[tip:x86/urgent] x86/asm: Guard against building the 32/ 64-bit versions of the asm-offsets*.c file directly

[tip-bot for Borislav Petkov]

Commit-ID:  5de2b61a63f0982641eb00b9a6a9650f23487eaa
Gitweb:     http://git.kernel.org/tip/5de2b61a63f0982641eb00b9a6a9650f23487eaa
Author:     Borislav Petkov <bp@xxxxxxx>
AuthorDate: Tue, 9 Dec 2014 16:45:17 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 11 Dec 2014 11:43:56 +0100

x86/asm: Guard against building the 32/64-bit versions of the asm-offsets*.c file directly

Sometimes it is helpful to build a kernel compilation unit
directly, i.e.:

  make .../<filename>.i

in order to look at compiler output.

Since asm-offsets_{32,64}.c are included by asm-offsets.c and
building them directly doesn't evaluate the macros used (thus
making the preprocessor output not very useful), error out when
an attempt is made to build them. Issue a hint for the user to
build asm-offsets.c instead.

Suggested-by: Michael Matz <matz@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Michal Marek <mmarek@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1418139917-12722-1-git-send-email-bp@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/kernel/asm-offsets_32.c | 4 ++++
 arch/x86/kernel/asm-offsets_64.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index d67c4be..3b3b9d3 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -1,3 +1,7 @@
+#ifndef __LINUX_KBUILD_H
+# error "Please do not build this file directly, build asm-offsets.c instead"
+#endif
+
 #include <asm/ucontext.h>
 
 #include <linux/lguest.h>
diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
index e7c798b..4c0c596 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -1,3 +1,7 @@
+#ifndef __LINUX_KBUILD_H
+# error "Please do not build this file directly, build asm-offsets.c instead"
+#endif
+
 #include <asm/ia32.h>
 
 #define __SYSCALL_64(nr, sym, compat) [nr] = 1,
--
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