2005-04-16 15:20:36 -07:00
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/*
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* Kernel Probes (KProbes)
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* kernel/kprobes.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2002, 2004
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*
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* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
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* Probes initial implementation (includes suggestions from
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* Rusty Russell).
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* 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
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* hlists and exceptions notifier as suggested by Andi Kleen.
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* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
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* interface to access function arguments.
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* 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
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* exceptions notifier to be first on the priority list.
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*/
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#include <linux/kprobes.h>
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#include <linux/spinlock.h>
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#include <linux/hash.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <asm/cacheflush.h>
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#include <asm/errno.h>
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#include <asm/kdebug.h>
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#define KPROBE_HASH_BITS 6
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#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
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static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
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unsigned int kprobe_cpu = NR_CPUS;
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static DEFINE_SPINLOCK(kprobe_lock);
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2005-05-05 16:15:42 -07:00
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static struct kprobe *curr_kprobe;
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2005-04-16 15:20:36 -07:00
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/* Locks kprobe: irqs must be disabled */
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void lock_kprobes(void)
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{
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spin_lock(&kprobe_lock);
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kprobe_cpu = smp_processor_id();
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}
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void unlock_kprobes(void)
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{
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kprobe_cpu = NR_CPUS;
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spin_unlock(&kprobe_lock);
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}
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/* You have to be holding the kprobe_lock */
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struct kprobe *get_kprobe(void *addr)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
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hlist_for_each(node, head) {
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struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
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if (p->addr == addr)
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return p;
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}
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return NULL;
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}
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2005-05-05 16:15:42 -07:00
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/*
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* Aggregate handlers for multiple kprobes support - these handlers
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* take care of invoking the individual kprobe handlers on p->list
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*/
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int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct kprobe *kp;
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list_for_each_entry(kp, &p->list, list) {
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if (kp->pre_handler) {
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curr_kprobe = kp;
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kp->pre_handler(kp, regs);
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curr_kprobe = NULL;
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}
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}
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return 0;
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}
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void aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
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unsigned long flags)
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{
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struct kprobe *kp;
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list_for_each_entry(kp, &p->list, list) {
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if (kp->post_handler) {
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curr_kprobe = kp;
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kp->post_handler(kp, regs, flags);
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curr_kprobe = NULL;
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}
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}
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return;
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}
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int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr)
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{
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/*
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* if we faulted "during" the execution of a user specified
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* probe handler, invoke just that probe's fault handler
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*/
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if (curr_kprobe && curr_kprobe->fault_handler) {
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if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr))
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return 1;
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}
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return 0;
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}
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/*
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* Fill in the required fields of the "manager kprobe". Replace the
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* earlier kprobe in the hlist with the manager kprobe
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*/
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static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
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{
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ap->addr = p->addr;
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ap->opcode = p->opcode;
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memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn));
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ap->pre_handler = aggr_pre_handler;
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ap->post_handler = aggr_post_handler;
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ap->fault_handler = aggr_fault_handler;
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INIT_LIST_HEAD(&ap->list);
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list_add(&p->list, &ap->list);
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INIT_HLIST_NODE(&ap->hlist);
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hlist_del(&p->hlist);
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hlist_add_head(&ap->hlist,
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&kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]);
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}
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/*
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* This is the second or subsequent kprobe at the address - handle
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* the intricacies
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* TODO: Move kcalloc outside the spinlock
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*/
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static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p)
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{
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int ret = 0;
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struct kprobe *ap;
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if (old_p->break_handler || p->break_handler) {
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ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */
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} else if (old_p->pre_handler == aggr_pre_handler) {
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list_add(&p->list, &old_p->list);
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} else {
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ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
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if (!ap)
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return -ENOMEM;
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add_aggr_kprobe(ap, old_p);
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list_add(&p->list, &ap->list);
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}
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return ret;
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}
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/* kprobe removal house-keeping routines */
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static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
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{
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*p->addr = p->opcode;
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hlist_del(&p->hlist);
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flush_icache_range((unsigned long) p->addr,
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(unsigned long) p->addr + sizeof(kprobe_opcode_t));
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spin_unlock_irqrestore(&kprobe_lock, flags);
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arch_remove_kprobe(p);
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}
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static inline void cleanup_aggr_kprobe(struct kprobe *old_p,
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struct kprobe *p, unsigned long flags)
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{
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list_del(&p->list);
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if (list_empty(&old_p->list)) {
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cleanup_kprobe(old_p, flags);
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kfree(old_p);
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} else
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spin_unlock_irqrestore(&kprobe_lock, flags);
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}
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2005-04-16 15:20:36 -07:00
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int register_kprobe(struct kprobe *p)
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{
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int ret = 0;
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unsigned long flags = 0;
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2005-05-05 16:15:42 -07:00
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struct kprobe *old_p;
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2005-04-16 15:20:36 -07:00
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if ((ret = arch_prepare_kprobe(p)) != 0) {
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goto rm_kprobe;
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}
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spin_lock_irqsave(&kprobe_lock, flags);
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2005-05-05 16:15:42 -07:00
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old_p = get_kprobe(p->addr);
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if (old_p) {
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ret = register_aggr_kprobe(old_p, p);
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2005-04-16 15:20:36 -07:00
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goto out;
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}
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2005-05-05 16:15:42 -07:00
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arch_copy_kprobe(p);
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INIT_HLIST_NODE(&p->hlist);
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2005-04-16 15:20:36 -07:00
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hlist_add_head(&p->hlist,
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&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
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p->opcode = *p->addr;
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*p->addr = BREAKPOINT_INSTRUCTION;
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flush_icache_range((unsigned long) p->addr,
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(unsigned long) p->addr + sizeof(kprobe_opcode_t));
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out:
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spin_unlock_irqrestore(&kprobe_lock, flags);
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rm_kprobe:
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if (ret == -EEXIST)
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arch_remove_kprobe(p);
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return ret;
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}
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void unregister_kprobe(struct kprobe *p)
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{
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unsigned long flags;
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2005-05-05 16:15:42 -07:00
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struct kprobe *old_p;
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2005-04-16 15:20:36 -07:00
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spin_lock_irqsave(&kprobe_lock, flags);
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2005-05-05 16:15:42 -07:00
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old_p = get_kprobe(p->addr);
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if (old_p) {
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if (old_p->pre_handler == aggr_pre_handler)
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cleanup_aggr_kprobe(old_p, p, flags);
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else
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cleanup_kprobe(p, flags);
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} else
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2005-05-05 16:15:41 -07:00
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spin_unlock_irqrestore(&kprobe_lock, flags);
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2005-04-16 15:20:36 -07:00
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}
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static struct notifier_block kprobe_exceptions_nb = {
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.notifier_call = kprobe_exceptions_notify,
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.priority = 0x7fffffff /* we need to notified first */
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};
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int register_jprobe(struct jprobe *jp)
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{
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/* Todo: Verify probepoint is a function entry point */
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jp->kp.pre_handler = setjmp_pre_handler;
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jp->kp.break_handler = longjmp_break_handler;
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return register_kprobe(&jp->kp);
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}
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void unregister_jprobe(struct jprobe *jp)
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{
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unregister_kprobe(&jp->kp);
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}
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static int __init init_kprobes(void)
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{
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int i, err = 0;
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/* FIXME allocate the probe table, currently defined statically */
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/* initialize all list heads */
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for (i = 0; i < KPROBE_TABLE_SIZE; i++)
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INIT_HLIST_HEAD(&kprobe_table[i]);
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err = register_die_notifier(&kprobe_exceptions_nb);
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return err;
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}
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__initcall(init_kprobes);
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EXPORT_SYMBOL_GPL(register_kprobe);
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EXPORT_SYMBOL_GPL(unregister_kprobe);
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EXPORT_SYMBOL_GPL(register_jprobe);
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EXPORT_SYMBOL_GPL(unregister_jprobe);
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EXPORT_SYMBOL_GPL(jprobe_return);
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