// SPDX-License-Identifier: GPL-2.0/* * trace binary printk * * Copyright (C) 2008 Lai Jiangshan <laijs@cn.fujitsu.com> * */#include <linux/seq_file.h>#include <linux/uaccess.h>#include <linux/kernel.h>#include <linux/ftrace.h>#include <linux/string.h>#include <linux/module.h>#include <linux/mutex.h>#include <linux/ctype.h>#include <linux/list.h>#include <linux/slab.h> #include "trace.h" #ifdef CONFIG_MODULES /* * modules trace_printk()'s formats are autosaved in struct trace_bprintk_fmt * which are queued on trace_bprintk_fmt_list. */static LIST_HEAD(trace_bprintk_fmt_list); /* serialize accesses to trace_bprintk_fmt_list */static DEFINE_MUTEX(btrace_mutex); struct trace_bprintk_fmt {	struct list_head list;	const char *fmt;}; static inline struct trace_bprintk_fmt *lookup_format(const char *fmt){	struct trace_bprintk_fmt *pos; 	if (!fmt)		return ERR_PTR(-EINVAL); 	list_for_each_entry(pos, &trace_bprintk_fmt_list, list) {		if (!strcmp(pos->fmt, fmt))			return pos;	}	return NULL;} staticvoid hold_module_trace_bprintk_format(const char **start, const char **end){	const char **iter;	char *fmt; 	/* allocate the trace_printk per cpu buffers */	if (start != end)		trace_printk_init_buffers(); 	mutex_lock(&btrace_mutex);	for (iter = start; iter < end; iter++) {		struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter);		if (tb_fmt) {			if (!IS_ERR(tb_fmt))				*iter = tb_fmt->fmt;			continue;		} 		fmt = NULL;		tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL);		if (tb_fmt) {			fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);			if (fmt) {				list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);				strcpy(fmt, *iter);				tb_fmt->fmt = fmt;			} else				kfree(tb_fmt);		}		*iter = fmt; 	}	mutex_unlock(&btrace_mutex);} static int module_trace_bprintk_format_notify(struct notifier_block *self,		unsigned long val, void *data){	struct module *mod = data;	if (mod->num_trace_bprintk_fmt) {		const char **start = mod->trace_bprintk_fmt_start;		const char **end = start + mod->num_trace_bprintk_fmt; 		if (val == MODULE_STATE_COMING)			hold_module_trace_bprintk_format(start, end);	}	return 0;} /* * The debugfs/tracing/printk_formats file maps the addresses with * the ASCII formats that are used in the bprintk events in the * buffer. For userspace tools to be able to decode the events from * the buffer, they need to be able to map the address with the format. * * The addresses of the bprintk formats are in their own section * __trace_printk_fmt. But for modules we copy them into a link list. * The code to print the formats and their addresses passes around the * address of the fmt string. If the fmt address passed into the seq * functions is within the kernel core __trace_printk_fmt section, then * it simply uses the next pointer in the list. * * When the fmt pointer is outside the kernel core __trace_printk_fmt * section, then we need to read the link list pointers. The trick is * we pass the address of the string to the seq function just like * we do for the kernel core formats. To get back the structure that * holds the format, we simply use container_of() and then go to the * next format in the list. */static const char **find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos){	struct trace_bprintk_fmt *mod_fmt; 	if (list_empty(&trace_bprintk_fmt_list))		return NULL; 	/*	 * v will point to the address of the fmt record from t_next	 * v will be NULL from t_start.	 * If this is the first pointer or called from start	 * then we need to walk the list.	 */	if (!v || start_index == *pos) {		struct trace_bprintk_fmt *p; 		/* search the module list */		list_for_each_entry(p, &trace_bprintk_fmt_list, list) {			if (start_index == *pos)				return &p->fmt;			start_index++;		}		/* pos > index */		return NULL;	} 	/*	 * v points to the address of the fmt field in the mod list	 * structure that holds the module print format.	 */	mod_fmt = container_of(v, typeof(*mod_fmt), fmt);	if (mod_fmt->list.next == &trace_bprintk_fmt_list)		return NULL; 	mod_fmt = container_of(mod_fmt->list.next, typeof(*mod_fmt), list); 	return &mod_fmt->fmt;} static void format_mod_start(void){	mutex_lock(&btrace_mutex);} static void format_mod_stop(void){	mutex_unlock(&btrace_mutex);} #else /* !CONFIG_MODULES */__init static intmodule_trace_bprintk_format_notify(struct notifier_block *self,		unsigned long val, void *data){	return 0;}static inline const char **find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos){	return NULL;}static inline void format_mod_start(void) { }static inline void format_mod_stop(void) { }#endif /* CONFIG_MODULES */ static bool __read_mostly trace_printk_enabled = true; void trace_printk_control(bool enabled){	trace_printk_enabled = enabled;} __initdata_or_module staticstruct notifier_block module_trace_bprintk_format_nb = {	.notifier_call = module_trace_bprintk_format_notify,}; int __trace_bprintk(unsigned long ip, const char *fmt, ...){	int ret;	va_list ap; 	if (unlikely(!fmt))		return 0; 	if (!trace_printk_enabled)		return 0; 	va_start(ap, fmt);	ret = trace_vbprintk(ip, fmt, ap);	va_end(ap);	return ret;}EXPORT_SYMBOL_GPL(__trace_bprintk); int __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap){	if (unlikely(!fmt))		return 0; 	if (!trace_printk_enabled)		return 0; 	return trace_vbprintk(ip, fmt, ap);}EXPORT_SYMBOL_GPL(__ftrace_vbprintk); int __trace_printk(unsigned long ip, const char *fmt, ...){	int ret;	va_list ap; 	if (!trace_printk_enabled)		return 0; 	va_start(ap, fmt);	ret = trace_vprintk(ip, fmt, ap);	va_end(ap);	return ret;}EXPORT_SYMBOL_GPL(__trace_printk); int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap){	if (!trace_printk_enabled)		return 0; 	return trace_vprintk(ip, fmt, ap);}EXPORT_SYMBOL_GPL(__ftrace_vprintk); static const char **find_next(void *v, loff_t *pos){	const char **fmt = v;	int start_index;	int last_index; 	start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt; 	if (*pos < start_index)		return __start___trace_bprintk_fmt + *pos; 	/*	 * The __tracepoint_str section is treated the same as the	 * __trace_printk_fmt section. The difference is that the	 * __trace_printk_fmt section should only be used by trace_printk()	 * in a debugging environment, as if anything exists in that section	 * the trace_prink() helper buffers are allocated, which would just	 * waste space in a production environment.	 *	 * The __tracepoint_str sections on the other hand are used by	 * tracepoints which need to map pointers to their strings to	 * the ASCII text for userspace.	 */	last_index = start_index;	start_index = __stop___tracepoint_str - __start___tracepoint_str; 	if (*pos < last_index + start_index)		return __start___tracepoint_str + (*pos - last_index); 	start_index += last_index;	return find_next_mod_format(start_index, v, fmt, pos);} static void *t_start(struct seq_file *m, loff_t *pos){	format_mod_start();	return find_next(NULL, pos);} static void *t_next(struct seq_file *m, void * v, loff_t *pos){	(*pos)++;	return find_next(v, pos);} static int t_show(struct seq_file *m, void *v){	const char **fmt = v;	const char *str = *fmt;	int i; 	if (!*fmt)		return 0; 	seq_printf(m, "0x%lx : \"", *(unsigned long *)fmt); 	/*	 * Tabs and new lines need to be converted.	 */	for (i = 0; str[i]; i++) {		switch (str[i]) {		case '\n':			seq_puts(m, "\\n");			break;		case '\t':			seq_puts(m, "\\t");			break;		case '\\':			seq_putc(m, '\\');			break;		case '"':			seq_puts(m, "\\\"");			break;		default:			seq_putc(m, str[i]);		}	}	seq_puts(m, "\"\n"); 	return 0;} static void t_stop(struct seq_file *m, void *p){	format_mod_stop();} static const struct seq_operations show_format_seq_ops = {	.start = t_start,	.next = t_next,	.show = t_show,	.stop = t_stop,}; static intftrace_formats_open(struct inode *inode, struct file *file){	return seq_open(file, &show_format_seq_ops);} static const struct file_operations ftrace_formats_fops = {	.open = ftrace_formats_open,	.read = seq_read,	.llseek = seq_lseek,	.release = seq_release,}; static __init int init_trace_printk_function_export(void){	struct dentry *d_tracer; 	d_tracer = tracing_init_dentry();	if (IS_ERR(d_tracer))		return 0; 	trace_create_file("printk_formats", 0444, d_tracer,				    NULL, &ftrace_formats_fops); 	return 0;} fs_initcall(init_trace_printk_function_export); static __init int init_trace_printk(void){	return register_module_notifier(&module_trace_bprintk_format_nb);} early_initcall(init_trace_printk);