diff options
| -rw-r--r-- | include/linux/ftrace.h | 38 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 242 |
2 files changed, 254 insertions, 26 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index acb35243ce5d..0b61371e287b 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -208,6 +208,43 @@ enum { FTRACE_OPS_FL_DIRECT = BIT(17), }; +/* + * FTRACE_OPS_CMD_* commands allow the ftrace core logic to request changes + * to a ftrace_ops. Note, the requests may fail. + * + * ENABLE_SHARE_IPMODIFY_SELF - enable a DIRECT ops to work on the same + * function as an ops with IPMODIFY. Called + * when the DIRECT ops is being registered. + * This is called with both direct_mutex and + * ftrace_lock are locked. + * + * ENABLE_SHARE_IPMODIFY_PEER - enable a DIRECT ops to work on the same + * function as an ops with IPMODIFY. Called + * when the other ops (the one with IPMODIFY) + * is being registered. + * This is called with direct_mutex locked. + * + * DISABLE_SHARE_IPMODIFY_PEER - disable a DIRECT ops to work on the same + * function as an ops with IPMODIFY. Called + * when the other ops (the one with IPMODIFY) + * is being unregistered. + * This is called with direct_mutex locked. + */ +enum ftrace_ops_cmd { + FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF, + FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER, + FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER, +}; + +/* + * For most ftrace_ops_cmd, + * Returns: + * 0 - Success. + * Negative on failure. The return value is dependent on the + * callback. + */ +typedef int (*ftrace_ops_func_t)(struct ftrace_ops *op, enum ftrace_ops_cmd cmd); + #ifdef CONFIG_DYNAMIC_FTRACE /* The hash used to know what functions callbacks trace */ struct ftrace_ops_hash { @@ -250,6 +287,7 @@ struct ftrace_ops { unsigned long trampoline; unsigned long trampoline_size; struct list_head list; + ftrace_ops_func_t ops_func; #endif }; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 5d67dc12231d..bc921a3f7ea8 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1861,6 +1861,8 @@ static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops, ftrace_hash_rec_update_modify(ops, filter_hash, 1); } +static bool ops_references_ip(struct ftrace_ops *ops, unsigned long ip); + /* * Try to update IPMODIFY flag on each ftrace_rec. Return 0 if it is OK * or no-needed to update, -EBUSY if it detects a conflict of the flag @@ -1869,6 +1871,13 @@ static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops, * - If the hash is NULL, it hits all recs (if IPMODIFY is set, this is rejected) * - If the hash is EMPTY_HASH, it hits nothing * - Anything else hits the recs which match the hash entries. + * + * DIRECT ops does not have IPMODIFY flag, but we still need to check it + * against functions with FTRACE_FL_IPMODIFY. If there is any overlap, call + * ops_func(SHARE_IPMODIFY_SELF) to make sure current ops can share with + * IPMODIFY. If ops_func(SHARE_IPMODIFY_SELF) returns non-zero, propagate + * the return value to the caller and eventually to the owner of the DIRECT + * ops. */ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops, struct ftrace_hash *old_hash, @@ -1877,17 +1886,26 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops, struct ftrace_page *pg; struct dyn_ftrace *rec, *end = NULL; int in_old, in_new; + bool is_ipmodify, is_direct; /* Only update if the ops has been registered */ if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) return 0; - if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY)) + is_ipmodify = ops->flags & FTRACE_OPS_FL_IPMODIFY; + is_direct = ops->flags & FTRACE_OPS_FL_DIRECT; + + /* neither IPMODIFY nor DIRECT, skip */ + if (!is_ipmodify && !is_direct) + return 0; + + if (WARN_ON_ONCE(is_ipmodify && is_direct)) return 0; /* - * Since the IPMODIFY is a very address sensitive action, we do not - * allow ftrace_ops to set all functions to new hash. + * Since the IPMODIFY and DIRECT are very address sensitive + * actions, we do not allow ftrace_ops to set all functions to new + * hash. */ if (!new_hash || !old_hash) return -EINVAL; @@ -1905,12 +1923,32 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops, continue; if (in_new) { - /* New entries must ensure no others are using it */ - if (rec->flags & FTRACE_FL_IPMODIFY) - goto rollback; - rec->flags |= FTRACE_FL_IPMODIFY; - } else /* Removed entry */ + if (rec->flags & FTRACE_FL_IPMODIFY) { + int ret; + + /* Cannot have two ipmodify on same rec */ + if (is_ipmodify) + goto rollback; + + FTRACE_WARN_ON(rec->flags & FTRACE_FL_DIRECT); + + /* + * Another ops with IPMODIFY is already + * attached. We are now attaching a direct + * ops. Run SHARE_IPMODIFY_SELF, to check + * whether sharing is supported. + */ + if (!ops->ops_func) + return -EBUSY; + ret = ops->ops_func(ops, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF); + if (ret) + return ret; + } else if (is_ipmodify) { + rec->flags |= FTRACE_FL_IPMODIFY; + } + } else if (is_ipmodify) { rec->flags &= ~FTRACE_FL_IPMODIFY; + } } while_for_each_ftrace_rec(); return 0; @@ -2454,8 +2492,7 @@ static void call_direct_funcs(unsigned long ip, unsigned long pip, struct ftrace_ops direct_ops = { .func = call_direct_funcs, - .flags = FTRACE_OPS_FL_IPMODIFY - | FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS + .flags = FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_PERMANENT, /* * By declaring the main trampoline as this trampoline @@ -3072,14 +3109,14 @@ static inline int ops_traces_mod(struct ftrace_ops *ops) } /* - * Check if the current ops references the record. + * Check if the current ops references the given ip. * * If the ops traces all functions, then it was already accounted for. * If the ops does not trace the current record function, skip it. * If the ops ignores the function via notrace filter, skip it. */ -static inline bool -ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec) +static bool +ops_references_ip(struct ftrace_ops *ops, unsigned long ip) { /* If ops isn't enabled, ignore it */ if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) @@ -3091,16 +3128,29 @@ ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec) /* The function must be in the filter */ if (!ftrace_hash_empty(ops->func_hash->filter_hash) && - !__ftrace_lookup_ip(ops->func_hash->filter_hash, rec->ip)) + !__ftrace_lookup_ip(ops->func_hash->filter_hash, ip)) return false; /* If in notrace hash, we ignore it too */ - if (ftrace_lookup_ip(ops->func_hash->notrace_hash, rec->ip)) + if (ftrace_lookup_ip(ops->func_hash->notrace_hash, ip)) return false; return true; } +/* + * Check if the current ops references the record. + * + * If the ops traces all functions, then it was already accounted for. + * If the ops does not trace the current record function, skip it. + * If the ops ignores the function via notrace filter, skip it. + */ +static bool +ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec) +{ + return ops_references_ip(ops, rec->ip); +} + static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs) { bool init_nop = ftrace_need_init_nop(); @@ -5215,6 +5265,8 @@ static struct ftrace_direct_func *ftrace_alloc_direct_func(unsigned long addr) return direct; } +static int register_ftrace_function_nolock(struct ftrace_ops *ops); + /** * register_ftrace_direct - Call a custom trampoline directly * @ip: The address of the nop at the beginning of a function @@ -5286,7 +5338,7 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr) ret = ftrace_set_filter_ip(&direct_ops, ip, 0, 0); if (!ret && !(direct_ops.flags & FTRACE_OPS_FL_ENABLED)) { - ret = register_ftrace_function(&direct_ops); + ret = register_ftrace_function_nolock(&direct_ops); if (ret) ftrace_set_filter_ip(&direct_ops, ip, 1, 0); } @@ -5545,8 +5597,7 @@ int modify_ftrace_direct(unsigned long ip, } EXPORT_SYMBOL_GPL(modify_ftrace_direct); -#define MULTI_FLAGS (FTRACE_OPS_FL_IPMODIFY | FTRACE_OPS_FL_DIRECT | \ - FTRACE_OPS_FL_SAVE_REGS) +#define MULTI_FLAGS (FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS) static int check_direct_multi(struct ftrace_ops *ops) { @@ -5639,7 +5690,7 @@ int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) ops->flags = MULTI_FLAGS; ops->trampoline = FTRACE_REGS_ADDR; - err = register_ftrace_function(ops); + err = register_ftrace_function_nolock(ops); out_remove: if (err) @@ -5709,7 +5760,7 @@ __modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) ftrace_ops_init(&tmp_ops); tmp_ops.func_hash = ops->func_hash; - err = register_ftrace_function(&tmp_ops); + err = register_ftrace_function_nolock(&tmp_ops); if (err) return err; @@ -8003,6 +8054,143 @@ int ftrace_is_dead(void) return ftrace_disabled; } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS +/* + * When registering ftrace_ops with IPMODIFY, it is necessary to make sure + * it doesn't conflict with any direct ftrace_ops. If there is existing + * direct ftrace_ops on a kernel function being patched, call + * FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER on it to enable sharing. + * + * @ops: ftrace_ops being registered. + * + * Returns: + * 0 on success; + * Negative on failure. + */ +static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops) +{ + struct ftrace_func_entry *entry; + struct ftrace_hash *hash; + struct ftrace_ops *op; + int size, i, ret; + + lockdep_assert_held_once(&direct_mutex); + + if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY)) + return 0; + + hash = ops->func_hash->filter_hash; + size = 1 << hash->size_bits; + for (i = 0; i < size; i++) { + hlist_for_each_entry(entry, &hash->buckets[i], hlist) { + unsigned long ip = entry->ip; + bool found_op = false; + + mutex_lock(&ftrace_lock); + do_for_each_ftrace_op(op, ftrace_ops_list) { + if (!(op->flags & FTRACE_OPS_FL_DIRECT)) + continue; + if (ops_references_ip(op, ip)) { + found_op = true; + break; + } + } while_for_each_ftrace_op(op); + mutex_unlock(&ftrace_lock); + + if (found_op) { + if (!op->ops_func) + return -EBUSY; + + ret = op->ops_func(op, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER); + if (ret) + return ret; + } + } + } + + return 0; +} + +/* + * Similar to prepare_direct_functions_for_ipmodify, clean up after ops + * with IPMODIFY is unregistered. The cleanup is optional for most DIRECT + * ops. + */ +static void cleanup_direct_functions_after_ipmodify(struct ftrace_ops *ops) +{ + struct ftrace_func_entry *entry; + struct ftrace_hash *hash; + struct ftrace_ops *op; + int size, i; + + if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY)) + return; + + mutex_lock(&direct_mutex); + + hash = ops->func_hash->filter_hash; + size = 1 << hash->size_bits; + for (i = 0; i < size; i++) { + hlist_for_each_entry(entry, &hash->buckets[i], hlist) { + unsigned long ip = entry->ip; + bool found_op = false; + + mutex_lock(&ftrace_lock); + do_for_each_ftrace_op(op, ftrace_ops_list) { + if (!(op->flags & FTRACE_OPS_FL_DIRECT)) + continue; + if (ops_references_ip(op, ip)) { + found_op = true; + break; + } + } while_for_each_ftrace_op(op); + mutex_unlock(&ftrace_lock); + + /* The cleanup is optional, ignore any errors */ + if (found_op && op->ops_func) + op->ops_func(op, FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER); + } + } + mutex_unlock(&direct_mutex); +} + +#define lock_direct_mutex() mutex_lock(&direct_mutex) +#define unlock_direct_mutex() mutex_unlock(&direct_mutex) + +#else /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ + +static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops) +{ + return 0; +} + +static void cleanup_direct_functions_after_ipmodify(struct ftrace_ops *ops) +{ +} + +#define lock_direct_mutex() do { } while (0) +#define unlock_direct_mutex() do { } while (0) + +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ + +/* + * Similar to register_ftrace_function, except we don't lock direct_mutex. + */ +static int register_ftrace_function_nolock(struct ftrace_ops *ops) +{ + int ret; + + ftrace_ops_init(ops); + + mutex_lock(&ftrace_lock); + + ret = ftrace_startup(ops, 0); + + mutex_unlock(&ftrace_lock); + + return ret; +} + /** * register_ftrace_function - register a function for profiling * @ops: ops structure that holds the function for profiling. @@ -8018,14 +8206,15 @@ int register_ftrace_function(struct ftrace_ops *ops) { int ret; - ftrace_ops_init(ops); - - mutex_lock(&ftrace_lock); - - ret = ftrace_startup(ops, 0); + lock_direct_mutex(); + ret = prepare_direct_functions_for_ipmodify(ops); + if (ret < 0) + goto out_unlock; - mutex_unlock(&ftrace_lock); + ret = register_ftrace_function_nolock(ops); +out_unlock: + unlock_direct_mutex(); return ret; } EXPORT_SYMBOL_GPL(register_ftrace_function); @@ -8044,6 +8233,7 @@ int unregister_ftrace_function(struct ftrace_ops *ops) ret = ftrace_shutdown(ops, 0); mutex_unlock(&ftrace_lock); + cleanup_direct_functions_after_ipmodify(ops); return ret; } EXPORT_SYMBOL_GPL(unregister_ftrace_function); |