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[213.77.89.56]) by smtp.gmail.com with ESMTPSA id h2-20020a0564020e8200b005532a337d51sm3288494eda.44.2023.12.22.17.51.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Dec 2023 17:51:54 -0800 (PST) From: =?UTF-8?q?=C5=81ukasz=20Bartosik?= To: Jason Baron , Jim Cromie , Andrew Morton , Kees Cook , Douglas Anderson Cc: Guenter Roeck , Yaniv Tzoreff , Benson Leung , Steven Rostedt , Vincent Whitchurch , Pekka Paalanen , Sean Paul , Daniel Vetter , Simon Ser , John Ogness , Petr Mladek , Sergey Senozhatsky , linux-kernel@vger.kernel.org, upstream@semihalf.com Subject: [PATCH v3 03/22] dyndbg: add write events to tracefs code Date: Sat, 23 Dec 2023 02:51:12 +0100 Message-ID: <20231223015131.2836090-4-lb@semihalf.com> X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog In-Reply-To: <20231223015131.2836090-1-lb@semihalf.com> References: <20231223015131.2836090-1-lb@semihalf.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jim Cromie 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 funcs: ddebug_printk() - print to both syslog/tracefs ddebug_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: __ddebug_{pr_debug,{,net,ib}dev_dbg}, replacing printk and dev_printk with the new funcs above. The _DPRINTK_FLAGS_TRACE flag character is 'T', so the following finds all callsites enabled for tracing: grep -P =3Dp?T /proc/dynamic_debug/control This patch,~1,~2 are basically copies of [1] with a few differences: - s/dynamic_/ddebug_/ on Vincent's additions - __printf attrs on the _printk funcs - reuses trace_console() event, not adding a new "printk:dyndbg" event. next patch replaces this with 2 new events [1] https://lore.kernel.org/lkml/20200825153338.17061-1-vincent.whitchurch@= axis.com 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/Documentat= ion/admin-guide/dynamic-debug-howto.rst index 0c526dac8428..19732b510cfc 100644 --- a/Documentation/admin-guide/dynamic-debug-howto.rst +++ b/Documentation/admin-guide/dynamic-debug-howto.rst @@ -209,8 +209,9 @@ of the characters:: =20 The flags are:: =20 - p enables the pr_debug() callsite. - _ enables no flags. + p callsite prints to syslog + T callsite issues a dyndbg:* trace-event + _ enables no flags =20 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 ee0cb37153ef..016f33c20251 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -36,6 +36,7 @@ #include #include #include +#include =20 #include =20 @@ -90,6 +91,7 @@ static inline const char *trim_prefix(const char *path) =20 static const struct { unsigned flag:8; char opt_char; } opt_array[] =3D { { _DPRINTK_FLAGS_PRINTK, 'p' }, + { _DPRINTK_FLAGS_TRACE, 'T' }, { _DPRINTK_FLAGS_INCL_MODNAME, 'm' }, { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' }, { _DPRINTK_FLAGS_INCL_SOURCENAME, 's' }, @@ -858,6 +860,98 @@ static inline char *dynamic_emit_prefix(struct _ddebug= *desc, char *buf) return buf; } =20 +/* + * 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 =3D __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 =3D this_cpu_ptr(ddebug_trace_bufs.bufs) + bufidx; + + len =3D 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; @@ -872,16 +966,18 @@ void __dynamic_pr_debug(struct _ddebug *descriptor, c= onst char *fmt, ...) vaf.fmt =3D fmt; vaf.va =3D &args; =20 - 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); =20 va_end(args); } EXPORT_SYMBOL(__dynamic_pr_debug); =20 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; =20 BUG_ON(!descriptor); @@ -891,16 +987,18 @@ void __dynamic_dev_dbg(struct _ddebug *descriptor, =20 vaf.fmt =3D fmt; vaf.va =3D &args; + flags =3D descriptor->flags; =20 if (!dev) { - printk(KERN_DEBUG "(NULL device *): %pV", &vaf); + ddebug_printk(flags, KERN_DEBUG "(NULL device *): %pV", + &vaf); } else { char buf[PREFIX_SIZE] =3D ""; =20 - 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); } =20 va_end(args); @@ -913,6 +1011,7 @@ 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; =20 BUG_ON(!descriptor); @@ -922,22 +1021,24 @@ void __dynamic_netdev_dbg(struct _ddebug *descriptor, =20 vaf.fmt =3D fmt; vaf.va =3D &args; + flags =3D descriptor->flags; =20 if (dev && dev->dev.parent) { char buf[PREFIX_SIZE] =3D ""; =20 - 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); } =20 va_end(args); @@ -953,26 +1054,29 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, { struct va_format vaf; va_list args; + unsigned int flags; =20 va_start(args, fmt); =20 vaf.fmt =3D fmt; vaf.va =3D &args; + flags =3D descriptor->flags; =20 if (ibdev && ibdev->dev.parent) { char buf[PREFIX_SIZE] =3D ""; =20 - 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); } =20 va_end(args); --=20 2.43.0.472.g3155946c3a-goog