From patchwork Mon Nov 15 15:28:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 12619851 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06D8DC433EF for ; Mon, 15 Nov 2021 15:31:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3DBE61B4C for ; Mon, 15 Nov 2021 15:31:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236463AbhKOPej (ORCPT ); Mon, 15 Nov 2021 10:34:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:52836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236661AbhKOPdd (ORCPT ); Mon, 15 Nov 2021 10:33:33 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A8DA36322C; Mon, 15 Nov 2021 15:29:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1636990196; bh=6ezrNyY6X7TMhSUddPomE1q3fqf6OJIG2WyGCj0Ttb4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ksaQ9eBJvO4Sn2/KkFT1NtOAYroxV25jFHzGNiirTyJElHoSDg3d9MSXMnpoeIqYj vRKFmtQ+yjvD9y570X0PuNo+iI0PJBxAe4FlUuCfEaIZyz/trVxVwd7brO1Bh2ybKf 0HpeGnRU+9nw0q2w6z8pyMzQ1d6aidtwqeQ+TwRRxr06U6OeTeSSxDAioDEYw3ZcfO Lh5pqqp5TkaS0DpLf7VsvxcrEbvFt/UEa23vPc5bhb18kGQilAGHGhlcQoal1ce0FO g5K6LXqtN1I7WJO5E8mO4cEN8QJ/MxQjaoYG9nUnzkMKAsCm0+viIukmeSofwHYXaX FP3pTlou1apHg== From: Mark Brown To: Catalin Marinas , Will Deacon , Shuah Khan , Shuah Khan Cc: Alan Hayward , Luis Machado , Salil Akerkar , Basant Kumar Dwivedi , Szabolcs Nagy , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, Mark Brown Subject: [PATCH v6 22/37] arm64/sme: Implement streaming SVE signal handling Date: Mon, 15 Nov 2021 15:28:20 +0000 Message-Id: <20211115152835.3212149-23-broonie@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211115152835.3212149-1-broonie@kernel.org> References: <20211115152835.3212149-1-broonie@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6926; h=from:subject; bh=6ezrNyY6X7TMhSUddPomE1q3fqf6OJIG2WyGCj0Ttb4=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBhknyWpnmtzABZ+ZVMLsQMlaiils4F/nlvjdVNowEZ GmNR2hqJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYZJ8lgAKCRAk1otyXVSH0FvMB/ kBFbDDD0qvQT8dReH9Q+3GjOVrzCudgAQxO5xYV13H08YZ5DsyelIsTXyTlYZY8YTCtWcope9sJ4EJ 0QHrHpW+6Jm5hiHQLPDgGsQJbo2Y0MsoVLNLtl3n4N99zXqiQHMa3h2aSgCSLmLqcR33gKqid9GZWh gJAEpF/CnK+2OJVPAoskY/qejz1Ak4PK/+2mgEV7pB/jZD5hwrYTXPKOFz6RGaCvg8bPHvPRmpwx/R +By2woMVIPgE64erJ9hXvosycVdYOY9hmj/AZS8drWYiMsM4nTcLEGbgyKuWqI1gxXZ7vf+teFM3lT /sWAAryUQniQJNe0LpgjJe/Rzw6WvN 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 8f6372b44b65..fea0e1d30449 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);