From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0D90C514758 for ; Fri, 18 Sep 2026 16:15:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789748113; cv=none; b=UdxH85hSHUiaQsCxA00+KJc4QaWpEp+GWoT8CRiQ9bwxDLz4vSzxDidL4NDvfll9mvpshWiI794VSuIWFVEBYvU9yKgGEW2KyI6yXYUPOsYapmPC71bXtzke/nkSHZkqXxmV4kn9wRg0EYVW/6kYxcYm/S+Kb0XR7+adWtj9kY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789748113; c=relaxed/simple; bh=8N+dMro6IY5WMzrJLEVXWe787chZDhO/60ie5X0SGSY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eARocZg8xRWXrHkfxYohClZrgeQ9kr0fcT1Kzg+N2xaFE3zehNzg7c7vVByvWLIG8zSIF5mheVXyL5PHZgSzdH7luM7RWMHSyNWLjdNo129BR6Hmy0FF+bmJYwbPIfHcomAwOOl1Pk3Uv504Tl3Sdiq5HuwkSWyKOYIFoKQVbIQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AW4leaLe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AW4leaLe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B7941F00898; Fri, 18 Sep 2026 16:15:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789748111; bh=PHdOX9xdJ/boaqPZ/GwtRSXh8g+Ri88d8K76J4PQiZA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AW4leaLe7j4HIbFH2dIJD4sVJv8bNmmtDS2WAAo4HLGUrfMxov+PMkjuIVqHRFL9b 3jTIF/zEjLp6fQwqp3r5PMg+RuxqLVDmnkvctgfNzjflj60eejygFy6fiBGIl+ByvM v7VkBY2mCW7HjhCo2TjPOhn8P3JeaTUd8TXi89dNH4KKwlHR0GWPjoOCSsD2naCidU FIUXzPe+EmQGG420NDLeSTXAYovB/SJOeJuYBhWvQzbx0TdD0IvOG2WNGUeBfJM2J/ FcBUNsduS9xkFTa3yjwuaYZgQVEFWhm3ZqUqQDXQHbQNDO8ySpEY/0BG/cFzhE/K/9 77wWm0LhbKWdA== From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Will Deacon , Arnd Bergmann , Ard Biesheuvel , Ada Couprie Diaz , David Hildenbrand , Catalin Marinas , Vladimir Murzin , Mark Rutland , Mostafa Saleh , Lorenzo Stoakes , Oliver Upton , Linus Walleij , Marc Zyngier Subject: [PATCH v2 16/21] arm64: entry: Implement EL1t exception handlers for overflow stack Date: Fri, 18 Sep 2026 17:14:00 +0100 Message-ID: <20260918161407.2300-17-will@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260918161407.2300-1-will@kernel.org> References: <20260918161407.2300-1-will@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In preparation for using EL1t to handle exceptions taken whilst running on the overflow stack, implement some simple wrappers around the EL1h handlers which perform a best-effort stack overflow check before proceeding. Cc: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/kernel/entry-common.c | 43 +++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index 72c03ccea59f..9738142780df 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -327,10 +327,45 @@ static void debug_exception_exit(struct pt_regs *regs) } NOKPROBE_SYMBOL(debug_exception_exit); -UNHANDLED(el1t, 64, sync) -UNHANDLED(el1t, 64, irq) -UNHANDLED(el1t, 64, fiq) -UNHANDLED(el1t, 64, error) +static void noinstr el1t_64_check_overflow_stack(struct pt_regs *regs) +{ + unsigned long sp = kernel_stack_pointer(regs) - sizeof(*regs); + unsigned long ovf_stack = (unsigned long)this_cpu_ptr(overflow_stack); + + /* + * We're in big trouble if we've overflowed the overflow stack + * so perform a best-effort check before we proceed. If our SP + * is outside of the overflow stack for this CPU then presumably + * we're already corrupting memory, so park ourselves here in an + * attempt to contain the damage. + */ + if (sp < ovf_stack || sp > ovf_stack + OVERFLOW_STACK_SIZE) + cpu_park_loop(); +} + +asmlinkage void noinstr el1t_64_sync_handler(struct pt_regs *regs) +{ + el1t_64_check_overflow_stack(regs); + el1h_64_sync_handler(regs); +} + +asmlinkage void noinstr el1t_64_irq_handler(struct pt_regs *regs) +{ + el1t_64_check_overflow_stack(regs); + el1h_64_irq_handler(regs); +} + +asmlinkage void noinstr el1t_64_fiq_handler(struct pt_regs *regs) +{ + el1t_64_check_overflow_stack(regs); + el1h_64_fiq_handler(regs); +} + +asmlinkage void noinstr el1t_64_error_handler(struct pt_regs *regs) +{ + el1t_64_check_overflow_stack(regs); + el1h_64_error_handler(regs); +} static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr) { -- 2.55.0.1082.g2b9226bbc0-goog