From patchwork Mon Jul 24 12:46:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13324594 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 C2075C001B0 for ; Mon, 24 Jul 2023 12:51:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231250AbjGXMv0 (ORCPT ); Mon, 24 Jul 2023 08:51:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230458AbjGXMuk (ORCPT ); Mon, 24 Jul 2023 08:50:40 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3418D4211; Mon, 24 Jul 2023 05:49:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 139CF61155; Mon, 24 Jul 2023 12:49:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DF04C433CC; Mon, 24 Jul 2023 12:48:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690202941; bh=QNLQ8kMMswSwDNNNdkC4JMSh/ccvZNRY7O5oRui945g=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=AlxmpCLETBmLqddSMK51fZ32WDvxGLvxDmnSYcRk7WdS9TC4Qhnxzw6V16gWpnSR6 r1jEsSzd718jMWwVDyLdCBdberKTExz/7IGv653VnmbLwLG7TxxWLHLpaRkqzyeTh7 rFKkDcJrScG+G4hyLQtRcjhEId4/m/ztZzFlzxQjQMEJkXGnMCJ0VlJ17e9603h3bx 732VzGlxNlU/U7E+V4yJQkh+4lG6+tDoWu4VhRtB/jAzCfe1XEzaxRfnfNxHqGuAEj /jPcX0zrOZgFSy3TtZfFyNG761KDQpHk68yOVckYs9L82CyEe4PTn2UV4y6x7cplCh zrveLkGtqZ5zw== From: Mark Brown Date: Mon, 24 Jul 2023 13:46:06 +0100 Subject: [PATCH v2 19/35] arm64/gcs: Allocate a new GCS for threads with GCS enabled MIME-Version: 1.0 Message-Id: <20230724-arm64-gcs-v2-19-dc2c1d44c2eb@kernel.org> References: <20230724-arm64-gcs-v2-0-dc2c1d44c2eb@kernel.org> In-Reply-To: <20230724-arm64-gcs-v2-0-dc2c1d44c2eb@kernel.org> To: Catalin Marinas , Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Kees Cook , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy Cc: "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Mark Brown X-Mailer: b4 0.13-dev-099c9 X-Developer-Signature: v=1; a=openpgp-sha256; l=5142; i=broonie@kernel.org; h=from:subject:message-id; bh=QNLQ8kMMswSwDNNNdkC4JMSh/ccvZNRY7O5oRui945g=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBkvnKjd5H4T7HVGGGvCV4nQfR+bRm0kpxekGX3nuqx YMIaxVeJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZL5yowAKCRAk1otyXVSH0N04B/ wNA+KKlovm9aHcWE4LguyaxlEw37PNfiCmNG3bV4WWtfSlphw1b9Td8f7QLubjaD7a2g3zEybvkLhW y5yxBPyH5PCleDM87YgHkVStgryUbU+z/x7gN4Bz0mNoaoddrxVeyNFfJi0Ao9VePvkSGOzZx/AK4v dJKB94ZJ+XndzypqJpDS4v/ETYh6WSUOgsySRju4Ew62J3jkSroWU2E8OJcYsBV9PFwxjga7LGZTjL ingXJAt8UvFrmIk83HqCCtAp+MSbX39oayG4Ak+NAiz+nSUFeWACASb/2oqHWB7LJcCuIyhV/jksq/ 9Lscn001s44mlUqgjQm2EkfbuZ33cc X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org We do not currently have a mechanism to specify a new GCS for a new thread so when a thread is created which has GCS enabled allocate one for it. Since there is no current API for specifying the size of the GCS we follow the extensively discussed x86 implementation and allocate min(RLIMIT_STACK, 4G). Since the GCS only stores the call stack and not any variables this should be more than sufficient for most applications. When allocating the stack we initialise GCSPR_EL0 to point to one entry below the end of the region allocated, this keeps the top entry of the stack 0 so software walking the GCS can easily detect the end of the region. Signed-off-by: Mark Brown --- arch/arm64/include/asm/gcs.h | 7 ++++++ arch/arm64/kernel/process.c | 30 ++++++++++++++++++++++++ arch/arm64/mm/gcs.c | 56 ++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 93 insertions(+) diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h index 04594ef59dad..4371a2f99b4a 100644 --- a/arch/arm64/include/asm/gcs.h +++ b/arch/arm64/include/asm/gcs.h @@ -58,6 +58,8 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task) void gcs_set_el0_mode(struct task_struct *task); void gcs_free(struct task_struct *task); void gcs_preserve_current_state(void); +unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, + unsigned long clone_flags, size_t size); #else @@ -69,6 +71,11 @@ 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 unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, + unsigned long clone_flags, size_t size) +{ + return -ENOTSUPP; +} #endif diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index b78f60d4a1e4..8589818166d7 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -284,9 +284,34 @@ static void flush_gcs(void) } } +static int copy_thread_gcs(struct task_struct *p, unsigned long clone_flags, + size_t stack_size) +{ + unsigned long gcs; + + if (!system_supports_gcs()) + return 0; + + if (!task_gcs_el0_enabled(p)) + return 0; + + p->thread.gcspr_el0 = read_sysreg_s(SYS_GCSPR_EL0); + + gcs = gcs_alloc_thread_stack(p, clone_flags, stack_size); + if (IS_ERR_VALUE(gcs)) + return PTR_ERR((void *)gcs); + + return 0; +} + #else static void flush_gcs(void) { } +static int copy_thread_gcs(struct task_struct *p, unsigned long clone_flags, + size_t stack_size) +{ + return 0; +} #endif @@ -368,6 +393,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) unsigned long stack_start = args->stack; unsigned long tls = args->tls; struct pt_regs *childregs = task_pt_regs(p); + int ret; memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context)); @@ -409,6 +435,10 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.uw.tp_value = tls; p->thread.tpidr2_el0 = 0; } + + ret = copy_thread_gcs(p, clone_flags, args->stack_size); + if (ret != 0) + return ret; } else { /* * A kthread has no context to ERET to, so ensure any buggy diff --git a/arch/arm64/mm/gcs.c b/arch/arm64/mm/gcs.c index b0a67efc522b..1e059c37088d 100644 --- a/arch/arm64/mm/gcs.c +++ b/arch/arm64/mm/gcs.c @@ -8,6 +8,62 @@ #include #include +static unsigned long alloc_gcs(unsigned long addr, unsigned long size, + unsigned long token_offset, bool set_res_tok) +{ + int flags = MAP_ANONYMOUS | MAP_PRIVATE; + struct mm_struct *mm = current->mm; + unsigned long mapped_addr, unused; + + if (addr) + flags |= MAP_FIXED_NOREPLACE; + + mmap_write_lock(mm); + mapped_addr = do_mmap(NULL, addr, size, PROT_READ, flags, + VM_SHADOW_STACK | VM_WRITE, 0, &unused, NULL); + mmap_write_unlock(mm); + + return mapped_addr; +} + +static unsigned long gcs_size(unsigned long size) +{ + if (size) + return PAGE_ALIGN(size); + + /* Allocate RLIMIT_STACK with limits of PAGE_SIZE..4G */ + size = PAGE_ALIGN(min_t(unsigned long long, + rlimit(RLIMIT_STACK), SZ_4G)); + return max(PAGE_SIZE, size); +} + +unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, + unsigned long clone_flags, size_t size) +{ + unsigned long addr; + + if (!system_supports_gcs()) + return 0; + + if (!task_gcs_el0_enabled(tsk)) + return 0; + + if ((clone_flags & (CLONE_VFORK | CLONE_VM)) != CLONE_VM) + return 0; + + size = gcs_size(size); + + addr = alloc_gcs(0, size, 0, 0); + if (IS_ERR_VALUE(addr)) + return addr; + + tsk->thread.gcs_base = addr; + tsk->thread.gcs_size = size; + tsk->thread.gcspr_el0 = addr + size - sizeof(u64); + + return addr; +} + /* * Apply the GCS mode configured for the specified task to the * hardware.