sh: panic on machvec section misalignment.

Now that __initmv references the machvec section unconditionally
there have been cases where folks have been mistakenly flagging
non-machvec structures with the machvec section attribute (presumably
to shut up modpost). This leads to obscure breakage in earlyprintk
amongst other places and is rather non-obvious.

Add a simple sanity check to try and catch __initmv misuse and
panic early.

Reported-by: Markus Brunner <super.firetwister@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/sh/kernel/machvec.c b/arch/sh/kernel/machvec.c
index 23c5948f0124..129b2cfd18a8 100644
--- a/arch/sh/kernel/machvec.c
+++ b/arch/sh/kernel/machvec.c
@@ -91,6 +91,13 @@ void __init sh_mv_setup(void)
                                 (unsigned long)&__machvec_start);
 
                 /*
+                 * Sanity check for machvec section alignment. Ensure
+                 * __initmv hasn't been misused.
+                 */
+                if (machvec_size % sizeof(struct sh_machine_vector))
+                        panic("machvec misaligned, invalid __initmv use?");
+
+                /*
                  * If the machvec hasn't been preselected, use the first
                  * vector (usually the only one) from .machvec.init.
                  */