diff options
Diffstat (limited to 'fs/pstore/ftrace.c')
| -rw-r--r-- | fs/pstore/ftrace.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c new file mode 100644 index 000000000..776cae20a --- /dev/null +++ b/fs/pstore/ftrace.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2012 Google, Inc. + */ + +#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 <linux/slab.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 ftrace_regs *fregs) +{ + int bit; + 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; + + bit = ftrace_test_recursion_trylock(ip, parent_ip); + if (bit < 0) + 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); + ftrace_test_recursion_unlock(bit); +} + +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 int pstore_set_ftrace_enabled(bool on) +{ + ssize_t ret; + + if (on == pstore_ftrace_enabled) + return 0; + + 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\n", + __func__, on ? "" : "un", ret); + } else { + pstore_ftrace_enabled = on; + } + + return ret; +} + +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); + ret = pstore_set_ftrace_enabled(on); + mutex_unlock(&pstore_ftrace_lock); + + if (ret == 0) + ret = count; + + 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, '\n' }; + + 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; + +static bool record_ftrace; +module_param(record_ftrace, bool, 0400); +MODULE_PARM_DESC(record_ftrace, + "enable ftrace recording immediately (default: off)"); + +void pstore_register_ftrace(void) +{ + if (!psinfo->write) + return; + + pstore_ftrace_dir = debugfs_create_dir("pstore", NULL); + + pstore_set_ftrace_enabled(record_ftrace); + + debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL, + &pstore_knob_fops); +} + +void pstore_unregister_ftrace(void) +{ + mutex_lock(&pstore_ftrace_lock); + if (pstore_ftrace_enabled) { + unregister_ftrace_function(&pstore_ftrace_ops); + pstore_ftrace_enabled = false; + } + mutex_unlock(&pstore_ftrace_lock); + + debugfs_remove_recursive(pstore_ftrace_dir); +} + +ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size, + const char *src_log, size_t src_log_size) +{ + size_t dest_size, src_size, total, dest_off, src_off; + size_t dest_idx = 0, src_idx = 0, merged_idx = 0; + void *merged_buf; + struct pstore_ftrace_record *drec, *srec, *mrec; + size_t record_size = sizeof(struct pstore_ftrace_record); + + dest_off = *dest_log_size % record_size; + dest_size = *dest_log_size - dest_off; + + src_off = src_log_size % record_size; + src_size = src_log_size - src_off; + + total = dest_size + src_size; + merged_buf = kmalloc(total, GFP_KERNEL); + if (!merged_buf) + return -ENOMEM; + + drec = (struct pstore_ftrace_record *)(*dest_log + dest_off); + srec = (struct pstore_ftrace_record *)(src_log + src_off); + mrec = (struct pstore_ftrace_record *)(merged_buf); + + while (dest_size > 0 && src_size > 0) { + if (pstore_ftrace_read_timestamp(&drec[dest_idx]) < + pstore_ftrace_read_timestamp(&srec[src_idx])) { + mrec[merged_idx++] = drec[dest_idx++]; + dest_size -= record_size; + } else { + mrec[merged_idx++] = srec[src_idx++]; + src_size -= record_size; + } + } + + while (dest_size > 0) { + mrec[merged_idx++] = drec[dest_idx++]; + dest_size -= record_size; + } + + while (src_size > 0) { + mrec[merged_idx++] = srec[src_idx++]; + src_size -= record_size; + } + + kfree(*dest_log); + *dest_log = merged_buf; + *dest_log_size = total; + + return 0; +} +EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log); |