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-rw-r--r--include/linux/ftrace_event.h6
-rw-r--r--include/trace/ftrace.h83
2 files changed, 61 insertions, 28 deletions
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index bc103d7b1ca..4ec5e67e18c 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -4,6 +4,7 @@
#include <linux/ring_buffer.h>
#include <linux/trace_seq.h>
#include <linux/percpu.h>
+#include <linux/hardirq.h>
struct trace_array;
struct tracer;
@@ -134,6 +135,11 @@ struct ftrace_event_call {
void (*profile_disable)(void);
};
+#define FTRACE_MAX_PROFILE_SIZE 2048
+
+extern char *trace_profile_buf;
+extern char *trace_profile_buf_nmi;
+
#define MAX_FILTER_PRED 32
#define MAX_FILTER_STR_VAL 256 /* Should handle KSYM_SYMBOL_LEN */
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index a822087857e..a0361cb6976 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -648,11 +648,12 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* struct ftrace_raw_##call *entry;
* u64 __addr = 0, __count = 1;
* unsigned long irq_flags;
+ * struct trace_entry *ent;
* int __entry_size;
* int __data_size;
+ * int __cpu
* int pc;
*
- * local_save_flags(irq_flags);
* pc = preempt_count();
*
* __data_size = ftrace_get_offsets_<call>(&__data_offsets, args);
@@ -663,25 +664,34 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
* sizeof(u64));
* __entry_size -= sizeof(u32);
*
- * do {
- * char raw_data[__entry_size]; <- allocate our sample in the stack
- * struct trace_entry *ent;
+ * // Protect the non nmi buffer
+ * // This also protects the rcu read side
+ * local_irq_save(irq_flags);
+ * __cpu = smp_processor_id();
+ *
+ * if (in_nmi())
+ * raw_data = rcu_dereference(trace_profile_buf_nmi);
+ * else
+ * raw_data = rcu_dereference(trace_profile_buf);
+ *
+ * if (!raw_data)
+ * goto end;
*
- * zero dead bytes from alignment to avoid stack leak to userspace:
+ * raw_data = per_cpu_ptr(raw_data, __cpu);
*
- * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
- * entry = (struct ftrace_raw_<call> *)raw_data;
- * ent = &entry->ent;
- * tracing_generic_entry_update(ent, irq_flags, pc);
- * ent->type = event_call->id;
+ * //zero dead bytes from alignment to avoid stack leak to userspace:
+ * *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
+ * entry = (struct ftrace_raw_<call> *)raw_data;
+ * ent = &entry->ent;
+ * tracing_generic_entry_update(ent, irq_flags, pc);
+ * ent->type = event_call->id;
*
- * <tstruct> <- do some jobs with dynamic arrays
+ * <tstruct> <- do some jobs with dynamic arrays
*
- * <assign> <- affect our values
+ * <assign> <- affect our values
*
- * perf_tpcounter_event(event_call->id, __addr, __count, entry,
- * __entry_size); <- submit them to perf counter
- * } while (0);
+ * perf_tpcounter_event(event_call->id, __addr, __count, entry,
+ * __entry_size); <- submit them to perf counter
*
* }
*/
@@ -704,11 +714,13 @@ static void ftrace_profile_##call(proto) \
struct ftrace_raw_##call *entry; \
u64 __addr = 0, __count = 1; \
unsigned long irq_flags; \
+ struct trace_entry *ent; \
int __entry_size; \
int __data_size; \
+ char *raw_data; \
+ int __cpu; \
int pc; \
\
- local_save_flags(irq_flags); \
pc = preempt_count(); \
\
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
@@ -716,23 +728,38 @@ static void ftrace_profile_##call(proto) \
sizeof(u64)); \
__entry_size -= sizeof(u32); \
\
- do { \
- char raw_data[__entry_size]; \
- struct trace_entry *ent; \
+ if (WARN_ONCE(__entry_size > FTRACE_MAX_PROFILE_SIZE, \
+ "profile buffer not large enough")) \
+ return; \
+ \
+ local_irq_save(irq_flags); \
+ __cpu = smp_processor_id(); \
\
- *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
- entry = (struct ftrace_raw_##call *)raw_data; \
- ent = &entry->ent; \
- tracing_generic_entry_update(ent, irq_flags, pc); \
- ent->type = event_call->id; \
+ if (in_nmi()) \
+ raw_data = rcu_dereference(trace_profile_buf_nmi); \
+ else \
+ raw_data = rcu_dereference(trace_profile_buf); \
\
- tstruct \
+ if (!raw_data) \
+ goto end; \
\
- { assign; } \
+ raw_data = per_cpu_ptr(raw_data, __cpu); \
\
- perf_tpcounter_event(event_call->id, __addr, __count, entry,\
+ *(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL; \
+ entry = (struct ftrace_raw_##call *)raw_data; \
+ ent = &entry->ent; \
+ tracing_generic_entry_update(ent, irq_flags, pc); \
+ ent->type = event_call->id; \
+ \
+ tstruct \
+ \
+ { assign; } \
+ \
+ perf_tpcounter_event(event_call->id, __addr, __count, entry, \
__entry_size); \
- } while (0); \
+ \
+end: \
+ local_irq_restore(irq_flags); \
\
}