[PATCH tip/master 3/3] kprobes/x86: Use kprobe_blacklist for .kprobes.text and .entry.text

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

Use kprobe_blackpoint for blacklisting .entry.text and .kprobees.text
instead of arch_within_kprobe_blacklist. This also makes them visible
via (debugfs)/kprobes/blacklist.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 arch/x86/kernel/kprobes/core.c |   11 +------
 include/linux/kprobes.h        |    1 +
 kernel/kprobes.c               |   64 ++++++++++++++++++++++++++++------------
 3 files changed, 48 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 1deffe6..8496f84 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1112,17 +1112,10 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 }
 NOKPROBE_SYMBOL(longjmp_break_handler);
 
-bool arch_within_kprobe_blacklist(unsigned long addr)
-{
-	return  (addr >= (unsigned long)__kprobes_text_start &&
-		 addr < (unsigned long)__kprobes_text_end) ||
-		(addr >= (unsigned long)__entry_text_start &&
-		 addr < (unsigned long)__entry_text_end);
-}
-
 int __init arch_init_kprobes(void)
 {
-	return 0;
+	return kprobe_blacklist_add_range((unsigned long)__entry_text_start,
+					  (unsigned long) __entry_text_end);
 }
 
 int arch_trampoline_kprobe(struct kprobe *p)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 1ab5475..a2eb53e 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -266,6 +266,7 @@ extern int arch_init_kprobes(void);
 extern void show_registers(struct pt_regs *regs);
 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 extern bool arch_within_kprobe_blacklist(unsigned long addr);
+extern int kprobe_blacklist_add_range(unsigned long start, unsigned long end);
 
 struct kprobe_insn_cache {
 	struct mutex mutex;
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 53951c3..e164a04 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1326,13 +1326,6 @@ out:
 	return ret;
 }
 
-bool __weak arch_within_kprobe_blacklist(unsigned long addr)
-{
-	/* The __kprobes marked functions and entry code must not be probed */
-	return addr >= (unsigned long)__kprobes_text_start &&
-	       addr < (unsigned long)__kprobes_text_end;
-}
-
 static struct kprobe_blacklist_entry *find_blacklist_entry(unsigned long addr)
 {
 	struct kprobe_blacklist_entry *ent;
@@ -1347,8 +1340,6 @@ static struct kprobe_blacklist_entry *find_blacklist_entry(unsigned long addr)
 
 static bool within_kprobe_blacklist(unsigned long addr)
 {
-	if (arch_within_kprobe_blacklist(addr))
-		return true;
 	/*
 	 * If there exists a kprobe_blacklist, verify and
 	 * fail any probe registration in the prohibited area
@@ -2055,6 +2046,40 @@ void dump_kprobe(struct kprobe *kp)
 }
 NOKPROBE_SYMBOL(dump_kprobe);
 
+static int __kprobe_blacklist_add(unsigned long start, unsigned long end)
+{
+	struct kprobe_blacklist_entry *ent;
+
+	ent = kmalloc(sizeof(*ent), GFP_KERNEL);
+	if (!ent)
+		return -ENOMEM;
+
+	ent->start_addr = start;
+	ent->end_addr = end;
+	INIT_LIST_HEAD(&ent->list);
+	list_add_tail(&ent->list, &kprobe_blacklist);
+	return 0;
+}
+
+int kprobe_blacklist_add_range(unsigned long start, unsigned long end)
+{
+	unsigned long offset = 0, size = 0;
+	int err = 0;
+
+	mutex_lock(&kprobe_blacklist_mutex);
+	while (!err && start < end) {
+		if (!kallsyms_lookup_size_offset(start, &size, &offset) ||
+		    size == 0) {
+			err = -ENOENT;
+			break;
+		}
+		err = __kprobe_blacklist_add(start, start + size);
+		start += size;
+	}
+	mutex_unlock(&kprobe_blacklist_mutex);
+	return err;
+}
+
 /*
  * Lookup and populate the kprobe_blacklist.
  *
@@ -2066,8 +2091,8 @@ NOKPROBE_SYMBOL(dump_kprobe);
 static int populate_kprobe_blacklist(unsigned long *start, unsigned long *end)
 {
 	unsigned long *iter;
-	struct kprobe_blacklist_entry *ent;
 	unsigned long entry, offset = 0, size = 0;
+	int ret;
 
 	mutex_lock(&kprobe_blacklist_mutex);
 	for (iter = start; iter < end; iter++) {
@@ -2079,14 +2104,7 @@ static int populate_kprobe_blacklist(unsigned long *start, unsigned long *end)
 				(void *)entry);
 			continue;
 		}
-
-		ent = kmalloc(sizeof(*ent), GFP_KERNEL);
-		if (!ent)
-			return -ENOMEM;
-		ent->start_addr = entry;
-		ent->end_addr = entry + size;
-		INIT_LIST_HEAD(&ent->list);
-		list_add_tail(&ent->list, &kprobe_blacklist);
+		ret = __kprobe_blacklist_add(entry, entry - offset + size);
 	}
 	mutex_unlock(&kprobe_blacklist_mutex);
 
@@ -2181,7 +2199,15 @@ static int __init init_kprobes(void)
 
 	err = populate_kprobe_blacklist(__start_kprobe_blacklist,
 					__stop_kprobe_blacklist);
-	if (err) {
+
+	if (err >= 0 && __kprobes_text_start != __kprobes_text_end) {
+		/* The __kprobes marked functions must not be probed */
+		err = kprobe_blacklist_add_range(
+					(unsigned long)__kprobes_text_start,
+					(unsigned long)__kprobes_text_end);
+	}
+
+	if (err < 0) {
 		pr_err("kprobes: failed to populate blacklist: %d\n", err);
 		pr_err("Please take care of using kprobes.\n");
 	}