* [PATCH] iw: set retain atrribute on sections
@ 2021-04-22 18:25 Manoj Gupta
2021-04-23 7:41 ` Greg KH
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Manoj Gupta @ 2021-04-22 18:25 UTC (permalink / raw)
To: Johannes Berg; +Cc: stable, maskray, llozano, manojgupta, linux-wireless
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>
Signed-off-by: Manoj Gupta <manojgupta@google.com>
---
iw.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/iw.h b/iw.h
index 7f7f4fc..67aa00c 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);\
--
2.31.1.498.g6c1eba8ee3d-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] iw: set retain atrribute on sections
2021-04-22 18:25 [PATCH] iw: set retain atrribute on sections Manoj Gupta
@ 2021-04-23 7:41 ` Greg KH
2021-04-24 0:31 ` Manoj Gupta
2021-04-26 16:30 ` [PATCH v2] " Manoj Gupta
2 siblings, 0 replies; 4+ messages in thread
From: Greg KH @ 2021-04-23 7:41 UTC (permalink / raw)
To: Manoj Gupta; +Cc: Johannes Berg, stable, maskray, llozano, linux-wireless
On Thu, Apr 22, 2021 at 11:25:45AM -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>
>
> Signed-off-by: Manoj Gupta <manojgupta@google.com>
> ---
> iw.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] iw: set retain atrribute on sections
2021-04-22 18:25 [PATCH] iw: set retain atrribute on sections Manoj Gupta
2021-04-23 7:41 ` Greg KH
@ 2021-04-24 0:31 ` Manoj Gupta
2021-04-26 16:30 ` [PATCH v2] " Manoj Gupta
2 siblings, 0 replies; 4+ messages in thread
From: Manoj Gupta @ 2021-04-24 0:31 UTC (permalink / raw)
To: Johannes Berg; +Cc: llozano, manojgupta, linux-wireless, Fangrui Song, stable
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>
---
iw.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/iw.h b/iw.h
index 7f7f4fc..67aa00c 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);\
--
2.31.1.498.g6c1eba8ee3d-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2] iw: set retain atrribute on sections
2021-04-22 18:25 [PATCH] iw: set retain atrribute on sections Manoj Gupta
2021-04-23 7:41 ` Greg KH
2021-04-24 0:31 ` Manoj Gupta
@ 2021-04-26 16:30 ` Manoj Gupta
2 siblings, 0 replies; 4+ messages in thread
From: Manoj Gupta @ 2021-04-26 16:30 UTC (permalink / raw)
To: Johannes Berg, Johannes Berg
Cc: llozano, manojgupta, linux-wireless, Fangrui Song, stable
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>
---
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2021-04-22 18:25 [PATCH] iw: set retain atrribute on sections Manoj Gupta
2021-04-23 7:41 ` Greg KH
2021-04-24 0:31 ` Manoj Gupta
2021-04-26 16:30 ` [PATCH v2] " Manoj Gupta
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