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343 lines
7.0 KiB
343 lines
7.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* fail_function.c: Function-based error injection |
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*/ |
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#include <linux/error-injection.h> |
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#include <linux/debugfs.h> |
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#include <linux/fault-inject.h> |
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#include <linux/kallsyms.h> |
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#include <linux/kprobes.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/slab.h> |
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#include <linux/uaccess.h> |
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static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); |
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static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs, |
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unsigned long flags) |
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{ |
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/* |
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* A dummy post handler is required to prohibit optimizing, because |
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* jump optimization does not support execution path overriding. |
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*/ |
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} |
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struct fei_attr { |
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struct list_head list; |
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struct kprobe kp; |
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unsigned long retval; |
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}; |
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static DEFINE_MUTEX(fei_lock); |
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static LIST_HEAD(fei_attr_list); |
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static DECLARE_FAULT_ATTR(fei_fault_attr); |
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static struct dentry *fei_debugfs_dir; |
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static unsigned long adjust_error_retval(unsigned long addr, unsigned long retv) |
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{ |
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switch (get_injectable_error_type(addr)) { |
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case EI_ETYPE_NULL: |
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return 0; |
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case EI_ETYPE_ERRNO: |
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if (retv < (unsigned long)-MAX_ERRNO) |
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return (unsigned long)-EINVAL; |
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break; |
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case EI_ETYPE_ERRNO_NULL: |
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if (retv != 0 && retv < (unsigned long)-MAX_ERRNO) |
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return (unsigned long)-EINVAL; |
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break; |
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case EI_ETYPE_TRUE: |
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return 1; |
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} |
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return retv; |
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} |
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static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr) |
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{ |
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struct fei_attr *attr; |
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attr = kzalloc(sizeof(*attr), GFP_KERNEL); |
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if (attr) { |
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attr->kp.symbol_name = kstrdup(sym, GFP_KERNEL); |
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if (!attr->kp.symbol_name) { |
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kfree(attr); |
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return NULL; |
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} |
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attr->kp.pre_handler = fei_kprobe_handler; |
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attr->kp.post_handler = fei_post_handler; |
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attr->retval = adjust_error_retval(addr, 0); |
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INIT_LIST_HEAD(&attr->list); |
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} |
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return attr; |
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} |
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static void fei_attr_free(struct fei_attr *attr) |
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{ |
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if (attr) { |
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kfree(attr->kp.symbol_name); |
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kfree(attr); |
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} |
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} |
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static struct fei_attr *fei_attr_lookup(const char *sym) |
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{ |
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struct fei_attr *attr; |
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list_for_each_entry(attr, &fei_attr_list, list) { |
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if (!strcmp(attr->kp.symbol_name, sym)) |
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return attr; |
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} |
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return NULL; |
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} |
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static bool fei_attr_is_valid(struct fei_attr *_attr) |
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{ |
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struct fei_attr *attr; |
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list_for_each_entry(attr, &fei_attr_list, list) { |
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if (attr == _attr) |
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return true; |
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} |
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return false; |
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} |
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static int fei_retval_set(void *data, u64 val) |
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{ |
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struct fei_attr *attr = data; |
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unsigned long retv = (unsigned long)val; |
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int err = 0; |
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mutex_lock(&fei_lock); |
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/* |
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* Since this operation can be done after retval file is removed, |
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* It is safer to check the attr is still valid before accessing |
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* its member. |
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*/ |
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if (!fei_attr_is_valid(attr)) { |
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err = -ENOENT; |
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goto out; |
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} |
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if (attr->kp.addr) { |
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if (adjust_error_retval((unsigned long)attr->kp.addr, |
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val) != retv) |
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err = -EINVAL; |
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} |
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if (!err) |
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attr->retval = val; |
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out: |
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mutex_unlock(&fei_lock); |
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return err; |
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} |
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static int fei_retval_get(void *data, u64 *val) |
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{ |
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struct fei_attr *attr = data; |
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int err = 0; |
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mutex_lock(&fei_lock); |
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/* Here we also validate @attr to ensure it still exists. */ |
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if (!fei_attr_is_valid(attr)) |
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err = -ENOENT; |
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else |
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*val = attr->retval; |
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mutex_unlock(&fei_lock); |
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return err; |
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} |
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DEFINE_DEBUGFS_ATTRIBUTE(fei_retval_ops, fei_retval_get, fei_retval_set, |
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"%llx\n"); |
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static void fei_debugfs_add_attr(struct fei_attr *attr) |
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{ |
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struct dentry *dir; |
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dir = debugfs_create_dir(attr->kp.symbol_name, fei_debugfs_dir); |
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debugfs_create_file("retval", 0600, dir, attr, &fei_retval_ops); |
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} |
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static void fei_debugfs_remove_attr(struct fei_attr *attr) |
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{ |
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struct dentry *dir; |
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dir = debugfs_lookup(attr->kp.symbol_name, fei_debugfs_dir); |
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debugfs_remove_recursive(dir); |
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} |
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static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs) |
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{ |
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struct fei_attr *attr = container_of(kp, struct fei_attr, kp); |
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if (should_fail(&fei_fault_attr, 1)) { |
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regs_set_return_value(regs, attr->retval); |
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override_function_with_return(regs); |
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return 1; |
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} |
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return 0; |
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} |
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NOKPROBE_SYMBOL(fei_kprobe_handler) |
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static void *fei_seq_start(struct seq_file *m, loff_t *pos) |
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{ |
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mutex_lock(&fei_lock); |
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return seq_list_start(&fei_attr_list, *pos); |
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} |
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static void fei_seq_stop(struct seq_file *m, void *v) |
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{ |
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mutex_unlock(&fei_lock); |
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} |
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static void *fei_seq_next(struct seq_file *m, void *v, loff_t *pos) |
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{ |
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return seq_list_next(v, &fei_attr_list, pos); |
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} |
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static int fei_seq_show(struct seq_file *m, void *v) |
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{ |
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struct fei_attr *attr = list_entry(v, struct fei_attr, list); |
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seq_printf(m, "%ps\n", attr->kp.addr); |
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return 0; |
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} |
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static const struct seq_operations fei_seq_ops = { |
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.start = fei_seq_start, |
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.next = fei_seq_next, |
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.stop = fei_seq_stop, |
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.show = fei_seq_show, |
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}; |
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static int fei_open(struct inode *inode, struct file *file) |
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{ |
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return seq_open(file, &fei_seq_ops); |
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} |
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static void fei_attr_remove(struct fei_attr *attr) |
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{ |
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fei_debugfs_remove_attr(attr); |
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unregister_kprobe(&attr->kp); |
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list_del(&attr->list); |
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fei_attr_free(attr); |
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} |
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static void fei_attr_remove_all(void) |
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{ |
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struct fei_attr *attr, *n; |
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list_for_each_entry_safe(attr, n, &fei_attr_list, list) { |
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fei_attr_remove(attr); |
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} |
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} |
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static ssize_t fei_write(struct file *file, const char __user *buffer, |
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size_t count, loff_t *ppos) |
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{ |
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struct fei_attr *attr; |
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unsigned long addr; |
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char *buf, *sym; |
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int ret; |
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/* cut off if it is too long */ |
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if (count > KSYM_NAME_LEN) |
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count = KSYM_NAME_LEN; |
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buf = kmalloc(count + 1, GFP_KERNEL); |
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if (!buf) |
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return -ENOMEM; |
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if (copy_from_user(buf, buffer, count)) { |
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ret = -EFAULT; |
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goto out_free; |
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} |
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buf[count] = '\0'; |
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sym = strstrip(buf); |
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mutex_lock(&fei_lock); |
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/* Writing just spaces will remove all injection points */ |
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if (sym[0] == '\0') { |
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fei_attr_remove_all(); |
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ret = count; |
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goto out; |
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} |
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/* Writing !function will remove one injection point */ |
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if (sym[0] == '!') { |
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attr = fei_attr_lookup(sym + 1); |
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if (!attr) { |
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ret = -ENOENT; |
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goto out; |
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} |
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fei_attr_remove(attr); |
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ret = count; |
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goto out; |
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} |
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addr = kallsyms_lookup_name(sym); |
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if (!addr) { |
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ret = -EINVAL; |
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goto out; |
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} |
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if (!within_error_injection_list(addr)) { |
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ret = -ERANGE; |
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goto out; |
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} |
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if (fei_attr_lookup(sym)) { |
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ret = -EBUSY; |
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goto out; |
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} |
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attr = fei_attr_new(sym, addr); |
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if (!attr) { |
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ret = -ENOMEM; |
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goto out; |
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} |
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ret = register_kprobe(&attr->kp); |
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if (!ret) |
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fei_debugfs_add_attr(attr); |
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if (ret < 0) |
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fei_attr_remove(attr); |
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else { |
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list_add_tail(&attr->list, &fei_attr_list); |
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ret = count; |
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} |
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out: |
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mutex_unlock(&fei_lock); |
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out_free: |
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kfree(buf); |
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return ret; |
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} |
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static const struct file_operations fei_ops = { |
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.open = fei_open, |
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.read = seq_read, |
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.write = fei_write, |
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.llseek = seq_lseek, |
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.release = seq_release, |
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}; |
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static int __init fei_debugfs_init(void) |
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{ |
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struct dentry *dir; |
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dir = fault_create_debugfs_attr("fail_function", NULL, |
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&fei_fault_attr); |
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if (IS_ERR(dir)) |
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return PTR_ERR(dir); |
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/* injectable attribute is just a symlink of error_inject/list */ |
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debugfs_create_symlink("injectable", dir, "../error_injection/list"); |
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debugfs_create_file("inject", 0600, dir, NULL, &fei_ops); |
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fei_debugfs_dir = dir; |
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return 0; |
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} |
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late_initcall(fei_debugfs_init);
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