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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7DDF1C433F5 for ; Sat, 7 May 2022 05:28:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1386655AbiEGFcG (ORCPT ); Sat, 7 May 2022 01:32:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1445691AbiEGFaz (ORCPT ); Sat, 7 May 2022 01:30:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 745656A066; Fri, 6 May 2022 22:27:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 110B76009B; Sat, 7 May 2022 05:27:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9EBA4C385AE; Sat, 7 May 2022 05:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651901220; bh=FMEGfemoYzGIDwcOWskeGKpazApsC3L5MMeQ97qcFSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a5A3lwsg8rVuyN4K+kI6MYS0Ydm+J7L3tI6MPHnWLL4VhjJ73nbbJENuL9iJX/HxI ZykjGTwQG1Vk7Z2gS1Uen7nWRaWkN/6iwY6f3qULVQZDy4Uz6Hs/K1a8acFNipWZV8 lRhcIocdnwSGD3F93IBqJHQVXEcnX0H4nA5itArMFnr6Gjrg6mMPwqIzlhMtEOBvE1 53qMU+7ul7+NYIbzEGoFifLaZrAgT6helOWFpjQQ4aRQ4aQEqcXBci5jDxTq0FYt0y FhVCeGtPLYj9a8TCOoWThMaDomex4JG7lj5M2Mb6mC4of6lhNYmwMG3ImQkWl8fvrO Dxbfx8JxTdKVw== From: Miguel Ojeda To: Linus Torvalds , Greg Kroah-Hartman Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Jarkko Sakkinen , Miguel Ojeda , Gary Guo , Alex Gaynor , Wedson Almeida Filho , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes Subject: [PATCH v6 14/23] vsprintf: add new `%pA` format specifier Date: Sat, 7 May 2022 07:24:12 +0200 Message-Id: <20220507052451.12890-15-ojeda@kernel.org> In-Reply-To: <20220507052451.12890-1-ojeda@kernel.org> References: <20220507052451.12890-1-ojeda@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Gary Guo This patch adds a format specifier `%pA` to `vsprintf` which formats a pointer as `core::fmt::Arguments`. Doing so allows us to directly format to the internal buffer of `printf`, so we do not have to use a temporary buffer on the stack to pre-assemble the message on the Rust side. This specifier is intended only to be used from Rust and not for C, so `checkpatch.pl` is intentionally unchanged to catch any misuse. Co-developed-by: Alex Gaynor Signed-off-by: Alex Gaynor Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Signed-off-by: Gary Guo Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda --- lib/vsprintf.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 40d26a07a133..00f71f91d991 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2270,6 +2270,9 @@ int __init no_hash_pointers_enable(char *str) } early_param("no_hash_pointers", no_hash_pointers_enable); +/* Used for Rust formatting ('%pA'). */ +char *rust_fmt_argument(char *buf, char *end, void *ptr); + /* * Show a '%p' thing. A kernel extension is that the '%p' is followed * by an extra set of alphanumeric characters that are extended format @@ -2396,6 +2399,10 @@ early_param("no_hash_pointers", no_hash_pointers_enable); * * Note: The default behaviour (unadorned %p) is to hash the address, * rendering it useful as a unique identifier. + * + * There is also a '%pA' format specifier, but it is only intended to be used + * from Rust code to format core::fmt::Arguments. Do *not* use it from C. + * See rust/kernel/print.rs for details. */ static noinline_for_stack char *pointer(const char *fmt, char *buf, char *end, void *ptr, @@ -2468,6 +2475,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return device_node_string(buf, end, ptr, spec, fmt + 1); case 'f': return fwnode_string(buf, end, ptr, spec, fmt + 1); + case 'A': + if (!IS_ENABLED(CONFIG_RUST)) { + WARN_ONCE(1, "Please remove %%pA from non-Rust code\n"); + return error_string(buf, end, "(%pA?)", spec); + } + return rust_fmt_argument(buf, end, ptr); case 'x': return pointer_string(buf, end, ptr, spec); case 'e': -- 2.35.3