From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BDDFA477983; Thu, 20 Aug 2026 15:31:52 +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=1787239915; cv=none; b=u/GXGga22620sSzix0ejND1k3FrH5x7Y24Vz+DyzXKHhcr+0j0NX8p0AURdgNaUuvQzFKUYi+Tl1DnF5DwT+GYUHuuHaI3ONamFMWGTEDFdge6ICgRg1qOMW5bns7/62aGOK2X/AJ706dqrbm0Hy0H8iY+AP1flNglCZgKFzevg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787239915; c=relaxed/simple; bh=KDuKqZCRSLoXodFYtXT1GvdkGt652Hs32fgPglj/sqk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MuXRvJvV78XBk0ljylN3mcTuc/w9B/h5EGJXpXuZ9Kx9kz9sws23nM1WCbomjxt63oC7basQ8m0oFlAvyPz1yONSdlU+F9B9HIdn90ch2C21ABa8FR+XB3x32MLvdi9VKZlrnhlQFNw4+xX18w9YxTcvw5xOL7LxudBnTOVU0CI= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=RvbTOVMi; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="RvbTOVMi" 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 85A631D34; Thu, 20 Aug 2026 08:31:47 -0700 (PDT) Received: from fedora (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AB7A53F763; Thu, 20 Aug 2026 08:31:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787239911; bh=KDuKqZCRSLoXodFYtXT1GvdkGt652Hs32fgPglj/sqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RvbTOVMi16WGZGxPuXwQ4W1DIIg9XvTg0IZQB9rHZskZCS0ffLI3HW+7e0Z8DseXY oXtSM75amqfwq8puYElP6x7pypEYaUQDrpxvl3r0l3gB5uI5p0UFwyU1I62lQB8ELc /2MlOXkFVpH+ymWM67FyxsK1BypdIJnHfG2KvAzg= From: Bill Roberts To: "H. Peter Anvin" , Albert Ou , Alexandre Ghiti , Borislav Petkov , Dave Hansen , Ingo Molnar , Palmer Dabbelt , Paul Walmsley , rick.p.edgecombe@intel.com, Shuah Khan , Thomas Gleixner , x86@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, Bill Roberts Subject: [PATCH v3 3/5] selftests/x86: add shadow stack lock test Date: Tue, 18 Aug 2026 17:54:26 -0500 Message-ID: <20260818225428.1983328-4-bill.roberts@arm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260818225428.1983328-1-bill.roberts@arm.com> References: <20260818225428.1983328-1-bill.roberts@arm.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a test that locks the shadow stack write bit and then attempts to disable write. The disable should fail with EPERM since it's in a locked state. This also preserves the write bit being set for the whole test suite as well as preserving the ability to unlock at the end. --- .../testing/selftests/x86/test_shadow_stack.c | 39 +++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/tools/testing/selftests/x86/test_shadow_stack.c b/tools/testing/selftests/x86/test_shadow_stack.c index b52c5420c137..72e7329d89d7 100644 --- a/tools/testing/selftests/x86/test_shadow_stack.c +++ b/tools/testing/selftests/x86/test_shadow_stack.c @@ -1060,6 +1060,24 @@ int test_ptrace(void) return 1; } +static int test_locking(void) +{ + + if (ARCH_PRCTL(ARCH_SHSTK_LOCK, ARCH_SHSTK_WRSS)) { + printf("[FAIL]\tCould not lock Shadow stack write\n"); + return 1; + } + + if (ARCH_PRCTL(ARCH_SHSTK_DISABLE, ARCH_SHSTK_WRSS) != -EPERM) { + printf("[FAIL]\tCould change Shadow stack write after lock\n"); + return 1; + } + + printf("[OK]\tShadow stack locking\n"); + + return 0; +} + int main(int argc, char *argv[]) { int ret = 0; @@ -1079,12 +1097,33 @@ int main(int argc, char *argv[]) return 1; } + /* Note: test_shadow_stack_lock() needs write enabled */ if (ARCH_PRCTL(ARCH_SHSTK_ENABLE, ARCH_SHSTK_WRSS)) { printf("[SKIP]\tCould not enable WRSS\n"); ret = 1; goto out; } + unsigned long status = 0; + + if (ARCH_PRCTL(ARCH_SHSTK_STATUS, &status)) { + printf("[FAIL]\tCould not get Shadow stack status\n"); + ret = 1; + goto out; + } + + if (status != (ARCH_SHSTK_WRSS|ARCH_SHSTK_SHSTK)) { + printf("[FAIL]\tStatus not as expected, got 0x%lx status, wanted: 0x%llx\n", + status, (ARCH_SHSTK_WRSS|ARCH_SHSTK_SHSTK)); + ret = 1; + goto out; + } + + if (test_locking()) { + ret = 1; + goto out; + } + /* Should have succeeded if here, but this is a test, so double check. */ if (!get_ssp()) { printf("[FAIL]\tShadow stack disabled\n"); -- 2.55.0