From patchwork Wed Sep 15 19:52:46 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 512550 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51D39C433F5 for ; Wed, 15 Sep 2021 19:54:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E60C61056 for ; Wed, 15 Sep 2021 19:54:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231592AbhIOT4C (ORCPT ); Wed, 15 Sep 2021 15:56:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231490AbhIOT4C (ORCPT ); Wed, 15 Sep 2021 15:56:02 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7A8AC061575 for ; Wed, 15 Sep 2021 12:54:42 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id o4-20020ae9f504000000b003d39d97b227so7215992qkg.2 for ; Wed, 15 Sep 2021 12:54:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:cc; bh=aeNnN9xag+ICPAe0ffKzWBBB/Z6CmxOcYPRHh7D2frs=; b=qIerQ+9u8w+7e+qc1Pt4BEtWWL4xi9o8Z0pshF/NwvFawnX2spGgfsa9wOdgOOK9XQ RsJjzY7WGt/x7Wfs3fZPhK7HV2XBvzYQhv2bGfwblwPJ+AxlvEq944N7y6+C/zP6st/K twrstG4QdSPG3LQcpZ+dcCdMORJbjS3Ap/fnWfckbmFtO9pZm6gHHt2z+NsiRWTxOh3N i1JHv9yIrsHipRryQvgavJikwchYg2qHfdG7ep7gkYP6fB7Fx4+dOei0JgekEhb01/g+ AxBKKH+J4nWVjPfNEtTSPGqEoxCFWJegufYxQbs+ajtcOyaU0QEDGRnDFLlHFR9Muinr y2iA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:cc; bh=aeNnN9xag+ICPAe0ffKzWBBB/Z6CmxOcYPRHh7D2frs=; b=0RgGm4COvPPtVaJfU5A8jwAbZbHvbNl28O2pwz/jEZBE3CWx9jIvOOBil68dVtiWD9 2pyzI2yO+QPBjVeZ6lzw1ZPIa1FeShpTCf6RnpQHlhMjRRsx/9E2H0OQr0SQT3h6uIHW TC/N78P0pWVn0d3sopO5dPtQZPOoQmGvr2XS9KfOCF1C/WodDhDVE6paJGU4Ioqf9qKT ykyiKVuPjkG58qxuN6Bk3utyFIjURvvGR/PeBMAhL7xe2vkROb6PpIsXoWQmTZix72gm isqimQdIowQTfxZe0Q2krhaKh+pTstJG/4MPOj5uRx49tN6ZT1+9ogEzNRcRQyZ2sioP BQSA== X-Gm-Message-State: AOAM5336uWeS/PUZZNWLqDOnMU1fw2M7nCsprxV4vGbb1W3V4qjowAX/ xOTpxkFXa5ZHKw6dux0kk1JVw0poujiE7wZ2uw== X-Google-Smtp-Source: ABdhPJz+DW0EgPkGnJfyhBQPsr8CaKufz8imI6mY2o3UUZTSwYh/1vOOeISmx+9v9/HDzO4mxi5M1R98Grqs+py63A== X-Received: from kaleshsingh.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2145]) (user=kaleshsingh job=sendgmr) by 2002:a0c:f58a:: with SMTP id k10mr1752710qvm.62.1631735681948; Wed, 15 Sep 2021 12:54:41 -0700 (PDT) Date: Wed, 15 Sep 2021 19:52:46 +0000 In-Reply-To: <20210915195306.612966-1-kaleshsingh@google.com> Message-Id: <20210915195306.612966-3-kaleshsingh@google.com> Mime-Version: 1.0 References: <20210915195306.612966-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.33.0.309.g3052b89438-goog Subject: [PATCH 2/5] tracing: Add division and multiplication support for hist triggers From: Kalesh Singh Cc: surenb@google.com, hridya@google.com, namhyung@kernel.org, Kalesh Singh , Jonathan Corbet , Steven Rostedt , Ingo Molnar , Shuah Khan , Tom Zanussi , Masami Hiramatsu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Adds basic support for division and multiplication operations for hist trigger variable expressions. For simplicity this patch only supports, division and multiplication for a single operation expression (e.g. x=$a/$b), as currently expressions are always evaluated right to left. This can lead to some incorrect results: e.g. echo 'hist:keys=common_pid:x=8-4-2' >> event/trigger 8-4-2 should evaluate to 2 i.e. (8-4)-2 but currently x evaluate to 6 i.e. 8-(4-2) Multiplication and division in sub-expressions will work correctly, once correct operator precedence support is added (See next patch in this series). For the undefined case of division by 0, the histogram expression evaluates to (u64)(-1). Since this cannot be detected when the expression is created, it is the responsibility of the user to be aware and account for this possibility. Examples: echo 'hist:keys=common_pid:a=8,b=4,x=$a/$b' \ >> event/trigger echo 'hist:keys=common_pid:x=5*$b' \ >> event/trigger Signed-off-by: Kalesh Singh --- kernel/trace/trace_events_hist.c | 72 +++++++++++++++++++++++++++++++- 1 file changed, 71 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 2802b211ccf3..dc28eb6fc73a 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -99,6 +99,8 @@ enum field_op_id { FIELD_OP_PLUS, FIELD_OP_MINUS, FIELD_OP_UNARY_MINUS, + FIELD_OP_DIV, + FIELD_OP_MULT, }; /* @@ -287,6 +289,40 @@ static u64 hist_field_minus(struct hist_field *hist_field, return val1 - val2; } +static u64 hist_field_div(struct hist_field *hist_field, + struct tracing_map_elt *elt, + struct trace_buffer *buffer, + struct ring_buffer_event *rbe, + void *event) +{ + struct hist_field *operand1 = hist_field->operands[0]; + struct hist_field *operand2 = hist_field->operands[1]; + + u64 val1 = operand1->fn(operand1, elt, buffer, rbe, event); + u64 val2 = operand2->fn(operand2, elt, buffer, rbe, event); + + /* Return -1 for the undefined case */ + if (!val2) + return -1; + + return val1 / val2; +} + +static u64 hist_field_mult(struct hist_field *hist_field, + struct tracing_map_elt *elt, + struct trace_buffer *buffer, + struct ring_buffer_event *rbe, + void *event) +{ + struct hist_field *operand1 = hist_field->operands[0]; + struct hist_field *operand2 = hist_field->operands[1]; + + u64 val1 = operand1->fn(operand1, elt, buffer, rbe, event); + u64 val2 = operand2->fn(operand2, elt, buffer, rbe, event); + + return val1 * val2; +} + static u64 hist_field_unary_minus(struct hist_field *hist_field, struct tracing_map_elt *elt, struct trace_buffer *buffer, @@ -1595,6 +1631,12 @@ static char *expr_str(struct hist_field *field, unsigned int level) case FIELD_OP_PLUS: strcat(expr, "+"); break; + case FIELD_OP_DIV: + strcat(expr, "/"); + break; + case FIELD_OP_MULT: + strcat(expr, "*"); + break; default: kfree(expr); return NULL; @@ -1610,7 +1652,7 @@ static int contains_operator(char *str) enum field_op_id field_op = FIELD_OP_NONE; char *op; - op = strpbrk(str, "+-"); + op = strpbrk(str, "+-/*"); if (!op) return FIELD_OP_NONE; @@ -1631,6 +1673,12 @@ static int contains_operator(char *str) case '+': field_op = FIELD_OP_PLUS; break; + case '/': + field_op = FIELD_OP_DIV; + break; + case '*': + field_op = FIELD_OP_MULT; + break; default: break; } @@ -2370,10 +2418,26 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data, case FIELD_OP_PLUS: sep = "+"; break; + case FIELD_OP_DIV: + sep = "/"; + break; + case FIELD_OP_MULT: + sep = "*"; + break; default: goto free; } + /* + * Multiplication and division are only supported in single operator + * expressions, since the expression is always evaluated from right + * to left. + */ + if ((field_op == FIELD_OP_DIV || field_op == FIELD_OP_MULT) && level > 0) { + hist_err(file->tr, HIST_ERR_TOO_MANY_SUBEXPR, errpos(str)); + return ERR_PTR(-EINVAL); + } + operand1_str = strsep(&str, sep); if (!operand1_str || !str) goto free; @@ -2445,6 +2509,12 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data, case FIELD_OP_PLUS: expr->fn = hist_field_plus; break; + case FIELD_OP_DIV: + expr->fn = hist_field_div; + break; + case FIELD_OP_MULT: + expr->fn = hist_field_mult; + break; default: ret = -EINVAL; goto free;