linux-kernel - Re: [patch V4 part 1 17/36] kprobes: Support NOKPROBE

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Date:   Wed, 6 May 2020 17:54:05 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>
Subject: Re: [patch V4 part 1 17/36] kprobes: Support NOKPROBE_SYMBOL() in
 modules


On 5/5/20 3:16 PM, Thomas Gleixner wrote:
> From: Masami Hiramatsu <mhiramat@...nel.org>
> 
> Support NOKPROBE_SYMBOL() in modules. NOKPROBE_SYMBOL() records only symbol
> address in "_kprobe_blacklist" section in the module.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Link: https://lkml.kernel.org/r/158523419989.24735.6665260504057165207.stgit@devnote2
> 
> ---
>   include/linux/module.h |    2 ++
>   kernel/kprobes.c       |   17 +++++++++++++++++
>   kernel/module.c        |    3 +++
>   3 files changed, 22 insertions(+)

Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>

alex.

> diff --git a/include/linux/module.h b/include/linux/module.h
> index 369c354f9207..1192097c9a69 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -492,6 +492,8 @@ struct module {
>   #ifdef CONFIG_KPROBES
>   	void *kprobes_text_start;
>   	unsigned int kprobes_text_size;
> +	unsigned long *kprobe_blacklist;
> +	unsigned int num_kprobe_blacklist;
>   #endif
>   
>   #ifdef CONFIG_LIVEPATCH
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index b7549992b9bd..9eb5acf0a9f3 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2192,6 +2192,11 @@ static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
>   	}
>   }
>   
> +static void kprobe_remove_ksym_blacklist(unsigned long entry)
> +{
> +	kprobe_remove_area_blacklist(entry, entry + 1);
> +}
> +
>   int __init __weak arch_populate_kprobe_blacklist(void)
>   {
>   	return 0;
> @@ -2231,6 +2236,12 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
>   static void add_module_kprobe_blacklist(struct module *mod)
>   {
>   	unsigned long start, end;
> +	int i;
> +
> +	if (mod->kprobe_blacklist) {
> +		for (i = 0; i < mod->num_kprobe_blacklist; i++)
> +			kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]);
> +	}
>   
>   	start = (unsigned long)mod->kprobes_text_start;
>   	if (start) {
> @@ -2242,6 +2253,12 @@ static void add_module_kprobe_blacklist(struct module *mod)
>   static void remove_module_kprobe_blacklist(struct module *mod)
>   {
>   	unsigned long start, end;
> +	int i;
> +
> +	if (mod->kprobe_blacklist) {
> +		for (i = 0; i < mod->num_kprobe_blacklist; i++)
> +			kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]);
> +	}
>   
>   	start = (unsigned long)mod->kprobes_text_start;
>   	if (start) {
> diff --git a/kernel/module.c b/kernel/module.c
> index f7712a923d63..7be011dacd8a 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3197,6 +3197,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
>   #ifdef CONFIG_KPROBES
>   	mod->kprobes_text_start = section_objs(info, ".kprobes.text", 1,
>   						&mod->kprobes_text_size);
> +	mod->kprobe_blacklist = section_objs(info, "_kprobe_blacklist",
> +						sizeof(unsigned long),
> +						&mod->num_kprobe_blacklist);
>   #endif
>   	mod->extable = section_objs(info, "__ex_table",
>   				    sizeof(*mod->extable), &mod->num_exentries);
> 
>