linux-kernel - [PATCH -tip 3/4] kprobes: Support NOKPROBE

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Date:   Thu, 26 Mar 2020 23:50:00 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Paul McKenney <paulmck@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH -tip 3/4] kprobes: Support NOKPROBE_SYMBOL() in modules

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>
---
 include/linux/module.h |    2 ++
 kernel/kprobes.c       |   17 +++++++++++++++++
 kernel/module.c        |    3 +++
 3 files changed, 22 insertions(+)

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);