From: Masami Hiramatsu <mhiramat@kernel.org>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@vger.kernel.org,
Andi Kleen <ak@linux.intel.com>, Jessica Yu <jeyu@kernel.org>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Masami Hiramatsu <mhiramat@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v3 3/3] kprobes: Flag out CONFIG_MODULES dependent code
Date: Wed, 15 Jul 2020 17:35:24 +0900 [thread overview]
Message-ID: <20200715173524.0f21afce3574b8e8596e751e@kernel.org> (raw)
In-Reply-To: <20200714223239.1543716-4-jarkko.sakkinen@linux.intel.com>
Hi Jarkko,
On Wed, 15 Jul 2020 01:32:29 +0300
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote:
> Remove CONFIG_MODULES dependency by flagging out the dependent code. This
> allows to use kprobes in a kernel without support for loadable modules,
> which could be useful for a test kernel or perhaps an embedded kernel.
>
OK, looks good, I just have 2 comments below.
> Cc: Andi Kleen <ak@linux.intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
> include/linux/module.h | 14 +++++++-------
> kernel/kprobes.c | 7 +++++++
> kernel/trace/trace_kprobe.c | 16 +++++++++++++++-
> 3 files changed, 29 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/module.h b/include/linux/module.h
> index 857b84bf9e90..eaa8ad02f75c 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -290,6 +290,13 @@ extern typeof(name) __mod_##type##__##name##_device_table \
>
> struct notifier_block;
>
> +enum module_state {
> + MODULE_STATE_LIVE, /* Normal state. */
> + MODULE_STATE_COMING, /* Full formed, running module_init. */
> + MODULE_STATE_GOING, /* Going away. */
> + MODULE_STATE_UNFORMED, /* Still setting it up. */
> +};
> +
> #ifdef CONFIG_MODULES
>
> extern int modules_disabled; /* for sysctl */
> @@ -305,13 +312,6 @@ struct module_use {
> struct module *source, *target;
> };
>
> -enum module_state {
> - MODULE_STATE_LIVE, /* Normal state. */
> - MODULE_STATE_COMING, /* Full formed, running module_init. */
> - MODULE_STATE_GOING, /* Going away. */
> - MODULE_STATE_UNFORMED, /* Still setting it up. */
> -};
> -
> struct mod_tree_node {
> struct module *mod;
> struct latch_tree_node node;
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index b4f3c24cd2ef..3039df13d34e 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2225,6 +2225,7 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
> return 0;
> }
>
> +#ifdef CONFIG_MODULES
> /* Remove all symbols in given area from kprobe blacklist */
> static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
> {
> @@ -2242,6 +2243,7 @@ static void kprobe_remove_ksym_blacklist(unsigned long entry)
> {
> kprobe_remove_area_blacklist(entry, entry + 1);
> }
> +#endif
>
> int __init __weak arch_populate_kprobe_blacklist(void)
> {
> @@ -2285,6 +2287,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
> return ret ? : arch_populate_kprobe_blacklist();
> }
>
> +#ifdef CONFIG_MODULES
> static void add_module_kprobe_blacklist(struct module *mod)
> {
> unsigned long start, end;
> @@ -2330,6 +2333,10 @@ static void remove_module_kprobe_blacklist(struct module *mod)
> kprobe_remove_area_blacklist(start, end);
> }
> }
> +#else
> +static void add_module_kprobe_blacklist(struct module *mod) {}
> +static void remove_module_kprobe_blacklist(struct module *mod) {}
> +#endif /* CONFIG_MODULES */
Please feel free to move the function. I would like to see;
#ifdef CONFIG_MODULES
/* Remove all symbols in given area from kprobe blacklist */
static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
{
...
}
static void add_module_kprobe_blacklist(struct module *mod)
{
...
}
#else
static void add_module_kprobe_blacklist(struct module *mod) {}
static void remove_module_kprobe_blacklist(struct module *mod) {}
#endif /* CONFIG_MODULES */
Rather than split #ifdefs.
>
> /* Module notifier call back, checking kprobes on the module */
> static int kprobes_module_callback(struct notifier_block *nb,
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 710ec6a6aa8f..7fcd1bf2d96e 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -103,8 +103,9 @@ static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
> return !!(kprobe_gone(&tk->rp.kp));
> }
>
> +#ifdef CONFIG_MODULES
> static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
> - struct module *mod)
> + struct module *mod)
> {
> int len = strlen(mod->name);
> const char *name = trace_kprobe_symbol(tk);
> @@ -129,6 +130,17 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
>
> return ret;
> }
> +#else
> +static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
> + struct module *mod)
> +{
> + return false;
> +}
> +static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
> +{
> + return false;
> +}
> +#endif
>
> static bool trace_kprobe_is_busy(struct dyn_event *ev)
> {
> @@ -685,10 +697,12 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
> /* Don't need to check busy - this should have gone. */
> __unregister_trace_kprobe(tk);
> ret = __register_trace_kprobe(tk);
> +#ifdef CONFIG_MODULES
> if (ret)
> pr_warn("Failed to re-register probe %s on %s: %d\n",
> trace_probe_name(&tk->tp),
> mod->name, ret);
> +#endif
I guess this CONFIG_MODULES is for avoiding build error according to mod->name,
if so, please use module_name(mod) macro instead of this #ifdef.
> }
> }
> mutex_unlock(&event_mutex);
> --
> 2.25.1
>
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2020-07-15 8:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-14 22:32 [PATCH v3 0/3] kprobes: Remove MODULES dependency Jarkko Sakkinen
2020-07-14 22:32 ` [PATCH v3 1/3] kprobes: Add text_alloc() and text_free() Jarkko Sakkinen
2020-07-15 0:59 ` kernel test robot
2020-07-15 8:27 ` Masami Hiramatsu
2020-07-15 19:38 ` Kees Cook
2020-07-16 17:32 ` Jarkko Sakkinen
2020-07-15 19:36 ` Kees Cook
2020-07-15 19:49 ` Mike Rapoport
2020-07-15 19:51 ` Kees Cook
2020-07-23 1:39 ` Jarkko Sakkinen
2020-07-16 9:02 ` Peter Zijlstra
2020-07-23 1:49 ` Jarkko Sakkinen
2020-07-14 22:32 ` [PATCH v3 2/3] module: Add lock_modules() and unlock_modules() Jarkko Sakkinen
2020-07-15 8:39 ` Masami Hiramatsu
2020-07-16 17:37 ` Jarkko Sakkinen
2020-07-14 22:32 ` [PATCH v3 3/3] kprobes: Flag out CONFIG_MODULES dependent code Jarkko Sakkinen
2020-07-15 8:35 ` Masami Hiramatsu [this message]
2020-07-16 17:36 ` Jarkko Sakkinen
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