sparc64: Fix stack debugging IRQ stack regression.

Commit 4f70f7a91bffdcc39f088748dc678953eb9a3fbd
(sparc64: Implement IRQ stacks.) has two bugs.

First, the softirq range check forgets to subtract STACK_BIAS
before comparing with %sp.  Next, on failure the wrong label
is jumped to, resulting in a bogus stack being loaded.

Reported-by: Igor Kovalenko <igor.v.kovalenko@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/sparc/lib/mcount.S b/arch/sparc/lib/mcount.S
index 7ce9c65f3592..24b8b12deed2 100644
--- a/arch/sparc/lib/mcount.S
+++ b/arch/sparc/lib/mcount.S
@@ -64,8 +64,9 @@ mcount:
 2:       sethi          %hi(softirq_stack), %g3
         or              %g3, %lo(softirq_stack), %g3
         ldx             [%g3 + %g1], %g7
+        sub             %g7, STACK_BIAS, %g7
         cmp             %sp, %g7
-        bleu,pt         %xcc, 2f
+        bleu,pt         %xcc, 3f
          sethi          %hi(THREAD_SIZE), %g3
         add             %g7, %g3, %g7
         cmp             %sp, %g7
@@ -75,7 +76,7 @@ mcount:
          * again, we are already trying to output the stack overflow
          * message.
          */
-        sethi           %hi(ovstack), %g7               ! cant move to panic stack fast enough
+3:      sethi           %hi(ovstack), %g7               ! cant move to panic stack fast enough
          or             %g7, %lo(ovstack), %g7
         add             %g7, OVSTACKSIZE, %g3
         sub             %g3, STACK_BIAS + 192, %g3