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[73.78.62.130]) by smtp.googlemail.com with ESMTPSA id o12-20020a92a80c000000b002dcd35bb030sm2342604ilh.74.2022.07.17.23.39.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 17 Jul 2022 23:39:11 -0700 (PDT) From: Jim Cromie To: jbaron@akamai.com Date: Mon, 18 Jul 2022 00:36:26 -0600 Message-Id: <20220718063641.9179-43-jim.cromie@gmail.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220718063641.9179-1-jim.cromie@gmail.com> References: <20220718063641.9179-1-jim.cromie@gmail.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v3 33/41] dyndbg: add write-events-to-tracefs code X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jim Cromie , nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, vincent.whitchurch@axis.com, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 1st, internals: adds: ddebug_trace() uses trace_console() temporarily to issue printk:console event uses internal-ish __ftrace_trace_stack code: 4-context buffer stack, barriers per Steve Rostedt call it from new mid-layer funcs: ddebug_printk() - ddebug_trace or vprintk (to syslog) ddebug_dev_printk() - ddebug_trace or dev_printk_emit 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 prefix for tracing. Finally, adjust the top-layer: __dynamic_{pr_debug,{,net,ib}dev_dbg), replacing printk/dev_printk_emit with ddebug_printk/ddebug_dev_printk. Interface additions: new 'T' flag decl in opt_array. existing code handles it like others. document the new flag. To enable drm.debug ATOMIC messages to tracefs: :#> echo class DRM_UT_ATOMIC +T > /proc/dynamic_debug/control NB: This patch,~1,~2 are basically direct copies of: https://lore.kernel.org/lkml/20200825153338.17061-1-vincent.whitchurch@axis.com/ with a few differences: - s/dynamic_/ddebug_/ on Vincent's additions, tighter naming. - __printf attrs on the _printk funcs. - reuses trace_console() event, not adding a new "printk:dyndbg" event. later patches differentiate to new events. - a flags arg remains unchanged, adapt later to *descriptor. CC: vincent.whitchurch@axis.com Signed-off-by: Jim Cromie --- .../admin-guide/dynamic-debug-howto.rst | 5 +- lib/dynamic_debug.c | 156 +++++++++++++++--- 2 files changed, 133 insertions(+), 28 deletions(-) diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst index cdf1da69e43c..103e79269bac 100644 --- a/Documentation/admin-guide/dynamic-debug-howto.rst +++ b/Documentation/admin-guide/dynamic-debug-howto.rst @@ -209,8 +209,9 @@ of the characters:: The flags are:: - p enables the pr_debug() callsite. - _ enables no flags. + p callsite prints to syslog + T callsite issues a dyndbg:* trace-event + _ enables no flags Decorator flags add to the message-prefix, in order: t Include thread ID, or diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 2a46c642373a..66f12b9127c7 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -36,6 +36,7 @@ #include #include #include +#include #include @@ -90,6 +91,7 @@ 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' }, @@ -835,6 +837,98 @@ 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 ddebug_trace_buf { + char buf[256]; +}; + +struct ddebug_trace_bufs { + struct ddebug_trace_buf bufs[DYNAMIC_TRACE_NESTING]; +}; + +static DEFINE_PER_CPU(struct ddebug_trace_bufs, ddebug_trace_bufs); +static DEFINE_PER_CPU(int, ddebug_trace_reserve); + +static void ddebug_trace(const char *fmt, va_list args) +{ + struct ddebug_trace_buf *buf; + int bufidx; + int len; + + preempt_disable_notrace(); + + bufidx = __this_cpu_inc_return(ddebug_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(ddebug_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(ddebug_trace_reserve); + preempt_enable_notrace(); +} + +__printf(2, 3) +static void ddebug_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. + */ + ddebug_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); + } +} + +__printf(3, 4) +static void ddebug_dev_printk(unsigned int flags, const struct device *dev, + const char *fmt, ...) +{ + + if (flags & _DPRINTK_FLAGS_TRACE) { + va_list args; + + va_start(args, fmt); + ddebug_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; @@ -849,16 +943,18 @@ 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); + ddebug_printk(descriptor->flags, KERN_DEBUG "%s%pV", + dynamic_emit_prefix(descriptor, buf), &vaf); va_end(args); } EXPORT_SYMBOL(__dynamic_pr_debug); void __dynamic_dev_dbg(struct _ddebug *descriptor, - const struct device *dev, const char *fmt, ...) + const struct device *dev, const char *fmt, ...) { struct va_format vaf; + unsigned int flags; va_list args; BUG_ON(!descriptor); @@ -868,16 +964,18 @@ 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); + ddebug_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); + ddebug_dev_printk(flags, dev, "%s%s %s: %pV", + dynamic_emit_prefix(descriptor, buf), + dev_driver_string(dev), dev_name(dev), + &vaf); } va_end(args); @@ -890,6 +988,7 @@ 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); @@ -899,22 +998,24 @@ 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); + ddebug_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); + ddebug_printk(flags, KERN_DEBUG "%s%s: %pV", + netdev_name(dev), netdev_reg_state(dev), &vaf); } else { - printk(KERN_DEBUG "(NULL net_device): %pV", &vaf); + ddebug_printk(flags, KERN_DEBUG "(NULL net_device): %pV", + &vaf); } va_end(args); @@ -930,26 +1031,29 @@ 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); + ddebug_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); + ddebug_printk(flags, KERN_DEBUG "%s: %pV", + dev_name(&ibdev->dev), &vaf); } else { - printk(KERN_DEBUG "(NULL ib_device): %pV", &vaf); + ddebug_printk(flags, KERN_DEBUG "(NULL ip_device): %pV", &vaf); } va_end(args);