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Date: Thu, 3 Mar 2022 11:21:40 -0800
From: Luis Chamberlain <mcgrof@...nel.org>
To: Christoph Hellwig <hch@...radead.org>
Cc: Daniel Thompson <daniel.thompson@...aro.org>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Aaron Tomlin <atomlin@...hat.com>,
"pmladek@...e.com" <pmladek@...e.com>,
"cl@...ux.com" <cl@...ux.com>, "mbenes@...e.cz" <mbenes@...e.cz>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"jeyu@...nel.org" <jeyu@...nel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-modules@...r.kernel.org" <linux-modules@...r.kernel.org>,
"void@...ifault.com" <void@...ifault.com>,
"atomlin@...mlin.com" <atomlin@...mlin.com>,
"allen.lkml@...il.com" <allen.lkml@...il.com>,
"joe@...ches.com" <joe@...ches.com>,
"msuchanek@...e.de" <msuchanek@...e.de>,
"oleksandr@...alenko.name" <oleksandr@...alenko.name>,
"jason.wessel@...driver.com" <jason.wessel@...driver.com>
Subject: Re: [PATCH v9 13/14] module: Move kdb_modules list out of core code
On Thu, Mar 03, 2022 at 09:54:14AM -0800, Christoph Hellwig wrote:
> On Thu, Mar 03, 2022 at 02:59:49PM +0000, Daniel Thompson wrote:
> >
> > One of the best ways that we can common up code might be to dust
> > off some code I wrote a while back to display seq_files from
> > kdb.
> >
> > The basic idea worked well enough but it often needs special
> > start/stop operatings to ensure the start meeds kdb's rather
> > odd locking restrictions. If there is a willingness for
> > something like the below to be included in the module code then we
> > could replace kdb_lsmod() with something that reused the code to
> > format /proc/modules.
>
> Displaying seq_files sounds nice to have, but in the short term I'm
> just thinking of something like this:
>
> diff --git a/include/linux/kdb.h b/include/linux/kdb.h
> index ea0f5e580fac2..07dfb6a20a1c4 100644
> --- a/include/linux/kdb.h
> +++ b/include/linux/kdb.h
> @@ -222,5 +222,6 @@ enum {
>
> extern int kdbgetintenv(const char *, int *);
> extern int kdb_set(int, const char **);
> +int kdb_lsmod(int argc, const char **argv);
Yes exactly.
> #endif /* !_KDB_H */
> diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> index 0852a537dad4c..292a407118a4f 100644
> --- a/kernel/debug/kdb/kdb_main.c
> +++ b/kernel/debug/kdb/kdb_main.c
> @@ -2004,54 +2004,6 @@ static int kdb_ef(int argc, const char **argv)
> return 0;
> }
>
> -#if defined(CONFIG_MODULES)
> -/*
> - * kdb_lsmod - This function implements the 'lsmod' command. Lists
> - * currently loaded kernel modules.
> - * Mostly taken from userland lsmod.
> - */
> -static int kdb_lsmod(int argc, const char **argv)
> -{
> - struct module *mod;
> -
> - if (argc != 0)
> - return KDB_ARGCOUNT;
> -
> - kdb_printf("Module Size modstruct Used by\n");
> - list_for_each_entry(mod, kdb_modules, list) {
> - if (mod->state == MODULE_STATE_UNFORMED)
> - continue;
> -
> - kdb_printf("%-20s%8u 0x%px ", mod->name,
> - mod->core_layout.size, (void *)mod);
> -#ifdef CONFIG_MODULE_UNLOAD
> - kdb_printf("%4d ", module_refcount(mod));
> -#endif
> - if (mod->state == MODULE_STATE_GOING)
> - kdb_printf(" (Unloading)");
> - else if (mod->state == MODULE_STATE_COMING)
> - kdb_printf(" (Loading)");
> - else
> - kdb_printf(" (Live)");
> - kdb_printf(" 0x%px", mod->core_layout.base);
> -
> -#ifdef CONFIG_MODULE_UNLOAD
> - {
> - struct module_use *use;
> - kdb_printf(" [ ");
> - list_for_each_entry(use, &mod->source_list,
> - source_list)
> - kdb_printf("%s ", use->target->name);
> - kdb_printf("]\n");
> - }
> -#endif
> - }
> -
> - return 0;
> -}
> -
> -#endif /* CONFIG_MODULES */
> -
> /*
> * kdb_env - This function implements the 'env' command. Display the
> * current environment variables.
> diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
> index 0d2f9feea0a46..1f8c519a5f81c 100644
> --- a/kernel/debug/kdb/kdb_private.h
> +++ b/kernel/debug/kdb/kdb_private.h
> @@ -226,10 +226,6 @@ extern void kdb_kbd_cleanup_state(void);
> #define kdb_kbd_cleanup_state()
> #endif /* ! CONFIG_KDB_KEYBOARD */
>
> -#ifdef CONFIG_MODULES
> -extern struct list_head *kdb_modules;
> -#endif /* CONFIG_MODULES */
> -
> extern char kdb_prompt_str[];
>
> #define KDB_WORD_SIZE ((int)sizeof(unsigned long))
> diff --git a/kernel/module.c b/kernel/module.c
> index 6cea788fd965c..754ec20aab4f1 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -57,6 +57,7 @@
> #include <linux/bsearch.h>
> #include <linux/dynamic_debug.h>
> #include <linux/audit.h>
> +#include <linux/kdb.h>
> #include <uapi/linux/module.h>
> #include "module-internal.h"
>
> @@ -252,10 +253,6 @@ static void mod_update_bounds(struct module *mod)
> __mod_update_bounds(mod->init_layout.base, mod->init_layout.size);
> }
>
> -#ifdef CONFIG_KGDB_KDB
> -struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
> -#endif /* CONFIG_KGDB_KDB */
> -
> static void module_assert_mutex_or_preempt(void)
> {
> #ifdef CONFIG_LOCKDEP
> @@ -4808,3 +4805,45 @@ void module_layout(struct module *mod,
> }
> EXPORT_SYMBOL(module_layout);
> #endif
> +
> +#ifdef CONFIG_KGDB_KDB
Yes! And then when we move all this crap to its own files on
kernel/module/Makefile:
obj-$(CONFIG_KGDB_KDB) += kdb.o
> +int kdb_lsmod(int argc, const char **argv)
> +{
> + struct module *mod;
> +
> + if (argc != 0)
> + return KDB_ARGCOUNT;
> +
> + kdb_printf("Module Size modstruct Used by\n");
Indeed, we need to do it this way because kdb_printf() which emits
messages directly to I/O drivers, bypassing the kernel log. Perhaps this
info should be added to the top of kernel/module/kdb.c
> + list_for_each_entry(mod, &modules, list) {
> + if (mod->state == MODULE_STATE_UNFORMED)
> + continue;
> +
> + kdb_printf("%-20s%8u 0x%px ", mod->name,
> + mod->core_layout.size, (void *)mod);
> +#ifdef CONFIG_MODULE_UNLOAD
> + kdb_printf("%4d ", module_refcount(mod));
> +#endif
Yes and later this can be if IS_ENABLED(CONFIG_MODULE_UNLOAD)
> + if (mod->state == MODULE_STATE_GOING)
> + kdb_printf(" (Unloading)");
> + else if (mod->state == MODULE_STATE_COMING)
> + kdb_printf(" (Loading)");
> + else
> + kdb_printf(" (Live)");
> + kdb_printf(" 0x%px", mod->core_layout.base);
> +
> +#ifdef CONFIG_MODULE_UNLOAD
and if IS_ENABLED(CONFIG_MODULE_UNLOAD) later
> + {
> + struct module_use *use;
> + kdb_printf(" [ ");
> + list_for_each_entry(use, &mod->source_list,
> + source_list)
> + kdb_printf("%s ", use->target->name);
> + kdb_printf("]\n");
> + }
> +#endif
> + }
> +
> + return 0;
> +}
> +#endif /* CONFIG_KGDB_KDB */
Luis
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