tile: improve illegal translation interrupt handling

First, don't re-enable interrupts blindly in the Linux trap handler.
We already handle page faults this way; synchronous interrupts like
ILL_TRANS will fire even when interrupts are disabled, and we don't
want to re-enable interrupts in that case.

For ILL_TRANS, we now pass the ILL_VA_PC reason into the trap handler
so we can report it properly; this is the address that caused the
illegal translation trap.  We print the address as part of the
pr_alert() message now if it's coming from the kernel.

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

1 files changed, 15 insertions, 10 deletions

diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
index 5b19a23c8908..a1bbc5de4d00 100644
--- a/arch/tile/kernel/traps.c
+++ b/arch/tile/kernel/traps.c
@@ -222,8 +222,9 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
         unsigned long address = 0;
         bundle_bits instr;
 
-        /* Re-enable interrupts. */
-        local_irq_enable();
+        /* Re-enable interrupts, if they were previously enabled. */
+        if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
+                local_irq_enable();
 
         /*
          * If it hits in kernel mode and we can't fix it up, just exit the
@@ -231,7 +232,8 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
          */
         if (!user_mode(regs)) {
                 const char *name;
-                if (fixup_exception(regs))  /* only UNALIGN_DATA in practice */
+                char buf[100];
+                if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */
                         return;
                 if (fault_num >= 0 &&
                     fault_num < sizeof(int_name)/sizeof(int_name[0]) &&
@@ -239,10 +241,16 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
                         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);
+                        snprintf(buf, sizeof(buf), "; GPV_REASON %#lx", reason);
+#ifdef __tilegx__
+                else if (fault_num == INT_ILL_TRANS)
+                        snprintf(buf, sizeof(buf), "; address %#lx", reason);
+#endif
+                else
+                        buf[0] = '\0';
+                pr_alert("Kernel took bad trap %d (%s) at PC %#lx%s\n",
+                         fault_num, name, regs->pc, buf);
                 show_regs(regs);
                 do_exit(SIGKILL);  /* FIXME: implement i386 die() */
                 return;
@@ -324,11 +332,8 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num,
                 fill_ra_stack();
 
                 signo = SIGSEGV;
+                address = reason;
                 code = SEGV_MAPERR;
-                if (reason & SPR_ILL_TRANS_REASON__I_STREAM_VA_RMASK)
-                        address = regs->pc;
-                else
-                        address = 0;  /* FIXME: GX: single-step for address */
                 break;
         }
 #endif