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fs/pstore/ftrace.c
3.63 KB
81f7e3824 Initial Release, ... |
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/* * 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 <linux/types.h> #include <linux/mutex.h> #include <linux/ftrace.h> #include <linux/fs.h> #include <linux/debugfs.h> #include <linux/err.h> #include <linux/cache.h> #include <asm/barrier.h> #include "internal.h" /* This doesn't need to be atomic: speed is chosen over correctness here. */ static u64 pstore_ftrace_stamp; static void notrace pstore_ftrace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct pt_regs *regs) { unsigned long flags; struct pstore_ftrace_record rec = {}; struct pstore_record record = { .type = PSTORE_TYPE_FTRACE, .buf = (char *)&rec, .size = sizeof(rec), .psi = psinfo, }; if (unlikely(oops_in_progress)) return; local_irq_save(flags); rec.ip = ip; rec.parent_ip = parent_ip; pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++); pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id()); psinfo->write(&record); local_irq_restore(flags); } static struct ftrace_ops pstore_ftrace_ops __read_mostly = { .func = pstore_ftrace_call, }; static DEFINE_MUTEX(pstore_ftrace_lock); static bool pstore_ftrace_enabled; static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf, size_t count, loff_t *ppos) { u8 on; ssize_t ret; ret = kstrtou8_from_user(buf, count, 2, &on); if (ret) return ret; mutex_lock(&pstore_ftrace_lock); if (!on ^ pstore_ftrace_enabled) goto out; if (on) { ftrace_ops_set_global_filter(&pstore_ftrace_ops); ret = register_ftrace_function(&pstore_ftrace_ops); } else { ret = unregister_ftrace_function(&pstore_ftrace_ops); } if (ret) { pr_err("%s: unable to %sregister ftrace ops: %zd ", __func__, on ? "" : "un", ret); goto err; } pstore_ftrace_enabled = on; out: ret = count; err: mutex_unlock(&pstore_ftrace_lock); return ret; } static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf, size_t count, loff_t *ppos) { char val[] = { '0' + pstore_ftrace_enabled, ' ' }; return simple_read_from_buffer(buf, count, ppos, val, sizeof(val)); } static const struct file_operations pstore_knob_fops = { .open = simple_open, .read = pstore_ftrace_knob_read, .write = pstore_ftrace_knob_write, }; static struct dentry *pstore_ftrace_dir; void pstore_register_ftrace(void) { struct dentry *file; if (!psinfo->write) return; pstore_ftrace_dir = debugfs_create_dir("pstore", NULL); if (!pstore_ftrace_dir) { pr_err("%s: unable to create pstore directory ", __func__); return; } file = debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL, &pstore_knob_fops); if (!file) { pr_err("%s: unable to create record_ftrace file ", __func__); goto err_file; } return; err_file: debugfs_remove(pstore_ftrace_dir); } void pstore_unregister_ftrace(void) { mutex_lock(&pstore_ftrace_lock); if (pstore_ftrace_enabled) { unregister_ftrace_function(&pstore_ftrace_ops); pstore_ftrace_enabled = 0; } mutex_unlock(&pstore_ftrace_lock); debugfs_remove_recursive(pstore_ftrace_dir); } |