[PATCH] modpost: Fix modpost's license checking V2

[Alessio Igor Bogani <abogani@kernel.org>]

The commit f02e8a6 sorts symbols placing each of them in its own elf section.
The sorting and merging into the canonical sections are done by the linker.
Unfortunately modpost to generate Module.symvers file parses vmlinux
(already linked) and all modules object files (which aren't linked yet).
These aren't sanitized by the linker yet. That breaks modpost that can't
detect license properly for modules. This patch makes modpost aware of
the new exported symbols structure. Thanks to Arnaud Lacombe
<lacombar@gmail.com> for providing useful suggestion about code.

This work was supported by a hardware donation from the CE Linux Forum.

Reported-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Alessio Igor Bogani <abogani@kernel.org>
---
 scripts/mod/modpost.c |   29 ++++++++++++++++++++++++++++-
 1 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 413c536..348db13 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -254,6 +254,28 @@ static enum export export_no(const char *s)
 	return export_unknown;
 }
 
+static const char *sec_name(struct elf_info *elf, int secindex);
+
+#define SEC_NAME_MATCH(name, str) (strncmp(name, str, strlen(str) - 1) == 0)
+
+static enum export export_from_secname(struct elf_info *elf, unsigned int sec)
+{
+	const char *secname = sec_name(elf, sec);
+
+	if (SEC_NAME_MATCH(secname, "___ksymtab+"))
+		return export_plain;
+	else if (SEC_NAME_MATCH(secname, "___ksymtab_unused+"))
+		return export_unused;
+	else if (SEC_NAME_MATCH(secname, "___ksymtab_gpl+"))
+		return export_gpl;
+	else if (SEC_NAME_MATCH(secname, "___ksymtab_unused_gpl+"))
+		return export_unused_gpl;
+	else if (SEC_NAME_MATCH(secname, "___ksymtab_gpl_future+"))
+		return export_gpl_future;
+	else
+		return export_unknown;
+}
+
 static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
 {
 	if (sec == elf->export_sec)
@@ -563,7 +585,12 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 			       Elf_Sym *sym, const char *symname)
 {
 	unsigned int crc;
-	enum export export = export_from_sec(info, get_secindex(info, sym));
+	enum export export;
+
+	if (!is_vmlinux(mod->name) && strncmp(symname, "__ksymtab", 9) == 0)
+		export = export_from_secname(info, get_secindex(info, sym));
+	else
+		export = export_from_sec(info, get_secindex(info, sym));
 
 	switch (sym->st_shndx) {
 	case SHN_COMMON:
-- 
1.7.4.1