - if (!bpf_probe_read_user(((struct augmented_arg *)payload_offset)->value, aug_size, arg)) - augmented = true; - } - } - - /* Augmented data size is limited to sizeof(augmented_arg->unnamed union with value field) */ - if (aug_size > value_size) - aug_size = value_size; - - /* write data to payload */ - if (augmented) { - int written = offsetof(struct augmented_arg, value) + aug_size; - - if (written < 0 || written > sizeof(struct augmented_arg)) - return 1; - - ((struct augmented_arg *)payload_offset)->size = aug_size; + written = augment_arg(args, i, beauty_map, payload_offset); + if (written < 0) + return 1; + if (written > 0) { output += written; payload_offset += written; do_output = true; -- 2.54.0