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Message-Id: <20231103131011.1316396-12-lb@semihalf.com>
Date: Fri, 3 Nov 2023 14:10:10 +0100
From: Łukasz Bartosik <lb@...ihalf.com>
To: Jason Baron <jbaron@...mai.com>, Jim Cromie <jim.cromie@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>,
Douglas Anderson <dianders@...omium.org>
Cc: Guenter Roeck <groeck@...gle.com>,
Yaniv Tzoreff <yanivt@...gle.com>,
Benson Leung <bleung@...gle.com>,
Steven Rostedt <rostedt@...dmis.org>,
Vincent Whitchurch <vincent.whitchurch@...s.com>,
Pekka Paalanen <ppaalanen@...il.com>,
Sean Paul <seanpaul@...omium.org>,
Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
upstream@...ihalf.com
Subject: [PATCH v1 11/12] dyndbg: write debug logs to trace instance
When trace is enabled (T flag is set) and trace_dst field is set
to value greater than 0 (0 is reserved for trace events) then
debug logs will be written to trace instance pointed by trace_dst
value, for example when trace_dst value is 2 then debug logs will
be written to <debugfs>/tracing/instances/dyndbg_inst_2 instance.
Given trace instance will not be initialized until debug logs are
requested to be written to it and afer init will persist until
reboot.
Signed-off-by: Łukasz Bartosik <lb@...ihalf.com>
---
lib/Kconfig.debug | 1 +
lib/dynamic_debug.c | 79 ++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 76 insertions(+), 4 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index fa307f93fa2e..9617e92c046d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -181,6 +181,7 @@ config DYNAMIC_DEBUG_CORE
bool "Enable core function of dynamic debug support"
depends on PRINTK
depends on (DEBUG_FS || PROC_FS)
+ depends on TRACING
help
Enable core functional support of dynamic debug. It is useful
when you want to tie dynamic debug to your kernel modules with
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c5cd28e74a02..541d9d522b3b 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -36,6 +36,7 @@
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/netdevice.h>
+#include <linux/trace.h>
#define CREATE_TRACE_POINTS
#include <trace/events/dyndbg.h>
@@ -81,6 +82,18 @@ module_param(verbose, int, 0644);
MODULE_PARM_DESC(verbose, " dynamic_debug/control processing "
"( 0 = off (default), 1 = module add/rm, 2 = >control summary, 3 = parsing, 4 = per-site changes)");
+/*
+ * When trace is enabled (T flag is set) and trace_dst field is set
+ * to value greater than 0 (0 is reserved for trace events) then
+ * debug logs will be written to trace instance pointed by trace_dst
+ * value, for example when trace_dst value is 2 then debug logs will
+ * be written to <debugfs>/tracing/instances/dyndbg_inst_2 instance.
+ * Given trace instance will not be initialized until debug logs are
+ * requested to be written to it and afer init will persist until
+ * reboot.
+ */
+static struct trace_array *trace_arr[TRACE_DST_MAX];
+
static inline struct dd_ctrl *get_ctrl(struct _ddebug *desc)
{
return &desc->ctrl;
@@ -255,6 +268,45 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
return NULL;
}
+static int handle_trace_dst(struct dd_ctrl *ctrl)
+{
+#define TRACE_INST_NAME_LEN 16
+ char instance_name[TRACE_INST_NAME_LEN];
+ struct trace_array *arr;
+ int ret = -EINVAL;
+
+ /* check if trace (T flag) is enabled */
+ if (!(ctrl->flags & _DPRINTK_FLAGS_TRACE))
+ return 0;
+
+ /* check if trace destination are trace events */
+ if (!ctrl->trace_dst)
+ return 0;
+
+ /* check if trace instance is already set up */
+ if (trace_arr[ctrl->trace_dst])
+ return 0;
+
+ snprintf(instance_name, TRACE_INST_NAME_LEN,
+ "dyndbg_inst_%u", ctrl->trace_dst);
+ arr = trace_array_get_by_name(instance_name);
+ if (!arr)
+ goto err;
+
+ ret = trace_array_init_printk(arr);
+ if (ret)
+ goto err_init;
+
+ trace_arr[ctrl->trace_dst] = arr;
+ return 0;
+
+err_init:
+ trace_array_put(arr);
+ trace_array_destroy(arr);
+err:
+ return ret;
+}
+
#define __outvar /* filled by callee */
/*
* Search the tables for _ddebug's which match the given `query' and
@@ -338,6 +390,9 @@ static int ddebug_change(const struct ddebug_query *query,
nctrl.trace_dst = modifiers->trace_dst;
if (!memcmp(&nctrl, get_ctrl(dp), sizeof(nctrl)))
continue;
+
+ if (handle_trace_dst(&nctrl))
+ continue;
#ifdef CONFIG_JUMP_LABEL
if (get_flags(dp) & _DPRINTK_FLAGS_ENABLED) {
if (!(nctrl.flags & _DPRINTK_FLAGS_ENABLED))
@@ -977,8 +1032,8 @@ static DEFINE_PER_CPU(struct ddebug_trace_bufs, ddebug_trace_bufs);
static DEFINE_PER_CPU(int, ddebug_trace_reserve);
__printf(3, 0)
-static void ddebug_trace(struct _ddebug *desc, const struct device *dev,
- const char *fmt, va_list args)
+static void ddebug_trace_event(struct _ddebug *desc, const struct device *dev,
+ const char *fmt, va_list args)
{
struct ddebug_trace_buf *buf;
int bufidx;
@@ -1010,6 +1065,15 @@ static void ddebug_trace(struct _ddebug *desc, const struct device *dev,
preempt_enable_notrace();
}
+__printf(2, 0)
+static void ddebug_trace_instance(struct _ddebug *desc, const char *fmt,
+ va_list *args)
+{
+ struct va_format vaf = { .fmt = fmt, .va = args};
+
+ trace_array_printk(trace_arr[get_trace_dst(desc)], _THIS_IP_, "%pV", &vaf);
+}
+
__printf(2, 3)
static void ddebug_printk(struct _ddebug *desc, const char *fmt, ...)
{
@@ -1022,7 +1086,11 @@ static void ddebug_printk(struct _ddebug *desc, const char *fmt, ...)
* All callers include the KERN_DEBUG prefix to keep the
* vprintk case simple; strip it out for tracing.
*/
- ddebug_trace(desc, NULL, fmt + strlen(KERN_DEBUG), args);
+ if (get_trace_dst(desc))
+ ddebug_trace_instance(desc, fmt, &args);
+ else
+ ddebug_trace_event(desc, NULL,
+ fmt + strlen(KERN_DEBUG), args);
va_end(args);
}
@@ -1044,7 +1112,10 @@ static void ddebug_dev_printk(struct _ddebug *desc, const struct device *dev,
va_list args;
va_start(args, fmt);
- ddebug_trace(desc, dev, fmt, args);
+ if (get_trace_dst(desc))
+ ddebug_trace_instance(desc, fmt, &args);
+ else
+ ddebug_trace_event(desc, dev, fmt, args);
va_end(args);
}
--
2.42.0.869.gea05f2083d-goog
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