sparc64: Add auxiliary vectors to report platform ADI properties

ADI feature on M7 and newer processors has three important properties
relevant to userspace apps using ADI capabilities - (1) Size of block of
memory an ADI version tag applies to, (2) Number of uppermost bits in
virtual address used to encode ADI tag, and (3) The value M7 processor
will force the ADI tags to if it detects uncorrectable error in an ADI
tagged cacheline. Kernel can retrieve these properties for a platform
through machine description provided by the firmware. This patch adds
code to retrieve these properties and report them to userspace through
auxiliary vectors.

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Khalid Aziz <khalid@gonehiking.org>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 96 insertions, 0 deletions

diff --git a/arch/sparc/kernel/adi_64.c b/arch/sparc/kernel/adi_64.c
new file mode 100644
index 000000000000..8fb72585d9f1
--- /dev/null
+++ b/arch/sparc/kernel/adi_64.c
@@ -0,0 +1,96 @@
+/* adi_64.c: support for ADI (Application Data Integrity) feature on
+ * sparc m7 and newer processors. This feature is also known as
+ * SSM (Silicon Secured Memory).
+ *
+ * Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
+ * Author: Khalid Aziz (khalid.aziz@oracle.com)
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+#include <linux/init.h>
+#include <asm/mdesc.h>
+#include <asm/adi_64.h>
+
+struct adi_config adi_state;
+
+/* mdesc_adi_init() : Parse machine description provided by the
+ *	hypervisor to detect ADI capabilities
+ *
+ * Hypervisor reports ADI capabilities of platform in "hwcap-list" property
+ * for "cpu" node. If the platform supports ADI, "hwcap-list" property
+ * contains the keyword "adp". If the platform supports ADI, "platform"
+ * node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
+ * to describe the ADI capabilities.
+ */
+void __init mdesc_adi_init(void)
+{
+	struct mdesc_handle *hp = mdesc_grab();
+	const char *prop;
+	u64 pn, *val;
+	int len;
+
+	if (!hp)
+		goto adi_not_found;
+
+	pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
+	if (pn == MDESC_NODE_NULL)
+		goto adi_not_found;
+
+	prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
+	if (!prop)
+		goto adi_not_found;
+
+	/*
+	 * Look for "adp" keyword in hwcap-list which would indicate
+	 * ADI support
+	 */
+	adi_state.enabled = false;
+	while (len) {
+		int plen;
+
+		if (!strcmp(prop, "adp")) {
+			adi_state.enabled = true;
+			break;
+		}
+
+		plen = strlen(prop) + 1;
+		prop += plen;
+		len -= plen;
+	}
+
+	if (!adi_state.enabled)
+		goto adi_not_found;
+
+	/* Find the ADI properties in "platform" node. If all ADI
+	 * properties are not found, ADI support is incomplete and
+	 * do not enable ADI in the kernel.
+	 */
+	pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
+	if (pn == MDESC_NODE_NULL)
+		goto adi_not_found;
+
+	val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
+	if (!val)
+		goto adi_not_found;
+	adi_state.caps.blksz = *val;
+
+	val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
+	if (!val)
+		goto adi_not_found;
+	adi_state.caps.nbits = *val;
+
+	val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
+	if (!val)
+		goto adi_not_found;
+	adi_state.caps.ue_on_adi = *val;
+
+	mdesc_release(hp);
+	return;
+
+adi_not_found:
+	adi_state.enabled = false;
+	adi_state.caps.blksz = 0;
+	adi_state.caps.nbits = 0;
+	if (hp)
+		mdesc_release(hp);
+}