From patchwork Thu Oct 17 13:39:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13840047 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3E42C1DDC21 for ; Thu, 17 Oct 2024 13:40:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729172416; cv=none; b=aGecj7CpsR4KoI5WCMFAiPB2fZnCWrNHQ16YLFeM+EBfhrIFPB/Pxf1qJuikDoG2KtqjB6jEiQxfA5k6wz6B6Or7To6UYuMXJEk9MD9Cub5Oev1NPJOCbkhECwL1aPeKM4uRW5phMV5XXLy77GdnG19inJGCa2DSE8D7a+8dWBs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729172416; c=relaxed/simple; bh=uPjgpFRn6PK4z83ZkSc7DFdlQhgX101XgPRDHGljUA8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Kw6369lKHCh8r4s2MjeEm25Y+fUlpb7RnUwbggS13jkDJqba8n15qu0suq7aBISmBg3PzG2Mf4Fl7QNhNpOZvSCE3zOhHaAwylM4iRM7N1zYHt4auNsgpOEwc6U3SCclQk/wIFR+/DrgW7dl2LEWFWWtyph2hXC80ZxC60O0vbI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1BD68DA7; Thu, 17 Oct 2024 06:40:41 -0700 (PDT) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D6C973F71E; Thu, 17 Oct 2024 06:40:08 -0700 (PDT) From: Kevin Brodsky To: linux-arm-kernel@lists.infradead.org Cc: Kevin Brodsky , akpm@linux-foundation.org, anshuman.khandual@arm.com, aruna.ramakrishna@oracle.com, broonie@kernel.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, dave.martin@arm.com, jeffxu@chromium.org, joey.gouly@arm.com, shuah@kernel.org, will@kernel.org, linux-kselftest@vger.kernel.org, x86@kernel.org Subject: [PATCH 0/5] Improve arm64 pkeys handling in signal delivery Date: Thu, 17 Oct 2024 14:39:04 +0100 Message-ID: <20241017133909.3837547-1-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This series is a follow-up to Joey's Permission Overlay Extension (POE) series [1] that recently landed on mainline. The goal is to improve the way we handle the register that governs which pkeys/POIndex are accessible (POR_EL0) during signal delivery. As things stand, we may unexpectedly fail to write the signal frame on the stack because POR_EL0 is not reset before the uaccess operations. See patch 3 for more details and the main changes this series brings. A similar series landed recently for x86/MPK [2]; the present series aims at aligning arm64 with x86. Worth noting: once the signal frame is written, POR_EL0 is still set to POR_EL0_INIT, granting access to pkey 0 only. This means that a program that sets up an alternate signal stack with a non-zero pkey will need some assembly trampoline to set POR_EL0 before invoking the real signal handler, as discussed here [3]. The x86 series also added kselftests to ensure that no spurious SIGSEGV occurs during signal delivery regardless of which pkey is accessible at the point where the signal is delivered. This series adapts those kselftests to allow running them on arm64 (patch 4-5). Finally patch 2 is a clean-up following feedback on Joey's series [4]. I have tested this series on arm64 and x86_64 (booting and running the protection_keys and pkey_sighandler_tests mm kselftests). - Kevin [1] https://lore.kernel.org/linux-arm-kernel/20240822151113.1479789-1-joey.gouly@arm.com/ [2] https://lore.kernel.org/lkml/20240802061318.2140081-1-aruna.ramakrishna@oracle.com/ [3] https://lore.kernel.org/lkml/CABi2SkWxNkP2O7ipkP67WKz0-LV33e5brReevTTtba6oKUfHRw@mail.gmail.com/ [4] https://lore.kernel.org/linux-arm-kernel/20241015114116.GA19334@willie-the-truck/ Cc: akpm@linux-foundation.org Cc: anshuman.khandual@arm.com Cc: aruna.ramakrishna@oracle.com Cc: broonie@kernel.org Cc: catalin.marinas@arm.com Cc: dave.hansen@linux.intel.com Cc: dave.martin@arm.com Cc: jeffxu@chromium.org Cc: joey.gouly@arm.com Cc: shuah@kernel.org Cc: will@kernel.org Cc: linux-kselftest@vger.kernel.org Cc: x86@kernel.org Kevin Brodsky (5): arm64: signal: Remove unused macro arm64: signal: Remove unnecessary check when saving POE state arm64: signal: Improve POR_EL0 handling to avoid uaccess failures selftests/mm: Use generic pkey register manipulation selftests/mm: Enable pkey_sighandler_tests on arm64 arch/arm64/kernel/signal.c | 92 +++++++++++++--- tools/testing/selftests/mm/Makefile | 8 +- tools/testing/selftests/mm/pkey-arm64.h | 1 + tools/testing/selftests/mm/pkey-x86.h | 2 + .../selftests/mm/pkey_sighandler_tests.c | 101 +++++++++++++----- 5 files changed, 159 insertions(+), 45 deletions(-)