diff options
Diffstat (limited to 'kernel/trace/fprobe.c')
| -rw-r--r-- | kernel/trace/fprobe.c | 972 |
1 files changed, 972 insertions, 0 deletions
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c new file mode 100644 index 000000000000..1188eefef07c --- /dev/null +++ b/kernel/trace/fprobe.c @@ -0,0 +1,972 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fprobe - Simple ftrace probe wrapper for function entry. + */ +#define pr_fmt(fmt) "fprobe: " fmt + +#include <linux/err.h> +#include <linux/fprobe.h> +#include <linux/kallsyms.h> +#include <linux/kprobes.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/rhashtable.h> +#include <linux/slab.h> +#include <linux/sort.h> + +#include <asm/fprobe.h> + +#include "trace.h" + +#define FPROBE_IP_HASH_BITS 8 +#define FPROBE_IP_TABLE_SIZE (1 << FPROBE_IP_HASH_BITS) + +#define FPROBE_HASH_BITS 6 +#define FPROBE_TABLE_SIZE (1 << FPROBE_HASH_BITS) + +#define SIZE_IN_LONG(x) ((x + sizeof(long) - 1) >> (sizeof(long) == 8 ? 3 : 2)) + +/* + * fprobe_table: hold 'fprobe_hlist::hlist' for checking the fprobe still + * exists. The key is the address of fprobe instance. + * fprobe_ip_table: hold 'fprobe_hlist::array[*]' for searching the fprobe + * instance related to the function address. The key is the ftrace IP + * address. + * + * When unregistering the fprobe, fprobe_hlist::fp and fprobe_hlist::array[*].fp + * are set NULL and delete those from both hash tables (by hlist_del_rcu). + * After an RCU grace period, the fprobe_hlist itself will be released. + * + * fprobe_table and fprobe_ip_table can be accessed from either + * - Normal hlist traversal and RCU add/del under 'fprobe_mutex' is held. + * - RCU hlist traversal under disabling preempt + */ +static struct hlist_head fprobe_table[FPROBE_TABLE_SIZE]; +static struct rhltable fprobe_ip_table; +static DEFINE_MUTEX(fprobe_mutex); +static struct fgraph_ops fprobe_graph_ops; + +static u32 fprobe_node_hashfn(const void *data, u32 len, u32 seed) +{ + return hash_ptr(*(unsigned long **)data, 32); +} + +static int fprobe_node_cmp(struct rhashtable_compare_arg *arg, + const void *ptr) +{ + unsigned long key = *(unsigned long *)arg->key; + const struct fprobe_hlist_node *n = ptr; + + return n->addr != key; +} + +static u32 fprobe_node_obj_hashfn(const void *data, u32 len, u32 seed) +{ + const struct fprobe_hlist_node *n = data; + + return hash_ptr((void *)n->addr, 32); +} + +static const struct rhashtable_params fprobe_rht_params = { + .head_offset = offsetof(struct fprobe_hlist_node, hlist), + .key_offset = offsetof(struct fprobe_hlist_node, addr), + .key_len = sizeof_field(struct fprobe_hlist_node, addr), + .hashfn = fprobe_node_hashfn, + .obj_hashfn = fprobe_node_obj_hashfn, + .obj_cmpfn = fprobe_node_cmp, + .automatic_shrinking = true, +}; + +/* Node insertion and deletion requires the fprobe_mutex */ +static int insert_fprobe_node(struct fprobe_hlist_node *node) +{ + lockdep_assert_held(&fprobe_mutex); + + return rhltable_insert(&fprobe_ip_table, &node->hlist, fprobe_rht_params); +} + +/* Return true if there are synonims */ +static bool delete_fprobe_node(struct fprobe_hlist_node *node) +{ + lockdep_assert_held(&fprobe_mutex); + bool ret; + + /* Avoid double deleting */ + if (READ_ONCE(node->fp) != NULL) { + WRITE_ONCE(node->fp, NULL); + rhltable_remove(&fprobe_ip_table, &node->hlist, + fprobe_rht_params); + } + + rcu_read_lock(); + ret = !!rhltable_lookup(&fprobe_ip_table, &node->addr, + fprobe_rht_params); + rcu_read_unlock(); + + return ret; +} + +/* Check existence of the fprobe */ +static bool is_fprobe_still_exist(struct fprobe *fp) +{ + struct hlist_head *head; + struct fprobe_hlist *fph; + + head = &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)]; + hlist_for_each_entry_rcu(fph, head, hlist, + lockdep_is_held(&fprobe_mutex)) { + if (fph->fp == fp) + return true; + } + return false; +} +NOKPROBE_SYMBOL(is_fprobe_still_exist); + +static int add_fprobe_hash(struct fprobe *fp) +{ + struct fprobe_hlist *fph = fp->hlist_array; + struct hlist_head *head; + + lockdep_assert_held(&fprobe_mutex); + + if (WARN_ON_ONCE(!fph)) + return -EINVAL; + + if (is_fprobe_still_exist(fp)) + return -EEXIST; + + head = &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)]; + hlist_add_head_rcu(&fp->hlist_array->hlist, head); + return 0; +} + +static int del_fprobe_hash(struct fprobe *fp) +{ + struct fprobe_hlist *fph = fp->hlist_array; + + lockdep_assert_held(&fprobe_mutex); + + if (WARN_ON_ONCE(!fph)) + return -EINVAL; + + if (!is_fprobe_still_exist(fp)) + return -ENOENT; + + fph->fp = NULL; + hlist_del_rcu(&fph->hlist); + return 0; +} + +#ifdef ARCH_DEFINE_ENCODE_FPROBE_HEADER + +/* The arch should encode fprobe_header info into one unsigned long */ +#define FPROBE_HEADER_SIZE_IN_LONG 1 + +static inline bool write_fprobe_header(unsigned long *stack, + struct fprobe *fp, unsigned int size_words) +{ + if (WARN_ON_ONCE(size_words > MAX_FPROBE_DATA_SIZE_WORD || + !arch_fprobe_header_encodable(fp))) + return false; + + *stack = arch_encode_fprobe_header(fp, size_words); + return true; +} + +static inline void read_fprobe_header(unsigned long *stack, + struct fprobe **fp, unsigned int *size_words) +{ + *fp = arch_decode_fprobe_header_fp(*stack); + *size_words = arch_decode_fprobe_header_size(*stack); +} + +#else + +/* Generic fprobe_header */ +struct __fprobe_header { + struct fprobe *fp; + unsigned long size_words; +} __packed; + +#define FPROBE_HEADER_SIZE_IN_LONG SIZE_IN_LONG(sizeof(struct __fprobe_header)) + +static inline bool write_fprobe_header(unsigned long *stack, + struct fprobe *fp, unsigned int size_words) +{ + struct __fprobe_header *fph = (struct __fprobe_header *)stack; + + if (WARN_ON_ONCE(size_words > MAX_FPROBE_DATA_SIZE_WORD)) + return false; + + fph->fp = fp; + fph->size_words = size_words; + return true; +} + +static inline void read_fprobe_header(unsigned long *stack, + struct fprobe **fp, unsigned int *size_words) +{ + struct __fprobe_header *fph = (struct __fprobe_header *)stack; + + *fp = fph->fp; + *size_words = fph->size_words; +} + +#endif + +/* + * fprobe shadow stack management: + * Since fprobe shares a single fgraph_ops, it needs to share the stack entry + * among the probes on the same function exit. Note that a new probe can be + * registered before a target function is returning, we can not use the hash + * table to find the corresponding probes. Thus the probe address is stored on + * the shadow stack with its entry data size. + * + */ +static inline int __fprobe_handler(unsigned long ip, unsigned long parent_ip, + struct fprobe *fp, struct ftrace_regs *fregs, + void *data) +{ + if (!fp->entry_handler) + return 0; + + return fp->entry_handler(fp, ip, parent_ip, fregs, data); +} + +static inline int __fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip, + struct fprobe *fp, struct ftrace_regs *fregs, + void *data) +{ + int ret; + /* + * This user handler is shared with other kprobes and is not expected to be + * called recursively. So if any other kprobe handler is running, this will + * exit as kprobe does. See the section 'Share the callbacks with kprobes' + * in Documentation/trace/fprobe.rst for more information. + */ + if (unlikely(kprobe_running())) { + fp->nmissed++; + return 0; + } + + kprobe_busy_begin(); + ret = __fprobe_handler(ip, parent_ip, fp, fregs, data); + kprobe_busy_end(); + return ret; +} + +#if defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) || defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS) +/* ftrace_ops callback, this processes fprobes which have only entry_handler. */ +static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct ftrace_regs *fregs) +{ + struct fprobe_hlist_node *node; + struct rhlist_head *head, *pos; + struct fprobe *fp; + int bit; + + bit = ftrace_test_recursion_trylock(ip, parent_ip); + if (bit < 0) + return; + + /* + * ftrace_test_recursion_trylock() disables preemption, but + * rhltable_lookup() checks whether rcu_read_lcok is held. + * So we take rcu_read_lock() here. + */ + rcu_read_lock(); + head = rhltable_lookup(&fprobe_ip_table, &ip, fprobe_rht_params); + + rhl_for_each_entry_rcu(node, pos, head, hlist) { + if (node->addr != ip) + break; + fp = READ_ONCE(node->fp); + if (unlikely(!fp || fprobe_disabled(fp) || fp->exit_handler)) + continue; + + if (fprobe_shared_with_kprobes(fp)) + __fprobe_kprobe_handler(ip, parent_ip, fp, fregs, NULL); + else + __fprobe_handler(ip, parent_ip, fp, fregs, NULL); + } + rcu_read_unlock(); + ftrace_test_recursion_unlock(bit); +} +NOKPROBE_SYMBOL(fprobe_ftrace_entry); + +static struct ftrace_ops fprobe_ftrace_ops = { + .func = fprobe_ftrace_entry, + .flags = FTRACE_OPS_FL_SAVE_ARGS, +}; +static int fprobe_ftrace_active; + +static int fprobe_ftrace_add_ips(unsigned long *addrs, int num) +{ + int ret; + + lockdep_assert_held(&fprobe_mutex); + + ret = ftrace_set_filter_ips(&fprobe_ftrace_ops, addrs, num, 0, 0); + if (ret) + return ret; + + if (!fprobe_ftrace_active) { + ret = register_ftrace_function(&fprobe_ftrace_ops); + if (ret) { + ftrace_free_filter(&fprobe_ftrace_ops); + return ret; + } + } + fprobe_ftrace_active++; + return 0; +} + +static void fprobe_ftrace_remove_ips(unsigned long *addrs, int num) +{ + lockdep_assert_held(&fprobe_mutex); + + fprobe_ftrace_active--; + if (!fprobe_ftrace_active) + unregister_ftrace_function(&fprobe_ftrace_ops); + if (num) + ftrace_set_filter_ips(&fprobe_ftrace_ops, addrs, num, 1, 0); +} + +static bool fprobe_is_ftrace(struct fprobe *fp) +{ + return !fp->exit_handler; +} + +#ifdef CONFIG_MODULES +static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove, + int reset) +{ + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset); + ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, remove, reset); +} +#endif +#else +static int fprobe_ftrace_add_ips(unsigned long *addrs, int num) +{ + return -ENOENT; +} + +static void fprobe_ftrace_remove_ips(unsigned long *addrs, int num) +{ +} + +static bool fprobe_is_ftrace(struct fprobe *fp) +{ + return false; +} + +#ifdef CONFIG_MODULES +static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove, + int reset) +{ + ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset); +} +#endif +#endif /* !CONFIG_DYNAMIC_FTRACE_WITH_ARGS && !CONFIG_DYNAMIC_FTRACE_WITH_REGS */ + +/* fgraph_ops callback, this processes fprobes which have exit_handler. */ +static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops, + struct ftrace_regs *fregs) +{ + unsigned long *fgraph_data = NULL; + unsigned long func = trace->func; + struct fprobe_hlist_node *node; + struct rhlist_head *head, *pos; + unsigned long ret_ip; + int reserved_words; + struct fprobe *fp; + int used, ret; + + if (WARN_ON_ONCE(!fregs)) + return 0; + + guard(rcu)(); + head = rhltable_lookup(&fprobe_ip_table, &func, fprobe_rht_params); + reserved_words = 0; + rhl_for_each_entry_rcu(node, pos, head, hlist) { + if (node->addr != func) + continue; + fp = READ_ONCE(node->fp); + if (!fp || !fp->exit_handler) + continue; + /* + * Since fprobe can be enabled until the next loop, we ignore the + * fprobe's disabled flag in this loop. + */ + reserved_words += + FPROBE_HEADER_SIZE_IN_LONG + SIZE_IN_LONG(fp->entry_data_size); + } + if (reserved_words) { + fgraph_data = fgraph_reserve_data(gops->idx, reserved_words * sizeof(long)); + if (unlikely(!fgraph_data)) { + rhl_for_each_entry_rcu(node, pos, head, hlist) { + if (node->addr != func) + continue; + fp = READ_ONCE(node->fp); + if (fp && !fprobe_disabled(fp) && !fprobe_is_ftrace(fp)) + fp->nmissed++; + } + return 0; + } + } + + /* + * TODO: recursion detection has been done in the fgraph. Thus we need + * to add a callback to increment missed counter. + */ + ret_ip = ftrace_regs_get_return_address(fregs); + used = 0; + rhl_for_each_entry_rcu(node, pos, head, hlist) { + int data_size; + void *data; + + if (node->addr != func) + continue; + fp = READ_ONCE(node->fp); + if (unlikely(!fp || fprobe_disabled(fp) || fprobe_is_ftrace(fp))) + continue; + + data_size = fp->entry_data_size; + if (data_size && fp->exit_handler) + data = fgraph_data + used + FPROBE_HEADER_SIZE_IN_LONG; + else + data = NULL; + + if (fprobe_shared_with_kprobes(fp)) + ret = __fprobe_kprobe_handler(func, ret_ip, fp, fregs, data); + else + ret = __fprobe_handler(func, ret_ip, fp, fregs, data); + + /* If entry_handler returns !0, nmissed is not counted but skips exit_handler. */ + if (!ret && fp->exit_handler) { + int size_words = SIZE_IN_LONG(data_size); + + if (write_fprobe_header(&fgraph_data[used], fp, size_words)) + used += FPROBE_HEADER_SIZE_IN_LONG + size_words; + } + } + if (used < reserved_words) + memset(fgraph_data + used, 0, reserved_words - used); + + /* If any exit_handler is set, data must be used. */ + return used != 0; +} +NOKPROBE_SYMBOL(fprobe_fgraph_entry); + +static void fprobe_return(struct ftrace_graph_ret *trace, + struct fgraph_ops *gops, + struct ftrace_regs *fregs) +{ + unsigned long *fgraph_data = NULL; + unsigned long ret_ip; + struct fprobe *fp; + int size, curr; + int size_words; + + fgraph_data = (unsigned long *)fgraph_retrieve_data(gops->idx, &size); + if (WARN_ON_ONCE(!fgraph_data)) + return; + size_words = SIZE_IN_LONG(size); + ret_ip = ftrace_regs_get_instruction_pointer(fregs); + + preempt_disable_notrace(); + + curr = 0; + while (size_words > curr) { + read_fprobe_header(&fgraph_data[curr], &fp, &size); + if (!fp) + break; + curr += FPROBE_HEADER_SIZE_IN_LONG; + if (is_fprobe_still_exist(fp) && !fprobe_disabled(fp)) { + if (WARN_ON_ONCE(curr + size > size_words)) + break; + fp->exit_handler(fp, trace->func, ret_ip, fregs, + size ? fgraph_data + curr : NULL); + } + curr += size; + } + preempt_enable_notrace(); +} +NOKPROBE_SYMBOL(fprobe_return); + +static struct fgraph_ops fprobe_graph_ops = { + .entryfunc = fprobe_fgraph_entry, + .retfunc = fprobe_return, +}; +static int fprobe_graph_active; + +/* Add @addrs to the ftrace filter and register fgraph if needed. */ +static int fprobe_graph_add_ips(unsigned long *addrs, int num) +{ + int ret; + + lockdep_assert_held(&fprobe_mutex); + + ret = ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 0, 0); + if (ret) + return ret; + + if (!fprobe_graph_active) { + ret = register_ftrace_graph(&fprobe_graph_ops); + if (WARN_ON_ONCE(ret)) { + ftrace_free_filter(&fprobe_graph_ops.ops); + return ret; + } + } + fprobe_graph_active++; + return 0; +} + +/* Remove @addrs from the ftrace filter and unregister fgraph if possible. */ +static void fprobe_graph_remove_ips(unsigned long *addrs, int num) +{ + lockdep_assert_held(&fprobe_mutex); + + fprobe_graph_active--; + /* Q: should we unregister it ? */ + if (!fprobe_graph_active) + unregister_ftrace_graph(&fprobe_graph_ops); + + if (num) + ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0); +} + +#ifdef CONFIG_MODULES + +#define FPROBE_IPS_BATCH_INIT 8 +/* instruction pointer address list */ +struct fprobe_addr_list { + int index; + int size; + unsigned long *addrs; +}; + +static int fprobe_addr_list_add(struct fprobe_addr_list *alist, unsigned long addr) +{ + unsigned long *addrs; + + /* Previously we failed to expand the list. */ + if (alist->index == alist->size) + return -ENOSPC; + + alist->addrs[alist->index++] = addr; + if (alist->index < alist->size) + return 0; + + /* Expand the address list */ + addrs = kcalloc(alist->size * 2, sizeof(*addrs), GFP_KERNEL); + if (!addrs) + return -ENOMEM; + + memcpy(addrs, alist->addrs, alist->size * sizeof(*addrs)); + alist->size *= 2; + kfree(alist->addrs); + alist->addrs = addrs; + + return 0; +} + +static void fprobe_remove_node_in_module(struct module *mod, struct fprobe_hlist_node *node, + struct fprobe_addr_list *alist) +{ + if (!within_module(node->addr, mod)) + return; + if (delete_fprobe_node(node)) + return; + /* + * If failed to update alist, just continue to update hlist. + * Therefore, at list user handler will not hit anymore. + */ + fprobe_addr_list_add(alist, node->addr); +} + +/* Handle module unloading to manage fprobe_ip_table. */ +static int fprobe_module_callback(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct fprobe_addr_list alist = {.size = FPROBE_IPS_BATCH_INIT}; + struct fprobe_hlist_node *node; + struct rhashtable_iter iter; + struct module *mod = data; + + if (val != MODULE_STATE_GOING) + return NOTIFY_DONE; + + alist.addrs = kcalloc(alist.size, sizeof(*alist.addrs), GFP_KERNEL); + /* If failed to alloc memory, we can not remove ips from hash. */ + if (!alist.addrs) + return NOTIFY_DONE; + + mutex_lock(&fprobe_mutex); + rhltable_walk_enter(&fprobe_ip_table, &iter); + do { + rhashtable_walk_start(&iter); + + while ((node = rhashtable_walk_next(&iter)) && !IS_ERR(node)) + fprobe_remove_node_in_module(mod, node, &alist); + + rhashtable_walk_stop(&iter); + } while (node == ERR_PTR(-EAGAIN)); + rhashtable_walk_exit(&iter); + + if (alist.index > 0) + fprobe_set_ips(alist.addrs, alist.index, 1, 0); + mutex_unlock(&fprobe_mutex); + + kfree(alist.addrs); + + return NOTIFY_DONE; +} + +static struct notifier_block fprobe_module_nb = { + .notifier_call = fprobe_module_callback, + .priority = 0, +}; + +static int __init init_fprobe_module(void) +{ + return register_module_notifier(&fprobe_module_nb); +} +early_initcall(init_fprobe_module); +#endif + +static int symbols_cmp(const void *a, const void *b) +{ + const char **str_a = (const char **) a; + const char **str_b = (const char **) b; + + return strcmp(*str_a, *str_b); +} + +/* Convert ftrace location address from symbols */ +static unsigned long *get_ftrace_locations(const char **syms, int num) +{ + unsigned long *addrs; + + /* Convert symbols to symbol address */ + addrs = kcalloc(num, sizeof(*addrs), GFP_KERNEL); + if (!addrs) + return ERR_PTR(-ENOMEM); + + /* ftrace_lookup_symbols expects sorted symbols */ + sort(syms, num, sizeof(*syms), symbols_cmp, NULL); + + if (!ftrace_lookup_symbols(syms, num, addrs)) + return addrs; + + kfree(addrs); + return ERR_PTR(-ENOENT); +} + +struct filter_match_data { + const char *filter; + const char *notfilter; + size_t index; + size_t size; + unsigned long *addrs; + struct module **mods; +}; + +static int filter_match_callback(void *data, const char *name, unsigned long addr) +{ + struct filter_match_data *match = data; + + if (!glob_match(match->filter, name) || + (match->notfilter && glob_match(match->notfilter, name))) + return 0; + + if (!ftrace_location(addr)) + return 0; + + if (match->addrs) { + struct module *mod = __module_text_address(addr); + + if (mod && !try_module_get(mod)) + return 0; + + match->mods[match->index] = mod; + match->addrs[match->index] = addr; + } + match->index++; + return match->index == match->size; +} + +/* + * Make IP list from the filter/no-filter glob patterns. + * Return the number of matched symbols, or errno. + * If @addrs == NULL, this just counts the number of matched symbols. If @addrs + * is passed with an array, we need to pass the an @mods array of the same size + * to increment the module refcount for each symbol. + * This means we also need to call `module_put` for each element of @mods after + * using the @addrs. + */ +static int get_ips_from_filter(const char *filter, const char *notfilter, + unsigned long *addrs, struct module **mods, + size_t size) +{ + struct filter_match_data match = { .filter = filter, .notfilter = notfilter, + .index = 0, .size = size, .addrs = addrs, .mods = mods}; + int ret; + + if (addrs && !mods) + return -EINVAL; + + ret = kallsyms_on_each_symbol(filter_match_callback, &match); + if (ret < 0) + return ret; + if (IS_ENABLED(CONFIG_MODULES)) { + ret = module_kallsyms_on_each_symbol(NULL, filter_match_callback, &match); + if (ret < 0) + return ret; + } + + return match.index ?: -ENOENT; +} + +static void fprobe_fail_cleanup(struct fprobe *fp) +{ + kfree(fp->hlist_array); + fp->hlist_array = NULL; +} + +/* Initialize the fprobe data structure. */ +static int fprobe_init(struct fprobe *fp, unsigned long *addrs, int num) +{ + struct fprobe_hlist *hlist_array; + unsigned long addr; + int size, i; + + if (!fp || !addrs || num <= 0) + return -EINVAL; + + size = ALIGN(fp->entry_data_size, sizeof(long)); + if (size > MAX_FPROBE_DATA_SIZE) + return -E2BIG; + fp->entry_data_size = size; + + hlist_array = kzalloc(struct_size(hlist_array, array, num), GFP_KERNEL); + if (!hlist_array) + return -ENOMEM; + + fp->nmissed = 0; + + hlist_array->size = num; + fp->hlist_array = hlist_array; + hlist_array->fp = fp; + for (i = 0; i < num; i++) { + hlist_array->array[i].fp = fp; + addr = ftrace_location(addrs[i]); + if (!addr) { + fprobe_fail_cleanup(fp); + return -ENOENT; + } + hlist_array->array[i].addr = addr; + } + return 0; +} + +#define FPROBE_IPS_MAX INT_MAX + +int fprobe_count_ips_from_filter(const char *filter, const char *notfilter) +{ + return get_ips_from_filter(filter, notfilter, NULL, NULL, FPROBE_IPS_MAX); +} + +/** + * register_fprobe() - Register fprobe to ftrace by pattern. + * @fp: A fprobe data structure to be registered. + * @filter: A wildcard pattern of probed symbols. + * @notfilter: A wildcard pattern of NOT probed symbols. + * + * Register @fp to ftrace for enabling the probe on the symbols matched to @filter. + * If @notfilter is not NULL, the symbols matched the @notfilter are not probed. + * + * Return 0 if @fp is registered successfully, -errno if not. + */ +int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter) +{ + unsigned long *addrs __free(kfree) = NULL; + struct module **mods __free(kfree) = NULL; + int ret, num; + + if (!fp || !filter) + return -EINVAL; + + num = get_ips_from_filter(filter, notfilter, NULL, NULL, FPROBE_IPS_MAX); + if (num < 0) + return num; + + addrs = kcalloc(num, sizeof(*addrs), GFP_KERNEL); + if (!addrs) + return -ENOMEM; + + mods = kcalloc(num, sizeof(*mods), GFP_KERNEL); + if (!mods) + return -ENOMEM; + + ret = get_ips_from_filter(filter, notfilter, addrs, mods, num); + if (ret < 0) + return ret; + + ret = register_fprobe_ips(fp, addrs, ret); + + for (int i = 0; i < num; i++) { + if (mods[i]) + module_put(mods[i]); + } + return ret; +} +EXPORT_SYMBOL_GPL(register_fprobe); + +/** + * register_fprobe_ips() - Register fprobe to ftrace by address. + * @fp: A fprobe data structure to be registered. + * @addrs: An array of target function address. + * @num: The number of entries of @addrs. + * + * Register @fp to ftrace for enabling the probe on the address given by @addrs. + * The @addrs must be the addresses of ftrace location address, which may be + * the symbol address + arch-dependent offset. + * If you unsure what this mean, please use other registration functions. + * + * Return 0 if @fp is registered successfully, -errno if not. + */ +int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num) +{ + struct fprobe_hlist *hlist_array; + int ret, i; + + ret = fprobe_init(fp, addrs, num); + if (ret) + return ret; + + mutex_lock(&fprobe_mutex); + + hlist_array = fp->hlist_array; + if (fprobe_is_ftrace(fp)) + ret = fprobe_ftrace_add_ips(addrs, num); + else + ret = fprobe_graph_add_ips(addrs, num); + + if (!ret) { + add_fprobe_hash(fp); + for (i = 0; i < hlist_array->size; i++) { + ret = insert_fprobe_node(&hlist_array->array[i]); + if (ret) + break; + } + /* fallback on insert error */ + if (ret) { + for (i--; i >= 0; i--) + delete_fprobe_node(&hlist_array->array[i]); + } + } + mutex_unlock(&fprobe_mutex); + + if (ret) + fprobe_fail_cleanup(fp); + + return ret; +} +EXPORT_SYMBOL_GPL(register_fprobe_ips); + +/** + * register_fprobe_syms() - Register fprobe to ftrace by symbols. + * @fp: A fprobe data structure to be registered. + * @syms: An array of target symbols. + * @num: The number of entries of @syms. + * + * Register @fp to the symbols given by @syms array. This will be useful if + * you are sure the symbols exist in the kernel. + * + * Return 0 if @fp is registered successfully, -errno if not. + */ +int register_fprobe_syms(struct fprobe *fp, const char **syms, int num) +{ + unsigned long *addrs; + int ret; + + if (!fp || !syms || num <= 0) + return -EINVAL; + + addrs = get_ftrace_locations(syms, num); + if (IS_ERR(addrs)) + return PTR_ERR(addrs); + + ret = register_fprobe_ips(fp, addrs, num); + + kfree(addrs); + + return ret; +} +EXPORT_SYMBOL_GPL(register_fprobe_syms); + +bool fprobe_is_registered(struct fprobe *fp) +{ + if (!fp || !fp->hlist_array) + return false; + return true; +} + +/** + * unregister_fprobe() - Unregister fprobe. + * @fp: A fprobe data structure to be unregistered. + * + * Unregister fprobe (and remove ftrace hooks from the function entries). + * + * Return 0 if @fp is unregistered successfully, -errno if not. + */ +int unregister_fprobe(struct fprobe *fp) +{ + struct fprobe_hlist *hlist_array; + unsigned long *addrs = NULL; + int ret = 0, i, count; + + mutex_lock(&fprobe_mutex); + if (!fp || !is_fprobe_still_exist(fp)) { + ret = -EINVAL; + goto out; + } + + hlist_array = fp->hlist_array; + addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL); + if (!addrs) { + ret = -ENOMEM; /* TODO: Fallback to one-by-one loop */ + goto out; + } + + /* Remove non-synonim ips from table and hash */ + count = 0; + for (i = 0; i < hlist_array->size; i++) { + if (!delete_fprobe_node(&hlist_array->array[i])) + addrs[count++] = hlist_array->array[i].addr; + } + del_fprobe_hash(fp); + + if (fprobe_is_ftrace(fp)) + fprobe_ftrace_remove_ips(addrs, count); + else + fprobe_graph_remove_ips(addrs, count); + + kfree_rcu(hlist_array, rcu); + fp->hlist_array = NULL; + +out: + mutex_unlock(&fprobe_mutex); + + kfree(addrs); + return ret; +} +EXPORT_SYMBOL_GPL(unregister_fprobe); + +static int __init fprobe_initcall(void) +{ + rhltable_init(&fprobe_ip_table, &fprobe_rht_params); + return 0; +} +core_initcall(fprobe_initcall); |