| Message ID | 20210426163021.3594482-1-manojgupta@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] iw: set retain atrribute on sections | expand |
(removing stable@vger.kernel.org from CC) On Mon, Apr 26, 2021 at 9:30 AM Manoj Gupta <manojgupta@google.com> wrote: > > LLD 13 and GNU ld 2.37 support -z start-stop-gc which allows garbage > collection of C identifier name sections despite the __start_/__stop_ > references. Simply set the retain attribute so that GCC 11 (if > configure-time binutils is 2.36 or newer)/Clang 13 will set the > SHF_GNU_RETAIN section attribute to prevent garbage collection. > > Without the patch, there are linker errors like the following with -z > start-stop-gc: > ld.lld: error: undefined symbol: __stop___cmd > >>> referenced by iw.c:418 > >>> iw.o:(__handle_cmd) > > Suggested-by: Fangrui Song <maskray@google.com> > > Cc: stable@vger.kernel.org > > Signed-off-by: Manoj Gupta <manojgupta@google.com> This is not a kernel patch and so should not be sent to the linux-stable list. I think Greg KH's bot already told you as much on earlier versions. See: https://git.kernel.org/pub/scm/linux/kernel/git/jberg/iw.git/tree/README "Please send all patches to Johannes Berg <johannes@sipsolutions.net> and CC linux-wireless@vger.kernel.org for community review." You're ~close. Brian
On Mon, 2021-04-26 at 09:30 -0700, Manoj Gupta wrote: > LLD 13 and GNU ld 2.37 support -z start-stop-gc which allows garbage > collection of C identifier name sections despite the __start_/__stop_ > references. Simply set the retain attribute so that GCC 11 (if > configure-time binutils is 2.36 or newer)/Clang 13 will set the > SHF_GNU_RETAIN section attribute to prevent garbage collection. > > Without the patch, there are linker errors like the following with -z > start-stop-gc: > ld.lld: error: undefined symbol: __stop___cmd > > > > referenced by iw.c:418 > > > > iw.o:(__handle_cmd) > > Suggested-by: Fangrui Song <maskray@google.com> > > Cc: stable@vger.kernel.org This is *clearly* inappropriate. > +++ b/iw.h > @@ -118,8 +118,9 @@ struct chandef { > .parent = _section, \ > .selector = (_sel), \ > }; \ > + _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ > static struct cmd *__cmd ## _ ## _symname ## _ ## _handler ## _ ## _nlcmd ## _ ## _idby ## _ ## _hidden ## _p \ > - __attribute__((used,section("__cmd"))) = \ > + __attribute__((used,retain,section("__cmd"))) = \ > &__cmd ## _ ## _symname ## _ ## _handler ## _ ## _nlcmd ## _ ## _idby ## _ ## _hidden > #define __ACMD(_section, _symname, _name, _args, _nlcmd, _flags, _hidden, _idby, _handler, _help, _sel, _alias)\ > __COMMAND(_section, _symname, _name, _args, _nlcmd, _flags, _hidden, _idby, _handler, _help, _sel);\ > @@ -141,16 +142,18 @@ struct chandef { > .handler = (_handler), \ > .help = (_help), \ > }; \ > + _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ > static struct cmd *__section ## _ ## _name ## _p \ > - __attribute__((used,section("__cmd"))) = &__section ## _ ## _name > + __attribute__((used,retain,section("__cmd"))) = &__section ## _ ## _name All of these cases are in macros, it feels it would be more appropriate to do _Pragma("GCC diagnostic push") and ...pop... around it? johannes
diff --git a/iw.h b/iw.h index 7f7f4fc..8ca8e44 100644 --- a/iw.h +++ b/iw.h @@ -118,8 +118,9 @@ struct chandef { .parent = _section, \ .selector = (_sel), \ }; \ + _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ static struct cmd *__cmd ## _ ## _symname ## _ ## _handler ## _ ## _nlcmd ## _ ## _idby ## _ ## _hidden ## _p \ - __attribute__((used,section("__cmd"))) = \ + __attribute__((used,retain,section("__cmd"))) = \ &__cmd ## _ ## _symname ## _ ## _handler ## _ ## _nlcmd ## _ ## _idby ## _ ## _hidden #define __ACMD(_section, _symname, _name, _args, _nlcmd, _flags, _hidden, _idby, _handler, _help, _sel, _alias)\ __COMMAND(_section, _symname, _name, _args, _nlcmd, _flags, _hidden, _idby, _handler, _help, _sel);\ @@ -141,16 +142,18 @@ struct chandef { .handler = (_handler), \ .help = (_help), \ }; \ + _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ static struct cmd *__section ## _ ## _name ## _p \ - __attribute__((used,section("__cmd"))) = &__section ## _ ## _name + __attribute__((used,retain,section("__cmd"))) = &__section ## _ ## _name #define SECTION(_name) \ struct cmd __section ## _ ## _name = { \ .name = (#_name), \ .hidden = 1, \ }; \ + _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ static struct cmd *__section ## _ ## _name ## _p \ - __attribute__((used,section("__cmd"))) = &__section ## _ ## _name + __attribute__((used,retain,section("__cmd"))) = &__section ## _ ## _name #define DECLARE_SECTION(_name) \ extern struct cmd __section ## _ ## _name; @@ -162,13 +165,14 @@ struct vendor_event { }; #define VENDOR_EVENT(_id, _subcmd, _callback) \ + _Pragma("GCC diagnostic ignored \"-Wattributes\"") \ const struct vendor_event \ vendor_event_ ## _id ## _ ## _subcmd = { \ .vendor_id = _id, \ .subcmd = _subcmd, \ .callback = _callback, \ }, * const vendor_event_ ## _id ## _ ## _subcmd ## _p \ - __attribute__((used,section("vendor_event"))) = \ + __attribute__((used,retain,section("vendor_event"))) = \ &vendor_event_ ## _id ## _ ## _subcmd extern const char iw_version[];