s390/zcrypt: hex string mask improvements for apmask and aqmask.

The sysfs attributes /sys/bus/ap/apmask and /sys/bus/ap/aqmask
and the kernel command line arguments ap.apm and ap.aqm get
an improvement of the value parsing with this patch:

The mask values are bitmaps in big endian order starting with bit 0.
So adapter number 0 is the leftmost bit, mask is 0x8000... The sysfs
attributes and the kernel command line accept 2 different formats:
 - Absolute hex string starting with 0x like "0x12345678" does set
   the mask starting from left to right. If the given string is shorter
   than the mask it is padded with 0s on the right. If the string is
   longer than the mask an error comes back (EINVAL).
 - Relative format - a concatenation (done with ',') of the terms
   +<bitnr>[-<bitnr>] or -<bitnr>[-<bitnr>]. <bitnr> may be any
   valid number (hex, decimal or octal) in the range 0...255.
   Here are some examples:
     "+0-15,+32,-128,-0xFF"
     "-0-255,+1-16,+0x128"

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/crypto/ap_bus.c

@@ -857,9 +857,13 @@ void ap_bus_force_rescan(void)
 EXPORT_SYMBOL(ap_bus_force_rescan);
 
 /*
- * AP bus attributes.
+ * hex2bitmap() - parse hex mask string and set bitmap.
+ * Valid strings are "0x012345678" with at least one valid hex number.
+ * Rest of the bitmap to the right is padded with 0. No spaces allowed
+ * within the string, the leading 0x may be omitted.
+ * Returns the bitmask with exactly the bits set as given by the hex
+ * string (both in big endian order).
  */
-
 static int hex2bitmap(const char *str, unsigned long *bitmap, int bits)
 {
 	int i, n, b;
@@ -883,12 +887,133 @@ static int hex2bitmap(const char *str, unsigned long *bitmap, int bits)
 		i += 4;
 	}
 
-	if (i < 4 || isxdigit(*str))
+	if (*str == '\n')
+		str++;
+	if (*str)
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ * str2clrsetmasks() - parse bitmask argument and set the clear and
+ * the set bitmap mask. A concatenation (done with ',') of these terms
+ * is recognized:
+ *   +<bitnr>[-<bitnr>] or -<bitnr>[-<bitnr>]
+ * <bitnr> may be any valid number (hex, decimal or octal) in the range
+ * 0...bits-1; the leading + or - is required. Here are some examples:
+ *   +0-15,+32,-128,-0xFF
+ *   -0-255,+1-16,+0x128
+ *   +1,+2,+3,+4,-5,-7-10
+ * Returns a clear and a set bitmask. Every positive value in the string
+ * results in a bit set in the set mask and every negative value in the
+ * string results in a bit SET in the clear mask. As a bit may be touched
+ * more than once, the last 'operation' wins: +0-255,-128 = all but bit
+ * 128 set in the set mask, only bit 128 set in the clear mask.
+ */
+static int str2clrsetmasks(const char *str,
+			   unsigned long *clrmap,
+			   unsigned long *setmap,
+			   int bits)
+{
+	int a, i, z;
+	char *np, sign;
+
+	/* bits needs to be a multiple of 8 */
+	if (bits & 0x07)
 		return -EINVAL;
 
+	memset(clrmap, 0, bits / 8);
+	memset(setmap, 0, bits / 8);
+
+	while (*str) {
+		sign = *str++;
+		if (sign != '+' && sign != '-')
+			return -EINVAL;
+		a = z = simple_strtoul(str, &np, 0);
+		if (str == np || a >= bits)
+			return -EINVAL;
+		str = np;
+		if (*str == '-') {
+			z = simple_strtoul(++str, &np, 0);
+			if (str == np || a > z || z >= bits)
+				return -EINVAL;
+			str = np;
+		}
+		for (i = a; i <= z; i++)
+			if (sign == '+') {
+				set_bit_inv(i, setmap);
+				clear_bit_inv(i, clrmap);
+			} else {
+				clear_bit_inv(i, setmap);
+				set_bit_inv(i, clrmap);
+			}
+		while (*str == ',' || *str == '\n')
+			str++;
+	}
+
 	return 0;
 }
 
+/*
+ * process_mask_arg() - parse a bitmap string and clear/set the
+ * bits in the bitmap accordingly. The string may be given as
+ * absolute value, a hex string like 0x1F2E3D4C5B6A" simple over-
+ * writing the current content of the bitmap. Or as relative string
+ * like "+1-16,-32,-0x40,+128" where only single bits or ranges of
+ * bits are cleared or set. Distinction is done based on the very
+ * first character which may be '+' or '-' for the relative string
+ * and othewise assume to be an absolute value string. If parsing fails
+ * a negative errno value is returned. All arguments and bitmaps are
+ * big endian order.
+ */
+static int process_mask_arg(const char *str,
+			    unsigned long *bitmap, int bits,
+			    struct mutex *lock)
+{
+	int i;
+
+	/* bits needs to be a multiple of 8 */
+	if (bits & 0x07)
+		return -EINVAL;
+
+	if (*str == '+' || *str == '-') {
+		DECLARE_BITMAP(clrm, bits);
+		DECLARE_BITMAP(setm, bits);
+
+		i = str2clrsetmasks(str, clrm, setm, bits);
+		if (i)
+			return i;
+		if (mutex_lock_interruptible(lock))
+			return -ERESTARTSYS;
+		for (i = 0; i < bits; i++) {
+			if (test_bit_inv(i, clrm))
+				clear_bit_inv(i, bitmap);
+			if (test_bit_inv(i, setm))
+				set_bit_inv(i, bitmap);
+		}
+	} else {
+		DECLARE_BITMAP(setm, bits);
+
+		i = hex2bitmap(str, setm, bits);
+		if (i)
+			return i;
+		if (mutex_lock_interruptible(lock))
+			return -ERESTARTSYS;
+		for (i = 0; i < bits; i++)
+			if (test_bit_inv(i, setm))
+				set_bit_inv(i, bitmap);
+			else
+				clear_bit_inv(i, bitmap);
+	}
+	mutex_unlock(lock);
+
+	return 0;
+}
+
+/*
+ * AP bus attributes.
+ */
+
 static ssize_t ap_domain_show(struct bus_type *bus, char *buf)
 {
 	return snprintf(buf, PAGE_SIZE, "%d\n", ap_domain_index);
@@ -1054,34 +1179,11 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf)
 static ssize_t apmask_store(struct bus_type *bus, const char *buf,
 			    size_t count)
 {
-	int i;
-
-	if (*buf == '+' || *buf == '-') {
-		if (kstrtoint(buf, 0, &i))
-			return -EINVAL;
-		if (i <= -AP_DEVICES || i >= AP_DEVICES)
-			return -EINVAL;
-		if (mutex_lock_interruptible(&ap_perms_mutex))
-			return -ERESTARTSYS;
-		if (*buf == '-')
-			clear_bit_inv(-i, ap_perms.apm);
-		else
-			set_bit_inv(i, ap_perms.apm);
-	} else {
-		DECLARE_BITMAP(apm, AP_DEVICES);
+	int rc;
 
-		i = hex2bitmap(buf, apm, AP_DEVICES);
-		if (i)
-			return i;
-		if (mutex_lock_interruptible(&ap_perms_mutex))
-			return -ERESTARTSYS;
-		for (i = 0; i < AP_DEVICES; i++)
-			if (test_bit_inv(i, apm))
-				set_bit_inv(i, ap_perms.apm);
-			else
-				clear_bit_inv(i, ap_perms.apm);
-	}
-	mutex_unlock(&ap_perms_mutex);
+	rc = process_mask_arg(buf, ap_perms.apm, AP_DEVICES, &ap_perms_mutex);
+	if (rc)
+		return rc;
 
 	ap_bus_revise_bindings();
 
@@ -1108,34 +1210,11 @@ static ssize_t aqmask_show(struct bus_type *bus, char *buf)
 static ssize_t aqmask_store(struct bus_type *bus, const char *buf,
 			    size_t count)
 {
-	int i;
-
-	if (*buf == '+' || *buf == '-') {
-		if (kstrtoint(buf, 0, &i))
-			return -EINVAL;
-		if (i <= -AP_DEVICES || i >= AP_DEVICES)
-			return -EINVAL;
-		if (mutex_lock_interruptible(&ap_perms_mutex))
-			return -ERESTARTSYS;
-		if (*buf == '-')
-			clear_bit_inv(-i, ap_perms.aqm);
-		else
-			set_bit_inv(i, ap_perms.aqm);
-	} else {
-		DECLARE_BITMAP(aqm, AP_DEVICES);
+	int rc;
 
-		i = hex2bitmap(buf, aqm, AP_DEVICES);
-		if (i)
-			return i;
-		if (mutex_lock_interruptible(&ap_perms_mutex))
-			return -ERESTARTSYS;
-		for (i = 0; i < AP_DEVICES; i++)
-			if (test_bit_inv(i, aqm))
-				set_bit_inv(i, ap_perms.aqm);
-			else
-				clear_bit_inv(i, ap_perms.aqm);
-	}
-	mutex_unlock(&ap_perms_mutex);
+	rc = process_mask_arg(buf, ap_perms.aqm, AP_DOMAINS, &ap_perms_mutex);
+	if (rc)
+		return rc;
 
 	ap_bus_revise_bindings();
 
@@ -1436,32 +1515,22 @@ static int __init ap_debug_init(void)
 
 static void __init ap_perms_init(void)
 {
-	int i, rc;
-
-	/* start with all resources useable */
+	/* all resources useable if no kernel parameter string given */
 	memset(&ap_perms.apm, 0xFF, sizeof(ap_perms.apm));
 	memset(&ap_perms.aqm, 0xFF, sizeof(ap_perms.aqm));
 
-	/* process kernel parameters apm and aqm if given */
+	/* apm kernel parameter string */
 	if (apm_str) {
-		DECLARE_BITMAP(apm, AP_DEVICES);
-
-		rc = hex2bitmap(apm_str, apm, AP_DEVICES);
-		if (rc == 0) {
-			for (i = 0; i < AP_DEVICES; i++)
-				if (!test_bit_inv(i, apm))
-					clear_bit_inv(i, ap_perms.apm);
-		}
+		memset(&ap_perms.apm, 0, sizeof(ap_perms.apm));
+		process_mask_arg(apm_str, ap_perms.apm, AP_DEVICES,
+				 &ap_perms_mutex);
 	}
-	if (aqm_str) {
-		DECLARE_BITMAP(aqm, AP_DOMAINS);
 
-		rc = hex2bitmap(aqm_str, aqm, AP_DOMAINS);
-		if (rc == 0) {
-			for (i = 0; i < AP_DOMAINS; i++)
-				if (!test_bit_inv(i, aqm))
-					clear_bit_inv(i, ap_perms.aqm);
-		}
+	/* aqm kernel parameter string */
+	if (aqm_str) {
+		memset(&ap_perms.aqm, 0, sizeof(ap_perms.aqm));
+		process_mask_arg(aqm_str, ap_perms.aqm, AP_DOMAINS,
+				 &ap_perms_mutex);
 	}
 }