[S390] kernel: Add z/VM LGR detection

Currently the following mechanisms are available to move active
Linux on System z instances between machines:
* z/VM 6.2 SSI (Single System Image)
* Suspend/resume
For moving Linux instances in this patch the term LGR (Linux Guest
Relocation) is used. Because such an operation is critical, it
should be detectable from Linux. With this patch for both, a live
system and a kernel dump, the information about LGRs is accessible.
To identify a guest, stsi and stfle data is used. A new function
lgr_info_log() compares the current data (lgr_info_cur) with the
last recorded one (lgr_info_last). In case the two data sets differ,
lgr_info_cur is logged to the "lgr" s390dbf.

The following trigger points call lgr_info_log():
* panic
* die
* kdump
* LGR timer
* PSW restart
* QDIO recovery
* resume

This patch also changes the s390dbf hex_ascii view. Now only printable ASCII
characters are shown.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/debug.h

@@ -131,6 +131,7 @@ void debug_unregister(debug_info_t* id);
 
 void debug_set_level(debug_info_t* id, int new_level);
 
+void debug_set_critical(void);
 void debug_stop_all(void);
 
 static inline debug_entry_t*

arch/s390/include/asm/ipl.h

@@ -169,5 +169,6 @@ enum diag308_rc {
 extern int diag308(unsigned long subcode, void *addr);
 extern void diag308_reset(void);
 extern void store_status(void);
+extern void lgr_info_log(void);
 
 #endif /* _ASM_S390_IPL_H */

arch/s390/include/asm/system.h

@@ -7,8 +7,10 @@
 #ifndef __ASM_SYSTEM_H
 #define __ASM_SYSTEM_H
 
+#include <linux/preempt.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
+#include <linux/string.h>
 #include <asm/types.h>
 #include <asm/ptrace.h>
 #include <asm/setup.h>
@@ -248,6 +250,38 @@ static inline int test_facility(unsigned long nr)
 	return (*ptr & (0x80 >> (nr & 7))) != 0;
 }
 
+/**
+ * stfle - Store facility list extended
+ * @stfle_fac_list: array where facility list can be stored
+ * @size: size of passed in array in double words
+ */
+static inline void stfle(u64 *stfle_fac_list, int size)
+{
+	unsigned long nr;
+
+	preempt_disable();
+	S390_lowcore.stfl_fac_list = 0;
+	asm volatile(
+		"	.insn s,0xb2b10000,0(0)\n" /* stfl */
+		"0:\n"
+		EX_TABLE(0b, 0b)
+		: "=m" (S390_lowcore.stfl_fac_list));
+	nr = 4; /* bytes stored by stfl */
+	memcpy(stfle_fac_list, &S390_lowcore.stfl_fac_list, 4);
+	if (S390_lowcore.stfl_fac_list & 0x01000000) {
+		/* More facility bits available with stfle */
+		register unsigned long reg0 asm("0") = size - 1;
+
+		asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
+			     : "+d" (reg0)
+			     : "a" (stfle_fac_list)
+			     : "memory", "cc");
+		nr = (reg0 + 1) * 8; /* # bytes stored by stfle */
+	}
+	memset((char *) stfle_fac_list + nr, 0, size * 8 - nr);
+	preempt_enable();
+}
+
 static inline unsigned short stap(void)
 {
 	unsigned short cpu_address;

arch/s390/kernel/Makefile

@@ -23,7 +23,7 @@ CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
 obj-y	:=  bitmap.o traps.o time.o process.o base.o early.o setup.o vtime.o \
 	    processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o \
 	    debug.o irq.o ipl.o dis.o diag.o mem_detect.o sclp.o vdso.o \
-	    sysinfo.o jump_label.o
+	    sysinfo.o jump_label.o lgr.o
 
 obj-y	+= $(if $(CONFIG_64BIT),entry64.o,entry.o)
 obj-y	+= $(if $(CONFIG_64BIT),reipl64.o,reipl.o)

arch/s390/kernel/debug.c

@@ -2,8 +2,8 @@
  *  arch/s390/kernel/debug.c
  *   S/390 debug facility
  *
- *    Copyright (C) 1999, 2000 IBM Deutschland Entwicklung GmbH,
- *                             IBM Corporation
+ *    Copyright IBM Corp. 1999, 2012
+ *
  *    Author(s): Michael Holzheu (holzheu@de.ibm.com),
  *               Holger Smolinski (Holger.Smolinski@de.ibm.com)
  *
@@ -167,6 +167,7 @@ static debug_info_t *debug_area_last = NULL;
 static DEFINE_MUTEX(debug_mutex);
 
 static int initialized;
+static int debug_critical;
 
 static const struct file_operations debug_file_ops = {
 	.owner   = THIS_MODULE,
@@ -932,6 +933,11 @@ debug_stop_all(void)
 }
 
 
+void debug_set_critical(void)
+{
+	debug_critical = 1;
+}
+
 /*
  * debug_event_common:
  * - write debug entry with given size
@@ -945,7 +951,11 @@ debug_event_common(debug_info_t * id, int level, const void *buf, int len)
 
 	if (!debug_active || !id->areas)
 		return NULL;
-	spin_lock_irqsave(&id->lock, flags);
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else
+		spin_lock_irqsave(&id->lock, flags);
 	active = get_active_entry(id);
 	memset(DEBUG_DATA(active), 0, id->buf_size);
 	memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
@@ -968,7 +978,11 @@ debug_entry_t
 
 	if (!debug_active || !id->areas)
 		return NULL;
-	spin_lock_irqsave(&id->lock, flags);
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else
+		spin_lock_irqsave(&id->lock, flags);
 	active = get_active_entry(id);
 	memset(DEBUG_DATA(active), 0, id->buf_size);
 	memcpy(DEBUG_DATA(active), buf, min(len, id->buf_size));
@@ -1013,7 +1027,11 @@ debug_sprintf_event(debug_info_t* id, int level,char *string,...)
 		return NULL;
 	numargs=debug_count_numargs(string);
 
-	spin_lock_irqsave(&id->lock, flags);
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else
+		spin_lock_irqsave(&id->lock, flags);
 	active = get_active_entry(id);
 	curr_event=(debug_sprintf_entry_t *) DEBUG_DATA(active);
 	va_start(ap,string);
@@ -1047,7 +1065,11 @@ debug_sprintf_exception(debug_info_t* id, int level,char *string,...)
 
 	numargs=debug_count_numargs(string);
 
-	spin_lock_irqsave(&id->lock, flags);
+	if (debug_critical) {
+		if (!spin_trylock_irqsave(&id->lock, flags))
+			return NULL;
+	} else
+		spin_lock_irqsave(&id->lock, flags);
 	active = get_active_entry(id);
 	curr_event=(debug_sprintf_entry_t *)DEBUG_DATA(active);
 	va_start(ap,string);
@@ -1428,10 +1450,10 @@ debug_hex_ascii_format_fn(debug_info_t * id, struct debug_view *view,
 	rc += sprintf(out_buf + rc, "| ");
 	for (i = 0; i < id->buf_size; i++) {
 		unsigned char c = in_buf[i];
-		if (!isprint(c))
-			rc += sprintf(out_buf + rc, ".");
-		else
+		if (isascii(c) && isprint(c))
 			rc += sprintf(out_buf + rc, "%c", c);
+		else
+			rc += sprintf(out_buf + rc, ".");
 	}
 	rc += sprintf(out_buf + rc, "\n");
 	return rc;

arch/s390/kernel/early.c

@@ -29,6 +29,7 @@
 #include <asm/sysinfo.h>
 #include <asm/cpcmd.h>
 #include <asm/sclp.h>
+#include <asm/system.h>
 #include "entry.h"
 
 /*
@@ -262,25 +263,8 @@ static noinline __init void setup_lowcore_early(void)
 
 static noinline __init void setup_facility_list(void)
 {
-	unsigned long nr;
-
-	S390_lowcore.stfl_fac_list = 0;
-	asm volatile(
-		"	.insn	s,0xb2b10000,0(0)\n" /* stfl */
-		"0:\n"
-		EX_TABLE(0b,0b) : "=m" (S390_lowcore.stfl_fac_list));
-	memcpy(&S390_lowcore.stfle_fac_list, &S390_lowcore.stfl_fac_list, 4);
-	nr = 4;				/* # bytes stored by stfl */
-	if (test_facility(7)) {
-		/* More facility bits available with stfle */
-		register unsigned long reg0 asm("0") = MAX_FACILITY_BIT/64 - 1;
-		asm volatile(".insn s,0xb2b00000,%0" /* stfle */
-			     : "=m" (S390_lowcore.stfle_fac_list), "+d" (reg0)
-			     : : "cc");
-		nr = (reg0 + 1) * 8;	/* # bytes stored by stfle */
-	}
-	memset((char *) S390_lowcore.stfle_fac_list + nr, 0,
-	       MAX_FACILITY_BIT/8 - nr);
+	stfle(S390_lowcore.stfle_fac_list,
+	      ARRAY_SIZE(S390_lowcore.stfle_fac_list));
 }
 
 static noinline __init void setup_hpage(void)

arch/s390/kernel/ipl.c

@@ -17,6 +17,7 @@
 #include <linux/fs.h>
 #include <linux/gfp.h>
 #include <linux/crash_dump.h>
+#include <linux/debug_locks.h>
 #include <asm/ipl.h>
 #include <asm/smp.h>
 #include <asm/setup.h>
@@ -26,6 +27,7 @@
 #include <asm/reset.h>
 #include <asm/sclp.h>
 #include <asm/checksum.h>
+#include <asm/debug.h>
 #include "entry.h"
 
 #define IPL_PARM_BLOCK_VERSION 0
@@ -1692,6 +1694,7 @@ static struct kobj_attribute on_panic_attr =
 
 static void do_panic(void)
 {
+	lgr_info_log();
 	on_panic_trigger.action->fn(&on_panic_trigger);
 	stop_run(&on_panic_trigger);
 }
@@ -1729,6 +1732,9 @@ static void __do_restart(void *ignore)
 
 void do_restart(void)
 {
+	tracing_off();
+	debug_locks_off();
+	lgr_info_log();
 	smp_call_online_cpu(__do_restart, NULL);
 }