@@ -797,6 +797,15 @@ config GCOV_PROFILE_FTRACE
Note that on a kernel compiled with this config, ftrace will
run significantly slower.
+config BOOTTIME_TRACING
+ bool "Boot-time Tracing support"
+ depends on SKC && TRACING
+ default y
+ help
+ Enable developer to setup ftrace subsystem via supplemental
+ kernel cmdline at boot time for debugging (tracing) driver
+ initialization and boot process.
+
endif # FTRACE
endif # TRACING_SUPPORT
@@ -82,6 +82,7 @@ endif
obj-$(CONFIG_DYNAMIC_EVENTS) += trace_dynevent.o
obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
obj-$(CONFIG_UPROBE_EVENTS) += trace_uprobe.o
+obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o
obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
@@ -158,7 +158,7 @@ union trace_eval_map_item {
static union trace_eval_map_item *trace_eval_maps;
#endif /* CONFIG_TRACE_EVAL_MAP_FILE */
-static int tracing_set_tracer(struct trace_array *tr, const char *buf);
+int tracing_set_tracer(struct trace_array *tr, const char *buf);
static void ftrace_trace_userstack(struct ring_buffer *buffer,
unsigned long flags, int pc);
@@ -178,6 +178,11 @@ static int __init set_cmdline_ftrace(char *str)
}
__setup("ftrace=", set_cmdline_ftrace);
+void __init trace_init_dump_on_oops(int mode)
+{
+ ftrace_dump_on_oops = mode;
+}
+
static int __init set_ftrace_dump_on_oops(char *str)
{
if (*str++ != '=' || !*str) {
@@ -4614,7 +4619,7 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
return 0;
}
-static int trace_set_options(struct trace_array *tr, char *option)
+int trace_set_options(struct trace_array *tr, char *option)
{
char *cmp;
int neg = 0;
@@ -5505,8 +5510,8 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr,
return ret;
}
-static ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
- unsigned long size, int cpu_id)
+ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
+ unsigned long size, int cpu_id)
{
int ret = size;
@@ -5585,7 +5590,7 @@ static void add_tracer_options(struct trace_array *tr, struct tracer *t)
create_trace_option_files(tr, t);
}
-static int tracing_set_tracer(struct trace_array *tr, const char *buf)
+int tracing_set_tracer(struct trace_array *tr, const char *buf)
{
struct tracer *t;
#ifdef CONFIG_TRACER_MAX_TRACE
@@ -9170,16 +9175,23 @@ __init static int tracer_alloc_buffers(void)
return ret;
}
+void __init trace_init_tracepoint_printk(void)
+{
+ tracepoint_printk = 1;
+
+ tracepoint_print_iter =
+ kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
+ if (WARN_ON(!tracepoint_print_iter))
+ tracepoint_printk = 0;
+ else
+ static_key_enable(&tracepoint_printk_key.key);
+}
+
void __init early_trace_init(void)
{
- if (tracepoint_printk) {
- tracepoint_print_iter =
- kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL);
- if (WARN_ON(!tracepoint_print_iter))
- tracepoint_printk = 0;
- else
- static_key_enable(&tracepoint_printk_key.key);
- }
+ if (tracepoint_printk)
+ trace_init_tracepoint_printk();
+
tracer_alloc_buffers();
}
new file mode 100644
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace_boot.c
+ * Tracing kernel boot-time
+ */
+
+#define pr_fmt(fmt) "trace_boot: " fmt
+
+#include <linux/ftrace.h>
+#include <linux/init.h>
+#include <linux/skc.h>
+
+#include "trace.h"
+
+#define MAX_BUF_LEN 256
+
+extern int trace_set_options(struct trace_array *tr, char *option);
+extern enum ftrace_dump_mode ftrace_dump_on_oops;
+extern int __disable_trace_on_warning;
+extern int tracing_set_tracer(struct trace_array *tr, const char *buf);
+extern void __init trace_init_tracepoint_printk(void);
+extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
+ unsigned long size, int cpu_id);
+
+static void __init
+trace_boot_set_ftrace_options(struct trace_array *tr, struct skc_node *node)
+{
+ struct skc_node *anode;
+ const char *p;
+ char buf[MAX_BUF_LEN];
+ unsigned long v = 0;
+ int err;
+
+ /* Common ftrace options */
+ skc_node_for_each_array_value(node, "options", anode, p) {
+ if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
+ pr_err("String is too long: %s\n", p);
+ continue;
+ }
+
+ if (trace_set_options(tr, buf) < 0)
+ pr_err("Failed to set option: %s\n", buf);
+ }
+
+ p = skc_node_find_value(node, "trace_clock", NULL);
+ if (p && *p != '\0') {
+ if (tracing_set_clock(tr, p) < 0)
+ pr_err("Failed to set trace clock: %s\n", p);
+ }
+
+ /* Command line boot options */
+ p = skc_node_find_value(node, "dump_on_oops", NULL);
+ if (p) {
+ err = kstrtoul(p, 0, &v);
+ if (err || v == 1)
+ ftrace_dump_on_oops = DUMP_ALL;
+ else if (!err && v == 2)
+ ftrace_dump_on_oops = DUMP_ORIG;
+ }
+
+ if (skc_node_find_value(node, "traceoff_on_warning", NULL))
+ __disable_trace_on_warning = 1;
+
+ if (skc_node_find_value(node, "tp_printk", NULL))
+ trace_init_tracepoint_printk();
+
+ p = skc_node_find_value(node, "buffer_size", NULL);
+ if (p && *p != '\0') {
+ v = memparse(p, NULL);
+ if (v < PAGE_SIZE)
+ pr_err("Buffer size is too small: %s\n", p);
+ if (tracing_resize_ring_buffer(tr, v, RING_BUFFER_ALL_CPUS) < 0)
+ pr_err("Failed to resize trace buffer to %s\n", p);
+ }
+
+ if (skc_node_find_value(node, "alloc_snapshot", NULL))
+ if (tracing_alloc_snapshot() < 0)
+ pr_err("Failed to allocate snapshot buffer\n");
+}
+
+#ifdef CONFIG_EVENT_TRACING
+extern int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
+
+static void __init
+trace_boot_enable_events(struct trace_array *tr, struct skc_node *node)
+{
+ struct skc_node *anode;
+ char buf[MAX_BUF_LEN];
+ const char *p;
+
+ skc_node_for_each_array_value(node, "events", anode, p) {
+ if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
+ pr_err("String is too long: %s\n", p);
+ continue;
+ }
+
+ if (ftrace_set_clr_event(tr, buf, 1) < 0)
+ pr_err("Failed to enable event: %s\n", p);
+ }
+}
+#else
+#define trace_boot_enable_events(tr, node) do {} while (0)
+#endif
+
+static void __init
+trace_boot_enable_tracer(struct trace_array *tr, struct skc_node *node)
+{
+ const char *p;
+
+ p = skc_node_find_value(node, "tracer", NULL);
+ if (p && *p != '\0') {
+ if (tracing_set_tracer(tr, p) < 0)
+ pr_err("Failed to set given tracer: %s\n", p);
+ }
+}
+
+static int __init trace_boot_init(void)
+{
+ struct skc_node *trace_node;
+ struct trace_array *tr;
+
+ trace_node = skc_find_node("ftrace");
+ if (!trace_node)
+ return 0;
+
+ tr = top_trace_array();
+ if (!tr)
+ return 0;
+
+ trace_boot_set_ftrace_options(tr, trace_node);
+ trace_boot_enable_events(tr, trace_node);
+ trace_boot_enable_tracer(tr, trace_node);
+
+ return 0;
+}
+
+fs_initcall(trace_boot_init);
Setup tracing options by supplemental kernel cmdline (skc) in addition to kernel parameters. In this patch, add following commands support - ftrace.options = OPT1[,OPT2...]; Enable given ftrace options. - ftrace.trace_clock = CLOCK; Set given CLOCK to ftrace's trace_clock. - ftrace.dump_on_oops [= MODE]; Dump ftrace on Oops. If MODE = 1 or omitted, dump trace buffer on all CPUs. If MODE = 2, dump a buffer on a CPU which kicks Oops. - ftrace.traceoff_on_warning; Stop tracing if WARN_ON() occurs. - ftrace.tp_printk; Output trace-event data on printk buffer too. - ftrace.buffer_size = SIZE; Configure ftrace buffer size to SIZE. You can use "KB" or "MB" for that SIZE. - ftrace.alloc_snapshot; Allocate snapshot buffer. - ftrace.events = EVENT[, EVENT2...]; Enable given events on boot. You can use a wild card in EVENT. - ftrace.tracer = TRACER; Set TRACER to current tracer on boot. (e.g. function) Since the kernel parameter is limited length, sometimes there is no space to setup the tracing options. This will read the tracing options from skc "ftrace" prefix and setup tracers at boot. Note that this is not replacing the kernel parameters, because this skc based setting is later than that. If you want to trace earlier boot events, you still need kernel parameters. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- kernel/trace/Kconfig | 9 +++ kernel/trace/Makefile | 1 kernel/trace/trace.c | 38 ++++++++---- kernel/trace/trace_boot.c | 137 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 172 insertions(+), 13 deletions(-) create mode 100644 kernel/trace/trace_boot.c