genksyms: track symbol checksum changes

Sometimes it is preferable to avoid changes of exported symbol checksums
(to avoid breaking externally provided modules).  When a checksum change
occurs, it can be hard to figure out what caused this change: underlying
types may have changed, or additional type information may simply have
become available at the point where a symbol is exported.

Add a new --reference option to genksyms which allows it to report why
checksums change, based on the type information dumps it creates with the
--dump-types flag.  Genksyms will read in such a dump from a previous run,
and report which symbols have changed (and why).

The behavior can be controlled for an entire build as follows: If
KBUILD_SYMTYPES is set, genksyms uses --dump-types to produce *.symtypes
dump files.  If any *.symref files exist, those will be used as the
reference to check against.  If KBUILD_PRESERVE is set, checksum changes
will fail the build.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/scripts/genksyms/genksyms.h b/scripts/genksyms/genksyms.h
index 2668287aa498..2831158426cd 100644
--- a/scripts/genksyms/genksyms.h
+++ b/scripts/genksyms/genksyms.h
@@ -29,6 +29,10 @@ enum symbol_type {
 	SYM_NORMAL, SYM_TYPEDEF, SYM_ENUM, SYM_STRUCT, SYM_UNION
 };
 
+enum symbol_status {
+	STATUS_UNCHANGED, STATUS_DEFINED, STATUS_MODIFIED
+};
+
 struct string_list {
 	struct string_list *next;
 	enum symbol_type tag;
@@ -43,6 +47,8 @@ struct symbol {
 	struct symbol *expansion_trail;
 	struct symbol *visited;
 	int is_extern;
+	int is_declared;
+	enum symbol_status status;
 };
 
 typedef struct string_list **yystype;