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@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Manoj Gupta <manojgupta@xxxxxxxxxx>
---
Changes v1 -> v2:
Apply the retain attribute to all places with attribute used.
iw.h | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
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[];
--
2.31.1.498.g6c1eba8ee3d-goog
