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 CBB57C00140 for ; Fri, 5 Aug 2022 15:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241081AbiHEPqI (ORCPT ); Fri, 5 Aug 2022 11:46:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241244AbiHEPo3 (ORCPT ); Fri, 5 Aug 2022 11:44:29 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D81C651A1C; Fri, 5 Aug 2022 08:44:00 -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 ams.source.kernel.org (Postfix) with ESMTPS id 98555B82986; Fri, 5 Aug 2022 15:43:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57C69C43470; Fri, 5 Aug 2022 15:43:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659714238; bh=LJMbIbsmGPh8jLekYZBgD3WYeoa1VFA5q4dxEXu4mdw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PKp/4Vv0TnHtJlfe+/ahygOjq18Jn5dHvo9ossvP42owNhBfsYn0CTcEWgJTXOlJm Vh3R1XXKxCeODfbBShRuyUGaH1hIZTgLUndM488qsYF0qz5/Th1uWck4dyCCo0jfey dTZHmlmiiE0kdfHg0FwaSbpteeBAvQawqKiC0eR57OiE7R95wwoZQ+w9kwfTEbTQAT 8kDIDVEVzKMEEd5DWPEfBPPmDbrWBOEjQaEYVUr/cQaOZdQ6l7cWg4oPCQFBm0jvd3 UVlbxQbYshIE5QxG5wTgZJKN0IRwoJJY2lVZ+JvGI5mPmrKbFvNMTuX4SxihvteUBE cRaMGDshcJB+w== 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 v9 14/27] vsprintf: add new `%pA` format specifier Date: Fri, 5 Aug 2022 17:41:59 +0200 Message-Id: <20220805154231.31257-15-ojeda@kernel.org> In-Reply-To: <20220805154231.31257-1-ojeda@kernel.org> References: <20220805154231.31257-1-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. 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': -- 2.37.1