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 A0AA4C433EF for ; Tue, 22 Feb 2022 17:01:01 +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:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RNpIXCZpm53+pVNScf9biKcpaGEwrrbHa5RP9TXHtLo=; b=OBgluIam2NZNIT z+CkmyZrE0XHQVnjK4m/VxPjnhXRWMGykze/D9E8oYa4QoKbWRKQu9ywYrlO0EHrCx2jTLKjf88N6 ZzJFc6xRMHS5FimZzhS2LiOuRWuFbGGg66T4YLJWGr7vSIr4Sa7jzO4XnjSVPYAnP4c+nnaA1365R 3X5YAiJnuqdvSkaexmhDR/V3S/VxNujHImP4eAWJxENnnI+TbiSVQrkOG9d0Dq66YnTk/VH6Si29z PBqG1Nt6NRYgeJRJ8elfb63assvDtU8w5rAsRzKeF8VMrS08Qq2pXoCis7GXlJcQ6X3MCgQLdwj8i hbIACQVnImIIHEWWIFtQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMYVN-00AoQt-S0; Tue, 22 Feb 2022 16:59:16 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nMYPZ-00AmDc-9x for linux-arm-kernel@lists.infradead.org; Tue, 22 Feb 2022 16:53:19 +0000 Received: from [192.168.254.32] (unknown [47.187.212.181]) by linux.microsoft.com (Postfix) with ESMTPSA id 5677D20C319A; Tue, 22 Feb 2022 08:53:01 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 5677D20C319A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1645548782; bh=eBE2w8R3jHrviJiZVR0GgUpvu31BZBoOrA+XHyhhM7E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hP5yscyobvLuXGG/CW09XIfWpvN9GhnQ3ML2ALJh/GNYMu44L/nUhAGV5YkrbFPla SnowneC1XiyZS2vsL66zukzCqcGvwHpJHkw4C/OJL38jcNc7NkeZlewv8/IfmbHbB4 ZfPBICTT8edfcB90xy/3naof4q1RK764MezHYL5Y= Message-ID: Date: Tue, 22 Feb 2022 10:53:00 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v13 05/11] arm64: Copy the task argument to unwind_state Content-Language: en-US To: Mark Rutland 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 References: <95691cae4f4504f33d0fc9075541b1e7deefe96f> <20220117145608.6781-1-madvenka@linux.microsoft.com> <20220117145608.6781-6-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220222_085313_427653_A0E7AFD6 X-CRM114-Status: GOOD ( 29.25 ) 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 It looks like I forgot to reply to this. Sorry about that. On 2/15/22 07:22, Mark Rutland wrote: > 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. > Will do. >> */ >> 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 ... OK. > >> struct pt_regs *regs) >> { >> - unwind_init_common(state); >> + unwind_init_common(state, task); > > ... and make this: > > unwind_init_common(state, current); OK. > > ... 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(). > OK. >> 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. > Will do. >> - unwind(task, &state, consume_entry, cookie); >> + unwind(&state, consume_entry, cookie); > > Otherwise, this looks good to me. Thanks. Madhavan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel