From patchwork Mon Oct 25 20:08:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12582861 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24542C433FE for ; Mon, 25 Oct 2021 20:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E96060527 for ; Mon, 25 Oct 2021 20:23:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237976AbhJYUZl (ORCPT ); Mon, 25 Oct 2021 16:25:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237509AbhJYUZd (ORCPT ); Mon, 25 Oct 2021 16:25:33 -0400 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CFC25C04A413 for ; Mon, 25 Oct 2021 13:10:07 -0700 (PDT) Received: by mail-pj1-x1049.google.com with SMTP id c20-20020a17090ad91400b001a1ea10d56cso225224pjv.1 for ; Mon, 25 Oct 2021 13:10:07 -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=+/27iLcVwsoRtZBbebC5PI/8sCrYV9o5nqqwoDvFwLQ=; b=JOtZFdoO+mQ/0k/uB+I/6TEKe/WTlXcWqeaRbPbw/SEYw+rdJRFMzl7/KpGcBfaMNa 6ySASfiBInMTzXb5+cvAcqUQA/aotl9IWl1W6kqoTU654K2C6p4num5nY2n0LsAbTjwU zPVwn+Zo2dMaO2117CzE2hFJyiWjNlIhTEvvQxe9YQTPNHT8Zbr+HxIO7HIbhNum+YOl nRxyfA2/aTxth9biy+qAEXlgUN/gGY9au25feTgdGdDp1GWGWqqmC8FkFpK8Pru+cAcF StnnbMpF+TNLIg4+5DFjZWVRJ87W9zQo6FSiIwVx3V3XKSlNkxn7ChQpjplxfwicbFj3 t/Cg== 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=+/27iLcVwsoRtZBbebC5PI/8sCrYV9o5nqqwoDvFwLQ=; b=j1EyIgSc87Dv679pjrG9U5sr6TN5H9l+fOs4VkGwHOJ9Vh2zWBFeYXELj7gL7qtH7K oohJVFnE6rCXmKZbfGV1iH2oyhWIIVQsiaYWXJC/+nTX2S+LsUVA6CKaLuvjYBoA3Uk2 Ghjej//lZI5uDNBIsD8GU33pCJw3eomHn/Z1BkWAAnFM8WTN3QRQ45/Njq0u06QSG7am bfhtvgDM7wvDdIgNVagNcEMLwA4prV66UW4ADaA2RjNJo7IfuCbOAHOFKJM2+WIrqIrr cx90vfvC2Xmtfuz+eOKeTx8wv0l3lqAmr8fEMW7ccTYo1XIUJeWkwey2LF8dCcGswu2r 7ZEg== X-Gm-Message-State: AOAM532P/a92z0+FvOPTfYh2RkZNsvQOhiySn3IhAC1QI58Gn7tNaF6C Ju+te7AlRVOf3NbFYIG2azi9zYOMl9V8j4grZA== X-Google-Smtp-Source: ABdhPJzkBLtClwx2VcWf/leMtZ/jaMFE+YFih9XQQYoQEY9CXn/SM7ReenZtrU64gtgqJHTypDnKVRQqtf+KaQam5Q== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:b783:5702:523e:d435]) (user=kaleshsingh job=sendgmr) by 2002:a17:90a:5285:: with SMTP id w5mr157982pjh.1.1635192606982; Mon, 25 Oct 2021 13:10:06 -0700 (PDT) Date: Mon, 25 Oct 2021 13:08:34 -0700 In-Reply-To: <20211025200852.3002369-1-kaleshsingh@google.com> Message-Id: <20211025200852.3002369-3-kaleshsingh@google.com> Mime-Version: 1.0 References: <20211025200852.3002369-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.33.0.1079.g6e70778dc9-goog Subject: [PATCH v4 2/8] tracing: Add division and multiplication support for hist triggers From: Kalesh Singh Cc: surenb@google.com, hridya@google.com, namhyung@kernel.org, kernel-team@android.com, Kalesh Singh , Jonathan Corbet , Steven Rostedt , Ingo Molnar , Shuah Khan , Masami Hiramatsu , Tom Zanussi , 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:y=5*$b' \ >> event/trigger Signed-off-by: Kalesh Singh --- Changes in v2: - Use div64 helper in hist_field_div() to avoid faults on x86 32-bit machines, per Steven Rostedt 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 28f711224944..522355a06f58 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -97,6 +97,8 @@ enum field_op_id { FIELD_OP_PLUS, FIELD_OP_MINUS, FIELD_OP_UNARY_MINUS, + FIELD_OP_DIV, + FIELD_OP_MULT, }; /* @@ -285,6 +287,40 @@ 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 div64_u64(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, @@ -1592,6 +1628,12 @@ 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; @@ -1607,7 +1649,7 @@ 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; @@ -1628,6 +1670,12 @@ 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; } @@ -2361,10 +2409,26 @@ 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; @@ -2436,6 +2500,12 @@ 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;