sh: machvec: Use char[] for section boundaries

[ Upstream commit c5783af354 ]

As done for other sections, define the extern as a character array,
which relaxes many of the compiler-time object size checks, which would
otherwise assume it's a single long. Solves the following build error:

arch/sh/kernel/machvec.c: error: array subscript 'struct sh_machine_vector[0]' is partly outside array bounds of 'long int[1]' [-Werror=array-bounds]:  => 105:33

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@vger.kernel.org
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/lkml/alpine.DEB.2.22.394.2209050944290.964530@ramsan.of.borg/
Fixes: 9655ad03af ("sh: Fixup machvec support.")
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Rich Felker <dalias@libc.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/sh/include/asm/sections.h

@@ -4,7 +4,7 @@
 
 #include <asm-generic/sections.h>
 
-extern long __machvec_start, __machvec_end;
+extern char __machvec_start[], __machvec_end[];
 extern char __uncached_start, __uncached_end;
 extern char __start_eh_frame[], __stop_eh_frame[];
 

arch/sh/kernel/machvec.c

@@ -20,8 +20,8 @@
 #define MV_NAME_SIZE 32
 
 #define for_each_mv(mv) \
-	for ((mv) = (struct sh_machine_vector *)&__machvec_start; \
-	     (mv) && (unsigned long)(mv) < (unsigned long)&__machvec_end; \
+	for ((mv) = (struct sh_machine_vector *)__machvec_start; \
+	     (mv) && (unsigned long)(mv) < (unsigned long)__machvec_end; \
 	     (mv)++)
 
 static struct sh_machine_vector * __init get_mv_byname(const char *name)
@@ -87,8 +87,8 @@ void __init sh_mv_setup(void)
 	if (!machvec_selected) {
 		unsigned long machvec_size;
 
-		machvec_size = ((unsigned long)&__machvec_end -
-				(unsigned long)&__machvec_start);
+		machvec_size = ((unsigned long)__machvec_end -
+				(unsigned long)__machvec_start);
 
 		/*
 		 * Sanity check for machvec section alignment. Ensure
@@ -102,7 +102,7 @@ void __init sh_mv_setup(void)
 		 * vector (usually the only one) from .machvec.init.
 		 */
 		if (machvec_size >= sizeof(struct sh_machine_vector))
-			sh_mv = *(struct sh_machine_vector *)&__machvec_start;
+			sh_mv = *(struct sh_machine_vector *)__machvec_start;
 	}
 
 	pr_notice("Booting machvec: %s\n", get_system_type());