From patchwork Tue Jan 25 00:10:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 12723233 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 72B4CC433F5 for ; Tue, 25 Jan 2022 03:34:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1384951AbiAYDen (ORCPT ); Mon, 24 Jan 2022 22:34:43 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:51970 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2374254AbiAYAQh (ORCPT ); Mon, 24 Jan 2022 19:16:37 -0500 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 1EFC161545 for ; Tue, 25 Jan 2022 00:16:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2E117C340E7; Tue, 25 Jan 2022 00:16:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643069796; bh=oW8pCZKYXjjBMZgQkaxtsed3e5u7xxSj/4h8WMIhNyc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sEY3SYdlUT57cDE/UGSwAFQx3z20x0/aHc5rKp4NQ3uOaJ8KsVWO91VEDW+fapyXj Iop0Q2ifOP7fjAGHt9B1cTR0bxSZBVe+yIm2B21l808ZJEq1xsZvd6EpVnvn55ETGF ZTs01+3BgNHIacvMJVq1+r7GnK3esJwwBTr1I9vQ1+NegTlGRiLq83TkcgdTeGz5oK A93T77vyJOruiB4cGjf3Fg+e9bmb518PaaopPjN7SCTC3PSgzun8QR4TKguSylJ+6l ek4iclHkS69UhaZNLvaH6xJ/tS1zwkZelrL2IU8thCgeSxv/siyQMiaQJopSPiS/2p bEk1kVX/r0Ocg== 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 19/38] arm64/sme: Implement ZA signal handling Date: Tue, 25 Jan 2022 00:10:55 +0000 Message-Id: <20220125001114.193425-20-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=8905; h=from:subject; bh=oW8pCZKYXjjBMZgQkaxtsed3e5u7xxSj/4h8WMIhNyc=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBh70AQ0hJdJxo+5Qop2soApSWgxTalG0mokuvaAz99 SzK+WkaJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCYe9AEAAKCRAk1otyXVSH0CaIB/ wKX6p46yDZ/hX6EqcuBTz5OcbBhLLWKwBB8JvE+btJu3lV/8DHcYVDO388xOgo6czvXEPgAuzwCsaD hb6ii1U8IjvEHmzytDiNkXgCqnLPFas9jD65S3zMFIngMduNiesc26zxBuzS9YLgw1g3TEK/xuRC02 mAnp4hfF7BQE6UR578Yas5HZBwGHGezwgnsJ943YZ855pOw33OEso/G4dDIePSucpyW56o6mL5aluX YwU6DgjozSYT/dndhce/gYx6mip8wfmjD248y8TdyZrDKy/fg6En/jooMot3eULcxkB9N3Duma1uNG SoFylKYSJRbilBe7iBrJ57+2i+7lAb X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Implement support for ZA in signal handling in a very similar way to how we implement support for SVE registers, using a signal context structure with optional register state after it. Where present this register state stores the ZA matrix as a series of horizontal vectors numbered from 0 to VL/8 in the endinanness independent format used for vectors. As with SVE we do not allow changes in the vector length during signal return but we do allow ZA to be enabled or disabled. Signed-off-by: Mark Brown --- arch/arm64/include/uapi/asm/sigcontext.h | 41 +++++++ arch/arm64/kernel/fpsimd.c | 3 - arch/arm64/kernel/signal.c | 139 +++++++++++++++++++++++ 3 files changed, 180 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h index 3a3366d4fbc2..d45bdf2c8b26 100644 --- a/arch/arm64/include/uapi/asm/sigcontext.h +++ b/arch/arm64/include/uapi/asm/sigcontext.h @@ -140,6 +140,14 @@ struct sve_context { #define SVE_SIG_FLAG_SM 0x1 /* Context describes streaming mode */ +#define ZA_MAGIC 0x54366345 + +struct za_context { + struct _aarch64_ctx head; + __u16 vl; + __u16 __reserved[3]; +}; + #endif /* !__ASSEMBLY__ */ #include @@ -259,4 +267,37 @@ struct sve_context { #define SVE_SIG_CONTEXT_SIZE(vq) \ (SVE_SIG_REGS_OFFSET + SVE_SIG_REGS_SIZE(vq)) +/* + * If the ZA register is enabled for the thread at signal delivery then, + * za_context.head.size >= ZA_SIG_CONTEXT_SIZE(sve_vq_from_vl(za_context.vl)) + * and the register data may be accessed using the ZA_SIG_*() macros. + * + * If za_context.head.size < ZA_SIG_CONTEXT_SIZE(sve_vq_from_vl(za_context.vl)) + * then ZA was not enabled and no register data was included in which case + * ZA register was not enabled for the thread and no register data + * the ZA_SIG_*() macros should not be used except for this check. + * + * The same convention applies when returning from a signal: a caller + * will need to remove or resize the za_context block if it wants to + * enable the ZA register when it was previously non-live or vice-versa. + * This may require the caller to allocate fresh memory and/or move other + * context blocks in the signal frame. + * + * Changing the vector length during signal return is not permitted: + * za_context.vl must equal the thread's current SME vector length when + * doing a sigreturn. + */ + +#define ZA_SIG_REGS_OFFSET \ + ((sizeof(struct za_context) + (__SVE_VQ_BYTES - 1)) \ + / __SVE_VQ_BYTES * __SVE_VQ_BYTES) + +#define ZA_SIG_REGS_SIZE(vq) ((vq * __SVE_VQ_BYTES) * (vq * __SVE_VQ_BYTES)) + +#define ZA_SIG_ZAV_OFFSET(vq, n) (ZA_SIG_REGS_OFFSET + \ + (SVE_SIG_ZREG_SIZE(vq) * n)) + +#define ZA_SIG_CONTEXT_SIZE(vq) \ + (ZA_SIG_REGS_OFFSET + ZA_SIG_REGS_SIZE(vq)) + #endif /* _UAPI__ASM_SIGCONTEXT_H */ diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 33f80512753d..2242c14a5a05 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1190,9 +1190,6 @@ void fpsimd_release_task(struct task_struct *dead_task) #ifdef CONFIG_ARM64_SME -/* This will move to uapi/asm/sigcontext.h when signals are implemented */ -#define ZA_SIG_REGS_SIZE(vq) ((vq * __SVE_VQ_BYTES) * (vq * __SVE_VQ_BYTES)) - /* * Ensure that task->thread.za_state is allocated and sufficiently large. * diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 5e6ec6ed8a1c..8efa78765cad 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -57,6 +57,7 @@ struct rt_sigframe_user_layout { unsigned long fpsimd_offset; unsigned long esr_offset; unsigned long sve_offset; + unsigned long za_offset; unsigned long extra_offset; unsigned long end_offset; }; @@ -219,6 +220,7 @@ static int restore_fpsimd_context(struct fpsimd_context __user *ctx) struct user_ctxs { struct fpsimd_context __user *fpsimd; struct sve_context __user *sve; + struct za_context __user *za; }; #ifdef CONFIG_ARM64_SVE @@ -347,6 +349,101 @@ extern int restore_sve_fpsimd_context(struct user_ctxs *user); #endif /* ! CONFIG_ARM64_SVE */ +#ifdef CONFIG_ARM64_SME + +static int preserve_za_context(struct za_context __user *ctx) +{ + int err = 0; + u16 reserved[ARRAY_SIZE(ctx->__reserved)]; + unsigned int vl = task_get_sme_vl(current); + unsigned int vq; + + if (thread_za_enabled(¤t->thread)) + vq = sve_vq_from_vl(vl); + else + vq = 0; + + memset(reserved, 0, sizeof(reserved)); + + __put_user_error(ZA_MAGIC, &ctx->head.magic, err); + __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16), + &ctx->head.size, err); + __put_user_error(vl, &ctx->vl, err); + BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved)); + err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved)); + + if (vq) { + /* + * This assumes that the ZA state has already been saved to + * the task struct by calling the function + * fpsimd_signal_preserve_current_state(). + */ + err |= __copy_to_user((char __user *)ctx + ZA_SIG_REGS_OFFSET, + current->thread.za_state, + ZA_SIG_REGS_SIZE(vq)); + } + + return err ? -EFAULT : 0; +} + +static int restore_za_context(struct user_ctxs __user *user) +{ + int err; + unsigned int vq; + struct za_context za; + + if (__copy_from_user(&za, user->za, sizeof(za))) + return -EFAULT; + + if (za.vl != task_get_sme_vl(current)) + return -EINVAL; + + if (za.head.size <= sizeof(*user->za)) { + current->thread.svcr &= ~SYS_SVCR_EL0_ZA_MASK; + return 0; + } + + vq = sve_vq_from_vl(za.vl); + + if (za.head.size < ZA_SIG_CONTEXT_SIZE(vq)) + return -EINVAL; + + /* + * Careful: we are about __copy_from_user() directly into + * thread.za_state with preemption enabled, so protection is + * needed to prevent a racing context switch from writing stale + * registers back over the new data. + */ + + fpsimd_flush_task_state(current); + /* From now, fpsimd_thread_switch() won't touch thread.sve_state */ + + sme_alloc(current); + if (!current->thread.za_state) { + current->thread.svcr &= ~SYS_SVCR_EL0_ZA_MASK; + clear_thread_flag(TIF_SME); + return -ENOMEM; + } + + err = __copy_from_user(current->thread.za_state, + (char __user const *)user->za + + ZA_SIG_REGS_OFFSET, + ZA_SIG_REGS_SIZE(vq)); + if (err) + return -EFAULT; + + set_thread_flag(TIF_SME); + current->thread.svcr |= SYS_SVCR_EL0_ZA_MASK; + + return 0; +} +#else /* ! CONFIG_ARM64_SME */ + +/* Turn any non-optimised out attempts to use these into a link error: */ +extern int preserve_za_context(void __user *ctx); +extern int restore_za_context(struct user_ctxs *user); + +#endif /* ! CONFIG_ARM64_SME */ static int parse_user_sigframe(struct user_ctxs *user, struct rt_sigframe __user *sf) @@ -361,6 +458,7 @@ static int parse_user_sigframe(struct user_ctxs *user, user->fpsimd = NULL; user->sve = NULL; + user->za = NULL; if (!IS_ALIGNED((unsigned long)base, 16)) goto invalid; @@ -426,6 +524,19 @@ static int parse_user_sigframe(struct user_ctxs *user, user->sve = (struct sve_context __user *)head; break; + case ZA_MAGIC: + if (!system_supports_sme()) + goto invalid; + + if (user->za) + goto invalid; + + if (size < sizeof(*user->za)) + goto invalid; + + user->za = (struct za_context __user *)head; + break; + case EXTRA_MAGIC: if (have_extra_context) goto invalid; @@ -549,6 +660,9 @@ static int restore_sigframe(struct pt_regs *regs, } } + if (err == 0 && system_supports_sme() && user.za) + err = restore_za_context(&user); + return err; } @@ -633,6 +747,24 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, return err; } + if (system_supports_sme()) { + unsigned int vl; + unsigned int vq = 0; + + if (add_all) + vl = sme_max_vl(); + else + vl = task_get_sme_vl(current); + + if (thread_za_enabled(¤t->thread)) + vq = sve_vq_from_vl(vl); + + err = sigframe_alloc(user, &user->za_offset, + ZA_SIG_CONTEXT_SIZE(vq)); + if (err) + return err; + } + return sigframe_alloc_end(user); } @@ -681,6 +813,13 @@ static int setup_sigframe(struct rt_sigframe_user_layout *user, err |= preserve_sve_context(sve_ctx); } + /* ZA state if present */ + if (system_supports_sme() && err == 0 && user->za_offset) { + struct za_context __user *za_ctx = + apply_user_offset(user, user->za_offset); + err |= preserve_za_context(za_ctx); + } + if (err == 0 && user->extra_offset) { char __user *sfp = (char __user *)user->sigframe; char __user *userp =