From nobody Fri Oct 3 06:34:21 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 3EBA02F8BC8; Thu, 4 Sep 2025 09:48:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756979329; cv=none; b=I8Xuc7yc+/zQgQIOW2v5vHoL4T842dC0WttE9+uPVUN92i66QVcLr2qucQyD/fvtFMS/PVa0x4jYmlr4KVCZwTBt7JvBe4oIcgcJIER2nynUa+n0lkE23xauE1nbDlwkynIXe0Uf2VRRl/C61WyeVuMd+0wHZbxVl1JyG9mj46U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756979329; c=relaxed/simple; bh=ZeNaLWxP8JNXz3GdhKzYMHnGisn8rI+YmPK5TSL2nJc=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=RLtxCh3037TcVBwWgh77WrTV5O1VZ+yuqHDT2qA869YDPfKl7IkkAFNQPzvqu/+07GMey0WJ15fLt6a6poieAS7Tyo4o3B9jFEu+M9ZbrFeLziEf5mMFq0ov8L3uKTwCcekxNoRM4nn5ryoRX5aBB7Jlj+M+b/TfSlRDI0X2FCs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=HY6bHnit; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=fqH13Mnr; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="HY6bHnit"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="fqH13Mnr" Date: Thu, 04 Sep 2025 09:48:45 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1756979326; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4HH9pr09meki1kL4+vEU0jH9yzJNZwlSmXQumSt741k=; b=HY6bHnitMaHKcuMt/DdlWgS/b4+5MITSDzeFuS+2kco42d0y1fV5dMwB66Le1HStyf7OXz wPiE3AVzgKsFX77yVgssUwRuEILZCYlGC6s44PTbmBZpB7m4oaWyZttkV1c0RmQdMiY36j P8uhzidtKbEfxLagDxkWH5GQXyYYw7E2i20Mppxw/ULqhEntx7ExqbLzMeEozwUi9g094u O60VHrfh4T68c9uJsYLyu1s9TaiW7rOYrb64kjeDmkYbJDhaIPFUfFRhO0yHmaqBxhPfNv EnMu9Jv63zJVrzMBSl74e2vhRX9NLZJ0fGfLdDTFT4fxOl3kJFp5zf4u7eU9KA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1756979326; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4HH9pr09meki1kL4+vEU0jH9yzJNZwlSmXQumSt741k=; b=fqH13MnrcmMbfOJ0Mky6Ug8OLpzR+0Egh4O87rr4VDydSEJObKzRkk7KAQnlzZqOQ9xMyP aI1yFv2IP1IYs6Bw== From: "tip-bot2 for Ian Rogers" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/vdso] vdso: Switch get/put_unaligned() from packed struct to memcpy() Cc: Ian Rogers , Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250722215754.672330-2-irogers@google.com> References: <20250722215754.672330-2-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <175697932523.1920.9579199289854234132.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the timers/vdso branch of tip: Commit-ID: 34a1cbf21227f1327ead30dcf2a52aac79bf4f15 Gitweb: https://git.kernel.org/tip/34a1cbf21227f1327ead30dcf2a52aac7= 9bf4f15 Author: Ian Rogers AuthorDate: Tue, 22 Jul 2025 14:57:52 -07:00 Committer: Thomas Gleixner CommitterDate: Thu, 04 Sep 2025 11:43:03 +02:00 vdso: Switch get/put_unaligned() from packed struct to memcpy() Type punning is necessary for get/put_unaligned() but the use of a packed struct violates strict aliasing rules, requiring -fno-strict-aliasing to be passed to the C compiler. Switch to using memcpy() so that -fno-strict-aliasing isn't necessary. Signed-off-by: Ian Rogers Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250722215754.672330-2-irogers@google.com --- include/vdso/unaligned.h | 41 +++++++++++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/include/vdso/unaligned.h b/include/vdso/unaligned.h index ff0c06b..9076483 100644 --- a/include/vdso/unaligned.h +++ b/include/vdso/unaligned.h @@ -2,14 +2,43 @@ #ifndef __VDSO_UNALIGNED_H #define __VDSO_UNALIGNED_H =20 -#define __get_unaligned_t(type, ptr) ({ \ - const struct { type x; } __packed * __get_pptr =3D (typeof(__get_pptr))(p= tr); \ - __get_pptr->x; \ +#include + +/** + * __get_unaligned_t - read an unaligned value from memory. + * @type: the type to load from the pointer. + * @ptr: the pointer to load from. + * + * Use memcpy to affect an unaligned type sized load avoiding undefined be= havior + * from approaches like type punning that require -fno-strict-aliasing in = order + * to be correct. As type may be const, use __unqual_scalar_typeof to map = to a + * non-const type - you can't memcpy into a const type. The + * __get_unaligned_ctrl_type gives __unqual_scalar_typeof its required + * expression rather than type, a pointer is used to avoid warnings about = mixing + * the use of 0 and NULL. The void* cast silences ubsan warnings. + */ +#define __get_unaligned_t(type, ptr) ({ \ + type *__get_unaligned_ctrl_type __always_unused =3D NULL; \ + __unqual_scalar_typeof(*__get_unaligned_ctrl_type) __get_unaligned_val; \ + __builtin_memcpy(&__get_unaligned_val, (void *)(ptr), \ + sizeof(__get_unaligned_val)); \ + __get_unaligned_val; \ }) =20 -#define __put_unaligned_t(type, val, ptr) do { \ - struct { type x; } __packed * __put_pptr =3D (typeof(__put_pptr))(ptr); \ - __put_pptr->x =3D (val); \ +/** + * __put_unaligned_t - write an unaligned value to memory. + * @type: the type of the value to store. + * @val: the value to store. + * @ptr: the pointer to store to. + * + * Use memcpy to affect an unaligned type sized store avoiding undefined + * behavior from approaches like type punning that require -fno-strict-ali= asing + * in order to be correct. The void* cast silences ubsan warnings. + */ +#define __put_unaligned_t(type, val, ptr) do { \ + type __put_unaligned_val =3D (val); \ + __builtin_memcpy((void *)(ptr), &__put_unaligned_val, \ + sizeof(__put_unaligned_val)); \ } while (0) =20 #endif /* __VDSO_UNALIGNED_H */