From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86AA1C00140 for ; Wed, 24 Aug 2022 05:31:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229483AbiHXFbq (ORCPT ); Wed, 24 Aug 2022 01:31:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229446AbiHXFbp (ORCPT ); Wed, 24 Aug 2022 01:31:45 -0400 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B54375FFC; Tue, 23 Aug 2022 22:31:44 -0700 (PDT) Received: by mail-pf1-x42a.google.com with SMTP id f17so9324725pfk.11; Tue, 23 Aug 2022 22:31:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:from:to:cc; bh=NwHAtPjAReXq/IjjS87Nz2IZAEkxk0WwcyPP68OUjKs=; b=dfETqFUX4r2doa8+YKnEM7KHNpmOIwbcjAyyTLvSbbf4Buq0Hqh0w/0LgI8xcQgtgy 7kLZJxgex/+rsLh43mWBx52978BzobJ77S2Z871ZHCIvvgcg9UgHp4eSAVcAo/p5zbMj 57sns4RFXk3S/yljREhwrWWOGeiozpHtwHbvtWO8jeo/qdjOR0qaIUhY0z1l1Us/e3ER qJDcSMIK/dusXJf1AcomNiRkntZq1rf0wtDT42rcDYeiKuSDhMh4IP8d3NrppybCKKcN eJKXkj0o0CUjteK3lioSHdejLz6cFG77AS/6SbzQiUZtNxr2X21peFeLwGyq4l9jtfMb SQXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:x-gm-message-state:from:to :cc; bh=NwHAtPjAReXq/IjjS87Nz2IZAEkxk0WwcyPP68OUjKs=; b=Og6v7crLSohZj2L8Lb8zDvxKk6cwK4ahci4YfiTMV/T3sspE+AVk/8mkS/8jrdpC7h iRoef74NQBlaiiPx/KIunSYZqJG1fFjDHvurxiNQKZ9bXHF0Jvca41X53HxbAgxL9Dt5 V1Uj0RMeby7POig12TbMlu/HUUwAcwc0GtGl1+LRyLj3UY+dn3b649DNfJCWslgRycG6 0qBoCy9jPPhf/DihVQa6phTrPWd+YfYuH/uB4lkVgi6P32lMExGUOqYFfhzd7MK6hMgn U2U+ndccmbTtWxiv0CRmnKXUq0M60vBQlQf9Lus1pPOdRMKMdpA5NjzWStLveLBqBfVc hIFQ== X-Gm-Message-State: ACgBeo3kbn1TI2dlkG3DrM/nChAeEGJJ1DxEG17SWYArlDc/AXRvccQs 1zOOovL47Mh7ignKR5zslSpxqBG3Pd4= X-Google-Smtp-Source: AA6agR5e/DKwfYI/Z4kodn0YLTc8GJCp2dQWpCLj0lHTsPJLAzBRncyfS5vP7zIyeYfGmbqxSiE4mg== X-Received: by 2002:a63:6d09:0:b0:427:bbb0:e62 with SMTP id i9-20020a636d09000000b00427bbb00e62mr22152708pgc.346.1661319103706; Tue, 23 Aug 2022 22:31:43 -0700 (PDT) Received: from localhost ([98.97.33.232]) by smtp.gmail.com with ESMTPSA id i17-20020a17090332d100b00172ff99d0afsm2841733plr.140.2022.08.23.22.31.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Aug 2022 22:31:42 -0700 (PDT) Date: Tue, 23 Aug 2022 22:31:40 -0700 From: John Fastabend To: Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Steven Rostedt , Peter Zijlstra , Ingo Molnar , bpf@vger.kernel.org, LKML Message-ID: <6305b7bcbd7a3_6d4fc208d9@john.notmuch> In-Reply-To: <20220823210354.1407473-1-namhyung@kernel.org> References: <20220823210354.1407473-1-namhyung@kernel.org> Subject: RE: [PATCH bpf-next] bpf: Add bpf_read_raw_record() helper Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Namhyung Kim wrote: > The helper is for BPF programs attached to perf_event in order to read > event-specific raw data. I followed the convention of the > bpf_read_branch_records() helper so that it can tell the size of > record using BPF_F_GET_RAW_RECORD flag. > > The use case is to filter perf event samples based on the HW provided > data which have more detailed information about the sample. > > Note that it only reads the first fragment of the raw record. But it > seems mostly ok since all the existing PMU raw data have only single > fragment and the multi-fragment records are only for BPF output attached > to sockets. So unless it's used with such an extreme case, it'd work > for most of tracing use cases. > > Signed-off-by: Namhyung Kim > --- Acked-by: John Fastabend > I don't know how to test this. As the raw data is available on some > hardware PMU only (e.g. AMD IBS). I tried a tracepoint event but it was > rejected by the verifier. Actually it needs a bpf_perf_event_data > context so that's not an option IIUC. not a pmu expert but also no good ideas on my side. ... > > +BPF_CALL_4(bpf_read_raw_record, struct bpf_perf_event_data_kern *, ctx, > + void *, buf, u32, size, u64, flags) > +{ > + struct perf_raw_record *raw = ctx->data->raw; > + struct perf_raw_frag *frag; > + u32 to_copy; > + > + if (unlikely(flags & ~BPF_F_GET_RAW_RECORD_SIZE)) > + return -EINVAL; > + > + if (unlikely(!raw)) > + return -ENOENT; > + > + if (flags & BPF_F_GET_RAW_RECORD_SIZE) > + return raw->size; > + > + if (!buf || (size % sizeof(u32) != 0)) > + return -EINVAL; > + > + frag = &raw->frag; > + WARN_ON_ONCE(!perf_raw_frag_last(frag)); > + > + to_copy = min_t(u32, frag->size, size); > + memcpy(buf, frag->data, to_copy); > + > + return to_copy; > +} > + > +static const struct bpf_func_proto bpf_read_raw_record_proto = { > + .func = bpf_read_raw_record, > + .gpl_only = true, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_PTR_TO_CTX, > + .arg2_type = ARG_PTR_TO_MEM_OR_NULL, > + .arg3_type = ARG_CONST_SIZE_OR_ZERO, > + .arg4_type = ARG_ANYTHING, > +}; Patch lgtm but curious why allow the ARG_PTR_TO_MEM_OR_NULL from API side instead of just ARG_PTR_TO_MEM? Maybe, just to match the existing perf_event_read()? I acked it as I think matching existing API is likely good enough reason. > + > static const struct bpf_func_proto * > pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) > { > @@ -1548,6 +1587,8 @@ pe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) > return &bpf_read_branch_records_proto; > case BPF_FUNC_get_attach_cookie: > return &bpf_get_attach_cookie_proto_pe; > + case BPF_FUNC_read_raw_record: > + return &bpf_read_raw_record_proto; > default: > return bpf_tracing_func_proto(func_id, prog); > } > -- > 2.37.2.609.g9ff673ca1a-goog >