// SPDX-License-Identifier: GPL-2.0/* * kdb helper for dumping the ftrace buffer * * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com> * * ftrace_dump_buf based on ftrace_dump: * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> * */#include <linux/init.h>#include <linux/kgdb.h>#include <linux/kdb.h>#include <linux/ftrace.h> #include "trace.h"#include "trace_output.h" static struct trace_iterator iter;static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS]; static void ftrace_dump_buf(int skip_entries, long cpu_file){	struct trace_array *tr;	unsigned int old_userobj;	int cnt = 0, cpu; 	tr = iter.tr; 	old_userobj = tr->trace_flags; 	/* don't look at user memory in panic mode */	tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; 	kdb_printf("Dumping ftrace buffer:\n");	if (skip_entries)		kdb_printf("(skipping %d entries)\n", skip_entries); 	trace_iterator_reset(&iter);	iter.iter_flags |= TRACE_FILE_LAT_FMT; 	if (cpu_file == RING_BUFFER_ALL_CPUS) {		for_each_tracing_cpu(cpu) {			iter.buffer_iter[cpu] =			ring_buffer_read_prepare(iter.array_buffer->buffer,						 cpu, GFP_ATOMIC);			ring_buffer_read_start(iter.buffer_iter[cpu]);			tracing_iter_reset(&iter, cpu);		}	} else {		iter.cpu_file = cpu_file;		iter.buffer_iter[cpu_file] =			ring_buffer_read_prepare(iter.array_buffer->buffer,						 cpu_file, GFP_ATOMIC);		ring_buffer_read_start(iter.buffer_iter[cpu_file]);		tracing_iter_reset(&iter, cpu_file);	} 	while (trace_find_next_entry_inc(&iter)) {		if (!cnt)			kdb_printf("---------------------------------\n");		cnt++; 		if (!skip_entries) {			print_trace_line(&iter);			trace_printk_seq(&iter.seq);		} else {			skip_entries--;		} 		if (KDB_FLAG(CMD_INTERRUPT))			goto out;	} 	if (!cnt)		kdb_printf("   (ftrace buffer empty)\n");	else		kdb_printf("---------------------------------\n"); out:	tr->trace_flags = old_userobj; 	for_each_tracing_cpu(cpu) {		if (iter.buffer_iter[cpu]) {			ring_buffer_read_finish(iter.buffer_iter[cpu]);			iter.buffer_iter[cpu] = NULL;		}	}} /* * kdb_ftdump - Dump the ftrace log buffer */static int kdb_ftdump(int argc, const char **argv){	int skip_entries = 0;	long cpu_file;	int err;	int cnt; 	if (argc > 2)		return KDB_ARGCOUNT; 	if (argc && kstrtoint(argv[1], 0, &skip_entries))		return KDB_BADINT; 	if (argc == 2) {		err = kstrtol(argv[2], 0, &cpu_file);		if (err || cpu_file >= NR_CPUS || cpu_file < 0 ||		    !cpu_online(cpu_file))			return KDB_BADINT;	} else {		cpu_file = RING_BUFFER_ALL_CPUS;	} 	kdb_trap_printk++; 	trace_init_global_iter(&iter);	iter.buffer_iter = buffer_iter; 	tracer_tracing_disable(iter.tr); 	/* A negative skip_entries means skip all but the last entries */	if (skip_entries < 0) {		if (cpu_file == RING_BUFFER_ALL_CPUS)			cnt = trace_total_entries(NULL);		else			cnt = trace_total_entries_cpu(NULL, cpu_file);		skip_entries = max(cnt + skip_entries, 0);	} 	ftrace_dump_buf(skip_entries, cpu_file); 	tracer_tracing_enable(iter.tr); 	kdb_trap_printk--; 	return 0;} static kdbtab_t ftdump_cmd = {	.name = "ftdump",	.func = kdb_ftdump,	.usage = "[skip_#entries] [cpu]",	.help = "Dump ftrace log; -skip dumps last #entries",	.flags = KDB_ENABLE_ALWAYS_SAFE,}; static __init int kdb_ftrace_register(void){	kdb_register(&ftdump_cmd);	return 0;} late_initcall(kdb_ftrace_register);