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fa1af7583e
When calling debugfs functions, there is no need to ever check the return value. The function can work or not, but the code logic should never do something different based on this. Cc: Kees Cook <keescook@chromium.org> Cc: Anton Vorontsov <anton@enomsg.org> Cc: Colin Cross <ccross@android.com> Cc: Tony Luck <tony.luck@intel.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Kees Cook <keescook@chromium.org>
135 lines
3.0 KiB
C
135 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright 2012 Google, Inc.
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*/
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#include <linux/kernel.h>
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#include <linux/compiler.h>
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#include <linux/irqflags.h>
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#include <linux/percpu.h>
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#include <linux/smp.h>
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#include <linux/atomic.h>
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#include <linux/types.h>
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#include <linux/mutex.h>
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#include <linux/ftrace.h>
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#include <linux/fs.h>
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#include <linux/debugfs.h>
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#include <linux/err.h>
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#include <linux/cache.h>
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#include <asm/barrier.h>
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#include "internal.h"
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/* This doesn't need to be atomic: speed is chosen over correctness here. */
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static u64 pstore_ftrace_stamp;
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static void notrace pstore_ftrace_call(unsigned long ip,
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unsigned long parent_ip,
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struct ftrace_ops *op,
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struct pt_regs *regs)
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{
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unsigned long flags;
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struct pstore_ftrace_record rec = {};
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struct pstore_record record = {
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.type = PSTORE_TYPE_FTRACE,
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.buf = (char *)&rec,
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.size = sizeof(rec),
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.psi = psinfo,
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};
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if (unlikely(oops_in_progress))
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return;
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local_irq_save(flags);
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rec.ip = ip;
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rec.parent_ip = parent_ip;
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pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
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pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
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psinfo->write(&record);
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local_irq_restore(flags);
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}
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static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
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.func = pstore_ftrace_call,
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};
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static DEFINE_MUTEX(pstore_ftrace_lock);
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static bool pstore_ftrace_enabled;
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static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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u8 on;
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ssize_t ret;
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ret = kstrtou8_from_user(buf, count, 2, &on);
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if (ret)
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return ret;
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mutex_lock(&pstore_ftrace_lock);
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if (!on ^ pstore_ftrace_enabled)
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goto out;
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if (on) {
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ftrace_ops_set_global_filter(&pstore_ftrace_ops);
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ret = register_ftrace_function(&pstore_ftrace_ops);
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} else {
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ret = unregister_ftrace_function(&pstore_ftrace_ops);
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}
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if (ret) {
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pr_err("%s: unable to %sregister ftrace ops: %zd\n",
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__func__, on ? "" : "un", ret);
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goto err;
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}
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pstore_ftrace_enabled = on;
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out:
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ret = count;
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err:
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mutex_unlock(&pstore_ftrace_lock);
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return ret;
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}
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static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
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size_t count, loff_t *ppos)
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{
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char val[] = { '0' + pstore_ftrace_enabled, '\n' };
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return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
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}
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static const struct file_operations pstore_knob_fops = {
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.open = simple_open,
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.read = pstore_ftrace_knob_read,
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.write = pstore_ftrace_knob_write,
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};
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static struct dentry *pstore_ftrace_dir;
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void pstore_register_ftrace(void)
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{
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if (!psinfo->write)
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return;
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pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
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debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
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&pstore_knob_fops);
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}
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void pstore_unregister_ftrace(void)
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{
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mutex_lock(&pstore_ftrace_lock);
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if (pstore_ftrace_enabled) {
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unregister_ftrace_function(&pstore_ftrace_ops);
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pstore_ftrace_enabled = false;
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}
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mutex_unlock(&pstore_ftrace_lock);
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debugfs_remove_recursive(pstore_ftrace_dir);
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}
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