[S390] Improved oops output.

This patch adds two improvements to the oops output. First it adds an
additional line after the PSW which decodes the different fields of it.
Second a disassembler is added that decodes the instructions surrounding
the faulting PSW. The output of a test oops now looks like this:

kernel BUG at init/main.c:419
illegal operation: 0001 [#1]
CPU:    0    Not tainted
Process swapper (pid: 0, task: 0000000000464968, ksp: 00000000004be000)
Krnl PSW : 0700000180000000 00000000000120b6 (rest_init+0x36/0x38)
           R:0 T:1 IO:1 EX:1 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 EA:3
Krnl GPRS: 0000000000000003 00000000004ba017 0000000000000022 0000000000000001
           000000000003a5f6 0000000000000000 00000000004be6a8 0000000000000000
           0000000000000000 00000000004b8200 0000000000003a50 0000000000008000
           0000000000516368 000000000033d008 00000000000120b2 00000000004bdee0
Krnl Code: 00000000000120a6: e3e0f0980024       stg     %r14,152(%r15)
           00000000000120ac: c0e500014296       brasl   %r14,3a5d8
           00000000000120b2: a7f40001           brc     15,120b4
          >00000000000120b6: 0707               bcr     0,%r7
           00000000000120b8: eb7ff0500024       stmg    %r7,%r15,80(%r15)
           00000000000120be: c0d000195825       larl    %r13,33d108
           00000000000120c4: a7f13f00           tmll    %r15,16128
           00000000000120c8: a7840001           brc     8,120ca
Call Trace:
([<00000000000120b2>] rest_init+0x32/0x38)
 [<00000000004be614>] start_kernel+0x37c/0x410
 [<0000000000012020>] _ehead+0x20/0x80
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

arch/s390/kernel/Makefile

@@ -6,7 +6,7 @@ EXTRA_AFLAGS	:= -traditional
 
 obj-y	:=  bitmap.o traps.o time.o process.o base.o early.o \
             setup.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o \
-	    semaphore.o s390_ext.o debug.o irq.o ipl.o
+	    semaphore.o s390_ext.o debug.o irq.o ipl.o dis.o
 
 obj-y	+= $(if $(CONFIG_64BIT),entry64.o,entry.o)
 obj-y	+= $(if $(CONFIG_64BIT),reipl64.o,reipl.o)

arch/s390/kernel/traps.c

@@ -188,18 +188,31 @@ void dump_stack(void)
 
 EXPORT_SYMBOL(dump_stack);
 
+static inline int mask_bits(struct pt_regs *regs, unsigned long bits)
+{
+	return (regs->psw.mask & bits) / ((~bits + 1) & bits);
+}
+
 void show_registers(struct pt_regs *regs)
 {
-	mm_segment_t old_fs;
 	char *mode;
-	int i;
 
 	mode = (regs->psw.mask & PSW_MASK_PSTATE) ? "User" : "Krnl";
 	printk("%s PSW : %p %p",
 	       mode, (void *) regs->psw.mask,
 	       (void *) regs->psw.addr);
 	print_symbol(" (%s)\n", regs->psw.addr & PSW_ADDR_INSN);
-	printk("%s GPRS: " FOURLONG, mode,
+	printk("           R:%x T:%x IO:%x EX:%x Key:%x M:%x W:%x "
+	       "P:%x AS:%x CC:%x PM:%x", mask_bits(regs, PSW_MASK_PER),
+	       mask_bits(regs, PSW_MASK_DAT), mask_bits(regs, PSW_MASK_IO),
+	       mask_bits(regs, PSW_MASK_EXT), mask_bits(regs, PSW_MASK_KEY),
+	       mask_bits(regs, PSW_MASK_MCHECK), mask_bits(regs, PSW_MASK_WAIT),
+	       mask_bits(regs, PSW_MASK_PSTATE), mask_bits(regs, PSW_MASK_ASC),
+	       mask_bits(regs, PSW_MASK_CC), mask_bits(regs, PSW_MASK_PM));
+#ifdef CONFIG_64BIT
+	printk(" EA:%x", mask_bits(regs, PSW_BASE_BITS));
+#endif
+	printk("\n%s GPRS: " FOURLONG, mode,
 	       regs->gprs[0], regs->gprs[1], regs->gprs[2], regs->gprs[3]);
 	printk("           " FOURLONG,
 	       regs->gprs[4], regs->gprs[5], regs->gprs[6], regs->gprs[7]);
@@ -208,41 +221,7 @@ void show_registers(struct pt_regs *regs)
 	printk("           " FOURLONG,
 	       regs->gprs[12], regs->gprs[13], regs->gprs[14], regs->gprs[15]);
 
-#if 0
-	/* FIXME: this isn't needed any more but it changes the ksymoops
-	 * input. To remove or not to remove ... */
-	save_access_regs(regs->acrs);
-	printk("%s ACRS: %08x %08x %08x %08x\n", mode,
-	       regs->acrs[0], regs->acrs[1], regs->acrs[2], regs->acrs[3]);
-	printk("           %08x %08x %08x %08x\n",
-	       regs->acrs[4], regs->acrs[5], regs->acrs[6], regs->acrs[7]);
-	printk("           %08x %08x %08x %08x\n",
-	       regs->acrs[8], regs->acrs[9], regs->acrs[10], regs->acrs[11]);
-	printk("           %08x %08x %08x %08x\n",
-	       regs->acrs[12], regs->acrs[13], regs->acrs[14], regs->acrs[15]);
-#endif
-
-	/*
-	 * Print the first 20 byte of the instruction stream at the
-	 * time of the fault.
-	 */
-	old_fs = get_fs();
-	if (regs->psw.mask & PSW_MASK_PSTATE)
-		set_fs(USER_DS);
-	else
-		set_fs(KERNEL_DS);
-	printk("%s Code: ", mode);
-	for (i = 0; i < 20; i++) {
-		unsigned char c;
-		if (__get_user(c, (char __user *)(regs->psw.addr + i))) {
-			printk(" Bad PSW.");
-			break;
-		}
-		printk("%02x ", c);
-	}
-	set_fs(old_fs);
-
-	printk("\n");
+	show_code(regs);
 }	
 
 /* This is called from fs/proc/array.c */

include/asm-s390/processor.h

@@ -196,6 +196,7 @@ extern unsigned long thread_saved_pc(struct task_struct *t);
 extern char *task_show_regs(struct task_struct *task, char *buffer);
 
 extern void show_registers(struct pt_regs *regs);
+extern void show_code(struct pt_regs *regs);
 extern void show_trace(struct task_struct *task, unsigned long *sp);
 
 unsigned long get_wchan(struct task_struct *p);