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 8D1D6C6FA94 for ; Tue, 27 Sep 2022 13:19:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232743AbiI0NTd (ORCPT ); Tue, 27 Sep 2022 09:19:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36044 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232729AbiI0NSl (ORCPT ); Tue, 27 Sep 2022 09:18:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA6924F392; Tue, 27 Sep 2022 06:17:15 -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 F042261962; Tue, 27 Sep 2022 13:16:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CD57C4347C; Tue, 27 Sep 2022 13:16:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664284619; bh=Bkvsyb2hltJId+jrdWzVG8kshzVtEqCat903Mdsnts0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FtLVMyUVs8+l4yx7BOTQsrXHHWK7tE5fD3XX7/bgcYCytGyEKFNFxB6I5Qnd4EFAL PNJtbBP13z18aEl8NYkVDXEQcoItEOWja6ot5gFwdxZlnCxfZ/XOHBM5L8hMj9rEBC zWeEL8pViczddLe95wbTbTdiPioMezK3ptRC3iHGo7GPQvCY1EYntNtW0vO+hpIejo 3eIJB8oNdp/UsE9A7KGjGXuGVlBKDsFv6v72586DhBOitao0EhQ0498Jj4ZM1DjYj3 MYfM5ff1y4NKC54H0+tA8j0fmRdKoiX3hc2WT/o7I1zHQFnKAM9kMjOFvLvXIHsZoQ PwcmVNfcF39pA== From: Miguel Ojeda To: Linus Torvalds , Greg Kroah-Hartman Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, patches@lists.linux.dev, Jarkko Sakkinen , Miguel Ojeda , Gary Guo , Kees Cook , Petr Mladek , Alex Gaynor , Wedson Almeida Filho , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , Jonathan Corbet , linux-doc@vger.kernel.org Subject: [PATCH v10 14/27] vsprintf: add new `%pA` format specifier Date: Tue, 27 Sep 2022 15:14:45 +0200 Message-Id: <20220927131518.30000-15-ojeda@kernel.org> In-Reply-To: <20220927131518.30000-1-ojeda@kernel.org> References: <20220927131518.30000-1-ojeda@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@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. Reviewed-by: Kees Cook Acked-by: Petr Mladek 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 --- Documentation/core-api/printk-formats.rst | 10 ++++++++++ lib/vsprintf.c | 13 +++++++++++++ 2 files changed, 23 insertions(+) diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index 5e89497ba314..dbe1aacc79d0 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -625,6 +625,16 @@ Examples:: %p4cc Y10 little-endian (0x20303159) %p4cc NV12 big-endian (0xb231564e) +Rust +---- + +:: + + %pA + +Only intended to be used from Rust code to format ``core::fmt::Arguments``. +Do *not* use it from C. + Thanks ====== diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 3c1853a9d1c0..c414a8d9f1ea 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2246,6 +2246,9 @@ 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 @@ -2372,6 +2375,10 @@ 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, @@ -2444,6 +2451,12 @@ 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': -- 2.37.3