Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Jessica Yu]

+++ AKASHI Takahiro [28/11/16 18:18 +0900]:

On Mon, Nov 28, 2016 at 08:59:40AM +0100, Andreas Ziegler wrote:

Hi Akashi,

your patch "module: extend 'rodata=off' boot cmdline parameter to module
mappings" showed up in linux-next today, and I noticed a small error in it.

The first modified #ifdef is fine, the second one, however, has a spelling
mistake in it: the CONFIG_ variable should be CONFIG_DEBUG_SET_MODULE_RONX
instead of CONFIG_SET_MODULE_RONX (note the missing DEBUG).


Thank you for pointing this out.
(I didn't notice it because DEBUG_RODATA is always on on arm64.)

Rusty, Jessica, should I submit v4 to correct it?


Andreas, Akashi -

The typo has been fixed with Arnd's patch:

  http://lkml.kernel.org/r/20161128145931.3350661-1-a...@arndb.de

Thanks for finding the issue!

Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Jessica Yu]

+++ AKASHI Takahiro [28/11/16 18:18 +0900]:

On Mon, Nov 28, 2016 at 08:59:40AM +0100, Andreas Ziegler wrote:

Hi Akashi,

your patch "module: extend 'rodata=off' boot cmdline parameter to module
mappings" showed up in linux-next today, and I noticed a small error in it.

The first modified #ifdef is fine, the second one, however, has a spelling
mistake in it: the CONFIG_ variable should be CONFIG_DEBUG_SET_MODULE_RONX
instead of CONFIG_SET_MODULE_RONX (note the missing DEBUG).


Thank you for pointing this out.
(I didn't notice it because DEBUG_RODATA is always on on arm64.)

Rusty, Jessica, should I submit v4 to correct it?


Andreas, Akashi -

The typo has been fixed with Arnd's patch:

  http://lkml.kernel.org/r/20161128145931.3350661-1-a...@arndb.de

Thanks for finding the issue!

Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Rusty Russell]

Jessica Yu  writes:

> +++ AKASHI Takahiro [14/11/16 15:15 +0900]:
>>The current "rodata=off" parameter disables read-only kernel mappings
>>under CONFIG_DEBUG_RODATA:
>>commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
>>to disable read-only kernel mappings")
>>
>>This patch is a logical extension to module mappings ie. read-only mappings
>>at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
>>(mainly for debug use). Please note, however, that it only affects RO/RW
>>permissions, keeping NX set.
>>
>>This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
>>(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.
>>
>>Suggested-by: and Acked-by: Mark Rutland 
>>Signed-off-by: AKASHI Takahiro 
>>Reviewed-by: Kees Cook 
>>Cc: Rusty Russell 
>
> Hi Rusty, could I get an (n)ack for this patch? :-)

Acked-by: Rusty Russell 

Cheers,
Rusty.

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Rusty Russell]

Jessica Yu  writes:

> +++ AKASHI Takahiro [14/11/16 15:15 +0900]:
>>The current "rodata=off" parameter disables read-only kernel mappings
>>under CONFIG_DEBUG_RODATA:
>>commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
>>to disable read-only kernel mappings")
>>
>>This patch is a logical extension to module mappings ie. read-only mappings
>>at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
>>(mainly for debug use). Please note, however, that it only affects RO/RW
>>permissions, keeping NX set.
>>
>>This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
>>(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.
>>
>>Suggested-by: and Acked-by: Mark Rutland 
>>Signed-off-by: AKASHI Takahiro 
>>Reviewed-by: Kees Cook 
>>Cc: Rusty Russell 
>
> Hi Rusty, could I get an (n)ack for this patch? :-)

Acked-by: Rusty Russell 

Cheers,
Rusty.

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Jessica Yu]

+++ AKASHI Takahiro [14/11/16 15:15 +0900]:

The current "rodata=off" parameter disables read-only kernel mappings
under CONFIG_DEBUG_RODATA:
   commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
   to disable read-only kernel mappings")

This patch is a logical extension to module mappings ie. read-only mappings
at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
(mainly for debug use). Please note, however, that it only affects RO/RW
permissions, keeping NX set.

This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.

Suggested-by: and Acked-by: Mark Rutland 
Signed-off-by: AKASHI Takahiro 
Reviewed-by: Kees Cook 
Cc: Rusty Russell 


Hi Rusty, could I get an (n)ack for this patch? :-)

Thanks!

Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Jessica Yu]

+++ AKASHI Takahiro [14/11/16 15:15 +0900]:

The current "rodata=off" parameter disables read-only kernel mappings
under CONFIG_DEBUG_RODATA:
   commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
   to disable read-only kernel mappings")

This patch is a logical extension to module mappings ie. read-only mappings
at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
(mainly for debug use). Please note, however, that it only affects RO/RW
permissions, keeping NX set.

This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.

Suggested-by: and Acked-by: Mark Rutland 
Signed-off-by: AKASHI Takahiro 
Reviewed-by: Kees Cook 
Cc: Rusty Russell 


Hi Rusty, could I get an (n)ack for this patch? :-)

Thanks!

Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[AKASHI Takahiro]

On Sat, Nov 12, 2016 at 07:04:22PM -0800, Jessica Yu wrote:
> +++ AKASHI Takahiro [21/10/16 10:13 +0900]:
> >The current "rodata=off" parameter disables read-only kernel mappings
> >under CONFIG_DEBUG_RODATA:
> >   commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
> >   to disable read-only kernel mappings")
> >
> >This patch is a logical extension to module mappings ie. read-only mappings
> >at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
> >(mainly for debug use). Please note, however, that it only affects RO/RW
> >permissions, keeping NX set.
> >
> >This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
> >(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.
> >
> >Suggested-by: Mark Rutland 
> >Signed-off-by: AKASHI Takahiro 
> >Reviewed-by: Kees Cook 
> >Cc: Rusty Russell 
> >---
> >v2:
> > * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate
> > * make "rodata_enabled" variable as __ro_after_init
> >v1:
> > * remove RFC's "module_ronx=" and merge it with "rodata="
> > * always keep NX set if CONFIG_SET_MODULE_RONX
> >
> >include/linux/init.h |  3 +++
> >init/main.c  |  7 +--
> >kernel/module.c  | 21 ++---
> >3 files changed, 26 insertions(+), 5 deletions(-)
> >
> >diff --git a/include/linux/init.h b/include/linux/init.h
> >index e30104c..885c3e6 100644
> >--- a/include/linux/init.h
> >+++ b/include/linux/init.h
> >@@ -126,6 +126,9 @@ void prepare_namespace(void);
> >void __init load_default_modules(void);
> >int __init init_rootfs(void);
> >
> >+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
> >+extern bool rodata_enabled;
> >+#endif
> >#ifdef CONFIG_DEBUG_RODATA
> >void mark_rodata_ro(void);
> >#endif
> >diff --git a/init/main.c b/init/main.c
> >index 2858be7..959a242 100644
> >--- a/init/main.c
> >+++ b/init/main.c
> >@@ -81,6 +81,7 @@
> >#include 
> >#include 
> >#include 
> >+#include 
> >
> >#include 
> >#include 
> >@@ -914,14 +915,16 @@ static int try_to_run_init_process(const char 
> >*init_filename)
> >
> >static noinline void __init kernel_init_freeable(void);
> >
> >-#ifdef CONFIG_DEBUG_RODATA
> >-static bool rodata_enabled = true;
> >+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_SET_MODULE_RONX)
> >+bool rodata_enabled __ro_after_init = true;
> >static int __init set_debug_rodata(char *str)
> >{
> > return strtobool(str, _enabled);
> >}
> >__setup("rodata=", set_debug_rodata);
> >+#endif
> >
> >+#ifdef CONFIG_DEBUG_RODATA
> >static void mark_readonly(void)
> >{
> > if (rodata_enabled)
> >diff --git a/kernel/module.c b/kernel/module.c
> >index f57dd63..34d1880 100644
> >--- a/kernel/module.c
> >+++ b/kernel/module.c
> >@@ -1910,6 +1910,9 @@ static void frob_writable_data(const struct 
> >module_layout *layout,
> >/* livepatching wants to disable read-only so it can frob module. */
> >void module_disable_ro(const struct module *mod)
> >{
> >+if (!rodata_enabled)
> >+return;
> >+
> > frob_text(>core_layout, set_memory_rw);
> > frob_rodata(>core_layout, set_memory_rw);
> > frob_ro_after_init(>core_layout, set_memory_rw);
> >@@ -1919,6 +1922,9 @@ void module_disable_ro(const struct module *mod)
> >
> >void module_enable_ro(const struct module *mod, bool after_init)
> >{
> >+if (!rodata_enabled)
> >+return;
> >+
> > frob_text(>core_layout, set_memory_ro);
> > frob_rodata(>core_layout, set_memory_ro);
> > frob_text(>init_layout, set_memory_ro);
> >@@ -1951,6 +1957,9 @@ void set_all_modules_text_rw(void)
> >{
> > struct module *mod;
> >
> >+if (!rodata_enabled)
> >+return;
> >+
> > mutex_lock(_mutex);
> > list_for_each_entry_rcu(mod, , list) {
> > if (mod->state == MODULE_STATE_UNFORMED)
> >@@ -1967,6 +1976,9 @@ void set_all_modules_text_ro(void)
> >{
> > struct module *mod;
> >
> >+if (!rodata_enabled)
> >+return;
> >+
> > mutex_lock(_mutex);
> > list_for_each_entry_rcu(mod, , list) {
> > if (mod->state == MODULE_STATE_UNFORMED)
> >@@ -1980,10 +1992,13 @@ void set_all_modules_text_ro(void)
> >
> >static void disable_ro_nx(const struct module_layout *layout)
> >{
> >-frob_text(layout, set_memory_rw);
> >-frob_rodata(layout, set_memory_rw);
> >+if (rodata_enabled) {
> >+frob_text(layout, set_memory_rw);
> >+frob_rodata(layout, set_memory_rw);
> >+}
> > frob_rodata(layout, set_memory_x);
> >-frob_ro_after_init(layout, set_memory_rw);
> >+if (rodata_enabled)
> >+frob_ro_after_init(layout, set_memory_rw);
> 
> Why not merge this hunk with the previous if (rodata_enabled) check?
> I think it's more readable that way. In any case, the rest of the
> patch looks good to me.

Sure. See my v3.

Thanks,
-Takahiro AKASHI

> Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[AKASHI Takahiro]

On Sat, Nov 12, 2016 at 07:04:22PM -0800, Jessica Yu wrote:
> +++ AKASHI Takahiro [21/10/16 10:13 +0900]:
> >The current "rodata=off" parameter disables read-only kernel mappings
> >under CONFIG_DEBUG_RODATA:
> >   commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
> >   to disable read-only kernel mappings")
> >
> >This patch is a logical extension to module mappings ie. read-only mappings
> >at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
> >(mainly for debug use). Please note, however, that it only affects RO/RW
> >permissions, keeping NX set.
> >
> >This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
> >(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.
> >
> >Suggested-by: Mark Rutland 
> >Signed-off-by: AKASHI Takahiro 
> >Reviewed-by: Kees Cook 
> >Cc: Rusty Russell 
> >---
> >v2:
> > * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate
> > * make "rodata_enabled" variable as __ro_after_init
> >v1:
> > * remove RFC's "module_ronx=" and merge it with "rodata="
> > * always keep NX set if CONFIG_SET_MODULE_RONX
> >
> >include/linux/init.h |  3 +++
> >init/main.c  |  7 +--
> >kernel/module.c  | 21 ++---
> >3 files changed, 26 insertions(+), 5 deletions(-)
> >
> >diff --git a/include/linux/init.h b/include/linux/init.h
> >index e30104c..885c3e6 100644
> >--- a/include/linux/init.h
> >+++ b/include/linux/init.h
> >@@ -126,6 +126,9 @@ void prepare_namespace(void);
> >void __init load_default_modules(void);
> >int __init init_rootfs(void);
> >
> >+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
> >+extern bool rodata_enabled;
> >+#endif
> >#ifdef CONFIG_DEBUG_RODATA
> >void mark_rodata_ro(void);
> >#endif
> >diff --git a/init/main.c b/init/main.c
> >index 2858be7..959a242 100644
> >--- a/init/main.c
> >+++ b/init/main.c
> >@@ -81,6 +81,7 @@
> >#include 
> >#include 
> >#include 
> >+#include 
> >
> >#include 
> >#include 
> >@@ -914,14 +915,16 @@ static int try_to_run_init_process(const char 
> >*init_filename)
> >
> >static noinline void __init kernel_init_freeable(void);
> >
> >-#ifdef CONFIG_DEBUG_RODATA
> >-static bool rodata_enabled = true;
> >+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_SET_MODULE_RONX)
> >+bool rodata_enabled __ro_after_init = true;
> >static int __init set_debug_rodata(char *str)
> >{
> > return strtobool(str, _enabled);
> >}
> >__setup("rodata=", set_debug_rodata);
> >+#endif
> >
> >+#ifdef CONFIG_DEBUG_RODATA
> >static void mark_readonly(void)
> >{
> > if (rodata_enabled)
> >diff --git a/kernel/module.c b/kernel/module.c
> >index f57dd63..34d1880 100644
> >--- a/kernel/module.c
> >+++ b/kernel/module.c
> >@@ -1910,6 +1910,9 @@ static void frob_writable_data(const struct 
> >module_layout *layout,
> >/* livepatching wants to disable read-only so it can frob module. */
> >void module_disable_ro(const struct module *mod)
> >{
> >+if (!rodata_enabled)
> >+return;
> >+
> > frob_text(>core_layout, set_memory_rw);
> > frob_rodata(>core_layout, set_memory_rw);
> > frob_ro_after_init(>core_layout, set_memory_rw);
> >@@ -1919,6 +1922,9 @@ void module_disable_ro(const struct module *mod)
> >
> >void module_enable_ro(const struct module *mod, bool after_init)
> >{
> >+if (!rodata_enabled)
> >+return;
> >+
> > frob_text(>core_layout, set_memory_ro);
> > frob_rodata(>core_layout, set_memory_ro);
> > frob_text(>init_layout, set_memory_ro);
> >@@ -1951,6 +1957,9 @@ void set_all_modules_text_rw(void)
> >{
> > struct module *mod;
> >
> >+if (!rodata_enabled)
> >+return;
> >+
> > mutex_lock(_mutex);
> > list_for_each_entry_rcu(mod, , list) {
> > if (mod->state == MODULE_STATE_UNFORMED)
> >@@ -1967,6 +1976,9 @@ void set_all_modules_text_ro(void)
> >{
> > struct module *mod;
> >
> >+if (!rodata_enabled)
> >+return;
> >+
> > mutex_lock(_mutex);
> > list_for_each_entry_rcu(mod, , list) {
> > if (mod->state == MODULE_STATE_UNFORMED)
> >@@ -1980,10 +1992,13 @@ void set_all_modules_text_ro(void)
> >
> >static void disable_ro_nx(const struct module_layout *layout)
> >{
> >-frob_text(layout, set_memory_rw);
> >-frob_rodata(layout, set_memory_rw);
> >+if (rodata_enabled) {
> >+frob_text(layout, set_memory_rw);
> >+frob_rodata(layout, set_memory_rw);
> >+}
> > frob_rodata(layout, set_memory_x);
> >-frob_ro_after_init(layout, set_memory_rw);
> >+if (rodata_enabled)
> >+frob_ro_after_init(layout, set_memory_rw);
> 
> Why not merge this hunk with the previous if (rodata_enabled) check?
> I think it's more readable that way. In any case, the rest of the
> patch looks good to me.

Sure. See my v3.

Thanks,
-Takahiro AKASHI

> Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Jessica Yu]

+++ AKASHI Takahiro [21/10/16 10:13 +0900]:

The current "rodata=off" parameter disables read-only kernel mappings
under CONFIG_DEBUG_RODATA:
   commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
   to disable read-only kernel mappings")

This patch is a logical extension to module mappings ie. read-only mappings
at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
(mainly for debug use). Please note, however, that it only affects RO/RW
permissions, keeping NX set.

This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.

Suggested-by: Mark Rutland 
Signed-off-by: AKASHI Takahiro 
Reviewed-by: Kees Cook 
Cc: Rusty Russell 
---
v2:
 * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate
 * make "rodata_enabled" variable as __ro_after_init
v1:
 * remove RFC's "module_ronx=" and merge it with "rodata="
 * always keep NX set if CONFIG_SET_MODULE_RONX

include/linux/init.h |  3 +++
init/main.c  |  7 +--
kernel/module.c  | 21 ++---
3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index e30104c..885c3e6 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -126,6 +126,9 @@ void prepare_namespace(void);
void __init load_default_modules(void);
int __init init_rootfs(void);

+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
+extern bool rodata_enabled;
+#endif
#ifdef CONFIG_DEBUG_RODATA
void mark_rodata_ro(void);
#endif
diff --git a/init/main.c b/init/main.c
index 2858be7..959a242 100644
--- a/init/main.c
+++ b/init/main.c
@@ -81,6 +81,7 @@
#include 
#include 
#include 
+#include 

#include 
#include 
@@ -914,14 +915,16 @@ static int try_to_run_init_process(const char 
*init_filename)

static noinline void __init kernel_init_freeable(void);

-#ifdef CONFIG_DEBUG_RODATA
-static bool rodata_enabled = true;
+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_SET_MODULE_RONX)
+bool rodata_enabled __ro_after_init = true;
static int __init set_debug_rodata(char *str)
{
return strtobool(str, _enabled);
}
__setup("rodata=", set_debug_rodata);
+#endif

+#ifdef CONFIG_DEBUG_RODATA
static void mark_readonly(void)
{
if (rodata_enabled)
diff --git a/kernel/module.c b/kernel/module.c
index f57dd63..34d1880 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1910,6 +1910,9 @@ static void frob_writable_data(const struct module_layout 
*layout,
/* livepatching wants to disable read-only so it can frob module. */
void module_disable_ro(const struct module *mod)
{
+   if (!rodata_enabled)
+   return;
+
frob_text(>core_layout, set_memory_rw);
frob_rodata(>core_layout, set_memory_rw);
frob_ro_after_init(>core_layout, set_memory_rw);
@@ -1919,6 +1922,9 @@ void module_disable_ro(const struct module *mod)

void module_enable_ro(const struct module *mod, bool after_init)
{
+   if (!rodata_enabled)
+   return;
+
frob_text(>core_layout, set_memory_ro);
frob_rodata(>core_layout, set_memory_ro);
frob_text(>init_layout, set_memory_ro);
@@ -1951,6 +1957,9 @@ void set_all_modules_text_rw(void)
{
struct module *mod;

+   if (!rodata_enabled)
+   return;
+
mutex_lock(_mutex);
list_for_each_entry_rcu(mod, , list) {
if (mod->state == MODULE_STATE_UNFORMED)
@@ -1967,6 +1976,9 @@ void set_all_modules_text_ro(void)
{
struct module *mod;

+   if (!rodata_enabled)
+   return;
+
mutex_lock(_mutex);
list_for_each_entry_rcu(mod, , list) {
if (mod->state == MODULE_STATE_UNFORMED)
@@ -1980,10 +1992,13 @@ void set_all_modules_text_ro(void)

static void disable_ro_nx(const struct module_layout *layout)
{
-   frob_text(layout, set_memory_rw);
-   frob_rodata(layout, set_memory_rw);
+   if (rodata_enabled) {
+   frob_text(layout, set_memory_rw);
+   frob_rodata(layout, set_memory_rw);
+   }
frob_rodata(layout, set_memory_x);
-   frob_ro_after_init(layout, set_memory_rw);
+   if (rodata_enabled)
+   frob_ro_after_init(layout, set_memory_rw);


Why not merge this hunk with the previous if (rodata_enabled) check?
I think it's more readable that way. In any case, the rest of the
patch looks good to me.

Jessica

Re: module: extend 'rodata=off' boot cmdline parameter to module mappings

[Jessica Yu]

+++ AKASHI Takahiro [21/10/16 10:13 +0900]:

The current "rodata=off" parameter disables read-only kernel mappings
under CONFIG_DEBUG_RODATA:
   commit d2aa1acad22f ("mm/init: Add 'rodata=off' boot cmdline parameter
   to disable read-only kernel mappings")

This patch is a logical extension to module mappings ie. read-only mappings
at module loading can be disabled even if CONFIG_DEBUG_SET_MODULE_RONX
(mainly for debug use). Please note, however, that it only affects RO/RW
permissions, keeping NX set.

This is the first step to make CONFIG_DEBUG_SET_MODULE_RONX mandatory
(always-on) in the future as CONFIG_DEBUG_RODATA on x86 and arm64.

Suggested-by: Mark Rutland 
Signed-off-by: AKASHI Takahiro 
Reviewed-by: Kees Cook 
Cc: Rusty Russell 
---
v2:
 * use CONFIG_DEBUG_RODATA/SET_MODULE_RONX guards better where appropriate
 * make "rodata_enabled" variable as __ro_after_init
v1:
 * remove RFC's "module_ronx=" and merge it with "rodata="
 * always keep NX set if CONFIG_SET_MODULE_RONX

include/linux/init.h |  3 +++
init/main.c  |  7 +--
kernel/module.c  | 21 ++---
3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index e30104c..885c3e6 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -126,6 +126,9 @@ void prepare_namespace(void);
void __init load_default_modules(void);
int __init init_rootfs(void);

+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
+extern bool rodata_enabled;
+#endif
#ifdef CONFIG_DEBUG_RODATA
void mark_rodata_ro(void);
#endif
diff --git a/init/main.c b/init/main.c
index 2858be7..959a242 100644
--- a/init/main.c
+++ b/init/main.c
@@ -81,6 +81,7 @@
#include 
#include 
#include 
+#include 

#include 
#include 
@@ -914,14 +915,16 @@ static int try_to_run_init_process(const char 
*init_filename)

static noinline void __init kernel_init_freeable(void);

-#ifdef CONFIG_DEBUG_RODATA
-static bool rodata_enabled = true;
+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_SET_MODULE_RONX)
+bool rodata_enabled __ro_after_init = true;
static int __init set_debug_rodata(char *str)
{
return strtobool(str, _enabled);
}
__setup("rodata=", set_debug_rodata);
+#endif

+#ifdef CONFIG_DEBUG_RODATA
static void mark_readonly(void)
{
if (rodata_enabled)
diff --git a/kernel/module.c b/kernel/module.c
index f57dd63..34d1880 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1910,6 +1910,9 @@ static void frob_writable_data(const struct module_layout 
*layout,
/* livepatching wants to disable read-only so it can frob module. */
void module_disable_ro(const struct module *mod)
{
+   if (!rodata_enabled)
+   return;
+
frob_text(>core_layout, set_memory_rw);
frob_rodata(>core_layout, set_memory_rw);
frob_ro_after_init(>core_layout, set_memory_rw);
@@ -1919,6 +1922,9 @@ void module_disable_ro(const struct module *mod)

void module_enable_ro(const struct module *mod, bool after_init)
{
+   if (!rodata_enabled)
+   return;
+
frob_text(>core_layout, set_memory_ro);
frob_rodata(>core_layout, set_memory_ro);
frob_text(>init_layout, set_memory_ro);
@@ -1951,6 +1957,9 @@ void set_all_modules_text_rw(void)
{
struct module *mod;

+   if (!rodata_enabled)
+   return;
+
mutex_lock(_mutex);
list_for_each_entry_rcu(mod, , list) {
if (mod->state == MODULE_STATE_UNFORMED)
@@ -1967,6 +1976,9 @@ void set_all_modules_text_ro(void)
{
struct module *mod;

+   if (!rodata_enabled)
+   return;
+
mutex_lock(_mutex);
list_for_each_entry_rcu(mod, , list) {
if (mod->state == MODULE_STATE_UNFORMED)
@@ -1980,10 +1992,13 @@ void set_all_modules_text_ro(void)

static void disable_ro_nx(const struct module_layout *layout)
{
-   frob_text(layout, set_memory_rw);
-   frob_rodata(layout, set_memory_rw);
+   if (rodata_enabled) {
+   frob_text(layout, set_memory_rw);
+   frob_rodata(layout, set_memory_rw);
+   }
frob_rodata(layout, set_memory_x);
-   frob_ro_after_init(layout, set_memory_rw);
+   if (rodata_enabled)
+   frob_ro_after_init(layout, set_memory_rw);


Why not merge this hunk with the previous if (rodata_enabled) check?
I think it's more readable that way. In any case, the rest of the
patch looks good to me.

Jessica