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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 50 insertions, 2 deletions

diff --git a/arch/s390/boot/boot.h b/arch/s390/boot/boot.h
index fc41e2277ea8..8665497fd335 100644
--- a/arch/s390/boot/boot.h
+++ b/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 */
diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 9dab596be98e..94e5374c3630 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/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 &&
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 4d441317cdeb..bdfc5549a299 100644
--- a/arch/s390/boot/startup.c
+++ b/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)) {