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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: "Brian Gerst" <brgerst@gmail.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Borislav Petkov" <bp@alien8.de>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Andy Lutomirski" <luto@kernel.org>
Subject: [PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately
Date: Thu, 12 Nov 2015 12:59:02 -0800
Message-ID: <99407f0ac7fa3ab03a3d31ce076d47b5c2f44795.1447361906.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1447361906.git.luto@kernel.org>

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>
---
 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>
-- 
2.5.0


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-12 20:58 [PATCH v3 0/5] x86 entry stuff, maybe for 4.4 Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 1/5] x86/entry/64: Fix irqflag tracing wrt context tracking Andy Lutomirski
2015-11-24  9:35   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 2/5] context_tracking: Switch to new static_branch API Andy Lutomirski
2015-11-24  9:35   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` Andy Lutomirski [this message]
2015-11-13 14:13   ` [PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately Thomas Gleixner
2015-11-24  9:35   ` [tip:x86/asm] x86/asm: Error out if asm/ jump_label.h " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 4/5] x86/asm: Add asm macros for static keys/jump labels Andy Lutomirski
2015-11-13 14:22   ` Thomas Gleixner
2015-11-24  9:36   ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2015-11-12 20:59 ` [PATCH v3 5/5] x86/entry/64: Bypass enter_from_user_mode on non-context-tracking boots Andy Lutomirski
2015-11-13 14:23   ` Thomas Gleixner
2015-11-13 15:26   ` Frederic Weisbecker
2015-11-16 19:10     ` Andy Lutomirski
2015-11-16 22:50       ` Frederic Weisbecker
2015-11-16 23:57         ` Andy Lutomirski
2015-11-19  0:57           ` Frederic Weisbecker
2015-11-24  9:36   ` [tip:x86/asm] " tip-bot for Andy Lutomirski

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