[PATCH v3 4/6] tools: expand export.h with VMLINUX_SYMBOL()

["Luis R. Rodriguez" <mcgrof@kernel.org>]

This will be used later by the linker-table userspace sandbox.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 tools/include/linux/export.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tools/include/linux/export.h b/tools/include/linux/export.h
index d07e586b9ba0..cb7d6b490e08 100644
--- a/tools/include/linux/export.h
+++ b/tools/include/linux/export.h
@@ -1,6 +1,28 @@
 #ifndef _TOOLS_LINUX_EXPORT_H_
 #define _TOOLS_LINUX_EXPORT_H_
 
+/*
+ * Export symbols from the kernel to modules.  Forked from module.h
+ * to reduce the amount of pointless cruft we feed to gcc when only
+ * exporting a simple symbol or two.
+ *
+ * Try not to add #includes here.  It slows compilation and makes kernel
+ * hackers place grumpy comments in header files.
+ */
+
+/* Some toolchains use a `_' prefix for all user symbols. */
+#ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
+#define __VMLINUX_SYMBOL(x) _##x
+#define __VMLINUX_SYMBOL_STR(x) "_" #x
+#else
+#define __VMLINUX_SYMBOL(x) x
+#define __VMLINUX_SYMBOL_STR(x) #x
+#endif
+
+/* Indirect, so macros are expanded before pasting. */
+#define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
+#define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
+
 #define EXPORT_SYMBOL(sym)
 #define EXPORT_SYMBOL_GPL(sym)
 #define EXPORT_SYMBOL_GPL_FUTURE(sym)
-- 
2.11.0