Messages in this thread Patch in this message | | | Date | Mon, 26 Aug 2019 18:21:38 +0200 | From | Jessica Yu <> | Subject | Re: [PATCH v3 04/11] modpost: add support for symbol namespaces |
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+++ Matthias Maennich [21/08/19 12:49 +0100]: >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> >--- > scripts/mod/modpost.c | 91 +++++++++++++++++++++++++++++++++++++------ > scripts/mod/modpost.h | 7 ++++ > 2 files changed, 87 insertions(+), 11 deletions(-) > >diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c >index f277e116e0eb..538bb24ffee3 100644 >--- a/scripts/mod/modpost.c >+++ b/scripts/mod/modpost.c >@@ -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; >@@ -312,6 +344,22 @@ 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 >@@ -319,16 +367,18 @@ static enum export export_from_sec(struct elf_info *elf, unsigned int sec) > static struct symbol *sym_add_exported(const char *name, struct module *mod, > enum export export) > { >- struct symbol *s = find_symbol(name); >+ const char *symbol_name = name; >+ const char *namespace = sym_extract_namespace(&symbol_name); >+ struct symbol *s = find_symbol(symbol_name); > > if (!s) { >- s = new_symbol(name, mod, export); >+ s = new_symbol(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, symbol_name, s->module->name, >+ is_vmlinux(s->module->name) ? "" : ".ko"); > } else { > /* In case Module.symvers was out of date */ > s->module = mod; >@@ -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); >@@ -2395,16 +2459,21 @@ 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", >- symbol->crc, symbol->name, >- symbol->module->name, >- export_str(symbol->export)); >+ if (dump_sym(symbol)) { >+ namespace = symbol->namespace; >+ buf_printf(&buf, "0x%08x\t%s%s%s\t%s\t%s\n", >+ symbol->crc, symbol->name, >+ namespace ? "." : "", >+ namespace ? namespace : "",
I think it might be cleaner to just have namespace be a separate field in Module.symvers, rather than appending a dot and the namespace at the end of a symbol name. Maybe something like
<crc> <symbol_name> <namespace> <module>
For symbols without a namespace, we could just have "", with all fields delimited by tabs. This is just a stylistic suggestion, what do you think?
Regardless of the chosen format, I think we need to document how namespaces are represented in Documentation/kbuild/modules.rst, where it describes the Module.symvers format.
Thanks!
Jessica
>+ symbol->module->name, >+ export_str(symbol->export)); >+ } > symbol = symbol->next; > } > } >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 { >-- >2.23.0.rc1.153.gdeed80330f-goog >
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