X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=kernel%2Fkprobes.c;h=9e47d8c493f3a7638d06892b2835ad87c859f7bf;hb=0397bad5b413226b8f55f599b185ab506d13b078;hp=6c86d67ed1a71aba7063b26c37afd6c7a40aa911;hpb=e3869792990f708c97be5877499cada70d469bd3;p=powerpc.git diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 6c86d67ed1..9e47d8c493 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -42,10 +42,12 @@ #include #include #include +#include + #include #include #include -#include +#include #define KPROBE_HASH_BITS 6 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) @@ -64,6 +66,9 @@ static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; static atomic_t kprobe_count; +/* NOTE: change this value only with kprobe_mutex held */ +static bool kprobe_enabled; + DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */ DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */ static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL; @@ -133,9 +138,8 @@ kprobe_opcode_t __kprobes *get_insn_slot(void) struct kprobe_insn_page *kip; struct hlist_node *pos; - retry: - hlist_for_each(pos, &kprobe_insn_pages) { - kip = hlist_entry(pos, struct kprobe_insn_page, hlist); + retry: + hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { if (kip->nused < INSNS_PER_PAGE) { int i; for (i = 0; i < INSNS_PER_PAGE; i++) { @@ -156,9 +160,8 @@ kprobe_opcode_t __kprobes *get_insn_slot(void) } /* All out of space. Need to allocate a new page. Use slot 0. */ kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); - if (!kip) { + if (!kip) return NULL; - } /* * Use module_alloc so this page is within +/- 2GB of where the @@ -214,9 +217,8 @@ static int __kprobes collect_garbage_slots(void) if (check_safety() != 0) return -EAGAIN; - hlist_for_each_safe(pos, next, &kprobe_insn_pages) { + hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) { int i; - kip = hlist_entry(pos, struct kprobe_insn_page, hlist); if (kip->ngarbage == 0) continue; kip->ngarbage = 0; /* we will collect all garbages */ @@ -235,8 +237,7 @@ void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) struct kprobe_insn_page *kip; struct hlist_node *pos; - hlist_for_each(pos, &kprobe_insn_pages) { - kip = hlist_entry(pos, struct kprobe_insn_page, hlist); + hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) { if (kip->insns <= slot && slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) { int i = (slot - kip->insns) / MAX_INSN_SIZE; @@ -249,9 +250,9 @@ void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) break; } } - if (dirty && (++kprobe_garbage_slots > INSNS_PER_PAGE)) { + + if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE) collect_garbage_slots(); - } } #endif @@ -317,7 +318,6 @@ static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs, reset_kprobe_instance(); } } - return; } static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, @@ -362,46 +362,6 @@ void __kprobes kprobes_inc_nmissed_count(struct kprobe *p) return; } -/* Called with kretprobe_lock held */ -struct kretprobe_instance __kprobes *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; -} - -/* Called with kretprobe_lock held */ -static struct kretprobe_instance __kprobes *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; -} - -/* Called with kretprobe_lock held */ -void __kprobes add_rp_inst(struct kretprobe_instance *ri) -{ - /* - * Remove rp inst off the free list - - * Add it back when probed function returns - */ - hlist_del(&ri->uflist); - - /* Add rp inst onto table */ - INIT_HLIST_NODE(&ri->hlist); - hlist_add_head(&ri->hlist, - &kretprobe_inst_table[hash_ptr(ri->task, 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); -} - /* Called with kretprobe_lock held */ void __kprobes recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head) @@ -455,7 +415,9 @@ void __kprobes kprobe_flush_task(struct task_struct *tk) static inline void free_rp_inst(struct kretprobe *rp) { struct kretprobe_instance *ri; - while ((ri = get_free_rp_inst(rp)) != NULL) { + struct hlist_node *pos, *next; + + hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, uflist) { hlist_del(&ri->uflist); kfree(ri); } @@ -536,8 +498,8 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p, static int __kprobes in_kprobes_functions(unsigned long addr) { - if (addr >= (unsigned long)__kprobes_text_start - && addr < (unsigned long)__kprobes_text_end) + if (addr >= (unsigned long)__kprobes_text_start && + addr < (unsigned long)__kprobes_text_end) return -EINVAL; return 0; } @@ -564,19 +526,24 @@ static int __kprobes __register_kprobe(struct kprobe *p, return -EINVAL; p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset); - if ((!kernel_text_address((unsigned long) p->addr)) || - in_kprobes_functions((unsigned long) p->addr)) + if (!kernel_text_address((unsigned long) p->addr) || + in_kprobes_functions((unsigned long) p->addr)) return -EINVAL; p->mod_refcounted = 0; - /* Check are we probing a module */ - if ((probed_mod = module_text_address((unsigned long) p->addr))) { + + /* + * Check if are we probing a module. + */ + probed_mod = module_text_address((unsigned long) p->addr); + if (probed_mod) { struct module *calling_mod = module_text_address(called_from); - /* We must allow modules to probe themself and - * in this case avoid incrementing the module refcount, - * so as to allow unloading of self probing modules. + /* + * We must allow modules to probe themself and in this case + * avoid incrementing the module refcount, so as to allow + * unloading of self probing modules. */ - if (calling_mod && (calling_mod != probed_mod)) { + if (calling_mod && calling_mod != probed_mod) { if (unlikely(!try_module_get(probed_mod))) return -EINVAL; p->mod_refcounted = 1; @@ -594,19 +561,21 @@ static int __kprobes __register_kprobe(struct kprobe *p, goto out; } - if ((ret = arch_prepare_kprobe(p)) != 0) + ret = arch_prepare_kprobe(p); + if (ret) goto out; INIT_HLIST_NODE(&p->hlist); hlist_add_head_rcu(&p->hlist, &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); - if (atomic_add_return(1, &kprobe_count) == \ + if (kprobe_enabled) { + if (atomic_add_return(1, &kprobe_count) == \ (ARCH_INACTIVE_KPROBE_COUNT + 1)) - register_page_fault_notifier(&kprobe_page_fault_nb); - - arch_arm_kprobe(p); + register_page_fault_notifier(&kprobe_page_fault_nb); + arch_arm_kprobe(p); + } out: mutex_unlock(&kprobe_mutex); @@ -617,8 +586,7 @@ out: int __kprobes register_kprobe(struct kprobe *p) { - return __register_kprobe(p, - (unsigned long)__builtin_return_address(0)); + return __register_kprobe(p, (unsigned long)__builtin_return_address(0)); } void __kprobes unregister_kprobe(struct kprobe *p) @@ -642,11 +610,16 @@ void __kprobes unregister_kprobe(struct kprobe *p) return; } valid_p: - if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) && - (p->list.next == &old_p->list) && - (p->list.prev == &old_p->list))) { - /* Only probe on the hash list */ - arch_disarm_kprobe(p); + if (old_p == p || + (old_p->pre_handler == aggr_pre_handler && + p->list.next == &old_p->list && p->list.prev == &old_p->list)) { + /* + * Only probe on the hash list. Disarm only if kprobes are + * enabled - otherwise, the breakpoint would already have + * been removed. We save on flushing icache. + */ + if (kprobe_enabled) + arch_disarm_kprobe(p); hlist_del_rcu(&old_p->hlist); cleanup_p = 1; } else { @@ -657,9 +630,11 @@ valid_p: mutex_unlock(&kprobe_mutex); synchronize_sched(); - if (p->mod_refcounted && - (mod = module_text_address((unsigned long)p->addr))) - module_put(mod); + if (p->mod_refcounted) { + mod = module_text_address((unsigned long)p->addr); + if (mod) + module_put(mod); + } if (cleanup_p) { if (p != old_p) { @@ -730,7 +705,21 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p, /*TODO: consider to only swap the RA after the last pre_handler fired */ spin_lock_irqsave(&kretprobe_lock, flags); - arch_prepare_kretprobe(rp, regs); + if (!hlist_empty(&rp->free_instances)) { + struct kretprobe_instance *ri; + + ri = hlist_entry(rp->free_instances.first, + struct kretprobe_instance, uflist); + ri->rp = rp; + ri->task = current; + arch_prepare_kretprobe(ri, regs); + + /* XXX(hch): why is there no hlist_move_head? */ + hlist_del(&ri->uflist); + hlist_add_head(&ri->uflist, &ri->rp->used_instances); + hlist_add_head(&ri->hlist, kretprobe_inst_table_head(ri->task)); + } else + rp->nmissed++; spin_unlock_irqrestore(&kretprobe_lock, flags); return 0; } @@ -793,11 +782,13 @@ void __kprobes unregister_kretprobe(struct kretprobe *rp) { unsigned long flags; struct kretprobe_instance *ri; + struct hlist_node *pos, *next; unregister_kprobe(&rp->kp); + /* No race here */ spin_lock_irqsave(&kretprobe_lock, flags); - while ((ri = get_used_rp_inst(rp)) != NULL) { + hlist_for_each_entry_safe(ri, pos, next, &rp->used_instances, uflist) { ri->rp = NULL; hlist_del(&ri->uflist); } @@ -817,6 +808,9 @@ static int __init init_kprobes(void) } atomic_set(&kprobe_count, 0); + /* By default, kprobes are enabled */ + kprobe_enabled = true; + err = arch_init_kprobes(); if (!err) err = register_die_notifier(&kprobe_exceptions_nb); @@ -826,7 +820,7 @@ static int __init init_kprobes(void) #ifdef CONFIG_DEBUG_FS static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p, - const char *sym, int offset,char *modname) + const char *sym, int offset,char *modname) { char *kprobe_type; @@ -868,13 +862,13 @@ static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v) struct kprobe *p, *kp; const char *sym = NULL; unsigned int i = *(loff_t *) v; - unsigned long size, offset = 0; + unsigned long offset = 0; char *modname, namebuf[128]; head = &kprobe_table[i]; preempt_disable(); hlist_for_each_entry_rcu(p, node, head, hlist) { - sym = kallsyms_lookup((unsigned long)p->addr, &size, + sym = kallsyms_lookup((unsigned long)p->addr, NULL, &offset, &modname, namebuf); if (p->pre_handler == aggr_pre_handler) { list_for_each_entry_rcu(kp, &p->list, list) @@ -905,9 +899,130 @@ static struct file_operations debugfs_kprobes_operations = { .release = seq_release, }; +static void __kprobes enable_all_kprobes(void) +{ + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p; + unsigned int i; + + mutex_lock(&kprobe_mutex); + + /* If kprobes are already enabled, just return */ + if (kprobe_enabled) + goto already_enabled; + + /* + * Re-register the page fault notifier only if there are any + * active probes at the time of enabling kprobes globally + */ + if (atomic_read(&kprobe_count) > ARCH_INACTIVE_KPROBE_COUNT) + register_page_fault_notifier(&kprobe_page_fault_nb); + + for (i = 0; i < KPROBE_TABLE_SIZE; i++) { + head = &kprobe_table[i]; + hlist_for_each_entry_rcu(p, node, head, hlist) + arch_arm_kprobe(p); + } + + kprobe_enabled = true; + printk(KERN_INFO "Kprobes globally enabled\n"); + +already_enabled: + mutex_unlock(&kprobe_mutex); + return; +} + +static void __kprobes disable_all_kprobes(void) +{ + struct hlist_head *head; + struct hlist_node *node; + struct kprobe *p; + unsigned int i; + + mutex_lock(&kprobe_mutex); + + /* If kprobes are already disabled, just return */ + if (!kprobe_enabled) + goto already_disabled; + + kprobe_enabled = false; + printk(KERN_INFO "Kprobes globally disabled\n"); + for (i = 0; i < KPROBE_TABLE_SIZE; i++) { + head = &kprobe_table[i]; + hlist_for_each_entry_rcu(p, node, head, hlist) { + if (!arch_trampoline_kprobe(p)) + arch_disarm_kprobe(p); + } + } + + mutex_unlock(&kprobe_mutex); + /* Allow all currently running kprobes to complete */ + synchronize_sched(); + + mutex_lock(&kprobe_mutex); + /* Unconditionally unregister the page_fault notifier */ + unregister_page_fault_notifier(&kprobe_page_fault_nb); + +already_disabled: + mutex_unlock(&kprobe_mutex); + return; +} + +/* + * XXX: The debugfs bool file interface doesn't allow for callbacks + * when the bool state is switched. We can reuse that facility when + * available + */ +static ssize_t read_enabled_file_bool(struct file *file, + char __user *user_buf, size_t count, loff_t *ppos) +{ + char buf[3]; + + if (kprobe_enabled) + buf[0] = '1'; + else + buf[0] = '0'; + buf[1] = '\n'; + buf[2] = 0x00; + return simple_read_from_buffer(user_buf, count, ppos, buf, 2); +} + +static ssize_t write_enabled_file_bool(struct file *file, + const char __user *user_buf, size_t count, loff_t *ppos) +{ + char buf[32]; + int buf_size; + + buf_size = min(count, (sizeof(buf)-1)); + if (copy_from_user(buf, user_buf, buf_size)) + return -EFAULT; + + switch (buf[0]) { + case 'y': + case 'Y': + case '1': + enable_all_kprobes(); + break; + case 'n': + case 'N': + case '0': + disable_all_kprobes(); + break; + } + + return count; +} + +static struct file_operations fops_kp = { + .read = read_enabled_file_bool, + .write = write_enabled_file_bool, +}; + static int __kprobes debugfs_kprobe_init(void) { struct dentry *dir, *file; + unsigned int value = 1; dir = debugfs_create_dir("kprobes", NULL); if (!dir) @@ -920,6 +1035,13 @@ static int __kprobes debugfs_kprobe_init(void) return -ENOMEM; } + file = debugfs_create_file("enabled", 0600, dir, + &value, &fops_kp); + if (!file) { + debugfs_remove(dir); + return -ENOMEM; + } + return 0; }