s390: allow overriding facilities via command line

Add "facilities=" command line option which allows to override
facility bits returned by stfle. The main purpose of that is debugging
aids which allows to test specific kernel behaviour depending on
specific facilities presence. It also affects CPU alternatives.

"facilities=" command line option format is comma separated list of
integer values to be additionally set or cleared (if value is starting
with "!"). Values ranges are also supported. e.g.:

facilities=!130-160,159,167-169
Reviewed-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/boot/boot.h

@@ -6,6 +6,7 @@ void startup_kernel(void);
 void detect_memory(void);
 void store_ipl_parmblock(void);
 void setup_boot_command_line(void);
+void parse_boot_command_line(void);
 void setup_memory_end(void);
 
 #endif /* BOOT_BOOT_H */

arch/s390/boot/ipl_parm.c

@@ -5,6 +5,7 @@
 #include <asm/sclp.h>
 #include <asm/sections.h>
 #include <asm/boot_data.h>
+#include <asm/facility.h>
 #include "boot.h"
 
 char __bootdata(early_command_line)[COMMAND_LINE_SIZE];
@@ -143,8 +144,51 @@ void setup_boot_command_line(void)
 		append_ipl_block_parm();
 }
 
+static void modify_facility(unsigned long nr, bool clear)
+{
+	if (clear)
+		__clear_facility(nr, S390_lowcore.stfle_fac_list);
+	else
+		__set_facility(nr, S390_lowcore.stfle_fac_list);
+}
+
+static void modify_fac_list(char *str)
+{
+	unsigned long val, endval;
+	char *endp;
+	bool clear;
+
+	while (*str) {
+		clear = false;
+		if (*str == '!') {
+			clear = true;
+			str++;
+		}
+		val = simple_strtoull(str, &endp, 0);
+		if (str == endp)
+			break;
+		str = endp;
+		if (*str == '-') {
+			str++;
+			endval = simple_strtoull(str, &endp, 0);
+			if (str == endp)
+				break;
+			str = endp;
+			while (val <= endval) {
+				modify_facility(val, clear);
+				val++;
+			}
+		} else {
+			modify_facility(val, clear);
+		}
+		if (*str != ',')
+			break;
+		str++;
+	}
+}
+
 static char command_line_buf[COMMAND_LINE_SIZE] __section(.data);
-static void parse_mem_opt(void)
+void parse_boot_command_line(void)
 {
 	char *param, *val;
 	bool enabled;
@@ -165,12 +209,14 @@ static void parse_mem_opt(void)
 			if (!rc && !enabled)
 				noexec_disabled = 1;
 		}
+
+		if (!strcmp(param, "facilities"))
+			modify_fac_list(val);
 	}
 }
 
 void setup_memory_end(void)
 {
-	parse_mem_opt();
 #ifdef CONFIG_CRASH_DUMP
 	if (!OLDMEM_BASE && early_ipl_block_valid &&
 	    early_ipl_block.hdr.pbt == DIAG308_IPL_TYPE_FCP &&

arch/s390/boot/startup.c

@@ -53,6 +53,7 @@ void startup_kernel(void)
 	sclp_early_read_info();
 	store_ipl_parmblock();
 	setup_boot_command_line();
+	parse_boot_command_line();
 	setup_memory_end();
 	detect_memory();
 	if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {