From patchwork Sun Jul 11 13:36:43 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: 12369149 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 21EC9C07E96 for ; Sun, 11 Jul 2021 13:36:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 05BFF613B2 for ; Sun, 11 Jul 2021 13:36:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232991AbhGKNjg (ORCPT ); Sun, 11 Jul 2021 09:39:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:49492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232990AbhGKNjf (ORCPT ); Sun, 11 Jul 2021 09:39:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CD2E661353; Sun, 11 Jul 2021 13:36:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626010609; bh=juSmhxL2xpDmE4nzcIHTKDR3pzJZ+yWbGObEWpwCpho=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c/zCE9d0rwI/6y/ZYt33+HnoQMCxqjJcWp2wadIorcAopZmYEolco34kWZSBcgmku ffoRndY/yqbMz9PMPasCmzByQtIHmp7IMDbPq0OowHV8p5R+3EG5liyte+a+XX69Hi 5hX9jgnrM3FSzRzNXhSX4jDZb0xyM3QFJH2uA9jImvk/WbtfX7ZPN4KxIz/nZiDfNu sSKcbwPqt+fmAytmtasHm5ORfhIB1OenYYN8SsLos/H9GDVUeEBHHTZtLDXtUEnywE plocVaZVLKoGDP8KEw2WnqOOX4fFGNO8CVMJkZ6kaIQlIq7znMt8JysrL+INOEUsFM moadj6BV3lSRQ== 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 v9 12/14] x86/unwind: Recover kretprobe trampoline entry Date: Sun, 11 Jul 2021 22:36:43 +0900 Message-Id: <162601060287.1318837.6088214100991156996.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <162601048053.1318837.1550594515476777588.stgit@devnote2> References: <162601048053.1318837.1550594515476777588.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Since the kretprobe replaces the function return address with the kretprobe_trampoline on the stack, x86 unwinders can not continue the stack unwinding at that point, or record kretprobe_trampoline instead of correct return address. To fix this issue, find the correct return address from task's kretprobe_instances as like as function-graph tracer does. With this fix, the unwinder can correctly unwind the stack from kretprobe event on x86, as below. <...>-135 [003] ...1 6.722338: r_full_proxy_read_0: (vfs_read+0xab/0x1a0 <- full_proxy_read) <...>-135 [003] ...1 6.722377: => kretprobe_trace_func+0x209/0x2f0 => kretprobe_dispatcher+0x4a/0x70 => __kretprobe_trampoline_handler+0xca/0x150 => trampoline_handler+0x44/0x70 => kretprobe_trampoline+0x2a/0x50 => vfs_read+0xab/0x1a0 => ksys_read+0x5f/0xe0 => do_syscall_64+0x33/0x40 => entry_SYSCALL_64_after_hwframe+0x44/0xae Reported-by: Daniel Xu Signed-off-by: Masami Hiramatsu Suggested-by: Josh Poimboeuf Tested-by: Andrii Nakryiko Acked-by: Josh Poimboeuf --- Changes in v9: - Update comment so that it explains why the strange address passed to unwind_recover_kretprobe(). Changes in v7: - Remove superfluous #include . Changes in v5: - Fix the case of interrupt happens on kretprobe_trampoline+0. Changes in v3: - Split out the kretprobe side patch - Fix build error when CONFIG_KRETPROBES=n. Changes in v2: - Remove kretprobe wrapper functions from unwind_orc.c - Do not fixup state->ip when unwinding with regs because kretprobe fixup instruction pointer before calling handler. --- arch/x86/include/asm/unwind.h | 23 +++++++++++++++++++++++ arch/x86/kernel/unwind_frame.c | 3 +-- arch/x86/kernel/unwind_guess.c | 3 +-- arch/x86/kernel/unwind_orc.c | 21 +++++++++++++++++---- 4 files changed, 42 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h index 70fc159ebe69..fca2e783e3ce 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -4,6 +4,7 @@ #include #include +#include #include #include @@ -15,6 +16,7 @@ struct unwind_state { unsigned long stack_mask; struct task_struct *task; int graph_idx; + struct llist_node *kr_cur; bool error; #if defined(CONFIG_UNWINDER_ORC) bool signal, full_regs; @@ -99,6 +101,27 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, void *orc, size_t orc_size) {} #endif +static inline +unsigned long unwind_recover_kretprobe(struct unwind_state *state, + unsigned long addr, unsigned long *addr_p) +{ + return is_kretprobe_trampoline(addr) ? + kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) : + addr; +} + +/* Recover the return address modified by kretprobe and ftrace_graph. */ +static inline +unsigned long unwind_recover_ret_addr(struct unwind_state *state, + unsigned long addr, unsigned long *addr_p) +{ + unsigned long ret; + + ret = ftrace_graph_ret_addr(state->task, &state->graph_idx, + addr, addr_p); + return unwind_recover_kretprobe(state, ret, addr_p); +} + /* * This disables KASAN checking when reading a value from another task's stack, * since the other task could be running on another CPU and could have poisoned diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index d7c44b257f7f..8e1c50c86e5d 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -240,8 +240,7 @@ static bool update_stack_state(struct unwind_state *state, else { addr_p = unwind_get_return_address_ptr(state); addr = READ_ONCE_TASK_STACK(state->task, *addr_p); - state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, - addr, addr_p); + state->ip = unwind_recover_ret_addr(state, addr, addr_p); } /* Save the original stack pointer for unwind_dump(): */ diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c index c49f10ffd8cd..884d68a6e714 100644 --- a/arch/x86/kernel/unwind_guess.c +++ b/arch/x86/kernel/unwind_guess.c @@ -15,8 +15,7 @@ unsigned long unwind_get_return_address(struct unwind_state *state) addr = READ_ONCE_NOCHECK(*state->sp); - return ftrace_graph_ret_addr(state->task, &state->graph_idx, - addr, state->sp); + return unwind_recover_ret_addr(state, addr, state->sp); } EXPORT_SYMBOL_GPL(unwind_get_return_address); diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c index a1202536fc57..e6f7592790af 100644 --- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -534,9 +534,8 @@ bool unwind_next_frame(struct unwind_state *state) if (!deref_stack_reg(state, ip_p, &state->ip)) goto err; - state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, - state->ip, (void *)ip_p); - + state->ip = unwind_recover_ret_addr(state, state->ip, + (unsigned long *)ip_p); state->sp = sp; state->regs = NULL; state->prev_regs = NULL; @@ -549,7 +548,18 @@ bool unwind_next_frame(struct unwind_state *state) (void *)orig_ip); goto err; } - + /* + * There is a small chance to interrupt at the entry of + * __kretprobe_trampoline() where the ORC info doesn't exist. + * That point is right after the RET to __kretprobe_trampoline() + * which was modified return address. + * At that point, the @addr_p of the unwind_recover_kretprobe() + * (this has to point the address of the stack entry storing + * the modified return address) must be "SP - (a stack entry)" + * because SP is incremented by the RET. + */ + state->ip = unwind_recover_kretprobe(state, state->ip, + (unsigned long *)(state->sp - sizeof(long))); state->regs = (struct pt_regs *)sp; state->prev_regs = NULL; state->full_regs = true; @@ -562,6 +572,9 @@ bool unwind_next_frame(struct unwind_state *state) (void *)orig_ip); goto err; } + /* See UNWIND_HINT_TYPE_REGS case comment. */ + state->ip = unwind_recover_kretprobe(state, state->ip, + (unsigned long *)(state->sp - sizeof(long))); if (state->full_regs) state->prev_regs = state->regs;