Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752720AbdGLWeS (ORCPT ); Wed, 12 Jul 2017 18:34:18 -0400 Received: from foss.arm.com ([217.140.101.70]:59118 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752523AbdGLWeQ (ORCPT ); Wed, 12 Jul 2017 18:34:16 -0400 From: Mark Rutland To: ard.biesheuvel@linaro.org, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: akashi.takahiro@linaro.org, catalin.marinas@arm.com, dave.martin@arm.com, james.morse@arm.com, labbott@fedoraproject.org, will.deacon@arm.com, keescook@chromium.org, Mark Rutland Subject: [RFC PATCH 5/6] arm64: keep track of current stack Date: Wed, 12 Jul 2017 23:33:02 +0100 Message-Id: <1499898783-25732-6-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1499898783-25732-1-git-send-email-mark.rutland@arm.com> References: <1499898783-25732-1-git-send-email-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3381 Lines: 109 To reliably check stack bounds, we'll need to know whether we're on a task stack, or an IRQ stack. Stash the base of the current stack in thread_info so that we have this information. Signed-off-by: Mark Rutland --- arch/arm64/include/asm/thread_info.h | 3 +++ arch/arm64/kernel/asm-offsets.c | 3 +++ arch/arm64/kernel/entry.S | 7 +++++++ arch/arm64/kernel/head.S | 6 ++++++ arch/arm64/kernel/process.c | 4 ++++ 5 files changed, 23 insertions(+) diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index 3684f86..ae4f44b 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -62,6 +62,9 @@ struct thread_info { #endif unsigned long pcp_offset; int preempt_count; /* 0 => preemptable, <0 => bug */ +#ifdef CONFIG_VMAP_STACK + unsigned long current_stack; +#endif }; #define INIT_THREAD_INFO(tsk) \ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 17001be..10c8ffa 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -40,6 +40,9 @@ int main(void) DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count)); DEFINE(TSK_TI_PCP, offsetof(struct task_struct, thread_info.pcp_offset)); DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit)); +#ifdef CONFIG_VMAP_STACK + DEFINE(TSK_TI_CUR_STK, offsetof(struct task_struct, thread_info.current_stack)); +#endif #ifdef CONFIG_ARM64_SW_TTBR0_PAN DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0)); #endif diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 773b3fea..7c8b164 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -258,6 +258,9 @@ alternative_else_nop_endif /* switch to the irq stack */ mov sp, x26 +#ifdef CONFIG_VMAP_STACK + str x25, [tsk, #TSK_TI_CUR_STK] +#endif /* * Add a dummy stack frame, this non-standard format is fixed up @@ -275,6 +278,10 @@ alternative_else_nop_endif */ .macro irq_stack_exit mov sp, x19 +#ifdef CONFIG_VMAP_STACK + and x19, x19, #~(THREAD_SIZE - 1) + str x19, [tsk, #TSK_TI_CUR_STK] +#endif .endm /* diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index db77cac..3363846 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -325,6 +325,9 @@ __primary_switched: add sp, x4, #THREAD_SIZE adr_l x5, init_task msr tpidr_el1, x5 // Save thread_info +#ifdef CONFIG_VMAP_STACK + str x4, [x5, #TSK_TI_CUR_STK] +#endif adr_l x8, vectors // load VBAR_EL1 with virtual msr vbar_el1, x8 // vector table address @@ -616,6 +619,9 @@ __secondary_switched: mov x3, #THREAD_START_SP add sp, x1, x3 ldr x2, [x0, #CPU_BOOT_TASK] +#ifdef CONFIG_VMAP_STACK + str x1, [x2, #TSK_TI_CUR_STK] +#endif msr tpidr_el1, x2 mov x29, #0 b secondary_start_kernel diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 4212da3..5dc5797 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -294,6 +294,10 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, ptrace_hw_copy_thread(p); +#ifdef CONFIG_VMAP_STACK + p->thread_info.current_stack = (unsigned long)p->stack; +#endif + return 0; } -- 1.9.1