From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D5165CA0EED for ; Mon, 25 Aug 2025 03:46:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=aIsakFJCSJTFKht6HLdSeux2VeHthGRYO/cfpn7qL9Y=; b=NibULkgwzsYWe+IbahpIbsR796 ntd96EPfNbjus1TdoxYno4ouJsJKbwFl+o4RhCdkwVRg3OmXBCW0jzVD913i11XqKq7JDt/OFsXhf e2/yUA03ppjWkF781JFA8xtg8Ze/u5CBfl1CXmeIlDQw2uSY/2YuWlVCo0udtmG2MIbjVjWC6JXmU EUtJ1JN8Z50JX+wk5mn8TbUDA16x4qgtOUmuSgl9qZqHurkxm+jgORoQcmyUUdgE3B4WlqrOGOyfV zJLhQLtjXIjZ+py/Y42CC3SVV8VCL+Wu/1Y+ZrdlSMAEpS/KY91yQp4/0YIyl3XYlQxXxDIw6HUYa nCeQ42Tg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqO9p-00000006qEn-3UE1; Mon, 25 Aug 2025 03:46:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uqNyd-00000006oht-0EEY for linux-arm-kernel@lists.infradead.org; Mon, 25 Aug 2025 03:34:36 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 599A52A9A; Sun, 24 Aug 2025 20:34:26 -0700 (PDT) Received: from u200865.usa.arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 711103F63F; Sun, 24 Aug 2025 20:34:33 -0700 (PDT) From: Jeremy Linton To: linux-trace-kernel@vger.kernel.org Cc: linux-perf-users@vger.kernel.org, mhiramat@kernel.org, oleg@redhat.com, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, thiago.bauermann@linaro.org, broonie@kernel.org, yury.khrustalev@arm.com, kristina.martsenko@arm.com, liaochang1@huawei.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jeremy Linton Subject: [PATCH v7 3/7] arm64: uaccess: Add additional userspace GCS accessors Date: Sun, 24 Aug 2025 22:34:17 -0500 Message-ID: <20250825033421.463669-4-jeremy.linton@arm.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250825033421.463669-1-jeremy.linton@arm.com> References: <20250825033421.463669-1-jeremy.linton@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250824_203435_221072_1DDE9547 X-CRM114-Status: GOOD ( 13.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Uprobes need more advanced read, push, and pop userspace GCS functionality. Implement those features using the existing gcsstr() and copy_from_user(). Its important to note that GCS pages can be read by normal instructions, but the hardware validates that pages used by GCS specific operations, have a GCS privilege set. We aren't validating this in load_user_gcs because it requires stabilizing the VMA over the read which may fault. Signed-off-by: Jeremy Linton Reviewed-by: Catalin Marinas Reviewed-by: Mark Brown --- arch/arm64/include/asm/gcs.h | 54 ++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h index 10c68d3e6e30..97801543380e 100644 --- a/arch/arm64/include/asm/gcs.h +++ b/arch/arm64/include/asm/gcs.h @@ -116,6 +116,47 @@ static inline void put_user_gcs(unsigned long val, unsigned long __user *addr, uaccess_ttbr0_disable(); } +static inline void push_user_gcs(unsigned long val, int *err) +{ + u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0); + + gcspr -= sizeof(u64); + put_user_gcs(val, (unsigned long __user *)gcspr, err); + if (!*err) + write_sysreg_s(gcspr, SYS_GCSPR_EL0); +} + +/* + * Unlike put/push_user_gcs() above, get/pop_user_gsc() doesn't + * validate the GCS permission is set on the page being read. This + * differs from how the hardware works when it consumes data stored at + * GCSPR. Callers should ensure this is acceptable. + */ +static inline u64 get_user_gcs(unsigned long __user *addr, int *err) +{ + unsigned long ret; + u64 load = 0; + + /* Ensure previous GCS operation are visible before we read the page */ + gcsb_dsync(); + ret = copy_from_user(&load, addr, sizeof(load)); + if (ret != 0) + *err = ret; + return load; +} + +static inline u64 pop_user_gcs(int *err) +{ + u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0); + u64 read_val; + + read_val = get_user_gcs((unsigned long __user *)gcspr, err); + if (!*err) + write_sysreg_s(gcspr + sizeof(u64), SYS_GCSPR_EL0); + + return read_val; +} + #else static inline bool task_gcs_el0_enabled(struct task_struct *task) @@ -126,6 +167,10 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task) static inline void gcs_set_el0_mode(struct task_struct *task) { } static inline void gcs_free(struct task_struct *task) { } static inline void gcs_preserve_current_state(void) { } +static inline void put_user_gcs(unsigned long val, unsigned long __user *addr, + int *err) { } +static inline void push_user_gcs(unsigned long val, int *err) { } + static inline unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, const struct kernel_clone_args *args) { @@ -136,6 +181,15 @@ static inline int gcs_check_locked(struct task_struct *task, { return 0; } +static inline u64 get_user_gcs(unsigned long __user *addr, int *err) +{ + *err = -EFAULT; + return 0; +} +static inline u64 pop_user_gcs(int *err) +{ + return 0; +} #endif -- 2.50.1