From patchwork Thu Jul 29 14:06:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 12408847 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64163C432BE for ; Thu, 29 Jul 2021 14:09:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F442601FF for ; Thu, 29 Jul 2021 14:09:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238375AbhG2OJi (ORCPT ); Thu, 29 Jul 2021 10:09:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:57016 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238649AbhG2OHd (ORCPT ); Thu, 29 Jul 2021 10:07:33 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id ACAB260EBD; Thu, 29 Jul 2021 14:06:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627567607; bh=m0w+6fZCQCy0gdqhL8LsWosP3J2P38jldAkchB4zGxA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jovHss9ZcmI5BGT2WmCuQ7JFsif4ouTqLHJL5bBaXB3Fy5IPZ0Ik42lpsXZsWg79w YBO7j7EQbctuhkCVw2K5HKrJFC8Qdt/hagjGLUX8cbr5eATrInsLufOkDbkOorfBq5 u4sI1tAui+5Et/cdoau6PWaKG9tJL3dospsgQdPwpzMw8bCOFP5vIGfEmLuwR6kWpW l8g+hCkRn5XDquo+vYF+h35jrAkQcplTyhfCuSyFK8jwZhDF58e9+nUOAwxJG0HWsE y5PyEhTws9b/valMhFtYXE4sbHA0pBkOG9WBfNsybkVpZoApWik/NlyzgKJmnWjy2I Z0aq4DykmY/FQ== From: Masami Hiramatsu To: Steven Rostedt , Josh Poimboeuf , Ingo Molnar Cc: X86 ML , Masami Hiramatsu , Daniel Xu , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kuba@kernel.org, mingo@redhat.com, ast@kernel.org, Thomas Gleixner , Borislav Petkov , Peter Zijlstra , kernel-team@fb.com, yhs@fb.com, linux-ia64@vger.kernel.org, Abhishek Sagar , Andrii Nakryiko Subject: [PATCH -tip v10 05/16] kprobes: Add kretprobe_find_ret_addr() for searching return address Date: Thu, 29 Jul 2021 23:06:43 +0900 Message-Id: <162756760325.301564.12904072044887058122.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <162756755600.301564.4957591913842010341.stgit@devnote2> References: <162756755600.301564.4957591913842010341.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Introduce kretprobe_find_ret_addr() and is_kretprobe_trampoline(). These APIs will be used by the ORC stack unwinder and ftrace, so that they can check whether the given address points kretprobe trampoline code and query the correct return address in that case. Signed-off-by: Masami Hiramatsu Tested-by: Andrii Nakryiko --- Changes in v10: - Add a document about kretprobe_find_ret_addr() and check cur == NULL. Changes in v9: - Update changelog to explain why this is introduced. - Move the prototype of kretprobe_find_ret_addr() and is_kretprobe_trampoline() in the same place. - Make __kretprobe_find_ret_addr() return 'kprobe_opcode_t *'. - Update comments in the __kretprobe_trampoline_handler(). Changes in v6: - Replace BUG_ON() with WARN_ON_ONCE() in __kretprobe_trampoline_handler(). Changes in v3: - Remove generic stacktrace fixup. Instead, it should be solved in each unwinder. This just provide the generic interface. Changes in v2: - Add is_kretprobe_trampoline() for checking address outside of kretprobe_find_ret_addr() - Remove unneeded addr from kretprobe_find_ret_addr() - Rename fixup_kretprobe_tramp_addr() to fixup_kretprobe_trampoline() --- include/linux/kprobes.h | 22 +++++++++ kernel/kprobes.c | 109 ++++++++++++++++++++++++++++++++++++----------- 2 files changed, 105 insertions(+), 26 deletions(-) diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index b6b2370f4a4c..6d47a9da1e0a 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -505,6 +505,28 @@ static inline bool is_kprobe_optinsn_slot(unsigned long addr) } #endif /* !CONFIG_OPTPROBES */ +#ifdef CONFIG_KRETPROBES +static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) +{ + return (void *)addr == kretprobe_trampoline_addr(); +} + +unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, + struct llist_node **cur); +#else +static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr) +{ + return false; +} + +static nokprobe_inline +unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, + struct llist_node **cur) +{ + return 0; +} +#endif + /* Returns true if kprobes handled the fault */ static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, unsigned int trap) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 6ed755111eea..833f07f33115 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1863,45 +1863,87 @@ static struct notifier_block kprobe_exceptions_nb = { #ifdef CONFIG_KRETPROBES -unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, - void *frame_pointer) +/* This assumes the 'tsk' is the current task or the is not running. */ +static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk, + struct llist_node **cur) { - kprobe_opcode_t *correct_ret_addr = NULL; struct kretprobe_instance *ri = NULL; - struct llist_node *first, *node; - struct kretprobe *rp; + struct llist_node *node = *cur; + + if (!node) + node = tsk->kretprobe_instances.first; + else + node = node->next; - /* Find all nodes for this frame. */ - first = node = current->kretprobe_instances.first; while (node) { ri = container_of(node, struct kretprobe_instance, llist); - - BUG_ON(ri->fp != frame_pointer); - if (ri->ret_addr != kretprobe_trampoline_addr()) { - correct_ret_addr = ri->ret_addr; - /* - * This is the real return address. Any other - * instances associated with this task are for - * other calls deeper on the call stack - */ - goto found; + *cur = node; + return ri->ret_addr; } - node = node->next; } - pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n"); - BUG_ON(1); + return NULL; +} +NOKPROBE_SYMBOL(__kretprobe_find_ret_addr); -found: - /* Unlink all nodes for this frame. */ - current->kretprobe_instances.first = node->next; - node->next = NULL; +/** + * kretprobe_find_ret_addr -- Find correct return address modified by kretprobe + * @tsk: Target task + * @fp: A frame pointer + * @cur: a storage of the loop cursor llist_node pointer for next call + * + * Find the correct return address modified by a kretprobe on @tsk in unsigned + * long type. If it finds the return address, this returns that address value, + * or this returns 0. + * The @tsk must be 'current' or a task which is not running. @fp is a hint + * to get the currect return address - which is compared with the + * kretprobe_instance::fp field. The @cur is a loop cursor for searching the + * kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the + * first call, but '@cur' itself must NOT NULL. + */ +unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp, + struct llist_node **cur) +{ + struct kretprobe_instance *ri = NULL; + kprobe_opcode_t *ret; + + if (WARN_ON_ONCE(!cur)) + return 0; + + do { + ret = __kretprobe_find_ret_addr(tsk, cur); + if (!ret) + break; + ri = container_of(*cur, struct kretprobe_instance, llist); + } while (ri->fp != fp); - /* Run them.. */ + return (unsigned long)ret; +} +NOKPROBE_SYMBOL(kretprobe_find_ret_addr); + +unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, + void *frame_pointer) +{ + kprobe_opcode_t *correct_ret_addr = NULL; + struct kretprobe_instance *ri = NULL; + struct llist_node *first, *node = NULL; + struct kretprobe *rp; + + /* Find correct address and all nodes for this frame. */ + correct_ret_addr = __kretprobe_find_ret_addr(current, &node); + if (!correct_ret_addr) { + pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n"); + BUG_ON(1); + } + + /* Run the user handler of the nodes. */ + first = current->kretprobe_instances.first; while (first) { ri = container_of(first, struct kretprobe_instance, llist); - first = first->next; + + if (WARN_ON_ONCE(ri->fp != frame_pointer)) + break; rp = get_kretprobe(ri); if (rp && rp->handler) { @@ -1912,6 +1954,21 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs, rp->handler(ri, regs); __this_cpu_write(current_kprobe, prev); } + if (first == node) + break; + + first = first->next; + } + + /* Unlink all nodes for this frame. */ + first = current->kretprobe_instances.first; + current->kretprobe_instances.first = node->next; + node->next = NULL; + + /* Recycle free instances. */ + while (first) { + ri = container_of(first, struct kretprobe_instance, llist); + first = first->next; recycle_rp_inst(ri); }