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modpost: add support for symbol namespaces 

Add support for symbols that are exported into namespaces. For that,
extract any namespace suffix from the symbol name. In addition, emit a
warning whenever a module refers to an exported symbol without
explicitly importing the namespace that it is defined in. This patch
consistently adds the namespace suffix to symbol names exported into
Module.symvers.

Example warning emitted by modpost in case of the above violation:

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

Co-developed-by: Martijn Coenen <maco@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
This commit is contained in:
Matthias Maennich 2019-09-06 11:32:28 +01:00 committed by Jessica Yu
parent 8651ec01da
commit cb9b55d21f
4 changed files with 101 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Documentation/kbuild/modules.rst
View File

@ -470,9 +470,12 @@ build.
The syntax of the Module.symvers file is::
<CRC> <Symbol> <module>
<CRC> <Symbol> <Namespace> <Module> <Export Type>
0x2d036834 scsi_remove_host drivers/scsi/scsi_mod
0xe1cc2a05 usb_stor_suspend USB_STORAGE drivers/usb/storage/usb-storage EXPORT_SYMBOL_GPL
The fields are separated by tabs and values may be empty (e.g.
if no namespace is defined for an exported symbol).
For a kernel build without CONFIG_MODVERSIONS enabled, the CRC
would read 0x00000000.

2
scripts/export_report.pl
View File

@ -94,7 +94,7 @@ if (defined $opt{'o'}) {
#
while ( <$module_symvers> ) {
chomp;
my (undef, $symbol, $module, $gpl) = split;
my (undef, $symbol, $namespace, $module, $gpl) = split('\t');
$SYMBOL { $symbol } = [ $module , "0" , $symbol, $gpl];
}
close($module_symvers);

98
scripts/mod/modpost.c
View File

@ -164,6 +164,7 @@ struct symbol {
struct module *module;
unsigned int crc;
int crc_valid;
const char *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
@ -233,6 +234,37 @@ static struct symbol *find_symbol(const char *name)
return NULL;
}
static bool contains_namespace(struct namespace_list *list,
const char *namespace)
{
struct namespace_list *ns_entry;
for (ns_entry = list; ns_entry != NULL; ns_entry = ns_entry->next)
if (strcmp(ns_entry->namespace, namespace) == 0)
return true;
return false;
}
static void add_namespace(struct namespace_list **list, const char *namespace)
{
struct namespace_list *ns_entry;
if (!contains_namespace(*list, namespace)) {
ns_entry = NOFAIL(malloc(sizeof(struct namespace_list) +
strlen(namespace) + 1));
strcpy(ns_entry->namespace, namespace);
ns_entry->next = *list;
*list = ns_entry;
}
}
static bool module_imports_namespace(struct module *module,
const char *namespace)
{
return contains_namespace(module->imported_namespaces, namespace);
}
static const struct {
const char *str;
enum export export;
@ -312,23 +344,39 @@ static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
return export_unknown;
}
static const char *sym_extract_namespace(const char **symname)
{
size_t n;
char *dupsymname;
n = strcspn(*symname, ".");
if (n < strlen(*symname) - 1) {
dupsymname = NOFAIL(strdup(*symname));
dupsymname[n] = '\0';
*symname = dupsymname;
return dupsymname + n + 1;
}
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, const char *namespace,
struct module *mod, enum export export)
{
struct symbol *s = find_symbol(name);
if (!s) {
s = new_symbol(name, mod, export);
s->namespace = namespace;
} else {
if (!s->preloaded) {
warn("%s: '%s' exported twice. Previous export "
"was in %s%s\n", mod->name, name,
s->module->name,
is_vmlinux(s->module->name) ?"":".ko");
warn("%s: '%s' exported twice. Previous export was in %s%s\n",
mod->name, name, s->module->name,
is_vmlinux(s->module->name) ? "" : ".ko");
} else {
/* In case Module.symvers was out of date */
s->module = mod;
@ -620,6 +668,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
unsigned int crc;
enum export export;
bool is_crc = false;
const char *name, *namespace;
if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
strstarts(symname, "__ksymtab"))
@ -691,8 +740,9 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
default:
/* All exported symbols */
if (strstarts(symname, "__ksymtab_")) {
sym_add_exported(symname + strlen("__ksymtab_"), mod,
export);
name = symname + strlen("__ksymtab_");
namespace = sym_extract_namespace(&name);
sym_add_exported(name, namespace, mod, export);
}
if (strcmp(symname, "init_module") == 0)
mod->has_init = 1;
@ -1943,6 +1993,7 @@ static void read_symbols(const char *modname)
const char *symname;
char *version;
char *license;
char *namespace;
struct module *mod;
struct elf_info info = { };
Elf_Sym *sym;
@ -1974,6 +2025,12 @@ static void read_symbols(const char *modname)
license = get_next_modinfo(&info, "license", license);
}
namespace = get_modinfo(&info, "import_ns");
while (namespace) {
add_namespace(&mod->imported_namespaces, namespace);
namespace = get_next_modinfo(&info, "import_ns", namespace);
}
for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
symname = remove_dot(info.strtab + sym->st_name);
@ -2118,6 +2175,13 @@ static int check_exports(struct module *mod)
basename++;
else
basename = mod->name;
if (exp->namespace &&
!module_imports_namespace(mod, exp->namespace)) {
warn("module %s uses symbol %s from namespace %s, but does not import it.\n",
basename, exp->name, exp->namespace);
}
if (!mod->gpl_compatible)
check_for_gpl_usage(exp->export, basename, exp->name);
check_for_unused(exp->export, basename, exp->name);
@ -2341,7 +2405,7 @@ static void read_dump(const char *fname, unsigned int kernel)
return;
while ((line = get_next_line(&pos, file, size))) {
char *symname, *modname, *d, *export, *end;
char *symname, *namespace, *modname, *d, *export, *end;
unsigned int crc;
struct module *mod;
struct symbol *s;
@ -2349,7 +2413,10 @@ static void read_dump(const char *fname, unsigned int kernel)
if (!(symname = strchr(line, '\t')))
goto fail;
*symname++ = '\0';
if (!(modname = strchr(symname, '\t')))
if (!(namespace = strchr(symname, '\t')))
goto fail;
*namespace++ = '\0';
if (!(modname = strchr(namespace, '\t')))
goto fail;
*modname++ = '\0';
if ((export = strchr(modname, '\t')) != NULL)
@ -2366,7 +2433,8 @@ static void read_dump(const char *fname, unsigned int kernel)
mod = new_module(modname);
mod->skip = 1;
}
s = sym_add_exported(symname, mod, export_no(export));
s = sym_add_exported(symname, namespace, mod,
export_no(export));
s->kernel = kernel;
s->preloaded = 1;
sym_update_crc(symname, mod, crc, export_no(export));
@ -2395,16 +2463,20 @@ static void write_dump(const char *fname)
{
struct buffer buf = { };
struct symbol *symbol;
const char *namespace;
int n;
for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
symbol = symbolhash[n];
while (symbol) {
if (dump_sym(symbol))
buf_printf(&buf, "0x%08x\t%s\t%s\t%s\n",
if (dump_sym(symbol)) {
namespace = symbol->namespace;
buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n",
symbol->crc, symbol->name,
namespace ? namespace : "",
symbol->module->name,
export_str(symbol->export));
}
symbol = symbol->next;
}
}

7
scripts/mod/modpost.h
View File

@ -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 {