From patchwork Fri Jan 7 05:29:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jim Cromie X-Patchwork-Id: 12706226 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 2872EC433F5 for ; Fri, 7 Jan 2022 05:29:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345703AbiAGF34 (ORCPT ); Fri, 7 Jan 2022 00:29:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346152AbiAGF3y (ORCPT ); Fri, 7 Jan 2022 00:29:54 -0500 Received: from mail-il1-x133.google.com (mail-il1-x133.google.com [IPv6:2607:f8b0:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09BBFC061245; Thu, 6 Jan 2022 21:29:54 -0800 (PST) Received: by mail-il1-x133.google.com with SMTP id v10so3811154ilj.3; Thu, 06 Jan 2022 21:29:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=iwfS1KATHD4qlF4EIAswj+v50MYv6dXEgUQ2kHGwxaY=; b=kLxZUeIiUHVpFydZkyGdzXJ27X73eVmnvUhjCBe6B6DjPI0Pf+xMAbzxg+u5iKIVNQ 4WM76bt3BfUMZbbTwgdsNVD6jnfZybduM/LCiv8jGZmFzAqq8akfEnHGeWxZ1+tiZjw6 Rq+2hbxKQx4aW9PNWwj6wvN9v9Neg+tTdIWV0i+ZetRoXN4hcr/wtT2P3fBostoTCDwZ h+zsCzE7033XDvFul+qtLtGkSKYLJLMg4aHvunIv5/WMkQjLgauWgd3HmELztB8Qyjaq tM/r4XIyGMG9FB+euiCZGnBekoii88bKl9KtUnfUepfzZJPNcoCbTO7pT0A7xiInYAjT pihg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=iwfS1KATHD4qlF4EIAswj+v50MYv6dXEgUQ2kHGwxaY=; b=yb44UQKpTDSK73uCrM3yrfRapaLIlFlzZKK+PVCFHkAbzhvYPbKQRGBIY7wuDs1MgW IJh/katO5+c92uKGlU90aQTCikrTi7Tu2BxQu/Bwq9zxqHIQHflTAkEt2NCiB8zBNW/0 8EtLDtaejGozfx5s/aqdsjYrvKfkUQeOf+L+oQUw7tcGMj+k8VIwmwfqyhvmVIm2DoX+ 05J/GfqdW/yBeu+SlKK5eYZbRkzzAcz/+AN29uNvV2hifP5FB9eVVNpgNQ8mG8FuAeTY /XLFnbPXuXy85k1fR6Y7vY+ZbzYFE7oRPAQWs1jTLJ/TcZZzC1Z8Iz0x88IIPqS49RPi Qhnw== X-Gm-Message-State: AOAM531qBXclSk9B7w6v9Wue31scr5ft9c9faH7PnBT4NvMQcBUIxLgO 3LSJLW367IFmoQJl3XK9lcI= X-Google-Smtp-Source: ABdhPJxJuqCjFl5e7DAMZoQn88gADlHCPWi3iC9gJSxC0rmA5z56lvaNsv1+DXz8Gou8DtO0ZHXUfg== X-Received: by 2002:a92:ddc4:: with SMTP id d4mr4637305ilr.281.1641533393416; Thu, 06 Jan 2022 21:29:53 -0800 (PST) Received: from frodo.. (c-24-9-77-57.hsd1.co.comcast.net. [24.9.77.57]) by smtp.googlemail.com with ESMTPSA id c18sm1843446iod.18.2022.01.06.21.29.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jan 2022 21:29:53 -0800 (PST) From: Jim Cromie To: jbaron@akamai.com, gregkh@linuxfoundation.org, linux@rasmusvillemoes.dk, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, daniel.vetter@ffwll.ch, seanpaul@chromium.org, robdclark@gmail.com, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: quic_saipraka@quicinc.com, will@kernel.org, catalin.marinas@arm.com, quic_psodagud@quicinc.com, maz@kernel.org, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, mingo@redhat.com, jim.cromie@gmail.com, vincent.whitchurch@axis.com Subject: [PATCH v11 03/19] dyndbg: add write-to-tracefs code Date: Thu, 6 Jan 2022 22:29:26 -0700 Message-Id: <20220107052942.1349447-4-jim.cromie@gmail.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20220107052942.1349447-1-jim.cromie@gmail.com> References: <20220107052942.1349447-1-jim.cromie@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org adds: dynamic_trace() uses trace_console() temporarily to issue printk:console event uses internal-ish __ftrace_trace_stack code: 4-context buffer stack, barriers per Steve call it from new funcs: dynamic_printk() - print to both syslog/tracefs dynamic_dev_printk() - dev-print to both syslog/tracefs These handle both _DPRINTK_FLAGS_PRINTK and _DPRINTK_FLAGS_TRACE cases, allowing to vsnprintf the message once and use it for both, skipping past the KERN_DEBUG character for tracing. Finally, adjust the callers: __dynamic_{pr_debug,{,net,ib}dev_dbg}, replacing printk and dev_printk with the new funcs above. The _DPRINTK_FLAGS_TRACE flag character s 'T', so the following finds all callsites enabled for tracing: grep -P =p?T /proc/dynamic_debug/control Enabling debug-to-tracefs is 2 steps: # event enable echo 1 > /sys/kernel/tracing/events/dyndbg/enable # callsite enable echo module foo +T > /proc/dynamic_debug/control This patch,~1,~2 are based upon: https://lore.kernel.org/lkml/20200825153338.17061-1-vincent.whitchurch@axis.com/ .. with simplification of temporarily reusing trace_console() rather than adding a new printk:dyndbg event. Soon, add 2 new events capturing the pr_debug & dev_dbg() args. CC: vincent.whitchurch@axis.com Signed-off-by: Jim Cromie --- .../admin-guide/dynamic-debug-howto.rst | 1 + lib/dynamic_debug.c | 155 +++++++++++++++--- 2 files changed, 130 insertions(+), 26 deletions(-) diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst index a89cfa083155..3c8f104a143f 100644 --- a/Documentation/admin-guide/dynamic-debug-howto.rst +++ b/Documentation/admin-guide/dynamic-debug-howto.rst @@ -228,6 +228,7 @@ of the characters:: The flags are:: p enables the pr_debug() callsite. + T enables callsite to issue a dyndbg:* trace-event f Include the function name in the printed message l Include line number in the printed message m Include module name in the printed message diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 78a2912976c1..3fd035cd4653 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -36,6 +36,7 @@ #include #include #include +#include #include @@ -87,6 +88,7 @@ static inline const char *trim_prefix(const char *path) static struct { unsigned flag:8; char opt_char; } opt_array[] = { { _DPRINTK_FLAGS_PRINTK, 'p' }, + { _DPRINTK_FLAGS_TRACE, 'T' }, { _DPRINTK_FLAGS_INCL_MODNAME, 'm' }, { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' }, { _DPRINTK_FLAGS_INCL_LINENO, 'l' }, @@ -628,6 +630,96 @@ static inline char *dynamic_emit_prefix(struct _ddebug *desc, char *buf) return buf; } +/* + * This code is heavily based on __ftrace_trace_stack(). + * + * Allow 4 levels of nesting: normal, softirq, irq, NMI. + */ +#define DYNAMIC_TRACE_NESTING 4 + +struct dynamic_trace_buf { + char buf[256]; +}; + +struct dynamic_trace_bufs { + struct dynamic_trace_buf bufs[DYNAMIC_TRACE_NESTING]; +}; + +static DEFINE_PER_CPU(struct dynamic_trace_bufs, dynamic_trace_bufs); +static DEFINE_PER_CPU(int, dynamic_trace_reserve); + +static void dynamic_trace(const char *fmt, va_list args) +{ + struct dynamic_trace_buf *buf; + int bufidx; + int len; + + preempt_disable_notrace(); + + bufidx = __this_cpu_inc_return(dynamic_trace_reserve) - 1; + + if (WARN_ON_ONCE(bufidx > DYNAMIC_TRACE_NESTING)) + goto out; + + /* For the same reasons as in __ftrace_trace_stack(). */ + barrier(); + + buf = this_cpu_ptr(dynamic_trace_bufs.bufs) + bufidx; + + len = vscnprintf(buf->buf, sizeof(buf->buf), fmt, args); + trace_console(buf->buf, len); + +out: + /* As above. */ + barrier(); + __this_cpu_dec(dynamic_trace_reserve); + preempt_enable_notrace(); +} + +static void dynamic_printk(unsigned int flags, const char *fmt, ...) +{ + if (flags & _DPRINTK_FLAGS_TRACE) { + va_list args; + + va_start(args, fmt); + /* + * All callers include the KERN_DEBUG prefix to keep the + * vprintk case simple; strip it out for tracing. + */ + dynamic_trace(fmt + strlen(KERN_DEBUG), args); + va_end(args); + } + + if (flags & _DPRINTK_FLAGS_PRINTK) { + va_list args; + + va_start(args, fmt); + vprintk(fmt, args); + va_end(args); + } +} + +static void dynamic_dev_printk(unsigned int flags, const struct device *dev, + const char *fmt, ...) +{ + + if (flags & _DPRINTK_FLAGS_TRACE) { + va_list args; + + va_start(args, fmt); + dynamic_trace(fmt, args); + va_end(args); + } + + if (flags & _DPRINTK_FLAGS_PRINTK) { + va_list args; + + va_start(args, fmt); + dev_vprintk_emit(LOGLEVEL_DEBUG, dev, fmt, args); + va_end(args); + } +} + void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...) { va_list args; @@ -642,7 +734,8 @@ void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...) vaf.fmt = fmt; vaf.va = &args; - printk(KERN_DEBUG "%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf); + dynamic_printk(descriptor->flags, KERN_DEBUG "%s%pV", + dynamic_emit_prefix(descriptor, buf), &vaf); va_end(args); } @@ -652,6 +745,7 @@ void __dynamic_dev_dbg(struct _ddebug *descriptor, const struct device *dev, const char *fmt, ...) { struct va_format vaf; + unsigned int flags; va_list args; BUG_ON(!descriptor); @@ -661,16 +755,18 @@ void __dynamic_dev_dbg(struct _ddebug *descriptor, vaf.fmt = fmt; vaf.va = &args; + flags = descriptor->flags; if (!dev) { - printk(KERN_DEBUG "(NULL device *): %pV", &vaf); + dynamic_printk(flags, KERN_DEBUG "(NULL device *): %pV", + &vaf); } else { char buf[PREFIX_SIZE] = ""; - dev_printk_emit(LOGLEVEL_DEBUG, dev, "%s%s %s: %pV", - dynamic_emit_prefix(descriptor, buf), - dev_driver_string(dev), dev_name(dev), - &vaf); + dynamic_dev_printk(flags, dev, "%s%s %s: %pV", + dynamic_emit_prefix(descriptor, buf), + dev_driver_string(dev), dev_name(dev), + &vaf); } va_end(args); @@ -683,6 +779,7 @@ void __dynamic_netdev_dbg(struct _ddebug *descriptor, const struct net_device *dev, const char *fmt, ...) { struct va_format vaf; + unsigned int flags; va_list args; BUG_ON(!descriptor); @@ -692,22 +789,24 @@ void __dynamic_netdev_dbg(struct _ddebug *descriptor, vaf.fmt = fmt; vaf.va = &args; + flags = descriptor->flags; if (dev && dev->dev.parent) { char buf[PREFIX_SIZE] = ""; - dev_printk_emit(LOGLEVEL_DEBUG, dev->dev.parent, - "%s%s %s %s%s: %pV", - dynamic_emit_prefix(descriptor, buf), - dev_driver_string(dev->dev.parent), - dev_name(dev->dev.parent), - netdev_name(dev), netdev_reg_state(dev), - &vaf); + dynamic_dev_printk(flags, dev->dev.parent, + "%s%s %s %s%s: %pV", + dynamic_emit_prefix(descriptor, buf), + dev_driver_string(dev->dev.parent), + dev_name(dev->dev.parent), + netdev_name(dev), netdev_reg_state(dev), + &vaf); } else if (dev) { - printk(KERN_DEBUG "%s%s: %pV", netdev_name(dev), - netdev_reg_state(dev), &vaf); + dynamic_printk(flags, KERN_DEBUG "%s%s: %pV", + netdev_name(dev), netdev_reg_state(dev), &vaf); } else { - printk(KERN_DEBUG "(NULL net_device): %pV", &vaf); + dynamic_printk(flags, KERN_DEBUG "(NULL net_device): %pV", + &vaf); } va_end(args); @@ -723,29 +822,33 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, { struct va_format vaf; va_list args; + unsigned int flags; va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; + flags = descriptor->flags; if (ibdev && ibdev->dev.parent) { char buf[PREFIX_SIZE] = ""; - dev_printk_emit(LOGLEVEL_DEBUG, ibdev->dev.parent, - "%s%s %s %s: %pV", - dynamic_emit_prefix(descriptor, buf), - dev_driver_string(ibdev->dev.parent), - dev_name(ibdev->dev.parent), - dev_name(&ibdev->dev), - &vaf); + dynamic_dev_printk(flags, ibdev->dev.parent, + "%s%s %s %s: %pV", + dynamic_emit_prefix(descriptor, buf), + dev_driver_string(ibdev->dev.parent), + dev_name(ibdev->dev.parent), + dev_name(&ibdev->dev), + &vaf); } else if (ibdev) { - printk(KERN_DEBUG "%s: %pV", dev_name(&ibdev->dev), &vaf); + dynamic_printk(flags, KERN_DEBUG "%s%s: %pV", + dev_name(&ibdev->dev), &vaf); } else { - printk(KERN_DEBUG "(NULL ib_device): %pV", &vaf); + dynamic_printk(flags, KERN_DEBUG "(NULL ip_device): %pV", + &vaf); } - va_end(args); +va_end(args); } EXPORT_SYMBOL(__dynamic_ibdev_dbg);