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 5CA0AC433FE for ; Thu, 9 Dec 2021 15:09:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239256AbhLIPMs (ORCPT ); Thu, 9 Dec 2021 10:12:48 -0500 Received: from smtp1.axis.com ([195.60.68.17]:43283 "EHLO smtp1.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239250AbhLIPMq (ORCPT ); Thu, 9 Dec 2021 10:12:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1639062552; x=1670598552; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=W2ubuTB0lhYmOjPQa69hEhEIuxyUGZeyP9M+nuyzdoI=; b=cHCAu2nF7Bl2Tq/QEzjewIpcx+W9wP0qgcSjKTmkLPbXDa3C42xvglxO ZsoW5NQyq6CAA4fQLqWMrQrqFm7hpBq+07yw5bAtiuDyyo+nCh22Hvi1D umBPEuPqXyFcVx+H4a+bQoeHMB0K52EVlIXbuVMM1hVke/yed4bnqyzIP F1n7s+Pur+Ud5bzsckIwR3x6Ho7T9/Z6B3NlMbGzTCsvOIcW8unW4HRtC XQI6JNcKgpyyqViYV3roX0pdIoEET/Vm5cTC/zIz3VcXmH3lgE81OHY5j DIHKniBY707fj5PvxZV3hk+TnsKGk4/NUBFcilXXybA1Z2kd6/CW6trY+ A==; Date: Thu, 9 Dec 2021 16:09:10 +0100 From: Vincent Whitchurch To: "jim.cromie@gmail.com" CC: Steven Rostedt , Jason Baron , Greg KH , "robdclark@gmail.com" , Sean Paul , Daniel Vetter , Sean Paul , "lyude@redhat.com" , LKML , "mathieu.desnoyers@efficios.com" , dri-devel , amd-gfx mailing list , "intel-gvt-dev@lists.freedesktop.org" , Intel Graphics Development , "quic_saipraka@quicinc.com" , Will Deacon , Catalin Marinas , "quic_psodagud@quicinc.com" , "maz@kernel.org" , Arnd Bergmann , Linux ARM , "linux-arm-msm@vger.kernel.org" , Ingo Molnar Subject: Re: [PATCH v10 08/10] dyndbg: add print-to-tracefs, selftest with it - RFC Message-ID: <20211209150910.GA23668@axis.com> References: <20211111220206.121610-1-jim.cromie@gmail.com> <20211111220206.121610-9-jim.cromie@gmail.com> <20211112114953.GA1381@axis.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 08, 2021 at 06:16:10AM +0100, jim.cromie@gmail.com wrote: > are you planning to dust this patchset off and resubmit it ? > > Ive been playing with it and learning ftrace (decade+ late), > I found your boot-line example very helpful as 1st steps > (still havent even tried the filtering) > > > with these adjustments (voiced partly to test my understanding) > I would support it, and rework my patchset to use it. > > - change flag to -e, good mnemonics for event/trace-event > T is good too, but uppercase, no need to go there. Any flag name works for me. > - include/trace/events/dyndbg.h - separate file, not mixed with print.h > dyndbg class, so trace_event=dyndbg:* > > - 1 event type per pr_debug, dev_dbg, netdev_dbg ? ibdev_dbg ? > with the extra args: descriptor that Steven wanted, > probably also struct <|net|ib>dev For my use cases I don't see much value in having separate events for the different debug functions, but since all of them can be easily enabled (dyndbg:*, as you noted), that works for me too. > If youre too busy for a while, I'd eventually take a (slow) run at it. You're welcome to have a go. I think you've already rebased the patchset, but here's a diff top of v5.16-rc4 for reference. I noticed a bug inside the CONFIG_JUMP_LABEL handling (also present in the last version I posted) which should be fixed as part of the diff below (I've added a comment). Proper tests for this, like the ones you are adding in your patchset, would certainly be a good idea. Thanks. 8<------------- diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst index a89cfa083155..b9c4e808befc 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. + x enables trace to the printk:dyndbg 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/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index dce631e678dd..bc21bfb0fdc6 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -27,7 +27,7 @@ struct _ddebug { * writes commands to /dynamic_debug/control */ #define _DPRINTK_FLAGS_NONE 0 -#define _DPRINTK_FLAGS_PRINT (1<<0) /* printk() a message using the format */ +#define _DPRINTK_FLAGS_PRINTK (1<<0) /* printk() a message using the format */ #define _DPRINTK_FLAGS_INCL_MODNAME (1<<1) #define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2) #define _DPRINTK_FLAGS_INCL_LINENO (1<<3) @@ -37,8 +37,11 @@ struct _ddebug { (_DPRINTK_FLAGS_INCL_MODNAME | _DPRINTK_FLAGS_INCL_FUNCNAME |\ _DPRINTK_FLAGS_INCL_LINENO | _DPRINTK_FLAGS_INCL_TID) +#define _DPRINTK_FLAGS_TRACE (1<<5) +#define _DPRINTK_FLAGS_ENABLE (_DPRINTK_FLAGS_PRINTK | \ + _DPRINTK_FLAGS_TRACE) #if defined DEBUG -#define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT +#define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINTK #else #define _DPRINTK_FLAGS_DEFAULT 0 #endif @@ -120,10 +123,10 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, #ifdef DEBUG #define DYNAMIC_DEBUG_BRANCH(descriptor) \ - likely(descriptor.flags & _DPRINTK_FLAGS_PRINT) + likely(descriptor.flags & _DPRINTK_FLAGS_ENABLE) #else #define DYNAMIC_DEBUG_BRANCH(descriptor) \ - unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT) + unlikely(descriptor.flags & _DPRINTK_FLAGS_ENABLE) #endif #endif /* CONFIG_JUMP_LABEL */ diff --git a/include/trace/events/printk.h b/include/trace/events/printk.h index 13d405b2fd8b..1f78bd237a91 100644 --- a/include/trace/events/printk.h +++ b/include/trace/events/printk.h @@ -7,7 +7,7 @@ #include -TRACE_EVENT(console, +DECLARE_EVENT_CLASS(printk, TP_PROTO(const char *text, size_t len), TP_ARGS(text, len), @@ -31,6 +31,16 @@ TRACE_EVENT(console, TP_printk("%s", __get_str(msg)) ); + +DEFINE_EVENT(printk, console, + TP_PROTO(const char *text, size_t len), + TP_ARGS(text, len) +); + +DEFINE_EVENT(printk, dyndbg, + TP_PROTO(const char *text, size_t len), + TP_ARGS(text, len) +); #endif /* _TRACE_PRINTK_H */ /* This part must be outside protection */ diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index dd7f56af9aed..161454fa0af8 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -36,6 +36,7 @@ #include #include #include +#include #include @@ -86,11 +87,12 @@ static inline const char *trim_prefix(const char *path) } static struct { unsigned flag:8; char opt_char; } opt_array[] = { - { _DPRINTK_FLAGS_PRINT, 'p' }, + { _DPRINTK_FLAGS_PRINTK, 'p' }, { _DPRINTK_FLAGS_INCL_MODNAME, 'm' }, { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' }, { _DPRINTK_FLAGS_INCL_LINENO, 'l' }, { _DPRINTK_FLAGS_INCL_TID, 't' }, + { _DPRINTK_FLAGS_TRACE, 'x' }, { _DPRINTK_FLAGS_NONE, '_' }, }; @@ -210,11 +212,23 @@ static int ddebug_change(const struct ddebug_query *query, if (newflags == dp->flags) continue; #ifdef CONFIG_JUMP_LABEL - if (dp->flags & _DPRINTK_FLAGS_PRINT) { - if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT)) + if (dp->flags & _DPRINTK_FLAGS_ENABLE) { + /* + * The newflags check is to ensure that the + * static branch doesn't get disabled in step + * 3: + * + * (1) +pf + * (2) +x + * (3) -pf + */ + if (!(modifiers->flags & _DPRINTK_FLAGS_ENABLE) && + !(newflags & _DPRINTK_FLAGS_ENABLE)) { static_branch_disable(&dp->key.dd_key_true); - } else if (modifiers->flags & _DPRINTK_FLAGS_PRINT) + } + } else if (modifiers->flags & _DPRINTK_FLAGS_ENABLE) { static_branch_enable(&dp->key.dd_key_true); + } #endif dp->flags = newflags; v4pr_info("changed %s:%d [%s]%s =%s\n", @@ -621,6 +635,96 @@ static char *__dynamic_emit_prefix(const 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_dyndbg(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); + } +} + static inline char *dynamic_emit_prefix(struct _ddebug *desc, char *buf) { if (unlikely(desc->flags & _DPRINTK_FLAGS_INCL_ANY)) @@ -642,7 +746,8 @@ 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 +757,7 @@ 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 +767,18 @@ 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 +791,7 @@ 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 +801,24 @@ 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); @@ -722,27 +833,31 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, const struct ib_device *ibdev, const char *fmt, ...) { struct va_format vaf; + unsigned int flags; va_list args; 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: %pV", + dev_name(&ibdev->dev), &vaf); } else { - printk(KERN_DEBUG "(NULL ib_device): %pV", &vaf); + dynamic_printk(flags, KERN_DEBUG "(NULL ib_device): %pV", + &vaf); } va_end(args);