---

yaml
---
r: 169556
b: refs/heads/master
c: 444a2a3
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 09879b99d44d701c603935ef2549004405d7f8f9
+refs/heads/master: 444a2a3bcd6d5bed5c823136f68fcc93c0fe283f

trunk/include/linux/ftrace_event.h

@@ -137,8 +137,13 @@ struct ftrace_event_call {
 
 #define FTRACE_MAX_PROFILE_SIZE	2048
 
-extern char			*trace_profile_buf;
-extern char			*trace_profile_buf_nmi;
+struct perf_trace_buf {
+	char	buf[FTRACE_MAX_PROFILE_SIZE];
+	int	recursion;
+};
+
+extern struct perf_trace_buf	*perf_trace_buf;
+extern struct perf_trace_buf	*perf_trace_buf_nmi;
 
 #define MAX_FILTER_PRED		32
 #define MAX_FILTER_STR_VAL	256	/* Should handle KSYM_SYMBOL_LEN */

trunk/include/trace/ftrace.h

@@ -649,6 +649,7 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
  *	struct ftrace_event_call *event_call = &event_<call>;
  *	extern void perf_tp_event(int, u64, u64, void *, int);
  *	struct ftrace_raw_##call *entry;
+ *	struct perf_trace_buf *trace_buf;
  *	u64 __addr = 0, __count = 1;
  *	unsigned long irq_flags;
  *	struct trace_entry *ent;
@@ -673,14 +674,25 @@ __attribute__((section("_ftrace_events"))) event_##call = {		\
  *	__cpu = smp_processor_id();
  *
  *	if (in_nmi())
- *		raw_data = rcu_dereference(trace_profile_buf_nmi);
+ *		trace_buf = rcu_dereference(perf_trace_buf_nmi);
  *	else
- *		raw_data = rcu_dereference(trace_profile_buf);
+ *		trace_buf = rcu_dereference(perf_trace_buf);
  *
- *	if (!raw_data)
+ *	if (!trace_buf)
  *		goto end;
  *
- *	raw_data = per_cpu_ptr(raw_data, __cpu);
+ *	trace_buf = per_cpu_ptr(trace_buf, __cpu);
+ *
+ * 	// Avoid recursion from perf that could mess up the buffer
+ * 	if (trace_buf->recursion++)
+ *		goto end_recursion;
+ *
+ * 	raw_data = trace_buf->buf;
+ *
+ *	// Make recursion update visible before entering perf_tp_event
+ *	// so that we protect from perf recursions.
+ *
+ *	barrier();
  *
  *	//zero dead bytes from alignment to avoid stack leak to userspace:
  *	*(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;
@@ -713,8 +725,9 @@ static void ftrace_profile_##call(proto)				\
 {									\
 	struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
 	struct ftrace_event_call *event_call = &event_##call;		\
-	extern void perf_tp_event(int, u64, u64, void *, int);	\
+	extern void perf_tp_event(int, u64, u64, void *, int);		\
 	struct ftrace_raw_##call *entry;				\
+	struct perf_trace_buf *trace_buf;				\
 	u64 __addr = 0, __count = 1;					\
 	unsigned long irq_flags;					\
 	struct trace_entry *ent;					\
@@ -739,14 +752,20 @@ static void ftrace_profile_##call(proto)				\
 	__cpu = smp_processor_id();					\
 									\
 	if (in_nmi())							\
-		raw_data = rcu_dereference(trace_profile_buf_nmi);		\
+		trace_buf = rcu_dereference(perf_trace_buf_nmi);	\
 	else								\
-		raw_data = rcu_dereference(trace_profile_buf);		\
+		trace_buf = rcu_dereference(perf_trace_buf);		\
 									\
-	if (!raw_data)							\
+	if (!trace_buf)							\
 		goto end;						\
 									\
-	raw_data = per_cpu_ptr(raw_data, __cpu);			\
+	trace_buf = per_cpu_ptr(trace_buf, __cpu);			\
+	if (trace_buf->recursion++)					\
+		goto end_recursion;					\
+									\
+	barrier();							\
+									\
+	raw_data = trace_buf->buf;					\
 									\
 	*(u64 *)(&raw_data[__entry_size - sizeof(u64)]) = 0ULL;		\
 	entry = (struct ftrace_raw_##call *)raw_data;			\
@@ -761,6 +780,8 @@ static void ftrace_profile_##call(proto)				\
 	perf_tp_event(event_call->id, __addr, __count, entry,		\
 			     __entry_size);				\
 									\
+end_recursion:								\
+	trace_buf->recursion--;						\
 end:									\
 	local_irq_restore(irq_flags);					\
 									\

trunk/kernel/trace/trace_event_profile.c

@@ -8,41 +8,36 @@
 #include <linux/module.h>
 #include "trace.h"
 
-/*
- * We can't use a size but a type in alloc_percpu()
- * So let's create a dummy type that matches the desired size
- */
-typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
 
-char		*trace_profile_buf;
-EXPORT_SYMBOL_GPL(trace_profile_buf);
+struct perf_trace_buf *perf_trace_buf;
+EXPORT_SYMBOL_GPL(perf_trace_buf);
 
-char		*trace_profile_buf_nmi;
-EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);
+struct perf_trace_buf *perf_trace_buf_nmi;
+EXPORT_SYMBOL_GPL(perf_trace_buf_nmi);
 
 /* Count the events in use (per event id, not per instance) */
 static int	total_profile_count;
 
 static int ftrace_profile_enable_event(struct ftrace_event_call *event)
 {
-	char *buf;
+	struct perf_trace_buf *buf;
 	int ret = -ENOMEM;
 
 	if (atomic_inc_return(&event->profile_count))
 		return 0;
 
 	if (!total_profile_count) {
-		buf = (char *)alloc_percpu(profile_buf_t);
+		buf = alloc_percpu(struct perf_trace_buf);
 		if (!buf)
 			goto fail_buf;
 
-		rcu_assign_pointer(trace_profile_buf, buf);
+		rcu_assign_pointer(perf_trace_buf, buf);
 
-		buf = (char *)alloc_percpu(profile_buf_t);
+		buf = alloc_percpu(struct perf_trace_buf);
 		if (!buf)
 			goto fail_buf_nmi;
 
-		rcu_assign_pointer(trace_profile_buf_nmi, buf);
+		rcu_assign_pointer(perf_trace_buf_nmi, buf);
 	}
 
 	ret = event->profile_enable(event);
@@ -53,10 +48,10 @@ static int ftrace_profile_enable_event(struct ftrace_event_call *event)
 
 fail_buf_nmi:
 	if (!total_profile_count) {
-		free_percpu(trace_profile_buf_nmi);
-		free_percpu(trace_profile_buf);
-		trace_profile_buf_nmi = NULL;
-		trace_profile_buf = NULL;
+		free_percpu(perf_trace_buf_nmi);
+		free_percpu(perf_trace_buf);
+		perf_trace_buf_nmi = NULL;
+		perf_trace_buf = NULL;
 	}
 fail_buf:
 	atomic_dec(&event->profile_count);
@@ -84,19 +79,19 @@ int ftrace_profile_enable(int event_id)
 
 static void ftrace_profile_disable_event(struct ftrace_event_call *event)
 {
-	char *buf, *nmi_buf;
+	struct perf_trace_buf *buf, *nmi_buf;
 
 	if (!atomic_add_negative(-1, &event->profile_count))
 		return;
 
 	event->profile_disable(event);
 
 	if (!--total_profile_count) {
-		buf = trace_profile_buf;
-		rcu_assign_pointer(trace_profile_buf, NULL);
+		buf = perf_trace_buf;
+		rcu_assign_pointer(perf_trace_buf, NULL);
 
-		nmi_buf = trace_profile_buf_nmi;
-		rcu_assign_pointer(trace_profile_buf_nmi, NULL);
+		nmi_buf = perf_trace_buf_nmi;
+		rcu_assign_pointer(perf_trace_buf_nmi, NULL);
 
 		/*
 		 * Ensure every events in profiling have finished before

trunk/kernel/trace/trace_kprobe.c

@@ -1208,6 +1208,7 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
 	struct ftrace_event_call *call = &tp->call;
 	struct kprobe_trace_entry *entry;
+	struct perf_trace_buf *trace_buf;
 	struct trace_entry *ent;
 	int size, __size, i, pc, __cpu;
 	unsigned long irq_flags;
@@ -1229,14 +1230,26 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	__cpu = smp_processor_id();
 
 	if (in_nmi())
-		raw_data = rcu_dereference(trace_profile_buf_nmi);
+		trace_buf = rcu_dereference(perf_trace_buf_nmi);
 	else
-		raw_data = rcu_dereference(trace_profile_buf);
+		trace_buf = rcu_dereference(perf_trace_buf);
 
-	if (!raw_data)
+	if (!trace_buf)
 		goto end;
 
-	raw_data = per_cpu_ptr(raw_data, __cpu);
+	trace_buf = per_cpu_ptr(trace_buf, __cpu);
+
+	if (trace_buf->recursion++)
+		goto end_recursion;
+
+	/*
+	 * Make recursion update visible before entering perf_tp_event
+	 * so that we protect from perf recursions.
+	 */
+	barrier();
+
+	raw_data = trace_buf->buf;
+
 	/* Zero dead bytes from alignment to avoid buffer leak to userspace */
 	*(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
 	entry = (struct kprobe_trace_entry *)raw_data;
@@ -1249,8 +1262,12 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	for (i = 0; i < tp->nr_args; i++)
 		entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
 	perf_tp_event(call->id, entry->ip, 1, entry, size);
+
+end_recursion:
+	trace_buf->recursion--;
 end:
 	local_irq_restore(irq_flags);
+
 	return 0;
 }
 
@@ -1261,6 +1278,7 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
 	struct ftrace_event_call *call = &tp->call;
 	struct kretprobe_trace_entry *entry;
+	struct perf_trace_buf *trace_buf;
 	struct trace_entry *ent;
 	int size, __size, i, pc, __cpu;
 	unsigned long irq_flags;
@@ -1282,14 +1300,26 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	__cpu = smp_processor_id();
 
 	if (in_nmi())
-		raw_data = rcu_dereference(trace_profile_buf_nmi);
+		trace_buf = rcu_dereference(perf_trace_buf_nmi);
 	else
-		raw_data = rcu_dereference(trace_profile_buf);
+		trace_buf = rcu_dereference(perf_trace_buf);
 
-	if (!raw_data)
+	if (!trace_buf)
 		goto end;
 
-	raw_data = per_cpu_ptr(raw_data, __cpu);
+	trace_buf = per_cpu_ptr(trace_buf, __cpu);
+
+	if (trace_buf->recursion++)
+		goto end_recursion;
+
+	/*
+	 * Make recursion update visible before entering perf_tp_event
+	 * so that we protect from perf recursions.
+	 */
+	barrier();
+
+	raw_data = trace_buf->buf;
+
 	/* Zero dead bytes from alignment to avoid buffer leak to userspace */
 	*(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
 	entry = (struct kretprobe_trace_entry *)raw_data;
@@ -1303,8 +1333,12 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	for (i = 0; i < tp->nr_args; i++)
 		entry->args[i] = call_fetch(&tp->args[i].fetch, regs);
 	perf_tp_event(call->id, entry->ret_ip, 1, entry, size);
+
+end_recursion:
+	trace_buf->recursion--;
 end:
 	local_irq_restore(irq_flags);
+
 	return 0;
 }
 

trunk/kernel/trace/trace_syscalls.c

@@ -477,6 +477,7 @@ static int sys_prof_refcount_exit;
 static void prof_syscall_enter(struct pt_regs *regs, long id)
 {
 	struct syscall_metadata *sys_data;
+	struct perf_trace_buf *trace_buf;
 	struct syscall_trace_enter *rec;
 	unsigned long flags;
 	char *raw_data;
@@ -507,14 +508,25 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
 	cpu = smp_processor_id();
 
 	if (in_nmi())
-		raw_data = rcu_dereference(trace_profile_buf_nmi);
+		trace_buf = rcu_dereference(perf_trace_buf_nmi);
 	else
-		raw_data = rcu_dereference(trace_profile_buf);
+		trace_buf = rcu_dereference(perf_trace_buf);
 
-	if (!raw_data)
+	if (!trace_buf)
 		goto end;
 
-	raw_data = per_cpu_ptr(raw_data, cpu);
+	trace_buf = per_cpu_ptr(trace_buf, cpu);
+
+	if (trace_buf->recursion++)
+		goto end_recursion;
+
+	/*
+	 * Make recursion update visible before entering perf_tp_event
+	 * so that we protect from perf recursions.
+	 */
+	barrier();
+
+	raw_data = trace_buf->buf;
 
 	/* zero the dead bytes from align to not leak stack to user */
 	*(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
@@ -527,6 +539,8 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
 			       (unsigned long *)&rec->args);
 	perf_tp_event(sys_data->enter_id, 0, 1, rec, size);
 
+end_recursion:
+	trace_buf->recursion--;
 end:
 	local_irq_restore(flags);
 }
@@ -574,6 +588,7 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
 {
 	struct syscall_metadata *sys_data;
 	struct syscall_trace_exit *rec;
+	struct perf_trace_buf *trace_buf;
 	unsigned long flags;
 	int syscall_nr;
 	char *raw_data;
@@ -605,14 +620,25 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
 	cpu = smp_processor_id();
 
 	if (in_nmi())
-		raw_data = rcu_dereference(trace_profile_buf_nmi);
+		trace_buf = rcu_dereference(perf_trace_buf_nmi);
 	else
-		raw_data = rcu_dereference(trace_profile_buf);
+		trace_buf = rcu_dereference(perf_trace_buf);
 
-	if (!raw_data)
+	if (!trace_buf)
 		goto end;
 
-	raw_data = per_cpu_ptr(raw_data, cpu);
+	trace_buf = per_cpu_ptr(trace_buf, cpu);
+
+	if (trace_buf->recursion++)
+		goto end_recursion;
+
+	/*
+	 * Make recursion update visible before entering perf_tp_event
+	 * so that we protect from perf recursions.
+	 */
+	barrier();
+
+	raw_data = trace_buf->buf;
 
 	/* zero the dead bytes from align to not leak stack to user */
 	*(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
@@ -626,6 +652,8 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
 
 	perf_tp_event(sys_data->exit_id, 0, 1, rec, size);
 
+end_recursion:
+	trace_buf->recursion--;
 end:
 	local_irq_restore(flags);
 }