linux-kernel - Re: [PATCH] lkdtm: hide unused functions

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Date:	Fri, 15 Jul 2016 15:54:38 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] lkdtm: hide unused functions

On Fri, Jul 15, 2016 at 4:35 AM, Arnd Bergmann <arnd@...db.de> wrote:
> A conversion of the lkdtm core module added an "#ifdef CONFIG_KPROBES" check,
> but a number of functions then become unused:
>
> drivers/misc/lkdtm_core.c:340:16: error: 'lkdtm_debugfs_entry' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:122:12: error: 'jp_generic_ide_ioctl' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:114:12: error: 'jp_scsi_dispatch_cmd' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:106:12: error: 'jp_hrtimer_start' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:97:22: error: 'jp_shrink_inactive_list' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:89:13: error: 'jp_ll_rw_block' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:83:13: error: 'jp_tasklet_action' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:75:20: error: 'jp_handle_irq_event' defined but not used [-Werror=unused-function]
> drivers/misc/lkdtm_core.c:68:21: error: 'jp_do_irq' defined but not used [-Werror=unused-function]
>
> This adds the same #ifdef everywhere. There is probably a better way to do the
> same thing, but for now this avoids the new warnings.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> Fixes: c479e3fd8870 ("lkdtm: use struct arrays instead of enums")

Ah! Thank you very much. I'm going to make a small change and get this
into my tree.

-Kees

> ---
>
> On Wednesday, July 6, 2016 3:33:31 PM CEST Kees Cook wrote:
>> +
>> +/* Define the possible places where we can trigger a crash point. */
>> +struct crashpoint crashpoints[] = {
>> +     CRASHPOINT("DIRECT",                    direct_entry,
>> +                NULL,                        NULL),
>> +#ifdef CONFIG_KPROBES
>> +     CRASHPOINT("INT_HARDWARE_ENTRY",        lkdtm_debugfs_entry,
>> +                "do_IRQ",                    jp_do_irq),
>> +     CRASHPOINT("INT_HW_IRQ_EN",             lkdtm_debugfs_entry,
>> +                "handle_IRQ_event",          jp_handle_irq_event),
>> +     CRASHPOINT("INT_TASKLET_ENTRY",         lkdtm_debugfs_entry,
>
> diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c
> index de29a339242a..6bdef16f95a2 100644
> --- a/drivers/misc/lkdtm_core.c
> +++ b/drivers/misc/lkdtm_core.c
> @@ -53,12 +53,14 @@
>
>  #define DEFAULT_COUNT 10
>
> -static void lkdtm_handler(void);
>  static int lkdtm_debugfs_open(struct inode *inode, struct file *file);
>  static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
>                 size_t count, loff_t *off);
>  static ssize_t direct_entry(struct file *f, const char __user *user_buf,
>                             size_t count, loff_t *off);
> +
> +#ifdef CONFIG_KPROBES
> +static void lkdtm_handler(void);
>  static ssize_t lkdtm_debugfs_entry(struct file *f,
>                                    const char __user *user_buf,
>                                    size_t count, loff_t *off);
> @@ -128,7 +130,7 @@ static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
>         return 0;
>  }
>  #endif
> -
> +#endif
>
>  /* Crash points */
>  struct crashpoint {
> @@ -240,7 +242,9 @@ struct crashtype *lkdtm_crashtype;
>
>  /* Global crash counter and spinlock. */
>  static int crash_count = DEFAULT_COUNT;
> +#ifdef CONFIG_KPROBES
>  static DEFINE_SPINLOCK(crash_count_lock);
> +#endif
>
>  /* Module parameters */
>  static int recur_count = -1;
> @@ -285,6 +289,7 @@ static noinline void lkdtm_do_action(struct crashtype *crashtype)
>         crashtype->func();
>  }
>
> +#ifdef CONFIG_KPROBES
>  /* Called by jprobe entry points. */
>  static void lkdtm_handler(void)
>  {
> @@ -307,6 +312,7 @@ static void lkdtm_handler(void)
>         if (do_it)
>                 lkdtm_do_action(lkdtm_crashtype);
>  }
> +#endif
>
>  static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
>                                  struct crashtype *crashtype)
> @@ -337,6 +343,7 @@ static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
>         return ret;
>  }
>
> +#ifdef CONFIG_KPROBES
>  static ssize_t lkdtm_debugfs_entry(struct file *f,
>                                    const char __user *user_buf,
>                                    size_t count, loff_t *off)
> @@ -374,6 +381,7 @@ static ssize_t lkdtm_debugfs_entry(struct file *f,
>
>         return count;
>  }
> +#endif
>
>  /* Generic read callback that just prints out the available crash types */
>  static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
>



-- 
Kees Cook
Chrome OS & Brillo Security