summaryrefslogtreecommitdiff
path: root/arch/s390/boot/als.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/s390/boot/als.c')
-rw-r--r--arch/s390/boot/als.c126
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();
+ }
+}