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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B0E2C433EF for ; Sun, 6 Feb 2022 17:43:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344768AbiBFRno (ORCPT ); Sun, 6 Feb 2022 12:43:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233776AbiBFRnm (ORCPT ); Sun, 6 Feb 2022 12:43:42 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5A2DC06173B for ; Sun, 6 Feb 2022 09:43:41 -0800 (PST) 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 88D62611C8 for ; Sun, 6 Feb 2022 17:43:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B45B3C340E9; Sun, 6 Feb 2022 17:43:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644169420; bh=fLik+MCx1UepZ3oiLpbRUYEqsM0GTJc2mQEVFX7OMVs=; h=From:To:Cc:Subject:Date:From; b=dwKJ8dfhJ2vipvS9I3ja1ER8/OLzBJwXrHjv3eNgndq6rBRLUdRBJJKvcluGWmKC4 ahA/nxYES7KZKNrHOxC6qrz4V+RP/1hXwT4FnHY/wLPcVAz6I3MtdPFcGXXq/ep7ta RsMWCFUcHUxZ6u+f74cpFh3XwuYiB4b5ablBiq78zZwDeY/ghyaJtfPe6jCGkY/j+J AvXFe3vkhMQ9rS17Y5O+XFAcrfp+PASSPKsyQxGQJSzi+Sx1f5WsyB2k/IWoUS3Klv ww2V3p0E3WQAHkt/rNPK68Lz72Brg+wB9GDUOkXJzeUsfbHxRjoWVGaT5CWWZahMfr CT6iKz1uQmYTg== From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] riscv: add irq stack support Date: Mon, 7 Feb 2022 01:36:00 +0800 Message-Id: <20220206173600.2784-1-jszhang@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, IRQs are still handled on the kernel stack of the current task on riscv platforms. If the task has a deep call stack at the time of interrupt, and handling the interrupt also requires a deep stack, it's possible to see stack overflow. Before this patch, the stack_max_size of a v5.17-rc1 kernel running on a lichee RV board gave: ~ # cat /sys/kernel/debug/tracing/stack_max_size 3736 After this patch, ~ # cat /sys/kernel/debug/tracing/stack_max_size 3176 We reduce the max kernel stack usage by 560 bytes! >From another side, after this patch, it's possible to reduce the THREAD_SIZE to 8KB for RV64 platforms. This is especially useful for those systems with small memory size, e.g the Allwinner D1S platform which is RV64 but only has 64MB DDR. Signed-off-by: Jisheng Zhang --- arch/riscv/include/asm/thread_info.h | 1 + arch/riscv/kernel/asm-offsets.c | 2 ++ arch/riscv/kernel/entry.S | 33 +++++++++++++++++++++++++--- arch/riscv/kernel/irq.c | 16 ++++++++++++++ 4 files changed, 49 insertions(+), 3 deletions(-) diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h index 60da0dcacf14..67387a8bcb34 100644 --- a/arch/riscv/include/asm/thread_info.h +++ b/arch/riscv/include/asm/thread_info.h @@ -19,6 +19,7 @@ #endif #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER) +#define IRQ_STACK_SIZE THREAD_SIZE /* * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c index df0519a64eaf..9619398a69e1 100644 --- a/arch/riscv/kernel/asm-offsets.c +++ b/arch/riscv/kernel/asm-offsets.c @@ -36,6 +36,8 @@ void asm_offsets(void) OFFSET(TASK_TI_PREEMPT_COUNT, task_struct, thread_info.preempt_count); OFFSET(TASK_TI_KERNEL_SP, task_struct, thread_info.kernel_sp); OFFSET(TASK_TI_USER_SP, task_struct, thread_info.user_sp); + OFFSET(TASK_TI_CPU, task_struct, thread_info.cpu); + OFFSET(TASK_STACK, task_struct, stack); OFFSET(TASK_THREAD_F0, task_struct, thread.fstate.f[0]); OFFSET(TASK_THREAD_F1, task_struct, thread.fstate.f[1]); diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index ed29e9c8f660..57c9b64e16a5 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -126,12 +126,39 @@ skip_context_tracking: */ bge s4, zero, 1f - la ra, ret_from_exception + /* preserve the sp */ + move s0, sp - /* Handle interrupts */ move a0, sp /* pt_regs */ + + /* + * Compare sp with the base of the task stack. + * If the top ~(THREAD_SIZE - 1) bits match, we are on a task stack, + * and should switch to the irq stack. + */ + REG_L t0, TASK_STACK(tp) + xor t0, t0, s0 + li t1, ~(THREAD_SIZE - 1) + and t0, t0, t1 + bnez t0, 2f + + la t1, irq_stack + REG_L t2, TASK_TI_CPU(tp) + slli t2, t2, RISCV_LGPTR + add t1, t1, t2 + REG_L t2, 0(t1) + li t1, IRQ_STACK_SIZE + /* switch to the irq stack */ + add sp, t2, t1 + +2: + /* Handle interrupts */ la a1, generic_handle_arch_irq - jr a1 + jalr a1 + + /* Restore sp */ + move sp, s0 + j ret_from_exception 1: /* * Exceptions run with interrupts enabled or disabled depending on the diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c index 7207fa08d78f..9b586d6ad7ca 100644 --- a/arch/riscv/kernel/irq.c +++ b/arch/riscv/kernel/irq.c @@ -10,6 +10,8 @@ #include #include +void *irq_stack[NR_CPUS]; + int arch_show_interrupts(struct seq_file *p, int prec) { show_ipi_stats(p, prec); @@ -18,7 +20,21 @@ int arch_show_interrupts(struct seq_file *p, int prec) void __init init_IRQ(void) { + int cpu; + irqchip_init(); if (!handle_arch_irq) panic("No interrupt controller found."); + + for_each_possible_cpu(cpu) { +#ifdef CONFIG_VMAP_STACK + void *s = __vmalloc_node(IRQ_STACK_SIZE, THREAD_ALIGN, + THREADINFO_GFP, cpu_to_node(cpu), + __builtin_return_address(0)); +#else + void *s = (void *)__get_free_pages(GFP_KERNEL, get_order(IRQ_STACK_SIZE)); +#endif + + irq_stack[cpu] = s; + } } -- 2.34.1