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Subject[PATCH 3/6] modpost: add support for checking symbol namespaces.
Date
Emits a warning whenever a module refers to an exported symbol without
explicitly importing the namespace that it is defined in.

Example:

WARNING: module ums-usbat uses symbol usb_stor_resume from namespace
USB_STORAGE_NS, but does not import it.

Signed-off-by: Martijn Coenen <maco@android.com>
---
scripts/mod/modpost.c | 70 +++++++++++++++++++++++++++++++++++++++----
scripts/mod/modpost.h | 7 +++++
2 files changed, 72 insertions(+), 5 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 1663fb19343a..a56a8461a96a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -165,6 +165,7 @@ struct symbol {
struct module *module;
unsigned int crc;
int crc_valid;
+ const char *ns; /* namespace */
unsigned int weak:1;
unsigned int vmlinux:1; /* 1 if symbol is defined in vmlinux */
unsigned int kernel:1; /* 1 if symbol is from kernel
@@ -234,6 +235,35 @@ static struct symbol *find_symbol(const char *name)
return NULL;
}

+static bool contains_namespace(struct namespace_list *list, const char *ns)
+{
+ struct namespace_list *ns_entry;
+
+ for (ns_entry = list; ns_entry != NULL; ns_entry = ns_entry->next) {
+ if (strcmp(ns_entry->namespace, ns) == 0)
+ return true;
+ }
+
+ return false;
+}
+
+static void add_namespace(struct namespace_list **list, const char *ns)
+{
+ struct namespace_list *ns_entry;
+
+ if (!contains_namespace(*list, ns)) {
+ ns_entry = NOFAIL(malloc(sizeof(struct namespace_list)));
+ strcpy(ns_entry->namespace, ns);
+ ns_entry->next = *list;
+ *list = ns_entry;
+ }
+}
+
+static bool module_imports_namespace(struct module *module, const char *ns)
+{
+ return contains_namespace(module->imported_namespaces, ns);
+}
+
static const struct {
const char *str;
enum export export;
@@ -313,21 +343,40 @@ static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
return export_unknown;
}

+static const char *sym_extract_ns(const char **symname)
+{
+ size_t n;
+
+ n = strcspn(*symname, ".");
+ if (n < strlen(*symname) - 1) {
+ char *dupsymname = NOFAIL(strdup(*symname));
+
+ dupsymname[n] = '\0';
+ *symname = dupsymname;
+ return dupsymname + n + 1;
+ } else {
+ return NULL;
+ }
+}
+
/**
* Add an exported symbol - it may have already been added without a
* CRC, in this case just update the CRC
**/
-static struct symbol *sym_add_exported(const char *name, struct module *mod,
- enum export export)
+static struct symbol *sym_add_exported(const char *name,
+ struct module *mod, enum export export)
{
- struct symbol *s = find_symbol(name);
+ const char *extract_name = name;
+ const char *ns = sym_extract_ns(&extract_name);
+ struct symbol *s = find_symbol(extract_name);

if (!s) {
- s = new_symbol(name, mod, export);
+ s = new_symbol(extract_name, mod, export);
+ s->ns = ns;
} else {
if (!s->preloaded) {
warn("%s: '%s' exported twice. Previous export "
- "was in %s%s\n", mod->name, name,
+ "was in %s%s\n", mod->name, extract_name,
s->module->name,
is_vmlinux(s->module->name) ?"":".ko");
} else {
@@ -697,6 +746,10 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
}
if (strcmp(symname, "init_module") == 0)
mod->has_init = 1;
+ if (strstarts(symname, "__knsimport_")) {
+ const char *name = symname + strlen("__knsimport_");
+ add_namespace(&mod->imported_namespaces, name);
+ }
if (strcmp(symname, "cleanup_module") == 0)
mod->has_cleanup = 1;
break;
@@ -2097,6 +2150,13 @@ static void check_exports(struct module *mod)
basename++;
else
basename = mod->name;
+
+ if (exp->ns && !module_imports_namespace(mod, exp->ns)) {
+ warn("module %s uses symbol %s from namespace %s, "
+ "but does not import it.\n",
+ basename, exp->name, exp->ns);
+ }
+
if (!mod->gpl_compatible)
check_for_gpl_usage(exp->export, basename, exp->name);
check_for_unused(exp->export, basename, exp->name);
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 8453d6ac2f77..9626bf3e7424 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -109,6 +109,11 @@ buf_printf(struct buffer *buf, const char *fmt, ...);
void
buf_write(struct buffer *buf, const char *s, int len);

+struct namespace_list {
+ struct namespace_list *next;
+ char namespace[0];
+};
+
struct module {
struct module *next;
const char *name;
@@ -121,6 +126,8 @@ struct module {
struct buffer dev_table_buf;
char srcversion[25];
int is_dot_o;
+ // Actual imported namespaces
+ struct namespace_list *imported_namespaces;
};

struct elf_info {
--
2.18.0.203.gfac676dfb9-goog
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