[PATCH v3 5/8] module: Add module_for_each_mod() function

[PATCH v3 5/8] module: Add module_for_each_mod() function

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

The tracing system needs a way to save all the currently loaded modules
and their addresses into persistent memory so that it can evaluate the
addresses on a reboot from a crash. When the persistent memory trace
starts, it will load the module addresses and names into the persistent
memory. To do so, it will call the module_for_each_mod() function and pass
it a function and data structure to get called on each loaded module. Then
it can record the memory.

This only implements that function.

Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: linux-modules@vger.kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
Changes since v2: https://lore.kernel.org/20250215034404.902259250@goodmis.org

- Use RCU guard instead of disabling preemption

 include/linux/module.h |  6 ++++++
 kernel/module/main.c   | 13 +++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/module.h b/include/linux/module.h
index 30e5b19bafa9..9a71dd2cb11f 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -782,6 +782,8 @@ static inline void *module_writable_address(struct module *mod, void *loc)
 	return __module_writable_address(mod, loc);
 }
 
+void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data);
+
 #else /* !CONFIG_MODULES... */
 
 static inline struct module *__module_address(unsigned long addr)
@@ -894,6 +896,10 @@ static inline void *module_writable_address(struct module *mod, void *loc)
 {
 	return loc;
 }
+
+static inline void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
+{
+}
 #endif /* CONFIG_MODULES */
 
 #ifdef CONFIG_SYSFS
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 1fb9ad289a6f..927a2e0ffd5f 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3809,6 +3809,19 @@ bool is_module_text_address(unsigned long addr)
 	return ret;
 }
 
+void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
+{
+	struct module *mod;
+
+	guard(rcu)();
+	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
+		if (func(mod, data))
+			break;
+	}
+}
+
 /**
  * __module_text_address() - get the module whose code contains an address.
  * @addr: the address.
-- 
2.47.2

Re: [PATCH v3 5/8] module: Add module_for_each_mod() function

[Steven Rostedt]

Luis,

Can I get an Acked-by from you?

This follows the changes you have in linux-next.

Thanks,

-- Steve




On Mon, 03 Mar 2025 20:25:21 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: Steven Rostedt <rostedt@goodmis.org>
> 
> The tracing system needs a way to save all the currently loaded modules
> and their addresses into persistent memory so that it can evaluate the
> addresses on a reboot from a crash. When the persistent memory trace
> starts, it will load the module addresses and names into the persistent
> memory. To do so, it will call the module_for_each_mod() function and pass
> it a function and data structure to get called on each loaded module. Then
> it can record the memory.
> 
> This only implements that function.
> 
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Petr Pavlu <petr.pavlu@suse.com>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Daniel Gomez <da.gomez@samsung.com>
> Cc: linux-modules@vger.kernel.org
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
> Changes since v2: https://lore.kernel.org/20250215034404.902259250@goodmis.org
> 
> - Use RCU guard instead of disabling preemption
> 
>  include/linux/module.h |  6 ++++++
>  kernel/module/main.c   | 13 +++++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/include/linux/module.h b/include/linux/module.h
> index 30e5b19bafa9..9a71dd2cb11f 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -782,6 +782,8 @@ static inline void *module_writable_address(struct module *mod, void *loc)
>  	return __module_writable_address(mod, loc);
>  }
>  
> +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data);
> +
>  #else /* !CONFIG_MODULES... */
>  
>  static inline struct module *__module_address(unsigned long addr)
> @@ -894,6 +896,10 @@ static inline void *module_writable_address(struct module *mod, void *loc)
>  {
>  	return loc;
>  }
> +
> +static inline void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
> +{
> +}
>  #endif /* CONFIG_MODULES */
>  
>  #ifdef CONFIG_SYSFS
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 1fb9ad289a6f..927a2e0ffd5f 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -3809,6 +3809,19 @@ bool is_module_text_address(unsigned long addr)
>  	return ret;
>  }
>  
> +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
> +{
> +	struct module *mod;
> +
> +	guard(rcu)();
> +	list_for_each_entry_rcu(mod, &modules, list) {
> +		if (mod->state == MODULE_STATE_UNFORMED)
> +			continue;
> +		if (func(mod, data))
> +			break;
> +	}
> +}
> +
>  /**
>   * __module_text_address() - get the module whose code contains an address.
>   * @addr: the address.

Re: [PATCH v3 5/8] module: Add module_for_each_mod() function

[Petr Pavlu]

On 3/4/25 15:57, Steven Rostedt wrote:
> 
> Luis,
> 
> Can I get an Acked-by from you?
> 
> This follows the changes you have in linux-next.

Hi Steven,

I'm not Luis, but we started rotating the modules maintenance every six
months and I'm currently looking after the modules tree. I see Luis
seemed ok with the change in the previous discussion and the patch looks
reasonable to me.

Acked-by: Petr Pavlu <petr.pavlu@suse.com>

-- 
Thanks,
Petr

> 
> 
> 
> 
> On Mon, 03 Mar 2025 20:25:21 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
>> From: Steven Rostedt <rostedt@goodmis.org>
>>
>> The tracing system needs a way to save all the currently loaded modules
>> and their addresses into persistent memory so that it can evaluate the
>> addresses on a reboot from a crash. When the persistent memory trace
>> starts, it will load the module addresses and names into the persistent
>> memory. To do so, it will call the module_for_each_mod() function and pass
>> it a function and data structure to get called on each loaded module. Then
>> it can record the memory.
>>
>> This only implements that function.
>>
>> Cc: Luis Chamberlain <mcgrof@kernel.org>
>> Cc: Petr Pavlu <petr.pavlu@suse.com>
>> Cc: Sami Tolvanen <samitolvanen@google.com>
>> Cc: Daniel Gomez <da.gomez@samsung.com>
>> Cc: linux-modules@vger.kernel.org
>> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
>> ---
>> Changes since v2: https://lore.kernel.org/20250215034404.902259250@goodmis.org
>>
>> - Use RCU guard instead of disabling preemption
>>
>>  include/linux/module.h |  6 ++++++
>>  kernel/module/main.c   | 13 +++++++++++++
>>  2 files changed, 19 insertions(+)
>>
>> diff --git a/include/linux/module.h b/include/linux/module.h
>> index 30e5b19bafa9..9a71dd2cb11f 100644
>> --- a/include/linux/module.h
>> +++ b/include/linux/module.h
>> @@ -782,6 +782,8 @@ static inline void *module_writable_address(struct module *mod, void *loc)
>>  	return __module_writable_address(mod, loc);
>>  }
>>  
>> +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data);
>> +
>>  #else /* !CONFIG_MODULES... */
>>  
>>  static inline struct module *__module_address(unsigned long addr)
>> @@ -894,6 +896,10 @@ static inline void *module_writable_address(struct module *mod, void *loc)
>>  {
>>  	return loc;
>>  }
>> +
>> +static inline void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
>> +{
>> +}
>>  #endif /* CONFIG_MODULES */
>>  
>>  #ifdef CONFIG_SYSFS
>> diff --git a/kernel/module/main.c b/kernel/module/main.c
>> index 1fb9ad289a6f..927a2e0ffd5f 100644
>> --- a/kernel/module/main.c
>> +++ b/kernel/module/main.c
>> @@ -3809,6 +3809,19 @@ bool is_module_text_address(unsigned long addr)
>>  	return ret;
>>  }
>>  
>> +void module_for_each_mod(int(*func)(struct module *mod, void *data), void *data)
>> +{
>> +	struct module *mod;
>> +
>> +	guard(rcu)();
>> +	list_for_each_entry_rcu(mod, &modules, list) {
>> +		if (mod->state == MODULE_STATE_UNFORMED)
>> +			continue;
>> +		if (func(mod, data))
>> +			break;
>> +	}
>> +}
>> +
>>  /**
>>   * __module_text_address() - get the module whose code contains an address.
>>   * @addr: the address.
> 

Re: [PATCH v3 5/8] module: Add module_for_each_mod() function

[Steven Rostedt]

On Wed, 5 Mar 2025 09:47:49 +0100
Petr Pavlu <petr.pavlu@suse.com> wrote:

> On 3/4/25 15:57, Steven Rostedt wrote:
> > 
> > Luis,
> > 
> > Can I get an Acked-by from you?
> > 
> > This follows the changes you have in linux-next.  
> 
> Hi Steven,
> 
> I'm not Luis, but we started rotating the modules maintenance every six
> months and I'm currently looking after the modules tree. I see Luis
> seemed ok with the change in the previous discussion and the patch looks
> reasonable to me.

Ah, you may want to update the MAINTAINERS file. Right now it has:

M:      Luis Chamberlain <mcgrof@kernel.org>
R:      Petr Pavlu <petr.pavlu@suse.com>
R:      Sami Tolvanen <samitolvanen@google.com>
R:      Daniel Gomez <da.gomez@samsung.com>

Which puts Luis as maintainer and you as a reviewer. If you rotate
maintainerships, you should update that to have an M: next to all that are
in that rotation.

> 
> Acked-by: Petr Pavlu <petr.pavlu@suse.com>
> 

Appreciate it.

-- Steve