From patchwork Tue Nov 19 00:23:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacob Keller X-Patchwork-Id: 13879242 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.21]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 670FEDDAB; Tue, 19 Nov 2024 00:23:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.21 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731975830; cv=none; b=VgSm8zOvazTVT7p32GpdMXmYEQF1mtZuXYcIZlfBgMwJL/EGr7LNslgNW8CY8dgZd/M6TxWFA548cqGJtJp+tq+4rUWfH31P0/DyrMBzxbHwjm8d0ogUNAwaT4FOsgUucT3Qv/3JcNz3kQxi3hmitoYkEHgaNvw2Os8qYuwRhhs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731975830; c=relaxed/simple; bh=MlXbHuvt3wGllLux/V5NooK/PasQZbsIt3aVkig4UAk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=mZyhTwk2gciEa0y9wrHJs7/OIHqPXbVIbPeWCL3GnJWQlXE1Wst3zKXbKSXIl4GRxWoQg8Yzp1oV4OZyok1IYzwyVL0uub93F6vQPtt+XCRRD4/vNAZXDpIGkSs7leHY85PZQHAAv2xmGbpuN9vYfRv3OgjrkD5GfEXxtcdf6l4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=aZmovvBu; arc=none smtp.client-ip=198.175.65.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="aZmovvBu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1731975828; x=1763511828; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=MlXbHuvt3wGllLux/V5NooK/PasQZbsIt3aVkig4UAk=; b=aZmovvBuxj/h2vURBEraM86cuVB9NMKFOWIYbl/vcTbSHMnIBt2SyZCw VgGHDE8bejeFpTKK4At2bKfVdAD1QFXnqWMY/JiiCc52xkjqnGoXx+hL6 vBRoVbmSpdrSizu64t931H3vprURV+IK7vim8oCC8BxjSnrFdqO37OHb2 mQgGLZu1EPZlhksWAfFFQOeVv+Xt/yxi8M6ukBwUZLrywN5O9Kp2HQZon l7eM1477NDaowFFCuKuMKzSxzDGEwRQEECVR9Ga3YKqipBRQ0ndlvIQE2 coDunaOJ3riIIuolW7WdpMkQjCxDTlzetEbhiENGnaP9FgBMwKbCL7UQ4 A==; X-CSE-ConnectionGUID: DttxobzSSqS+1VZD8DZSQA== X-CSE-MsgGUID: pSdI3NqrQDSvamAUB7RdKA== X-IronPort-AV: E=McAfee;i="6700,10204,11260"; a="31892426" X-IronPort-AV: E=Sophos;i="6.12,165,1728975600"; d="scan'208";a="31892426" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Nov 2024 16:23:45 -0800 X-CSE-ConnectionGUID: PScl7W65QUCQvpnlII99Uw== X-CSE-MsgGUID: 0iza6fo8QwmsKgUE0/iFAA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,165,1728975600"; d="scan'208";a="89162719" Received: from jekeller-desk.jf.intel.com ([10.166.241.20]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Nov 2024 16:23:45 -0800 From: Jacob Keller Date: Mon, 18 Nov 2024 16:23:39 -0800 Subject: [PATCH net-next RFC v6 2/9] lib: packing: demote truncation error in pack() to a warning in __pack() Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241118-packing-pack-fields-and-ice-implementation-v6-2-6af8b658a6c3@intel.com> References: <20241118-packing-pack-fields-and-ice-implementation-v6-0-6af8b658a6c3@intel.com> In-Reply-To: <20241118-packing-pack-fields-and-ice-implementation-v6-0-6af8b658a6c3@intel.com> To: Vladimir Oltean , Andrew Morton , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Tony Nguyen , Przemek Kitszel , Masahiro Yamada , netdev Cc: linux-kbuild@vger.kernel.org, Jacob Keller , Vladimir Oltean X-Mailer: b4 0.14.1 From: Vladimir Oltean Most of the sanity checks in pack() and unpack() can be covered at compile time. There is only one exception, and that is truncation of the uval during a pack() operation. We'd like the error-less __pack() to catch that condition as well. But at the same time, it is currently the responsibility of consumer drivers (currently just sja1105) to print anything at all when this error occurs, and then discard the return code. We can just print a loud warning in the library code and continue with the truncated __pack() operation. In practice, having the warning is very important, see commit 24deec6b9e4a ("net: dsa: sja1105: disallow C45 transactions on the BASE-TX MDIO bus") where the bug was caught exactly by noticing this print. Add the first print to the packing library, and at the same time remove the print for the same condition from the sja1105 driver, to avoid double printing. Signed-off-by: Vladimir Oltean --- drivers/net/dsa/sja1105/sja1105_static_config.c | 8 ++------ lib/packing.c | 26 ++++++++++--------------- 2 files changed, 12 insertions(+), 22 deletions(-) diff --git a/drivers/net/dsa/sja1105/sja1105_static_config.c b/drivers/net/dsa/sja1105/sja1105_static_config.c index baba204ad62f..3d790f8c6f4d 100644 --- a/drivers/net/dsa/sja1105/sja1105_static_config.c +++ b/drivers/net/dsa/sja1105/sja1105_static_config.c @@ -26,12 +26,8 @@ void sja1105_pack(void *buf, const u64 *val, int start, int end, size_t len) pr_err("Start bit (%d) expected to be larger than end (%d)\n", start, end); } else if (rc == -ERANGE) { - if ((start - end + 1) > 64) - pr_err("Field %d-%d too large for 64 bits!\n", - start, end); - else - pr_err("Cannot store %llx inside bits %d-%d (would truncate)\n", - *val, start, end); + pr_err("Field %d-%d too large for 64 bits!\n", + start, end); } dump_stack(); } diff --git a/lib/packing.c b/lib/packing.c index f237b8af99f5..09a2d195b943 100644 --- a/lib/packing.c +++ b/lib/packing.c @@ -59,8 +59,17 @@ static void __pack(void *pbuf, u64 uval, size_t startbit, size_t endbit, */ int plogical_first_u8 = startbit / BITS_PER_BYTE; int plogical_last_u8 = endbit / BITS_PER_BYTE; + int value_width = startbit - endbit + 1; int box; + /* Check if "uval" fits in "value_width" bits. + * The test only works for value_width < 64, but in the latter case, + * any 64-bit uval will surely fit. + */ + WARN(value_width < 64 && uval >= (1ull << value_width), + "Cannot store 0x%llx inside bits %zu-%zu - will truncate\n", + uval, startbit, endbit); + /* Iterate through an idealistic view of the pbuf as an u64 with * no quirks, u8 by u8 (aligned at u8 boundaries), from high to low * logical bit significance. "box" denotes the current logical u8. @@ -143,9 +152,6 @@ static void __pack(void *pbuf, u64 uval, size_t startbit, size_t endbit, int pack(void *pbuf, u64 uval, size_t startbit, size_t endbit, size_t pbuflen, u8 quirks) { - /* width of the field to access in the pbuf */ - u64 value_width; - /* startbit is expected to be larger than endbit, and both are * expected to be within the logically addressable range of the buffer. */ @@ -153,19 +159,7 @@ int pack(void *pbuf, u64 uval, size_t startbit, size_t endbit, size_t pbuflen, /* Invalid function call */ return -EINVAL; - value_width = startbit - endbit + 1; - if (unlikely(value_width > 64)) - return -ERANGE; - - /* Check if "uval" fits in "value_width" bits. - * If value_width is 64, the check will fail, but any - * 64-bit uval will surely fit. - */ - if (value_width < 64 && uval >= (1ull << value_width)) - /* Cannot store "uval" inside "value_width" bits. - * Truncating "uval" is most certainly not desirable, - * so simply erroring out is appropriate. - */ + if (unlikely(startbit - endbit >= 64)) return -ERANGE; __pack(pbuf, uval, startbit, endbit, pbuflen, quirks);