[PATCH v2] mod/file2alias: make modpost compile on darwin again

["Andreas Bießmann" <andreas@biessmann.de>]

commit e49ce14150c64b29a8dd211df785576fa19a9858 breaks cross compiling
the linux kernel on darwin hosts.
This fix introduce some minimal glue to adopt linker section handling
for darwin hosts.

Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Jochen Friedrich <jochen@scram.de>
CC: Samuel Ortiz <sameo@linux.intel.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
---
since v1:
 * change 'checkpatch' whitespace fixews back

 scripts/mod/file2alias.c |   35 +++++++++++++++++++++++++++++++----
 1 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index d0de2a2..b89efe6 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -46,11 +46,37 @@ struct devtable {
 	void *function;
 };
 
+#define ___cat(a,b) a ## b
+#define __cat(a,b) ___cat(a,b)
+
+/* we need some special handling for this host tool running eventually on
+ * Darwin. The Mach-O section handling is a bit different than ELF section
+ * handling. The differnces in detail are:
+ *  a) we have segments which have sections
+ *  b) we need a API call to get the respective section symbols */
+#if defined(__MACH__)
+#include <mach-o/getsect.h>
+
+#define INIT_SECTION(name)  do {					\
+		unsigned long name ## _len;				\
+		char *__cat(pstart_,name) = getsectdata("__TEXT",	\
+			#name, &__cat(name,_len));			\
+		char *__cat(pstop_,name) = __cat(pstart_,name) +	\
+			__cat(name, _len);				\
+		__cat(__start_,name) = (void *)__cat(pstart_,name);	\
+		__cat(__stop_,name) = (void *)__cat(pstop_,name);	\
+	} while (0)
+#define SECTION(name)   __attribute__((section("__TEXT, " #name)))
+
+struct devtable **__start___devtable, **__stop___devtable;
+#else
+#define INIT_SECTION(name) /* no-op for ELF */
+#define SECTION(name)   __attribute__((section(#name)))
+
 /* We construct a table of pointers in an ELF section (pointers generally
  * go unpadded by gcc).  ld creates boundary syms for us. */
 extern struct devtable *__start___devtable[], *__stop___devtable[];
-#define ___cat(a,b) a ## b
-#define __cat(a,b) ___cat(a,b)
+#endif /* __MACH__ */
 
 #if __GNUC__ == 3 && __GNUC_MINOR__ < 3
 # define __used			__attribute__((__unused__))
@@ -65,8 +91,8 @@ extern struct devtable *__start___devtable[], *__stop___devtable[];
 						(type *)NULL,		\
 						(char *)NULL)),		\
 		sizeof(type), (function) };				\
-	static struct devtable *__attribute__((section("__devtable"))) \
-		__used __cat(devtable_ptr,__LINE__) = &__cat(devtable,__LINE__)
+	static struct devtable *SECTION(__devtable) __used \
+		__cat(devtable_ptr,__LINE__) = &__cat(devtable,__LINE__)
 
 #define ADD(str, sep, cond, field)                              \
 do {                                                            \
@@ -1080,6 +1106,7 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
 		do_pnp_card_entries(symval, sym->st_size, mod);
 	else {
 		struct devtable **p;
+		INIT_SECTION(__devtable);
 
 		for (p = __start___devtable; p < __stop___devtable; p++) {
 			if (sym_is(name, namelen, (*p)->device_id)) {
-- 
1.7.9.1