arch/tile: add descriptive text if the kernel reports a bad trap

If the kernel unexpectedly takes a bad trap, it's convenient to
have it report the type of trap as part of the error.  This gives
customers a bit more context before they call up customer support.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 28 insertions, 2 deletions

diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index 73cff814ac57..5b19a23c8908 100644
--- a/arch/tile/kernel/traps.c
+++ b/arch/tile/kernel/traps.c
@@ -195,6 +195,25 @@ static int special_ill(bundle_bits bundle, int *sigp, int *codep)
         return 1;
 }
 
+static const char *const int_name[] = {
+        [INT_MEM_ERROR] = "Memory error",
+        [INT_ILL] = "Illegal instruction",
+        [INT_GPV] = "General protection violation",
+        [INT_UDN_ACCESS] = "UDN access",
+        [INT_IDN_ACCESS] = "IDN access",
+#if CHIP_HAS_SN()
+        [INT_SN_ACCESS] = "SN access",
+#endif
+        [INT_SWINT_3] = "Software interrupt 3",
+        [INT_SWINT_2] = "Software interrupt 2",
+        [INT_SWINT_0] = "Software interrupt 0",
+        [INT_UNALIGN_DATA] = "Unaligned data",
+        [INT_DOUBLE_FAULT] = "Double fault",
+#ifdef __tilegx__
+        [INT_ILL_TRANS] = "Illegal virtual address",
+#endif
+};
+
 void __kprobes do_trap(struct pt_regs *regs, int fault_num,
                        unsigned long reason)
 {
@@ -211,10 +230,17 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
          * current process and hope for the best.
          */
         if (!user_mode(regs)) {
+                const char *name;
                 if (fixup_exception(regs))  /* only UNALIGN_DATA in practice */
                         return;
-                pr_alert("Kernel took bad trap %d at PC %#lx\n",
-                       fault_num, regs->pc);
+                if (fault_num >= 0 &&
+                    fault_num < sizeof(int_name)/sizeof(int_name[0]) &&
+                    int_name[fault_num] != NULL)
+                        name = int_name[fault_num];
+                else
+                        name = "Unknown interrupt";
+                pr_alert("Kernel took bad trap %d (%s) at PC %#lx\n",
+                         fault_num, name, regs->pc);
                 if (fault_num == INT_GPV)
                         pr_alert("GPV_REASON is %#lx\n", reason);
                 show_regs(regs);