Blackfin arch: Fix random crash issue found by Michael.

This is fixes a problem where we could jump to the wrong address. By
doing a "p0 = reti; jump (p0)". If a different, higher level interrupt
came in, just before, rather than returning to the calling function, we
would return to a random place in the kernel.

This very elegant fix from Bernd grabs the return location off the
stack, and places it into P0, so when we do a return, it goes to the
correct place.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/kernel/entry.S b/arch/blackfin/kernel/entry.S
index 65c5ba4..65f4e67 100644 (file)
--- a/arch/blackfin/kernel/entry.S
+++ b/arch/blackfin/kernel/entry.S
@@ -54,9 +54,11 @@ ENTRY(_ret_from_fork)
        [sp + PT_IPEND] = r0;
        /* do a 'fake' RTI by jumping to [RETI]
         * to avoid clearing supervisor mode in child
-       */
+        */
+       r0 = [sp + PT_PC];
+       [sp + PT_P0] = r0;
+
        RESTORE_ALL_SYS
-       p0 = reti;
        jump (p0);
 ENDPROC(_ret_from_fork)