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 40EDE51FCA5 for ; Mon, 7 Sep 2026 16:43:55 +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=1788799436; cv=none; b=PhPnsbKvTjtE0J5snwqgpAaBj97AuSuuaduL7tc07NUTJq+qvP2FikC1fvK2BVGVtQkWdI+oCFa0Sry43EiVEU7eKV47tns8H7XxDEX7ZnNOvq8wh1RVAeQGM6Dk4EAAFED4ieFU+dS7oKLuEgs6zDuKcsGsmpPSZSuCygv5828= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788799436; c=relaxed/simple; bh=OjwrxO+Yb3VNhrFuMQv9vy/22rWY6qBRMH79RZf/xZM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ejnya2wV0eYU4Duavo9BCYSH4nGQO1IafchEKI3mWmCBCH+SIsF7QsGdcGpzUhCBDFXG9UW+0ZEB+OR1wXdyF2Cas5npDfe+UrURnhrjH43GKlLpqHULnIH/W7i0K1sG4cR9fiI7kUv+my27IOvASMnMt4zogM8SbtS12CJOe9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZoqkleTP; 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="ZoqkleTP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 014211F00ACA; Mon, 7 Sep 2026 16:43:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788799434; bh=4B7ig5JOoqM/sFSoDwiMA77B2+r7GUXRB2lSds3AJ1E=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZoqkleTPnHZFWHuFBC5xHFyP3BP9O1hjKw2d5rYkM2MLLe3ztBAyg38Gruwde31aS jWJRkAiHsf7M7fxkT743JrzWBtbXc7avZ6a3lIOMUjP+4MUWi/DF+pYEn87+RJxXTR CbmjaGIyGsemrCX2J59wRJx953ODDyyNCEvjMNyYdCBvbQztdnNuzYh1AEnN8cuzbI XZluHaDSekTuobMXbIG7FeQkQUliobvqTwa8p49dDI2DkKbphNiqxzhHMudrp6w1Dd lwTb+jrLO3mkW7qape3i59DZkmdj5UVmLv50Mp27xt6I8D9KttLFsOBPcEmpnD1dAZ 3+xisjdqBFSuA== 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 16/21] arm64: entry: Implement EL1t exception handlers for overflow stack Date: Mon, 7 Sep 2026 17:42:41 +0100 Message-ID: <20260907164247.17223-17-will@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260907164247.17223-1-will@kernel.org> References: <20260907164247.17223-1-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) { -- 2.55.0.979.g7e5102b832-goog