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[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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220106_212954_379168_F4809D62 X-CRM114-Status: GOOD ( 21.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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);