s390/mm: print control registers and page table walk on crash

Print extra debugging information to the console if the kernel or a user
space process crashed (with user space debugging enabled):

- contents of control register 7 and 13
- failing address and translation exception identification
- page table walk for the failing address

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

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 19f623f..2f51a99 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -126,6 +126,133 @@ static inline int user_space_fault(struct pt_regs *regs)
        return 0;
 }
 
+static int bad_address(void *p)
+{
+       unsigned long dummy;
+
+       return probe_kernel_address((unsigned long *)p, dummy);
+}
+
+#ifdef CONFIG_64BIT
+static void dump_pagetable(unsigned long asce, unsigned long address)
+{
+       unsigned long *table = __va(asce & PAGE_MASK);
+
+       pr_alert("AS:%016lx ", asce);
+       switch (asce & _ASCE_TYPE_MASK) {
+       case _ASCE_TYPE_REGION1:
+               table = table + ((address >> 53) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("R1:%016lx ", *table);
+               if (*table & _REGION_ENTRY_INVALID)
+                       goto out;
+               table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+               /* fallthrough */
+       case _ASCE_TYPE_REGION2:
+               table = table + ((address >> 42) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("R2:%016lx ", *table);
+               if (*table & _REGION_ENTRY_INVALID)
+                       goto out;
+               table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+               /* fallthrough */
+       case _ASCE_TYPE_REGION3:
+               table = table + ((address >> 31) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("R3:%016lx ", *table);
+               if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
+                       goto out;
+               table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+               /* fallthrough */
+       case _ASCE_TYPE_SEGMENT:
+               table = table + ((address >> 20) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont(KERN_CONT "S:%016lx ", *table);
+               if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
+                       goto out;
+               table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
+       }
+       table = table + ((address >> 12) & 0xff);
+       if (bad_address(table))
+               goto bad;
+       pr_cont("P:%016lx ", *table);
+out:
+       pr_cont("\n");
+       return;
+bad:
+       pr_cont("BAD\n");
+}
+
+#else /* CONFIG_64BIT */
+
+static void dump_pagetable(unsigned long asce, unsigned long address)
+{
+       unsigned long *table = __va(asce & PAGE_MASK);
+
+       pr_alert("AS:%08lx ", asce);
+       table = table + ((address >> 20) & 0x7ff);
+       if (bad_address(table))
+               goto bad;
+       pr_cont("S:%08lx ", *table);
+       if (*table & _SEGMENT_ENTRY_INVALID)
+               goto out;
+       table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
+       table = table + ((address >> 12) & 0xff);
+       if (bad_address(table))
+               goto bad;
+       pr_cont("P:%08lx ", *table);
+out:
+       pr_cont("\n");
+       return;
+bad:
+       pr_cont("BAD\n");
+}
+
+#endif /* CONFIG_64BIT */
+
+static void dump_fault_info(struct pt_regs *regs)
+{
+       unsigned long asce;
+
+       pr_alert("Fault in ");
+       switch (regs->int_parm_long & 3) {
+       case 3:
+               pr_cont("home space ");
+               break;
+       case 2:
+               pr_cont("secondary space ");
+               break;
+       case 1:
+               pr_cont("access register ");
+               break;
+       case 0:
+               pr_cont("primary space ");
+               break;
+       }
+       pr_cont("mode while using ");
+       if (!user_space_fault(regs)) {
+               asce = S390_lowcore.kernel_asce;
+               pr_cont("kernel ");
+       }
+#ifdef CONFIG_PGSTE
+       else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
+               struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
+               asce = gmap->asce;
+               pr_cont("gmap ");
+       }
+#endif
+       else {
+               asce = S390_lowcore.user_asce;
+               pr_cont("user ");
+       }
+       pr_cont("ASCE.\n");
+       dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
+}
+
 static inline void report_user_fault(struct pt_regs *regs, long signr)
 {
        if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
@@ -138,8 +265,9 @@ static inline void report_user_fault(struct pt_regs *regs, long signr)
               regs->int_code);
        print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
        printk(KERN_CONT "\n");
-       printk(KERN_ALERT "failing address: %lX\n",
-              regs->int_parm_long & __FAIL_ADDR_MASK);
+       printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
+              regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
+       dump_fault_info(regs);
        show_regs(regs);
 }
 
@@ -177,11 +305,13 @@ static noinline void do_no_context(struct pt_regs *regs)
        address = regs->int_parm_long & __FAIL_ADDR_MASK;
        if (!user_space_fault(regs))
                printk(KERN_ALERT "Unable to handle kernel pointer dereference"
-                      " at virtual kernel address %p\n", (void *)address);
+                      " in virtual kernel address space\n");
        else
                printk(KERN_ALERT "Unable to handle kernel paging request"
-                      " at virtual user address %p\n", (void *)address);
-
+                      " in virtual user address space\n");
+       printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
+              regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
+       dump_fault_info(regs);
        die(regs, "Oops");
        do_exit(SIGKILL);
 }