s390/dump: Add firmware sysfs attribute for dump area size

Dump tools from s390-tools such as zipl need to know the correct dump area
size of the machine they run on in order to be able to create valid
standalone dumper images. Therefore, allow it to be obtained through
the new sysfs read-only attribute /sys/firmware/dump/dump_area_size.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Suggested-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 638fa149ace944491b902b6b7cf8ef087d6ba37a..edbb52ce3f1ec23d8e464fce3fddee64d2327848 100644 (file)
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -1717,6 +1717,24 @@ static ssize_t dump_type_store(struct kobject *kobj,
 static struct kobj_attribute dump_type_attr =
        __ATTR(dump_type, 0644, dump_type_show, dump_type_store);
 
+static ssize_t dump_area_size_show(struct kobject *kobj,
+                                  struct kobj_attribute *attr, char *page)
+{
+       return sysfs_emit(page, "%lu\n", sclp.hsa_size);
+}
+
+static struct kobj_attribute dump_area_size_attr = __ATTR_RO(dump_area_size);
+
+static struct attribute *dump_attrs[] = {
+       &dump_type_attr.attr,
+       &dump_area_size_attr.attr,
+       NULL,
+};
+
+static struct attribute_group dump_attr_group = {
+       .attrs = dump_attrs,
+};
+
 static struct kset *dump_kset;
 
 static void diag308_dump(void *dump_block)
@@ -1853,7 +1871,7 @@ static int __init dump_init(void)
        dump_kset = kset_create_and_add("dump", NULL, firmware_kobj);
        if (!dump_kset)
                return -ENOMEM;
-       rc = sysfs_create_file(&dump_kset->kobj, &dump_type_attr.attr);
+       rc = sysfs_create_group(&dump_kset->kobj, &dump_attr_group);
        if (rc) {
                kset_unregister(dump_kset);
                return rc;