s390/als: convert architecture level set code to C

There is no reason to have this code in assembly language. Therefore
convert it to C.

Note that this code needs special treatment: it is called very early
and one of the side effects is that e.g. the bss section is not
cleared. Therefore the preferred way for static variables is to put
them on the stack which has a size of 16KB.

There is no functional change with this patch.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/boot/compressed/Makefile

@@ -18,7 +18,7 @@ KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
 
 GCOV_PROFILE := n
 
-OBJECTS := $(addprefix $(objtree)/arch/s390/kernel/, head.o sclp.o ebcdic.o)
+OBJECTS := $(addprefix $(objtree)/arch/s390/kernel/, head.o sclp.o ebcdic.o als.o)
 OBJECTS += $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o
 
 LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T

arch/s390/kernel/Makefile

@@ -4,6 +4,7 @@
 
 KCOV_INSTRUMENT_early.o := n
 KCOV_INSTRUMENT_sclp.o := n
+KCOV_INSTRUMENT_als.o := n
 
 ifdef CONFIG_FUNCTION_TRACER
 # Don't trace early setup code and tracing code
@@ -32,13 +33,16 @@ CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
 CFLAGS_sysinfo.o += -w
 
 #
-# Use -march=z900 for sclp.c to be able to print an error message if
-# the kernel is started on a machine which is too old
+# Use -march=z900 for sclp.c and als.c to be able to print an error
+# message if the kernel is started on a machine which is too old
 #
 CFLAGS_REMOVE_sclp.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_als.o = $(CC_FLAGS_FTRACE)
 ifneq ($(CC_FLAGS_MARCH),-march=z900)
 CFLAGS_REMOVE_sclp.o	+= $(CC_FLAGS_MARCH)
 CFLAGS_sclp.o		+= -march=z900
+CFLAGS_REMOVE_als.o	+= $(CC_FLAGS_MARCH)
+CFLAGS_als.o		+= -march=z900
 AFLAGS_REMOVE_head.o	+= $(CC_FLAGS_MARCH)
 AFLAGS_head.o		+= -march=z900
 endif
@@ -46,7 +50,7 @@ GCOV_PROFILE_sclp.o := n
 
 obj-y	:= traps.o time.o process.o base.o early.o setup.o idle.o vtime.o
 obj-y	+= processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
-obj-y	+= debug.o irq.o ipl.o dis.o diag.o sclp.o vdso.o
+obj-y	+= debug.o irq.o ipl.o dis.o diag.o sclp.o vdso.o als.o
 obj-y	+= sysinfo.o jump_label.o lgr.o os_info.o machine_kexec.o pgm_check.o
 obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o
 obj-y	+= entry.o reipl.o relocate_kernel.o

arch/s390/kernel/als.c

@@ -0,0 +1,46 @@
+/*
+ *    Copyright IBM Corp. 2016
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <asm/processor.h>
+#include <asm/facility.h>
+#include <asm/lowcore.h>
+#include <asm/sclp.h>
+#include "entry.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[] __initdata = { FACILITIES_ALS };
+
+void __init 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])
+			continue;
+		_sclp_print_early("The Linux kernel requires more recent processor hardware");
+		disabled_wait(0x8badcccc);
+	}
+}

arch/s390/kernel/entry.h

@@ -79,4 +79,6 @@ long sys_s390_pci_mmio_read(unsigned long, void __user *, size_t);
 
 DECLARE_PER_CPU(u64, mt_cycles[8]);
 
+void verify_facilities(void);
+
 #endif /* _ENTRY_H */

arch/s390/kernel/head.S

@@ -306,49 +306,14 @@ ENTRY(startup_kdump)
 	stck	__LC_LAST_UPDATE_CLOCK
 	spt	6f-.LPG0(%r13)
 	mvc	__LC_LAST_UPDATE_TIMER(8),6f-.LPG0(%r13)
-	stfl	0(%r0)			# store facilities @ __LC_STFL_FAC_LIST
-	mvc	__LC_STFLE_FAC_LIST(4),__LC_STFL_FAC_LIST
-	tm	__LC_STFLE_FAC_LIST,0x01	# stfle available ?
-	jz	0f
-	lghi	%r0,FACILITIES_ALS_DWORDS-1
-	.insn	s,0xb2b00000,__LC_STFLE_FAC_LIST # store facility list extended
-	# verify if all required facilities are supported by the machine
-0:	la	%r1,__LC_STFLE_FAC_LIST
-	la	%r2,3f+8-.LPG0(%r13)
-	lhi	%r3,FACILITIES_ALS_DWORDS
-1:	lg	%r0,0(%r1)
-	ng	%r0,0(%r2)
-	clg	%r0,0(%r2)
-	jne	2f
-	la	%r1,8(%r1)
-	la	%r2,8(%r2)
-	ahi	%r3,-1
-	jnz	1b
-	j	4f
-2:	l	%r15,.Lstack-.LPG0(%r13)
+	l	%r15,.Lstack-.LPG0(%r13)
 	ahi	%r15,-STACK_FRAME_OVERHEAD
-	la	%r2,.Lals_string-.LPG0(%r13)
-	l	%r3,.Lsclp_print-.LPG0(%r13)
-	basr	%r14,%r3
-	lpsw	3f-.LPG0(%r13)		# machine type not good enough, crash
-.Lals_string:
-	.asciz	"The Linux kernel requires more recent processor hardware"
-.Lsclp_print:
-	.long	_sclp_print_early
-.Lstack:
-	.long	0x8000 + (1<<(PAGE_SHIFT+THREAD_ORDER))
-	.align 16
-3:	.long	0x000a0000,0x8badcccc
-
-# List of facilities that are required. If not all facilities are present
-# the kernel will crash.
-
-	.quad FACILITIES_ALS
-
-4:
+	brasl	%r14,verify_facilities
 	/* Continue with startup code in head64.S */
 	jg	startup_continue
 
+.Lstack:
+	.long	0x8000 + (1<<(PAGE_SHIFT+THREAD_ORDER))
 	.align	8
 6:	.long	0x7fffffff,0xffffffff