From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 53E8CC433EF for ; Tue, 15 Feb 2022 13:24:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=blSbBRN6ke+qkpT64Pa2C3U7lYwa9qUTKyddjbQlie8=; b=Sh4ier9CZZ9/hR O5LqqP3CAgWLnefr7c4yajxjcNJUGPBddWFXNMhbddZpbBQ77jFivnn/h3uJ/wsrFicDSYglOf/+m ubRGrXKznBxmWsaxYkZ1ce8d2cWU1avJgm+9riToJOUYKp/ol8W6zAyBHkfQV2ssFfdUSMWCTCEA2 LZYrWfLzToMaieSFGtNTsY01SnDPQGTGy9g6zGSsIF7x4CniAi3oZEShqFDlxMrg6qKQ8UDQD3BOY W21fexl2iD47tNqkEkDI1ow0LEgnDZOCVvyLAb3/amtbamryav+OmBggel4nqX8k9CsBHR+2wswmh jBjDKwE6OcxjaeNBrGMA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nJxnF-002py7-L7; Tue, 15 Feb 2022 13:22:57 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nJxn7-002pw0-M1 for linux-arm-kernel@lists.infradead.org; Tue, 15 Feb 2022 13:22:55 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 688541480; Tue, 15 Feb 2022 05:22:48 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.89.173]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8A9D33F718; Tue, 15 Feb 2022 05:22:46 -0800 (PST) Date: Tue, 15 Feb 2022 13:22:42 +0000 From: Mark Rutland To: madvenka@linux.microsoft.com Cc: broonie@kernel.org, jpoimboe@redhat.com, ardb@kernel.org, nobuta.keiya@fujitsu.com, sjitindarsingh@gmail.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v13 05/11] arm64: Copy the task argument to unwind_state Message-ID: References: <95691cae4f4504f33d0fc9075541b1e7deefe96f> <20220117145608.6781-1-madvenka@linux.microsoft.com> <20220117145608.6781-6-madvenka@linux.microsoft.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220117145608.6781-6-madvenka@linux.microsoft.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220215_052249_839894_DDF60C5E X-CRM114-Status: GOOD ( 28.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jan 17, 2022 at 08:56:02AM -0600, madvenka@linux.microsoft.com wrote: > From: "Madhavan T. Venkataraman" > > Copy the task argument passed to arch_stack_walk() to unwind_state so that > it can be passed to unwind functions via unwind_state rather than as a > separate argument. The task is a fundamental part of the unwind state. > > Signed-off-by: Madhavan T. Venkataraman > --- > arch/arm64/include/asm/stacktrace.h | 3 +++ > arch/arm64/kernel/stacktrace.c | 29 ++++++++++++++++------------- > 2 files changed, 19 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h > index 41ec360515f6..af423f5d7ad8 100644 > --- a/arch/arm64/include/asm/stacktrace.h > +++ b/arch/arm64/include/asm/stacktrace.h > @@ -51,6 +51,8 @@ struct stack_info { > * @kr_cur: When KRETPROBES is selected, holds the kretprobe instance > * associated with the most recently encountered replacement lr > * value. > + * > + * @task: Pointer to the task structure. Can we please say: @task: The task being unwound. > */ > struct unwind_state { > unsigned long fp; > @@ -61,6 +63,7 @@ struct unwind_state { > #ifdef CONFIG_KRETPROBES > struct llist_node *kr_cur; > #endif > + struct task_struct *task; > }; > > extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk, > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > index b2b568e5deba..1b32e55735aa 100644 > --- a/arch/arm64/kernel/stacktrace.c > +++ b/arch/arm64/kernel/stacktrace.c > @@ -33,8 +33,10 @@ > */ > > > -static void unwind_init_common(struct unwind_state *state) > +static void unwind_init_common(struct unwind_state *state, > + struct task_struct *task) > { > + state->task = task; > #ifdef CONFIG_KRETPROBES > state->kr_cur = NULL; > #endif > @@ -57,9 +59,10 @@ static void unwind_init_common(struct unwind_state *state) > * TODO: document requirements here. > */ > static inline void unwind_init_from_regs(struct unwind_state *state, > + struct task_struct *task, Please drop the `task` parameter here ... > struct pt_regs *regs) > { > - unwind_init_common(state); > + unwind_init_common(state, task); ... and make this: unwind_init_common(state, current); ... since that way it's *impossible* to have ismatched parameters, which is one of the reasons for having separate functions in the first place. > state->fp = regs->regs[29]; > state->pc = regs->pc; > @@ -71,9 +74,10 @@ static inline void unwind_init_from_regs(struct unwind_state *state, > * Note: this is always inlined, and we expect our caller to be a noinline > * function, such that this starts from our caller's caller. > */ > -static __always_inline void unwind_init_from_current(struct unwind_state *state) > +static __always_inline void unwind_init_from_current(struct unwind_state *state, > + struct task_struct *task) > { > - unwind_init_common(state); > + unwind_init_common(state, task); Same comments as for unwind_init_from_regs(): please drop the `task` parameter and hard-code `current` in the call to unwind_init_common(). > state->fp = (unsigned long)__builtin_frame_address(1); > state->pc = (unsigned long)__builtin_return_address(0); > @@ -87,7 +91,7 @@ static __always_inline void unwind_init_from_current(struct unwind_state *state) > static inline void unwind_init_from_task(struct unwind_state *state, > struct task_struct *task) > { > - unwind_init_common(state); > + unwind_init_common(state, task); > > state->fp = thread_saved_fp(task); > state->pc = thread_saved_pc(task); > @@ -100,11 +104,11 @@ static inline void unwind_init_from_task(struct unwind_state *state, > * records (e.g. a cycle), determined based on the location and fp value of A > * and the location (but not the fp value) of B. > */ > -static int notrace unwind_next(struct task_struct *tsk, > - struct unwind_state *state) > +static int notrace unwind_next(struct unwind_state *state) > { > unsigned long fp = state->fp; > struct stack_info info; > + struct task_struct *tsk = state->task; > > /* Final frame; nothing to unwind */ > if (fp == (unsigned long)task_pt_regs(tsk)->stackframe) > @@ -176,8 +180,7 @@ static int notrace unwind_next(struct task_struct *tsk, > } > NOKPROBE_SYMBOL(unwind_next); > > -static void notrace unwind(struct task_struct *tsk, > - struct unwind_state *state, > +static void notrace unwind(struct unwind_state *state, > bool (*fn)(void *, unsigned long), void *data) > { > while (1) { > @@ -185,7 +188,7 @@ static void notrace unwind(struct task_struct *tsk, > > if (!fn(data, state->pc)) > break; > - ret = unwind_next(tsk, state); > + ret = unwind_next(state); > if (ret < 0) > break; > } > @@ -232,11 +235,11 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, > struct unwind_state state; > > if (regs) > - unwind_init_from_regs(&state, regs); > + unwind_init_from_regs(&state, task, regs); > else if (task == current) > - unwind_init_from_current(&state); > + unwind_init_from_current(&state, task); > else > unwind_init_from_task(&state, task); As above we shouldn't need these two changes. For the regs case we might want to sanity-check that task == current. > - unwind(task, &state, consume_entry, cookie); > + unwind(&state, consume_entry, cookie); Otherwise, this looks good to me. Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel