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[213.175.37.12]) by smtp.gmail.com with ESMTPSA id t3sm7861433wmj.33.2021.10.08.02.14.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Oct 2021 02:14:19 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa To: "Steven Rostedt (VMware)" Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Subject: [PATCH 7/8] ftrace: Add multi direct modify interface Date: Fri, 8 Oct 2021 11:13:35 +0200 Message-Id: <20211008091336.33616-8-jolsa@kernel.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211008091336.33616-1-jolsa@kernel.org> References: <20211008091336.33616-1-jolsa@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Adding interface to modify registered direct function for ftrace_ops. Adding following function: modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) The function changes the currently registered direct function for all attached functions. Signed-off-by: Jiri Olsa --- include/linux/ftrace.h | 6 ++++ kernel/trace/ftrace.c | 62 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index ba5d02ba8166..c15b767f39cf 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -318,6 +318,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry, unsigned long ftrace_find_rec_direct(unsigned long ip); int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr); int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr); +int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr); + #else struct ftrace_ops; # define ftrace_direct_func_count 0 @@ -357,6 +359,10 @@ static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigne { return -ENODEV; } +static inline int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) +{ + return -ENODEV; +} #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f9df7bffb770..d92f2591c3fc 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5547,6 +5547,68 @@ int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) return err; } EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi); + +/** + * modify_ftrace_direct_multi - Modify an existing direct 'multi' call + * to call something else + * @ops: The address of the struct ftrace_ops object + * @addr: The address of the new trampoline to call at @ops functions + * + * This is used to unregister currently registered direct caller and + * register new one @addr on functions registered in @ops object. + * + * Note there's window between ftrace_shutdown and ftrace_startup calls + * where there will be no callbacks called. + * + * Returns: zero on success. Non zero on error, which includes: + * -EINVAL - The @ops object was not properly registered. + */ +int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) +{ + struct ftrace_hash *hash = ops->func_hash->filter_hash; + struct ftrace_func_entry *entry, *iter; + int i, size; + int err; + + if (check_direct_multi(ops)) + return -EINVAL; + if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) + return -EINVAL; + + mutex_lock(&direct_mutex); + mutex_lock(&ftrace_lock); + + /* + * Shutdown the ops, change 'direct' pointer for each + * ops entry in direct_functions hash and startup the + * ops back again. + * + * Note there is no callback called for @ops object after + * this ftrace_shutdown call until ftrace_startup is called + * later on. + */ + err = ftrace_shutdown(ops, 0); + if (err) + goto out_unlock; + + size = 1 << hash->size_bits; + for (i = 0; i < size; i++) { + hlist_for_each_entry(iter, &hash->buckets[i], hlist) { + entry = __ftrace_lookup_ip(direct_functions, iter->ip); + if (!entry) + continue; + entry->direct = addr; + } + } + + err = ftrace_startup(ops, 0); + + out_unlock: + mutex_unlock(&ftrace_lock); + mutex_unlock(&direct_mutex); + return err; +} +EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi); #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ /** -- 2.31.1