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-rw-r--r--Documentation/kernel-parameters.txt18
-rw-r--r--include/linux/ftrace.h7
-rw-r--r--init/main.c4
-rw-r--r--kernel/sysctl.c7
-rw-r--r--kernel/trace/trace.c25
-rw-r--r--kernel/trace/trace.h14
-rw-r--r--kernel/trace/trace_events.c42
-rw-r--r--kernel/trace/trace_syscalls.c7
8 files changed, 116 insertions, 8 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1de8335..bda85f1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3570,6 +3570,24 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
See also Documentation/trace/ftrace.txt "trace options"
section.
+ tp_printk[FTRACE]
+ Have the tracepoints sent to printk as well as the
+ tracing ring buffer. This is useful for early boot up
+ where the system hangs or reboots and does not give the
+ option for reading the tracing buffer or performing a
+ ftrace_dump_on_oops.
+
+ To turn off having tracepoints sent to printk,
+ echo 0 > /proc/sys/kernel/tracepoint_printk
+ Note, echoing 1 into this file without the
+ tracepoint_printk kernel cmdline option has no effect.
+
+ ** CAUTION **
+
+ Having tracepoints sent to printk() and activating high
+ frequency tracepoints such as irq or sched, can cause
+ the system to live lock.
+
traceoff_on_warning
[FTRACE] enable this option to disable tracing when a
warning is hit. This turns off "tracing_on". Tracing can
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ed50195..1da6029 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -39,6 +39,12 @@
# define FTRACE_FORCE_LIST_FUNC 0
#endif
+/* Main tracing buffer and events set up */
+#ifdef CONFIG_TRACING
+void trace_init(void);
+#else
+static inline void trace_init(void) { }
+#endif
struct module;
struct ftrace_hash;
@@ -873,6 +879,7 @@ static inline int test_tsk_trace_graph(struct task_struct *tsk)
enum ftrace_dump_mode;
extern enum ftrace_dump_mode ftrace_dump_on_oops;
+extern int tracepoint_printk;
extern void disable_trace_on_warning(void);
extern int __disable_trace_on_warning;
diff --git a/init/main.c b/init/main.c
index 8a914b7..747ecc4 100644
--- a/init/main.c
+++ b/init/main.c
@@ -578,6 +578,10 @@ asmlinkage __visible void __init start_kernel(void)
local_irq_disable();
idr_init_cache();
rcu_init();
+
+ /* trace_printk() and trace points may be used after this */
+ trace_init();
+
context_tracking_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7c54ff7..137c7f6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -623,6 +623,13 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
+ {
+ .procname = "tracepoint_printk",
+ .data = &tracepoint_printk,
+ .maxlen = sizeof(tracepoint_printk),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
#endif
#ifdef CONFIG_KEXEC
{
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ab76b7b..2e76797 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -63,6 +63,10 @@ static bool __read_mostly tracing_selftest_running;
*/
bool __read_mostly tracing_selftest_disabled;
+/* Pipe tracepoints to printk */
+struct trace_iterator *tracepoint_print_iter;
+int tracepoint_printk;
+
/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
{ }
@@ -193,6 +197,13 @@ static int __init set_trace_boot_clock(char *str)
}
__setup("trace_clock=", set_trace_boot_clock);
+static int __init set_tracepoint_printk(char *str)
+{
+ if ((strcmp(str, "=0") != 0 && strcmp(str, "=off") != 0))
+ tracepoint_printk = 1;
+ return 1;
+}
+__setup("tp_printk", set_tracepoint_printk);
unsigned long long ns2usecs(cycle_t nsec)
{
@@ -6898,6 +6909,19 @@ out:
return ret;
}
+void __init 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;
+ }
+ tracer_alloc_buffers();
+ init_ftrace_syscalls();
+ trace_event_init();
+}
+
__init static int clear_boot_tracer(void)
{
/*
@@ -6917,6 +6941,5 @@ __init static int clear_boot_tracer(void)
return 0;
}
-early_initcall(tracer_alloc_buffers);
fs_initcall(tracer_init_debugfs);
late_initcall(clear_boot_tracer);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3255dfb..8de48ba 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1301,4 +1301,18 @@ int perf_ftrace_event_register(struct ftrace_event_call *call,
#define perf_ftrace_event_register NULL
#endif
+#ifdef CONFIG_FTRACE_SYSCALLS
+void init_ftrace_syscalls(void);
+#else
+static inline void init_ftrace_syscalls(void) { }
+#endif
+
+#ifdef CONFIG_EVENT_TRACING
+void trace_event_init(void);
+#else
+static inline void __init trace_event_init(void) { }
+#endif
+
+extern struct trace_iterator *tracepoint_print_iter;
+
#endif /* _LINUX_KERNEL_TRACE_H */
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index d0e4f92..366a78a 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -212,8 +212,40 @@ void *ftrace_event_buffer_reserve(struct ftrace_event_buffer *fbuffer,
}
EXPORT_SYMBOL_GPL(ftrace_event_buffer_reserve);
+static DEFINE_SPINLOCK(tracepoint_iter_lock);
+
+static void output_printk(struct ftrace_event_buffer *fbuffer)
+{
+ struct ftrace_event_call *event_call;
+ struct trace_event *event;
+ unsigned long flags;
+ struct trace_iterator *iter = tracepoint_print_iter;
+
+ if (!iter)
+ return;
+
+ event_call = fbuffer->ftrace_file->event_call;
+ if (!event_call || !event_call->event.funcs ||
+ !event_call->event.funcs->trace)
+ return;
+
+ event = &fbuffer->ftrace_file->event_call->event;
+
+ spin_lock_irqsave(&tracepoint_iter_lock, flags);
+ trace_seq_init(&iter->seq);
+ iter->ent = fbuffer->entry;
+ event_call->event.funcs->trace(iter, 0, event);
+ trace_seq_putc(&iter->seq, 0);
+ printk("%s", iter->seq.buffer);
+
+ spin_unlock_irqrestore(&tracepoint_iter_lock, flags);
+}
+
void ftrace_event_buffer_commit(struct ftrace_event_buffer *fbuffer)
{
+ if (tracepoint_printk)
+ output_printk(fbuffer);
+
event_trigger_unlock_commit(fbuffer->ftrace_file, fbuffer->buffer,
fbuffer->event, fbuffer->entry,
fbuffer->flags, fbuffer->pc);
@@ -2480,8 +2512,14 @@ static __init int event_trace_init(void)
#endif
return 0;
}
-early_initcall(event_trace_memsetup);
-core_initcall(event_trace_enable);
+
+void __init trace_event_init(void)
+{
+ event_trace_memsetup();
+ init_ftrace_syscalls();
+ event_trace_enable();
+}
+
fs_initcall(event_trace_init);
#ifdef CONFIG_FTRACE_STARTUP_TEST
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index dfe00a4..c6ee36f 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -514,7 +514,7 @@ unsigned long __init __weak arch_syscall_addr(int nr)
return (unsigned long)sys_call_table[nr];
}
-static int __init init_ftrace_syscalls(void)
+void __init init_ftrace_syscalls(void)
{
struct syscall_metadata *meta;
unsigned long addr;
@@ -524,7 +524,7 @@ static int __init init_ftrace_syscalls(void)
GFP_KERNEL);
if (!syscalls_metadata) {
WARN_ON(1);
- return -ENOMEM;
+ return;
}
for (i = 0; i < NR_syscalls; i++) {
@@ -536,10 +536,7 @@ static int __init init_ftrace_syscalls(void)
meta->syscall_nr = i;
syscalls_metadata[i] = meta;
}
-
- return 0;
}
-early_initcall(init_ftrace_syscalls);
#ifdef CONFIG_PERF_EVENTS
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