From c28454332fe0b65e22c3a2717e5bf05b5b47ca20 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski <luto@kernel.org> Date: Thu, 12 Nov 2015 12:59:02 -0800 Subject: [PATCH] x86/asm: Error out if asm/jump_label.h is included inappropriately Rather than potentially generating incorrect code on a non-HAVE_JUMP_LABEL kernel if someone includes asm/jump_label.h, error out. Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/99407f0ac7fa3ab03a3d31ce076d47b5c2f44795.1447361906.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/include/asm/jump_label.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 5daeca3d0f9e..96872dc96597 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -1,6 +1,19 @@ #ifndef _ASM_X86_JUMP_LABEL_H #define _ASM_X86_JUMP_LABEL_H +#ifndef HAVE_JUMP_LABEL +/* + * For better or for worse, if jump labels (the gcc extension) are missing, + * then the entire static branch patching infrastructure is compiled out. + * If that happens, the code in here will malfunction. Raise a compiler + * error instead. + * + * In theory, jump labels and the static branch patching infrastructure + * could be decoupled to fix this. + */ +#error asm/jump_label.h included on a non-jump-label kernel +#endif + #ifndef __ASSEMBLY__ #include <linux/stringify.h> -- GitLab