objtool, compiler.h: Fix __unreachable section relocation size

jpoimboe · Ingo Molnar · commit 55149d06534a · 2017-03-01T14:20:18.000+01:00
Linus reported the following commit broke module loading on his laptop: d1091c7 ("objtool: Improve detection of BUG() and other dead ends") It showed errors like the following: module: overflow in relocation type 10 val ffffffffc02afc81 module: 'nvme' likely not compiled with -mcmodel=kernel The problem is that the __unreachable section addresses are stored using the '.long' asm directive, which isn't big enough for .text section kernel addresses. Use relative addresses instead: ".long %c0b - .\t\n" Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: d1091c7 ("objtool: Improve detection of BUG() and other dead ends") Link: http://lkml.kernel.org/r/20170301060504.oltm3iws6fmubnom@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
@@ -201,7 +201,7 @@
 #define annotate_unreachable() ({					\
 	asm("%c0:\t\n"							\
 	    ".pushsection __unreachable, \"a\"\t\n"			\
-	    ".long %c0b\t\n"						\
+	    ".long %c0b - .\t\n"					\
 	    ".popsection\t\n" : : "i" (__LINE__));			\
 })
 #else
