3 files changed, 192 insertions, 163 deletions

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 2e060c58b860..b69795efa226 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -23,25 +23,6 @@
 /* Long is fine, even if it is only 4 bytes ;-) */
 static long *ftrace_nop;
 
-struct ftrace_record {
-	struct dyn_ftrace	rec;
-	int			failed;
-} __attribute__((packed));
-
-struct ftrace_page {
-	struct ftrace_page	*next;
-	int			index;
-	struct ftrace_record	records[];
-} __attribute__((packed));
-
-#define ENTRIES_PER_PAGE \
-  ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct ftrace_record))
-
-/* estimate from running different kernels */
-#define NR_TO_INIT		10000
-
-#define MCOUNT_ADDR ((long)(&mcount))
-
 union ftrace_code_union {
 	char code[5];
 	struct {
@@ -50,33 +31,41 @@ union ftrace_code_union {
 	} __attribute__((packed));
 };
 
-static struct ftrace_page	*ftrace_pages_start;
-static struct ftrace_page	*ftrace_pages;
-
-notrace struct dyn_ftrace *ftrace_alloc_shutdown_node(unsigned long ip)
+notrace int ftrace_ip_converted(unsigned long ip)
 {
-	struct ftrace_record *rec;
 	unsigned long save;
 
 	ip -= CALL_BACK;
 	save = *(long *)ip;
 
-	/* If this was already converted, skip it */
-	if (save == *ftrace_nop)
-		return NULL;
+	return save == *ftrace_nop;
+}
 
-	if (ftrace_pages->index == ENTRIES_PER_PAGE) {
-		if (!ftrace_pages->next)
-			return NULL;
-		ftrace_pages = ftrace_pages->next;
-	}
+static int notrace ftrace_calc_offset(long ip, long addr)
+{
+	return (int)(addr - ip);
+}
 
-	rec = &ftrace_pages->records[ftrace_pages->index++];
+notrace unsigned char *ftrace_nop_replace(void)
+{
+	return (char *)ftrace_nop;
+}
+
+notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+{
+	static union ftrace_code_union calc;
 
-	return &rec->rec;
+	calc.e8		= 0xe8;
+	calc.offset	= ftrace_calc_offset(ip, addr);
+
+	/*
+	 * No locking needed, this must be called via kstop_machine
+	 * which in essence is like running on a uniprocessor machine.
+	 */
+	return calc.code;
 }
 
-static int notrace
+notrace int
 ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 		   unsigned char *new_code)
 {
@@ -86,6 +75,9 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 	unsigned char newch = new_code[4];
 	int faulted = 0;
 
+	/* move the IP back to the start of the call */
+	ip -= CALL_BACK;
+
 	/*
 	 * Note: Due to modules and __init, code can
 	 *  disappear and change, we need to protect against faulting
@@ -117,129 +109,12 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 	return faulted;
 }
 
-static int notrace ftrace_calc_offset(long ip)
-{
-	return (int)(MCOUNT_ADDR - ip);
-}
-
-notrace void ftrace_code_disable(struct dyn_ftrace *rec)
-{
-	unsigned long ip;
-	union ftrace_code_union save;
-	struct ftrace_record *r =
-		container_of(rec, struct ftrace_record, rec);
-
-	ip = rec->ip;
-
-	save.e8		= 0xe8;
-	save.offset 	= ftrace_calc_offset(ip);
-
-	/* move the IP back to the start of the call */
-	ip -= CALL_BACK;
-
-	r->failed = ftrace_modify_code(ip, save.code, (char *)ftrace_nop);
-}
-
-static void notrace ftrace_replace_code(int saved)
-{
-	unsigned char *new = NULL, *old = NULL;
-	struct ftrace_record *rec;
-	struct ftrace_page *pg;
-	unsigned long ip;
-	int i;
-
-	if (saved)
-		old = (char *)ftrace_nop;
-	else
-		new = (char *)ftrace_nop;
-
-	for (pg = ftrace_pages_start; pg; pg = pg->next) {
-		for (i = 0; i < pg->index; i++) {
-			union ftrace_code_union calc;
-			rec = &pg->records[i];
-
-			/* don't modify code that has already faulted */
-			if (rec->failed)
-				continue;
-
-			ip = rec->rec.ip;
-
-			calc.e8		= 0xe8;
-			calc.offset	= ftrace_calc_offset(ip);
-
-			if (saved)
-				new = calc.code;
-			else
-				old = calc.code;
-
-			ip -= CALL_BACK;
-
-			rec->failed = ftrace_modify_code(ip, old, new);
-		}
-	}
-
-}
-
-notrace void ftrace_startup_code(void)
-{
-	ftrace_replace_code(1);
-}
-
-notrace void ftrace_shutdown_code(void)
-{
-	ftrace_replace_code(0);
-}
-
-notrace void ftrace_shutdown_replenish(void)
-{
-	if (ftrace_pages->next)
-		return;
-
-	/* allocate another page */
-	ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
-}
-
-notrace int __init ftrace_shutdown_arch_init(void)
+int __init ftrace_dyn_arch_init(void)
 {
 	const unsigned char *const *noptable = find_nop_table();
-	struct ftrace_page *pg;
-	int cnt;
-	int i;
 
 	ftrace_nop = (unsigned long *)noptable[CALL_BACK];
 
-	/* allocate a few pages */
-	ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
-	if (!ftrace_pages_start)
-		return -1;
-
-	/*
-	 * Allocate a few more pages.
-	 *
-	 * TODO: have some parser search vmlinux before
-	 *   final linking to find all calls to ftrace.
-	 *   Then we can:
-	 *    a) know how many pages to allocate.
-	 *     and/or
-	 *    b) set up the table then.
-	 *
-	 *  The dynamic code is still necessary for
-	 *  modules.
-	 */
-
-	pg = ftrace_pages = ftrace_pages_start;
-
-	cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
-
-	for (i = 0; i < cnt; i++) {
-		pg->next = (void *)get_zeroed_page(GFP_KERNEL);
-
-		/* If we fail, we'll try later anyway */
-		if (!pg->next)
-			break;
-
-		pg = pg->next;
-	}
-
 	return 0;
 }
+
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ccd8537dbdb7..d509ad6c9cb8 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -42,19 +42,23 @@ extern void mcount(void);
 # define FTRACE_HASHBITS	10
 # define FTRACE_HASHSIZE	(1<<FTRACE_HASHBITS)
 
+enum {
+	FTRACE_FL_FAILED	= (1<<0),
+};
+
 struct dyn_ftrace {
 	struct hlist_node node;
 	unsigned long	  ip;
+	unsigned long	  flags;
 };
 
 /* defined in arch */
-extern struct dyn_ftrace *
-ftrace_alloc_shutdown_node(unsigned long ip);
-extern int ftrace_shutdown_arch_init(void);
-extern void ftrace_code_disable(struct dyn_ftrace *rec);
-extern void ftrace_startup_code(void);
-extern void ftrace_shutdown_code(void);
-extern void ftrace_shutdown_replenish(void);
+extern int ftrace_ip_converted(unsigned long ip);
+extern unsigned char *ftrace_nop_replace(void);
+extern unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr);
+extern int ftrace_dyn_arch_init(void);
+extern int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+			      unsigned char *new_code);
 #endif
 
 #ifdef CONFIG_FRAME_POINTER
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d3de37299ba4..f6d9af3bf66b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -156,6 +156,21 @@ static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
 static DEFINE_SPINLOCK(ftrace_shutdown_lock);
 static DEFINE_MUTEX(ftraced_lock);
 
+struct ftrace_page {
+	struct ftrace_page	*next;
+	int			index;
+	struct dyn_ftrace	records[];
+} __attribute__((packed));
+
+#define ENTRIES_PER_PAGE \
+  ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
+
+/* estimate from running different kernels */
+#define NR_TO_INIT		10000
+
+static struct ftrace_page	*ftrace_pages_start;
+static struct ftrace_page	*ftrace_pages;
+
 static int ftraced_trigger;
 static int ftraced_suspend;
 
@@ -184,6 +199,21 @@ ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
 	hlist_add_head(&node->node, &ftrace_hash[key]);
 }
 
+static notrace struct dyn_ftrace *ftrace_alloc_shutdown_node(unsigned long ip)
+{
+	/* If this was already converted, skip it */
+	if (ftrace_ip_converted(ip))
+		return NULL;
+
+	if (ftrace_pages->index == ENTRIES_PER_PAGE) {
+		if (!ftrace_pages->next)
+			return NULL;
+		ftrace_pages = ftrace_pages->next;
+	}
+
+	return &ftrace_pages->records[ftrace_pages->index++];
+}
+
 static void notrace
 ftrace_record_ip(unsigned long ip, unsigned long parent_ip)
 {
@@ -252,6 +282,62 @@ static struct ftrace_ops ftrace_shutdown_ops __read_mostly =
 	.func = ftrace_record_ip,
 };
 
+#define MCOUNT_ADDR ((long)(&mcount))
+
+static void notrace ftrace_replace_code(int saved)
+{
+	unsigned char *new = NULL, *old = NULL;
+	struct dyn_ftrace *rec;
+	struct ftrace_page *pg;
+	unsigned long ip;
+	int failed;
+	int i;
+
+	if (saved)
+		old = ftrace_nop_replace();
+	else
+		new = ftrace_nop_replace();
+
+	for (pg = ftrace_pages_start; pg; pg = pg->next) {
+		for (i = 0; i < pg->index; i++) {
+			rec = &pg->records[i];
+
+			/* don't modify code that has already faulted */
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+
+			ip = rec->ip;
+
+			if (saved)
+				new = ftrace_call_replace(ip, MCOUNT_ADDR);
+			else
+				old = ftrace_call_replace(ip, MCOUNT_ADDR);
+
+			failed = ftrace_modify_code(ip, old, new);
+			if (failed)
+				rec->flags |= FTRACE_FL_FAILED;
+		}
+	}
+}
+
+static notrace void ftrace_startup_code(void)
+{
+	ftrace_replace_code(1);
+}
+
+static notrace void ftrace_shutdown_code(void)
+{
+	ftrace_replace_code(0);
+}
+
+static notrace void ftrace_shutdown_replenish(void)
+{
+	if (ftrace_pages->next)
+		return;
+
+	/* allocate another page */
+	ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
+}
 
 static int notrace __ftrace_modify_code(void *data)
 {
@@ -261,6 +347,23 @@ static int notrace __ftrace_modify_code(void *data)
 	return 0;
 }
 
+static notrace void
+ftrace_code_disable(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned long ip;
+	unsigned char *nop, *call;
+	int failed;
+
+	ip = rec->ip;
+
+	nop = ftrace_nop_replace();
+	call = ftrace_call_replace(ip, addr);
+
+	failed = ftrace_modify_code(ip, call, nop);
+	if (failed)
+		rec->flags |= FTRACE_FL_FAILED;
+}
+
 static void notrace ftrace_run_startup_code(void)
 {
 	stop_machine_run(__ftrace_modify_code, ftrace_startup_code, NR_CPUS);
@@ -346,7 +449,7 @@ static int notrace __ftrace_update_code(void *ignore)
 
 		/* all CPUS are stopped, we are safe to modify code */
 		hlist_for_each_entry(p, t, &head, node) {
-			ftrace_code_disable(p);
+			ftrace_code_disable(p, MCOUNT_ADDR);
 			ftrace_update_cnt++;
 		}
 
@@ -407,12 +510,59 @@ static int notrace ftraced(void *ignore)
 	return 0;
 }
 
+static int __init ftrace_dyn_table_alloc(void)
+{
+	struct ftrace_page *pg;
+	int cnt;
+	int i;
+	int ret;
+
+	ret = ftrace_dyn_arch_init();
+	if (ret)
+		return ret;
+
+	/* allocate a few pages */
+	ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!ftrace_pages_start)
+		return -1;
+
+	/*
+	 * Allocate a few more pages.
+	 *
+	 * TODO: have some parser search vmlinux before
+	 *   final linking to find all calls to ftrace.
+	 *   Then we can:
+	 *    a) know how many pages to allocate.
+	 *     and/or
+	 *    b) set up the table then.
+	 *
+	 *  The dynamic code is still necessary for
+	 *  modules.
+	 */
+
+	pg = ftrace_pages = ftrace_pages_start;
+
+	cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
+
+	for (i = 0; i < cnt; i++) {
+		pg->next = (void *)get_zeroed_page(GFP_KERNEL);
+
+		/* If we fail, we'll try later anyway */
+		if (!pg->next)
+			break;
+
+		pg = pg->next;
+	}
+
+	return 0;
+}
+
 static int __init notrace ftrace_shutdown_init(void)
 {
 	struct task_struct *p;
 	int ret;
 
-	ret = ftrace_shutdown_arch_init();
+	ret = ftrace_dyn_table_alloc();
 	if (ret)
 		return ret;