| /* |
| * Kernel Probes (KProbes) |
| * kernel/kprobes.c |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * 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. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| * |
| * Copyright (C) IBM Corporation, 2002, 2004 |
| * |
| * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
| * Probes initial implementation (includes suggestions from |
| * Rusty Russell). |
| * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with |
| * hlists and exceptions notifier as suggested by Andi Kleen. |
| * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
| * interface to access function arguments. |
| * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes |
| * exceptions notifier to be first on the priority list. |
| * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
| * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi |
| * <prasanna@in.ibm.com> added function-return probes. |
| */ |
| #include <linux/kprobes.h> |
| #include <linux/spinlock.h> |
| #include <linux/hash.h> |
| #include <linux/init.h> |
| #include <linux/module.h> |
| #include <asm/cacheflush.h> |
| #include <asm/errno.h> |
| #include <asm/kdebug.h> |
| |
| #define KPROBE_HASH_BITS 6 |
| #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) |
| |
| static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; |
| static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; |
| |
| unsigned int kprobe_cpu = NR_CPUS; |
| static DEFINE_SPINLOCK(kprobe_lock); |
| static struct kprobe *curr_kprobe; |
| |
| /* Locks kprobe: irqs must be disabled */ |
| void lock_kprobes(void) |
| { |
| spin_lock(&kprobe_lock); |
| kprobe_cpu = smp_processor_id(); |
| } |
| |
| void unlock_kprobes(void) |
| { |
| kprobe_cpu = NR_CPUS; |
| spin_unlock(&kprobe_lock); |
| } |
| |
| /* You have to be holding the kprobe_lock */ |
| struct kprobe *get_kprobe(void *addr) |
| { |
| struct hlist_head *head; |
| struct hlist_node *node; |
| |
| head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; |
| hlist_for_each(node, head) { |
| struct kprobe *p = hlist_entry(node, struct kprobe, hlist); |
| if (p->addr == addr) |
| return p; |
| } |
| return NULL; |
| } |
| |
| /* |
| * Aggregate handlers for multiple kprobes support - these handlers |
| * take care of invoking the individual kprobe handlers on p->list |
| */ |
| static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| { |
| struct kprobe *kp; |
| |
| list_for_each_entry(kp, &p->list, list) { |
| if (kp->pre_handler) { |
| curr_kprobe = kp; |
| kp->pre_handler(kp, regs); |
| curr_kprobe = NULL; |
| } |
| } |
| return 0; |
| } |
| |
| static void aggr_post_handler(struct kprobe *p, struct pt_regs *regs, |
| unsigned long flags) |
| { |
| struct kprobe *kp; |
| |
| list_for_each_entry(kp, &p->list, list) { |
| if (kp->post_handler) { |
| curr_kprobe = kp; |
| kp->post_handler(kp, regs, flags); |
| curr_kprobe = NULL; |
| } |
| } |
| return; |
| } |
| |
| static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, |
| int trapnr) |
| { |
| /* |
| * if we faulted "during" the execution of a user specified |
| * probe handler, invoke just that probe's fault handler |
| */ |
| if (curr_kprobe && curr_kprobe->fault_handler) { |
| if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr)) |
| return 1; |
| } |
| return 0; |
| } |
| |
| struct kprobe trampoline_p = { |
| .addr = (kprobe_opcode_t *) &kretprobe_trampoline, |
| .pre_handler = trampoline_probe_handler, |
| .post_handler = trampoline_post_handler |
| }; |
| |
| struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp) |
| { |
| struct hlist_node *node; |
| struct kretprobe_instance *ri; |
| hlist_for_each_entry(ri, node, &rp->free_instances, uflist) |
| return ri; |
| return NULL; |
| } |
| |
| static struct kretprobe_instance *get_used_rp_inst(struct kretprobe *rp) |
| { |
| struct hlist_node *node; |
| struct kretprobe_instance *ri; |
| hlist_for_each_entry(ri, node, &rp->used_instances, uflist) |
| return ri; |
| return NULL; |
| } |
| |
| struct kretprobe_instance *get_rp_inst(void *sara) |
| { |
| struct hlist_head *head; |
| struct hlist_node *node; |
| struct task_struct *tsk; |
| struct kretprobe_instance *ri; |
| |
| tsk = arch_get_kprobe_task(sara); |
| head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; |
| hlist_for_each_entry(ri, node, head, hlist) { |
| if (ri->stack_addr == sara) |
| return ri; |
| } |
| return NULL; |
| } |
| |
| void add_rp_inst(struct kretprobe_instance *ri) |
| { |
| struct task_struct *tsk; |
| /* |
| * Remove rp inst off the free list - |
| * Add it back when probed function returns |
| */ |
| hlist_del(&ri->uflist); |
| tsk = arch_get_kprobe_task(ri->stack_addr); |
| /* Add rp inst onto table */ |
| INIT_HLIST_NODE(&ri->hlist); |
| hlist_add_head(&ri->hlist, |
| &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]); |
| |
| /* Also add this rp inst to the used list. */ |
| INIT_HLIST_NODE(&ri->uflist); |
| hlist_add_head(&ri->uflist, &ri->rp->used_instances); |
| } |
| |
| void recycle_rp_inst(struct kretprobe_instance *ri) |
| { |
| /* remove rp inst off the rprobe_inst_table */ |
| hlist_del(&ri->hlist); |
| if (ri->rp) { |
| /* remove rp inst off the used list */ |
| hlist_del(&ri->uflist); |
| /* put rp inst back onto the free list */ |
| INIT_HLIST_NODE(&ri->uflist); |
| hlist_add_head(&ri->uflist, &ri->rp->free_instances); |
| } else |
| /* Unregistering */ |
| kfree(ri); |
| } |
| |
| struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk) |
| { |
| return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]; |
| } |
| |
| struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk) |
| { |
| struct task_struct *tsk; |
| struct hlist_head *head; |
| struct hlist_node *node; |
| struct kretprobe_instance *ri; |
| |
| head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)]; |
| |
| hlist_for_each_entry(ri, node, head, hlist) { |
| tsk = arch_get_kprobe_task(ri->stack_addr); |
| if (tsk == tk) |
| return ri; |
| } |
| return NULL; |
| } |
| |
| /* |
| * This function is called from do_exit or do_execv when task tk's stack is |
| * about to be recycled. Recycle any function-return probe instances |
| * associated with this task. These represent probed functions that have |
| * been called but may never return. |
| */ |
| void kprobe_flush_task(struct task_struct *tk) |
| { |
| unsigned long flags = 0; |
| spin_lock_irqsave(&kprobe_lock, flags); |
| arch_kprobe_flush_task(tk); |
| spin_unlock_irqrestore(&kprobe_lock, flags); |
| } |
| |
| /* |
| * This kprobe pre_handler is registered with every kretprobe. When probe |
| * hits it will set up the return probe. |
| */ |
| static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs) |
| { |
| struct kretprobe *rp = container_of(p, struct kretprobe, kp); |
| |
| /*TODO: consider to only swap the RA after the last pre_handler fired */ |
| arch_prepare_kretprobe(rp, regs); |
| return 0; |
| } |
| |
| static inline void free_rp_inst(struct kretprobe *rp) |
| { |
| struct kretprobe_instance *ri; |
| while ((ri = get_free_rp_inst(rp)) != NULL) { |
| hlist_del(&ri->uflist); |
| kfree(ri); |
| } |
| } |
| |
| /* |
| * Fill in the required fields of the "manager kprobe". Replace the |
| * earlier kprobe in the hlist with the manager kprobe |
| */ |
| static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) |
| { |
| ap->addr = p->addr; |
| memcpy(&ap->opcode, &p->opcode, sizeof(kprobe_opcode_t)); |
| memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn)); |
| |
| ap->pre_handler = aggr_pre_handler; |
| ap->post_handler = aggr_post_handler; |
| ap->fault_handler = aggr_fault_handler; |
| |
| INIT_LIST_HEAD(&ap->list); |
| list_add(&p->list, &ap->list); |
| |
| INIT_HLIST_NODE(&ap->hlist); |
| hlist_del(&p->hlist); |
| hlist_add_head(&ap->hlist, |
| &kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]); |
| } |
| |
| /* |
| * This is the second or subsequent kprobe at the address - handle |
| * the intricacies |
| * TODO: Move kcalloc outside the spinlock |
| */ |
| static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) |
| { |
| int ret = 0; |
| struct kprobe *ap; |
| |
| if (old_p->break_handler || p->break_handler) { |
| ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */ |
| } else if (old_p->pre_handler == aggr_pre_handler) { |
| list_add(&p->list, &old_p->list); |
| } else { |
| ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC); |
| if (!ap) |
| return -ENOMEM; |
| add_aggr_kprobe(ap, old_p); |
| list_add(&p->list, &ap->list); |
| } |
| return ret; |
| } |
| |
| /* kprobe removal house-keeping routines */ |
| static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) |
| { |
| arch_disarm_kprobe(p); |
| hlist_del(&p->hlist); |
| spin_unlock_irqrestore(&kprobe_lock, flags); |
| arch_remove_kprobe(p); |
| } |
| |
| static inline void cleanup_aggr_kprobe(struct kprobe *old_p, |
| struct kprobe *p, unsigned long flags) |
| { |
| list_del(&p->list); |
| if (list_empty(&old_p->list)) { |
| cleanup_kprobe(old_p, flags); |
| kfree(old_p); |
| } else |
| spin_unlock_irqrestore(&kprobe_lock, flags); |
| } |
| |
| int register_kprobe(struct kprobe *p) |
| { |
| int ret = 0; |
| unsigned long flags = 0; |
| struct kprobe *old_p; |
| |
| if ((ret = arch_prepare_kprobe(p)) != 0) { |
| goto rm_kprobe; |
| } |
| spin_lock_irqsave(&kprobe_lock, flags); |
| old_p = get_kprobe(p->addr); |
| if (old_p) { |
| ret = register_aggr_kprobe(old_p, p); |
| goto out; |
| } |
| |
| arch_copy_kprobe(p); |
| INIT_HLIST_NODE(&p->hlist); |
| hlist_add_head(&p->hlist, |
| &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); |
| |
| arch_arm_kprobe(p); |
| |
| out: |
| spin_unlock_irqrestore(&kprobe_lock, flags); |
| rm_kprobe: |
| if (ret == -EEXIST) |
| arch_remove_kprobe(p); |
| return ret; |
| } |
| |
| void unregister_kprobe(struct kprobe *p) |
| { |
| unsigned long flags; |
| struct kprobe *old_p; |
| |
| spin_lock_irqsave(&kprobe_lock, flags); |
| old_p = get_kprobe(p->addr); |
| if (old_p) { |
| if (old_p->pre_handler == aggr_pre_handler) |
| cleanup_aggr_kprobe(old_p, p, flags); |
| else |
| cleanup_kprobe(p, flags); |
| } else |
| spin_unlock_irqrestore(&kprobe_lock, flags); |
| } |
| |
| static struct notifier_block kprobe_exceptions_nb = { |
| .notifier_call = kprobe_exceptions_notify, |
| .priority = 0x7fffffff /* we need to notified first */ |
| }; |
| |
| int register_jprobe(struct jprobe *jp) |
| { |
| /* Todo: Verify probepoint is a function entry point */ |
| jp->kp.pre_handler = setjmp_pre_handler; |
| jp->kp.break_handler = longjmp_break_handler; |
| |
| return register_kprobe(&jp->kp); |
| } |
| |
| void unregister_jprobe(struct jprobe *jp) |
| { |
| unregister_kprobe(&jp->kp); |
| } |
| |
| #ifdef ARCH_SUPPORTS_KRETPROBES |
| |
| int register_kretprobe(struct kretprobe *rp) |
| { |
| int ret = 0; |
| struct kretprobe_instance *inst; |
| int i; |
| |
| rp->kp.pre_handler = pre_handler_kretprobe; |
| |
| /* Pre-allocate memory for max kretprobe instances */ |
| if (rp->maxactive <= 0) { |
| #ifdef CONFIG_PREEMPT |
| rp->maxactive = max(10, 2 * NR_CPUS); |
| #else |
| rp->maxactive = NR_CPUS; |
| #endif |
| } |
| INIT_HLIST_HEAD(&rp->used_instances); |
| INIT_HLIST_HEAD(&rp->free_instances); |
| for (i = 0; i < rp->maxactive; i++) { |
| inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL); |
| if (inst == NULL) { |
| free_rp_inst(rp); |
| return -ENOMEM; |
| } |
| INIT_HLIST_NODE(&inst->uflist); |
| hlist_add_head(&inst->uflist, &rp->free_instances); |
| } |
| |
| rp->nmissed = 0; |
| /* Establish function entry probe point */ |
| if ((ret = register_kprobe(&rp->kp)) != 0) |
| free_rp_inst(rp); |
| return ret; |
| } |
| |
| #else /* ARCH_SUPPORTS_KRETPROBES */ |
| |
| int register_kretprobe(struct kretprobe *rp) |
| { |
| return -ENOSYS; |
| } |
| |
| #endif /* ARCH_SUPPORTS_KRETPROBES */ |
| |
| void unregister_kretprobe(struct kretprobe *rp) |
| { |
| unsigned long flags; |
| struct kretprobe_instance *ri; |
| |
| unregister_kprobe(&rp->kp); |
| /* No race here */ |
| spin_lock_irqsave(&kprobe_lock, flags); |
| free_rp_inst(rp); |
| while ((ri = get_used_rp_inst(rp)) != NULL) { |
| ri->rp = NULL; |
| hlist_del(&ri->uflist); |
| } |
| spin_unlock_irqrestore(&kprobe_lock, flags); |
| } |
| |
| static int __init init_kprobes(void) |
| { |
| int i, err = 0; |
| |
| /* FIXME allocate the probe table, currently defined statically */ |
| /* initialize all list heads */ |
| for (i = 0; i < KPROBE_TABLE_SIZE; i++) { |
| INIT_HLIST_HEAD(&kprobe_table[i]); |
| INIT_HLIST_HEAD(&kretprobe_inst_table[i]); |
| } |
| |
| err = register_die_notifier(&kprobe_exceptions_nb); |
| /* Register the trampoline probe for return probe */ |
| register_kprobe(&trampoline_p); |
| return err; |
| } |
| |
| __initcall(init_kprobes); |
| |
| EXPORT_SYMBOL_GPL(register_kprobe); |
| EXPORT_SYMBOL_GPL(unregister_kprobe); |
| EXPORT_SYMBOL_GPL(register_jprobe); |
| EXPORT_SYMBOL_GPL(unregister_jprobe); |
| EXPORT_SYMBOL_GPL(jprobe_return); |
| EXPORT_SYMBOL_GPL(register_kretprobe); |
| EXPORT_SYMBOL_GPL(unregister_kretprobe); |
| |