From patchwork Wed Oct 20 01:31:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12571483 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 6642FC433EF for ; Wed, 20 Oct 2021 01:34:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 484F16117A for ; Wed, 20 Oct 2021 01:34:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229555AbhJTBgY (ORCPT ); Tue, 19 Oct 2021 21:36:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229839AbhJTBgX (ORCPT ); Tue, 19 Oct 2021 21:36:23 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD2BAC061749 for ; Tue, 19 Oct 2021 18:34:09 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id y18-20020a25a092000000b005bddb39f160so26394275ybh.10 for ; Tue, 19 Oct 2021 18:34:09 -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=QoyL/j4Wj5xtQouIJDIdg2CMTweye3z9i1beCqJqXYs=; b=Zw3jTItRnv/CJli7JslBJen12pbdK99RkpUXc0nkc0zUSAySAtJbYkRKEI8joNJr59 cBZqPCZX3zMuHXTJADhzSz/ru2z+OsZoqvnKok1CLc27jw0jAWWi8zDpMz3O5b/wDU5f UwFb1/Iqj0Foq0RC2L4ntvG+WBje7P2yca6VG/6tl4FHPyxxpeuYKGSr0/+x8dDagRPP nKl2dh/WItLL0Brnetrw3YCGNd6lueLntINApGPWW+iUK+sfkbXgNfeZKhNjBFtQwSfx r3gCve22ppGU0Z99Eh+UYIqYCAWgXOiL1K3dsSOi3Pxsk77v2jBb/U9jQrLwTuAsYaMw x7Tw== 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=QoyL/j4Wj5xtQouIJDIdg2CMTweye3z9i1beCqJqXYs=; b=NBm+aCPo1lxJyKTqprm22Bc0kreHYH9OOIgsQF6AaX1nSehD4ssJdgaaQgXY+Qdsk8 nDLh6hP9xHd11TqZDXyePTgA55OsMm7DJlX87XdauQ4s7sSPhbnqCvKYIfnbs74aDKGX nycb8X9ThxM2pxF1Jm/s0kyXOzWCES7oFWg1JCxf58/m1EuehAlyIdm3MLSJiJEynCh2 cmWXjekgUQ1VtMwcfBiCxbOaBj0DPAHeAzPKaRAoivmjWdSRsuKW2b7zMURc1mzGqqYc XaOLokitLuNUGlkun8aoh4siVIN6sWSF/iwL1GxAs7RQztiYoQNDk26GkznP+f8v64AT 8Rbg== X-Gm-Message-State: AOAM5302gJbQFmha0wsGTZCo00W8BYvEOSFtYa1PDa5enAqBrp0rgVz8 Zvbb2DYzGcYtUVpREiKBZ+fCm6Uss31sAL5dog== X-Google-Smtp-Source: ABdhPJyDLS9Bp3kyfvBbh/WllX3HyAO9JB+5Aw4IPjnhXh1jJvgcTD9BGo3pTTYMLjQzjXA1Fssg+oNmS6BG+vmtWg== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:1953:b886:7a6c:bf0]) (user=kaleshsingh job=sendgmr) by 2002:a25:c696:: with SMTP id k144mr37146969ybf.296.1634693649086; Tue, 19 Oct 2021 18:34:09 -0700 (PDT) Date: Tue, 19 Oct 2021 18:31:39 -0700 In-Reply-To: <20211020013153.4106001-1-kaleshsingh@google.com> Message-Id: <20211020013153.4106001-3-kaleshsingh@google.com> Mime-Version: 1.0 References: <20211020013153.4106001-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.33.0.1079.g6e70778dc9-goog Subject: [PATCH v2 2/5] 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 8563a2d51f65..9415ee65acc0 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 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, @@ -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;