pstore: Add persistent function tracing

With this support kernel can save function call chain log into a persistent ram buffer that can be decoded and dumped after reboot through pstore filesystem. It can be used to determine what function was last called before a reset or panic. We store the log in a binary format and then decode it at read time. p.s. Mostly the code comes from trace_persistent.c driver found in the Android git tree, written by Colin Cross <ccross@android.com> (according to sign-off history). I reworked the driver a little bit, and ported it to pstore. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

pstore: Add persistent function tracing
With this support kernel can save function call chain log into a persistent ram buffer that can be decoded and dumped after reboot through pstore filesystem. It can be used to determine what function was last called before a reset or panic. We store the log in a binary format and then decode it at read time. p.s. Mostly the code comes from trace_persistent.c driver found in the Android git tree, written by Colin Cross <ccross@android.com> (according to sign-off history). I reworked the driver a little bit, and ported it to pstore. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Anton Vorontsov · Greg Kroah-Hartman
1 parent 897dba0274
Showing 7 changed files with 208 additions and 5 deletions Side-by-side Diff
fs/pstore/Kconfig
fs/pstore/Makefile
fs/pstore/ftrace.c
fs/pstore/inode.c
fs/pstore/internal.h
fs/pstore/platform.c
include/linux/pstore.h
@@ -19,6 +19,18 @@
 	  When the option is enabled, pstore will log all kernel
 	  messages, even if no oops or panic happened.
  
+config PSTORE_FTRACE
+	bool "Persistent function tracer"
+	depends on PSTORE
+	depends on FUNCTION_TRACER
+	help
+	  With this option kernel traces function calls into a persistent
+	  ram buffer that can be decoded and dumped after reboot through
+	  pstore filesystem. It can be used to determine what function
+	  was last called before a reset or panic.
+
+	  If unsure, say N.
+
 config PSTORE_RAM
 	tristate "Log panic/oops to a RAM buffer"
 	depends on PSTORE
@@ -5,6 +5,7 @@
 obj-y += pstore.o
  
 pstore-objs += inode.o platform.o
+obj-$(CONFIG_PSTORE_FTRACE)	+= ftrace.o
  
 ramoops-objs += ram.o ram_core.o
 obj-$(CONFIG_PSTORE_RAM)	+= ramoops.o
+/*
+ * Copyright 2012  Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/compiler.h>
+#include <linux/irqflags.h>
+#include <linux/percpu.h>
+#include <linux/smp.h>
+#include <linux/atomic.h>
+#include <asm/barrier.h>
+#include "internal.h"
+
+void notrace pstore_ftrace_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct pstore_ftrace_record rec = {};
+
+	if (unlikely(oops_in_progress))
+		return;
+
+	rec.ip = ip;
+	rec.parent_ip = parent_ip;
+	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
+	psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
+			  sizeof(rec), psinfo);
+}
@@ -27,6 +27,7 @@
 #include <linux/list.h>
 #include <linux/string.h>
 #include <linux/mount.h>
+#include <linux/seq_file.h>
 #include <linux/ramfs.h>
 #include <linux/parser.h>
 #include <linux/sched.h>
  
  
  
  
@@ -52,18 +53,117 @@
 	char	data[];
 };
  
+struct pstore_ftrace_seq_data {
+	const void *ptr;
+	size_t off;
+	size_t size;
+};
+
+#define REC_SIZE sizeof(struct pstore_ftrace_record)
+
+static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return NULL;
+
+	data->off = ps->size % REC_SIZE;
+	data->off += *pos * REC_SIZE;
+	if (data->off + REC_SIZE > ps->size) {
+		kfree(data);
+		return NULL;
+	}
+
+	return data;
+
+}
+
+static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
+{
+	kfree(v);
+}
+
+static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+
+	data->off += REC_SIZE;
+	if (data->off + REC_SIZE > ps->size)
+		return NULL;
+
+	(*pos)++;
+	return data;
+}
+
+static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+	struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
+
+	seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
+		pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
+		(void *)rec->ip, (void *)rec->parent_ip);
+
+	return 0;
+}
+
+static const struct seq_operations pstore_ftrace_seq_ops = {
+	.start	= pstore_ftrace_seq_start,
+	.next	= pstore_ftrace_seq_next,
+	.stop	= pstore_ftrace_seq_stop,
+	.show	= pstore_ftrace_seq_show,
+};
+
 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 						size_t count, loff_t *ppos)
 {
-	struct pstore_private *ps = file->private_data;
+	struct seq_file *sf = file->private_data;
+	struct pstore_private *ps = sf->private;
  
+	if (ps->type == PSTORE_TYPE_FTRACE)
+		return seq_read(file, userbuf, count, ppos);
 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
 }
  
+static int pstore_file_open(struct inode *inode, struct file *file)
+{
+	struct pstore_private *ps = inode->i_private;
+	struct seq_file *sf;
+	int err;
+	const struct seq_operations *sops = NULL;
+
+	if (ps->type == PSTORE_TYPE_FTRACE)
+		sops = &pstore_ftrace_seq_ops;
+
+	err = seq_open(file, sops);
+	if (err < 0)
+		return err;
+
+	sf = file->private_data;
+	sf->private = ps;
+
+	return 0;
+}
+
+static loff_t pstore_file_llseek(struct file *file, loff_t off, int origin)
+{
+	struct seq_file *sf = file->private_data;
+
+	if (sf->op)
+		return seq_lseek(file, off, origin);
+	return default_llseek(file, off, origin);
+}
+
 static const struct file_operations pstore_file_operations = {
-	.open	= simple_open,
-	.read	= pstore_file_read,
-	.llseek	= default_llseek,
+	.open		= pstore_file_open,
+	.read		= pstore_file_read,
+	.llseek		= pstore_file_llseek,
+	.release	= seq_release,
 };
  
 /*
@@ -214,6 +314,9 @@
 		break;
 	case PSTORE_TYPE_CONSOLE:
 		sprintf(name, "console-%s", psname);
+		break;
+	case PSTORE_TYPE_FTRACE:
+		sprintf(name, "ftrace-%s", psname);
 		break;
 	case PSTORE_TYPE_MCE:
 		sprintf(name, "mce-%s-%lld", psname, id);
+#ifndef __PSTORE_INTERNAL_H__
+#define __PSTORE_INTERNAL_H__
+
+#include <linux/pstore.h>
+
+#if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
+#define PSTORE_CPU_IN_IP 0x1
+#elif NR_CPUS <= 4 && defined(CONFIG_ARM)
+#define PSTORE_CPU_IN_IP 0x3
+#endif
+
+struct pstore_ftrace_record {
+	unsigned long ip;
+	unsigned long parent_ip;
+#ifndef PSTORE_CPU_IN_IP
+	unsigned int cpu;
+#endif
+};
+
+static inline void
+pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
+{
+#ifndef PSTORE_CPU_IN_IP
+	rec->cpu = cpu;
+#else
+	rec->ip |= cpu;
+#endif
+}
+
+static inline unsigned int
+pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
+{
+#ifndef PSTORE_CPU_IN_IP
+	return rec->cpu;
+#else
+	return rec->ip & PSTORE_CPU_IN_IP;
+#endif
+}
+
+extern struct pstore_info *psinfo;
+
 extern void	pstore_set_kmsg_bytes(int);
 extern void	pstore_get_records(int);
 extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
 			      char *data, size_t size,
 			      struct timespec time, struct pstore_info *psi);
 extern int	pstore_is_mounted(void);
+
+#endif
@@ -61,7 +61,7 @@
  * calls to pstore_register()
  */
 static DEFINE_SPINLOCK(pstore_lock);
-static struct pstore_info *psinfo;
+struct pstore_info *psinfo;
  
 static char *backend;
  
@@ -30,6 +30,7 @@
 	PSTORE_TYPE_DMESG	= 0,
 	PSTORE_TYPE_MCE		= 1,
 	PSTORE_TYPE_CONSOLE	= 2,
+	PSTORE_TYPE_FTRACE	= 3,
 	PSTORE_TYPE_UNKNOWN	= 255
 };
  
@@ -56,6 +57,14 @@
 			struct pstore_info *psi);
 	void		*data;
 };
+
+
+#ifdef CONFIG_PSTORE_FTRACE
+extern void pstore_ftrace_call(unsigned long ip, unsigned long parent_ip);
+#else
+static inline void pstore_ftrace_call(unsigned long ip, unsigned long parent_ip)
+{ }
+#endif
  
 #ifdef CONFIG_PSTORE
 extern int pstore_register(struct pstore_info *);
...	...	@@ -19,6 +19,18 @@
19	19	When the option is enabled, pstore will log all kernel
20	20	messages, even if no oops or panic happened.
21	21
	22	+config PSTORE_FTRACE
	23	+ bool "Persistent function tracer"
	24	+ depends on PSTORE
	25	+ depends on FUNCTION_TRACER
	26	+ help
	27	+ With this option kernel traces function calls into a persistent
	28	+ ram buffer that can be decoded and dumped after reboot through
	29	+ pstore filesystem. It can be used to determine what function
	30	+ was last called before a reset or panic.
	31	+
	32	+ If unsure, say N.
	33	+
22	34	config PSTORE_RAM
23	35	tristate "Log panic/oops to a RAM buffer"
24	36	depends on PSTORE
...	...	@@ -5,6 +5,7 @@
5	5	obj-y += pstore.o
6	6
7	7	pstore-objs += inode.o platform.o
	8	+obj-$(CONFIG_PSTORE_FTRACE) += ftrace.o
8	9
9	10	ramoops-objs += ram.o ram_core.o
10	11	obj-$(CONFIG_PSTORE_RAM) += ramoops.o
	1	+/*
	2	+ * Copyright 2012 Google, Inc.
	3	+ *
	4	+ * This software is licensed under the terms of the GNU General Public
	5	+ * License version 2, as published by the Free Software Foundation, and
	6	+ * may be copied, distributed, and modified under those terms.
	7	+ *
	8	+ * This program is distributed in the hope that it will be useful,
	9	+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	11	+ * GNU General Public License for more details.
	12	+ */
	13	+
	14	+#include <linux/kernel.h>
	15	+#include <linux/compiler.h>
	16	+#include <linux/irqflags.h>
	17	+#include <linux/percpu.h>
	18	+#include <linux/smp.h>
	19	+#include <linux/atomic.h>
	20	+#include <asm/barrier.h>
	21	+#include "internal.h"
	22	+
	23	+void notrace pstore_ftrace_call(unsigned long ip, unsigned long parent_ip)
	24	+{
	25	+ struct pstore_ftrace_record rec = {};
	26	+
	27	+ if (unlikely(oops_in_progress))
	28	+ return;
	29	+
	30	+ rec.ip = ip;
	31	+ rec.parent_ip = parent_ip;
	32	+ pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
	33	+ psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
	34	+ sizeof(rec), psinfo);
	35	+}
...	...	@@ -27,6 +27,7 @@
27	27	#include <linux/list.h>
28	28	#include <linux/string.h>
29	29	#include <linux/mount.h>
	30	+#include <linux/seq_file.h>
30	31	#include <linux/ramfs.h>
31	32	#include <linux/parser.h>
32	33	#include <linux/sched.h>
33	34
34	35
35	36
36	37
...	...	@@ -52,18 +53,117 @@
52	53	char data[];
53	54	};
54	55
	56	+struct pstore_ftrace_seq_data {
	57	+ const void *ptr;
	58	+ size_t off;
	59	+ size_t size;
	60	+};
	61	+
	62	+#define REC_SIZE sizeof(struct pstore_ftrace_record)
	63	+
	64	+static void pstore_ftrace_seq_start(struct seq_file s, loff_t *pos)
	65	+{
	66	+ struct pstore_private *ps = s->private;
	67	+ struct pstore_ftrace_seq_data *data;
	68	+
	69	+ data = kzalloc(sizeof(*data), GFP_KERNEL);
	70	+ if (!data)
	71	+ return NULL;
	72	+
	73	+ data->off = ps->size % REC_SIZE;
	74	+ data->off += pos REC_SIZE;
	75	+ if (data->off + REC_SIZE > ps->size) {
	76	+ kfree(data);
	77	+ return NULL;
	78	+ }
	79	+
	80	+ return data;
	81	+
	82	+}
	83	+
	84	+static void pstore_ftrace_seq_stop(struct seq_file s, void v)
	85	+{
	86	+ kfree(v);
	87	+}
	88	+
	89	+static void pstore_ftrace_seq_next(struct seq_file s, void v, loff_t pos)
	90	+{
	91	+ struct pstore_private *ps = s->private;
	92	+ struct pstore_ftrace_seq_data *data = v;
	93	+
	94	+ data->off += REC_SIZE;
	95	+ if (data->off + REC_SIZE > ps->size)
	96	+ return NULL;
	97	+
	98	+ (*pos)++;
	99	+ return data;
	100	+}
	101	+
	102	+static int pstore_ftrace_seq_show(struct seq_file s, void v)
	103	+{
	104	+ struct pstore_private *ps = s->private;
	105	+ struct pstore_ftrace_seq_data *data = v;
	106	+ struct pstore_ftrace_record rec = (void )(ps->data + data->off);
	107	+
	108	+ seq_printf(s, "%d %08lx %08lx %pf <- %pF\n",
	109	+ pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
	110	+ (void )rec->ip, (void )rec->parent_ip);
	111	+
	112	+ return 0;
	113	+}
	114	+
	115	+static const struct seq_operations pstore_ftrace_seq_ops = {
	116	+ .start = pstore_ftrace_seq_start,
	117	+ .next = pstore_ftrace_seq_next,
	118	+ .stop = pstore_ftrace_seq_stop,
	119	+ .show = pstore_ftrace_seq_show,
	120	+};
	121	+
55	122	static ssize_t pstore_file_read(struct file file, char __user userbuf,
56	123	size_t count, loff_t *ppos)
57	124	{
58		- struct pstore_private *ps = file->private_data;
	125	+ struct seq_file *sf = file->private_data;
	126	+ struct pstore_private *ps = sf->private;
59	127
	128	+ if (ps->type == PSTORE_TYPE_FTRACE)
	129	+ return seq_read(file, userbuf, count, ppos);
60	130	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
61	131	}
62	132
	133	+static int pstore_file_open(struct inode inode, struct file file)
	134	+{
	135	+ struct pstore_private *ps = inode->i_private;
	136	+ struct seq_file *sf;
	137	+ int err;
	138	+ const struct seq_operations *sops = NULL;
	139	+
	140	+ if (ps->type == PSTORE_TYPE_FTRACE)
	141	+ sops = &pstore_ftrace_seq_ops;
	142	+
	143	+ err = seq_open(file, sops);
	144	+ if (err < 0)
	145	+ return err;
	146	+
	147	+ sf = file->private_data;
	148	+ sf->private = ps;
	149	+
	150	+ return 0;
	151	+}
	152	+
	153	+static loff_t pstore_file_llseek(struct file *file, loff_t off, int origin)
	154	+{
	155	+ struct seq_file *sf = file->private_data;
	156	+
	157	+ if (sf->op)
	158	+ return seq_lseek(file, off, origin);
	159	+ return default_llseek(file, off, origin);
	160	+}
	161	+
63	162	static const struct file_operations pstore_file_operations = {
64		- .open = simple_open,
65		- .read = pstore_file_read,
66		- .llseek = default_llseek,
	163	+ .open = pstore_file_open,
	164	+ .read = pstore_file_read,
	165	+ .llseek = pstore_file_llseek,
	166	+ .release = seq_release,
67	167	};
68	168
69	169	/*
...	...	@@ -214,6 +314,9 @@
214	314	break;
215	315	case PSTORE_TYPE_CONSOLE:
216	316	sprintf(name, "console-%s", psname);
	317	+ break;
	318	+ case PSTORE_TYPE_FTRACE:
	319	+ sprintf(name, "ftrace-%s", psname);
217	320	break;
218	321	case PSTORE_TYPE_MCE:
219	322	sprintf(name, "mce-%s-%lld", psname, id);
	1	+#ifndef __PSTORE_INTERNAL_H__
	2	+#define __PSTORE_INTERNAL_H__
	3	+
	4	+#include <linux/pstore.h>
	5	+
	6	+#if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
	7	+#define PSTORE_CPU_IN_IP 0x1
	8	+#elif NR_CPUS <= 4 && defined(CONFIG_ARM)
	9	+#define PSTORE_CPU_IN_IP 0x3
	10	+#endif
	11	+
	12	+struct pstore_ftrace_record {
	13	+ unsigned long ip;
	14	+ unsigned long parent_ip;
	15	+#ifndef PSTORE_CPU_IN_IP
	16	+ unsigned int cpu;
	17	+#endif
	18	+};
	19	+
	20	+static inline void
	21	+pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
	22	+{
	23	+#ifndef PSTORE_CPU_IN_IP
	24	+ rec->cpu = cpu;
	25	+#else
	26	+ rec->ip \|= cpu;
	27	+#endif
	28	+}
	29	+
	30	+static inline unsigned int
	31	+pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
	32	+{
	33	+#ifndef PSTORE_CPU_IN_IP
	34	+ return rec->cpu;
	35	+#else
	36	+ return rec->ip & PSTORE_CPU_IN_IP;
	37	+#endif
	38	+}
	39	+
	40	+extern struct pstore_info *psinfo;
	41	+
1	42	extern void pstore_set_kmsg_bytes(int);
2	43	extern void pstore_get_records(int);
3	44	extern int pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
4	45	char *data, size_t size,
5	46	struct timespec time, struct pstore_info *psi);
6	47	extern int pstore_is_mounted(void);
	48	+
	49	+#endif
...	...	@@ -61,7 +61,7 @@
61	61	* calls to pstore_register()
62	62	*/
63	63	static DEFINE_SPINLOCK(pstore_lock);
64		-static struct pstore_info *psinfo;
	64	+struct pstore_info *psinfo;
65	65
66	66	static char *backend;
67	67
...	...	@@ -30,6 +30,7 @@
30	30	PSTORE_TYPE_DMESG = 0,
31	31	PSTORE_TYPE_MCE = 1,
32	32	PSTORE_TYPE_CONSOLE = 2,
	33	+ PSTORE_TYPE_FTRACE = 3,
33	34	PSTORE_TYPE_UNKNOWN = 255
34	35	};
35	36
...	...	@@ -56,6 +57,14 @@
56	57	struct pstore_info *psi);
57	58	void *data;
58	59	};
	60	+
	61	+
	62	+#ifdef CONFIG_PSTORE_FTRACE
	63	+extern void pstore_ftrace_call(unsigned long ip, unsigned long parent_ip);
	64	+#else
	65	+static inline void pstore_ftrace_call(unsigned long ip, unsigned long parent_ip)
	66	+{ }
	67	+#endif
59	68
60	69	#ifdef CONFIG_PSTORE
61	70	extern int pstore_register(struct pstore_info *);