1 files changed, 126 insertions, 0 deletions
diff --git a/arch/s390/boot/als.c b/arch/s390/boot/als.c
new file mode 100644
index 000000000000..d592e0d90d9f
--- /dev/null
+++ b/arch/s390/boot/als.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *    Copyright IBM Corp. 2016
+ */
+#include <linux/kernel.h>
+#include <asm/processor.h>
+#include <asm/facility.h>
+#include <asm/lowcore.h>
+#include <asm/sclp.h>
+
+/*
+ * The code within this file will be called very early. It may _not_
+ * access anything within the bss section, since that is not cleared
+ * yet and may contain data (e.g. initrd) that must be saved by other
+ * code.
+ * For temporary objects the stack (16k) should be used.
+ */
+
+static unsigned long als[] = { FACILITIES_ALS };
+
+static void u16_to_hex(char *str, u16 val)
+{
+	int i, num;
+
+	for (i = 1; i <= 4; i++) {
+		num = (val >> (16 - 4 * i)) & 0xf;
+		if (num >= 10)
+			num += 7;
+		*str++ = '0' + num;
+	}
+	*str = '\0';
+}
+
+static void print_machine_type(void)
+{
+	static char mach_str[80] = "Detected machine-type number: ";
+	char type_str[5];
+	struct cpuid id;
+
+	get_cpu_id(&id);
+	u16_to_hex(type_str, id.machine);
+	strcat(mach_str, type_str);
+	strcat(mach_str, "\n");
+	sclp_early_printk(mach_str);
+}
+
+static void u16_to_decimal(char *str, u16 val)
+{
+	int div = 1;
+
+	while (div * 10 <= val)
+		div *= 10;
+	while (div) {
+		*str++ = '0' + val / div;
+		val %= div;
+		div /= 10;
+	}
+	*str = '\0';
+}
+
+static void print_missing_facilities(void)
+{
+	static char als_str[80] = "Missing facilities: ";
+	unsigned long val;
+	char val_str[6];
+	int i, j, first;
+
+	first = 1;
+	for (i = 0; i < ARRAY_SIZE(als); i++) {
+		val = ~S390_lowcore.stfle_fac_list[i] & als[i];
+		for (j = 0; j < BITS_PER_LONG; j++) {
+			if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
+				continue;
+			if (!first)
+				strcat(als_str, ",");
+			/*
+			 * Make sure we stay within one line. Consider that
+			 * each facility bit adds up to five characters and
+			 * z/VM adds a four character prefix.
+			 */
+			if (strlen(als_str) > 70) {
+				strcat(als_str, "\n");
+				sclp_early_printk(als_str);
+				*als_str = '\0';
+			}
+			u16_to_decimal(val_str, i * BITS_PER_LONG + j);
+			strcat(als_str, val_str);
+			first = 0;
+		}
+	}
+	strcat(als_str, "\n");
+	sclp_early_printk(als_str);
+	sclp_early_printk("See Principles of Operations for facility bits\n");
+}
+
+static void facility_mismatch(void)
+{
+	sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
+	print_machine_type();
+	print_missing_facilities();
+	disabled_wait(0x8badcccc);
+}
+
+void verify_facilities(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
+		S390_lowcore.stfle_fac_list[i] = 0;
+	asm volatile(
+		"	stfl	0(0)\n"
+		: "=m" (S390_lowcore.stfl_fac_list));
+	S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
+	if (S390_lowcore.stfl_fac_list & 0x01000000) {
+		register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
+
+		asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
+			     : "+d" (reg0)
+			     : "a" (&S390_lowcore.stfle_fac_list)
+			     : "memory", "cc");
+	}
+	for (i = 0; i < ARRAY_SIZE(als); i++) {
+		if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
+			facility_mismatch();
+	}
+}