From patchwork Tue Jan 25 00:10:54 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 12723243 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 582A0C433FE for ; Tue, 25 Jan 2022 03:36:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1385092AbiAYDgB (ORCPT ); Mon, 24 Jan 2022 22:36:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S3421169AbiAYC0Y (ORCPT ); Mon, 24 Jan 2022 21:26:24 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C97F2C038AEE for ; Mon, 24 Jan 2022 16:16:33 -0800 (PST) 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 4EE9561546 for ; Tue, 25 Jan 2022 00:16:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A9DBC340EC; Tue, 25 Jan 2022 00:16:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643069792; bh=aUBAeA8epzt4DxHOr/8Fwmtcfowksew8sOb3hVCUWlo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cPoFiVQbiusTPfZNLhESrlIr8HfCxPQOiOUdQzY6zGjap9gdFcjhzrwng/EqyzILa buCbiM5Zzos9lcZSk4w09X2YtnTBoQvKUsNH/BcWs5hJuT90irEF0ZgA2jV39impCs h25HXTql0vWoAOtkGh5zZDxiPMHlQi81PKPmza4GszLggJTjD/olyLvJEH9K1SmLex 6A8fD2++EKkFjOcLKBUVicHVsiQhSCXU/yEdI18a2l1JgU2jyYmBDTX2PkqW3fmMmH 9hicogGrnMsUPHG2tFb4tpU9rh8p8A1aWzhqJ46IMt7Nf9sfxaX6Tsix/Fxk8lT2JY rfivp/ZWJtF/Q== From: Mark Brown To: Catalin Marinas , Will Deacon , Marc Zyngier , Shuah Khan , Shuah Khan Cc: Alan Hayward , Luis Machado , Salil Akerkar , Basant Kumar Dwivedi , Szabolcs Nagy , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Mark Brown Subject: [PATCH v8 18/38] arm64/sme: Implement streaming SVE signal handling Date: Tue, 25 Jan 2022 00:10:54 +0000 Message-Id: <20220125001114.193425-19-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220125001114.193425-1-broonie@kernel.org> References: <20220125001114.193425-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6926; h=from:subject; bh=aUBAeA8epzt4DxHOr/8Fwmtcfowksew8sOb3hVCUWlo=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBh70APyZffwLSh1gpayP6gvSuF62lS+Td1u15fNbZg CYIMJzOJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYe9ADwAKCRAk1otyXVSH0NprB/ 4hfkLYsOxS3yAbpyuAQ9SUSzjFqp+jmbvWusNVyk8B+7MLyrLcLH8yGTK5eHEha+Y1F/RZvElTqjaN TR6/uLddQ9JCRwtM2XqW4EA1JlObb/k+chSmdk1LCBez+M1EDDfSFgWYo+VHx3gzvYK7LJU8WVroS6 tN2zaStmfERLH1x0F9qKlkcHTETziaPneJC73bOK+/w1uxTUp+4IBVs2MTQckCGA+yEHoBVkqvUvR4 ptTqFTQmqYThB6Xh0sz2b8Id5M3Q9bKAuRicVb5reCdByS7Pt98Go2r+sgkG1n8bxLw9m4keDXBTXO IYUIIRQjxvDz6I97X4E90E2izn+tB/ X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org When in streaming mode we have the same set of SVE registers as we do in regular SVE mode with the exception of FFR and the use of the SME vector length. Provide signal handling for these registers by taking one of the reserved words in the SVE signal context as a flags field and defining a flag with a flag which is set for streaming mode. When the flag is set the vector length is set to the streaming mode vector length and we save and restore streaming mode data. We support entering or leaving streaming mode based on the value of the flag but do not support changing the vector length, this is not currently supported SVE signal handling. We could instead allocate a separate record in the signal frame for the streaming mode SVE context but this inflates the size of the maximal signal frame required and adds complication when validating signal frames from userspace, especially given the current structure of the code. Any implementation of support for streaming mode vectors in signals will have some potential for causing issues for applications that attempt to handle SVE vectors in signals, use streaming mode but do not understand streaming mode in their signal handling code, it is hard to identify a case that is clearly better than any other - they all have cases where they could cause unexpected register corruption or faults. Signed-off-by: Mark Brown --- arch/arm64/include/uapi/asm/sigcontext.h | 16 ++++++-- arch/arm64/kernel/signal.c | 48 ++++++++++++++++++------ 2 files changed, 50 insertions(+), 14 deletions(-) diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h index 0c796c795dbe..3a3366d4fbc2 100644 --- a/arch/arm64/include/uapi/asm/sigcontext.h +++ b/arch/arm64/include/uapi/asm/sigcontext.h @@ -134,9 +134,12 @@ struct extra_context { struct sve_context { struct _aarch64_ctx head; __u16 vl; - __u16 __reserved[3]; + __u16 flags; + __u16 __reserved[2]; }; +#define SVE_SIG_FLAG_SM 0x1 /* Context describes streaming mode */ + #endif /* !__ASSEMBLY__ */ #include @@ -186,9 +189,16 @@ struct sve_context { * sve_context.vl must equal the thread's current vector length when * doing a sigreturn. * + * On systems with support for SME the SVE register state may reflect either + * streaming or non-streaming mode. In streaming mode the streaming mode + * vector length will be used and the flag SVE_SIG_FLAG_SM will be set in + * the flags field. It is permitted to enter or leave streaming mode in + * a signal return, applications should take care to ensure that any difference + * in vector length between the two modes is handled, including any resixing + * and movement of context blocks. * - * Note: for all these macros, the "vq" argument denotes the SVE - * vector length in quadwords (i.e., units of 128 bits). + * Note: for all these macros, the "vq" argument denotes the vector length + * in quadwords (i.e., units of 128 bits). * * The correct way to obtain vq is to use sve_vq_from_vl(vl). The * result is valid if and only if sve_vl_valid(vl) is true. This is diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index cda04fd73333..5e6ec6ed8a1c 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -227,11 +227,17 @@ static int preserve_sve_context(struct sve_context __user *ctx) { int err = 0; u16 reserved[ARRAY_SIZE(ctx->__reserved)]; + u16 flags = 0; unsigned int vl = task_get_sve_vl(current); unsigned int vq = 0; - if (test_thread_flag(TIF_SVE)) + if (thread_sm_enabled(¤t->thread)) { + vl = task_get_sme_vl(current); vq = sve_vq_from_vl(vl); + flags |= SVE_SIG_FLAG_SM; + } else if (test_thread_flag(TIF_SVE)) { + vq = sve_vq_from_vl(vl); + } memset(reserved, 0, sizeof(reserved)); @@ -239,6 +245,7 @@ static int preserve_sve_context(struct sve_context __user *ctx) __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16), &ctx->head.size, err); __put_user_error(vl, &ctx->vl, err); + __put_user_error(flags, &ctx->flags, err); BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved)); err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved)); @@ -259,18 +266,28 @@ static int preserve_sve_context(struct sve_context __user *ctx) static int restore_sve_fpsimd_context(struct user_ctxs *user) { int err; - unsigned int vq; + unsigned int vl, vq; struct user_fpsimd_state fpsimd; struct sve_context sve; if (__copy_from_user(&sve, user->sve, sizeof(sve))) return -EFAULT; - if (sve.vl != task_get_sve_vl(current)) + if (sve.flags & SVE_SIG_FLAG_SM) { + if (!system_supports_sme()) + return -EINVAL; + + vl = task_get_sme_vl(current); + } else { + vl = task_get_sve_vl(current); + } + + if (sve.vl != vl) return -EINVAL; if (sve.head.size <= sizeof(*user->sve)) { clear_thread_flag(TIF_SVE); + current->thread.svcr &= ~SYS_SVCR_EL0_SM_MASK; goto fpsimd_only; } @@ -302,7 +319,10 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user) if (err) return -EFAULT; - set_thread_flag(TIF_SVE); + if (sve.flags & SVE_SIG_FLAG_SM) + current->thread.svcr |= SYS_SVCR_EL0_SM_MASK; + else + set_thread_flag(TIF_SVE); fpsimd_only: /* copy the FP and status/control registers */ @@ -394,7 +414,7 @@ static int parse_user_sigframe(struct user_ctxs *user, break; case SVE_MAGIC: - if (!system_supports_sve()) + if (!system_supports_sve() && !system_supports_sme()) goto invalid; if (user->sve) @@ -593,11 +613,16 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, if (system_supports_sve()) { unsigned int vq = 0; - if (add_all || test_thread_flag(TIF_SVE)) { - int vl = sve_max_vl(); + if (add_all || test_thread_flag(TIF_SVE) || + thread_sm_enabled(¤t->thread)) { + int vl = max(sve_max_vl(), sme_max_vl()); - if (!add_all) - vl = task_get_sve_vl(current); + if (!add_all) { + if (thread_sm_enabled(¤t->thread)) + vl = task_get_sme_vl(current); + else + vl = task_get_sve_vl(current); + } vq = sve_vq_from_vl(vl); } @@ -648,8 +673,9 @@ static int setup_sigframe(struct rt_sigframe_user_layout *user, __put_user_error(current->thread.fault_code, &esr_ctx->esr, err); } - /* Scalable Vector Extension state, if present */ - if (system_supports_sve() && err == 0 && user->sve_offset) { + /* Scalable Vector Extension state (including streaming), if present */ + if ((system_supports_sve() || system_supports_sme()) && + err == 0 && user->sve_offset) { struct sve_context __user *sve_ctx = apply_user_offset(user, user->sve_offset); err |= preserve_sve_context(sve_ctx);