From: Toby Collett <toby.collett@xxxxxxxxxxxxxx>
The symbol lookup can take a long time and kprobes is
initialised very early in boot, so delay symbol lookup
until the blacklist is first used.
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Reviewed-by: Radovan Lekanovic <radovan.lekanovic@xxxxxxxxxxxxxx>
Signed-off-by: Toby Collett <toby.collett@xxxxxxxxxxxxxx>
Signed-off-by: Oskar Andero <oskar.andero@xxxxxxxxxxxxxx>
---
kernel/kprobes.c | 100 ++++++++++++++++++++++++++++++++++---------------------
1 file changed, 62 insertions(+), 38 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index e35be53..c8c2281 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -68,6 +68,7 @@
#endif
static int kprobes_initialized;
+static bool kprobe_blacklist_initialized;
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
@@ -102,6 +103,62 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
{NULL} /* Terminator */
};
+/* it can take some time ( > 100ms ) to initialise the
+ * blacklist so we delay this until we actually need it
+ */
+static void init_kprobe_blacklist(void)
+{
+ int i;
+ unsigned long offset = 0, size = 0;
+ char *modname, namebuf[128];
+ const char *symbol_name;
+ void *addr;
+ struct kprobe_blackpoint *kb;
+
+ mutex_lock(&kprobe_mutex);
+ if (kprobe_blacklist_initialized)
+ goto out;
+
+ /*
+ * Lookup and populate the kprobe_blacklist.
+ *
+ * Unlike the kretprobe blacklist, we'll need to determine
+ * the range of addresses that belong to the said functions,
+ * since a kprobe need not necessarily be at the beginning
+ * of a function.
+ */
+ for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
+ kprobe_lookup_name(kb->name, addr);
+ if (!addr)
+ continue;
+
+ kb->start_addr = (unsigned long)addr;
+ symbol_name = kallsyms_lookup(kb->start_addr,
+ &size, &offset, &modname, namebuf);
+ if (!symbol_name)
+ kb->range = 0;
+ else
+ kb->range = size;
+ }
+
+ if (kretprobe_blacklist_size) {
+ /* lookup the function address from its name */
+ for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
+ kprobe_lookup_name(kretprobe_blacklist[i].name,
+ kretprobe_blacklist[i].addr);
+ if (!kretprobe_blacklist[i].addr)
+ printk("kretprobe: lookup failed: %s\n",
+ kretprobe_blacklist[i].name);
+ }
+ }
+
+ smp_wmb();
+ kprobe_blacklist_initialized = true;
+
+out:
+ mutex_unlock(&kprobe_mutex);
+}
+
#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
/*
* kprobe->ainsn.insn points to the copy of the instruction to be
@@ -1331,6 +1388,9 @@ static int __kprobes in_kprobes_functions(unsigned long addr)
if (addr >= (unsigned long)__kprobes_text_start &&
addr < (unsigned long)__kprobes_text_end)
return -EINVAL;
+
+ if (unlikely(!kprobe_blacklist_initialized))
+ init_kprobe_blacklist();
/*
* If there exists a kprobe_blacklist, verify and
* fail any probe registration in the prohibited area
@@ -1816,6 +1876,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp)
void *addr;
if (kretprobe_blacklist_size) {
+ if (unlikely(!kprobe_blacklist_initialized))
+ init_kprobe_blacklist();
addr = kprobe_addr(&rp->kp);
if (IS_ERR(addr))
return PTR_ERR(addr);
@@ -2065,11 +2127,6 @@ static struct notifier_block kprobe_module_nb = {
static int __init init_kprobes(void)
{
int i, err = 0;
- unsigned long offset = 0, size = 0;
- char *modname, namebuf[128];
- const char *symbol_name;
- void *addr;
- struct kprobe_blackpoint *kb;
/* FIXME allocate the probe table, currently defined statically */
/* initialize all list heads */
@@ -2079,39 +2136,6 @@ static int __init init_kprobes(void)
raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
}
- /*
- * Lookup and populate the kprobe_blacklist.
- *
- * Unlike the kretprobe blacklist, we'll need to determine
- * the range of addresses that belong to the said functions,
- * since a kprobe need not necessarily be at the beginning
- * of a function.
- */
- for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
- kprobe_lookup_name(kb->name, addr);
- if (!addr)
- continue;
-
- kb->start_addr = (unsigned long)addr;
- symbol_name = kallsyms_lookup(kb->start_addr,
- &size, &offset, &modname, namebuf);
- if (!symbol_name)
- kb->range = 0;
- else
- kb->range = size;
- }
-
- if (kretprobe_blacklist_size) {
- /* lookup the function address from its name */
- for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
- kprobe_lookup_name(kretprobe_blacklist[i].name,
- kretprobe_blacklist[i].addr);
- if (!kretprobe_blacklist[i].addr)
- printk("kretprobe: lookup failed: %s\n",
- kretprobe_blacklist[i].name);
- }
- }
-
#if defined(CONFIG_OPTPROBES)
#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
/* Init kprobe_optinsn_slots */
--
1.8.1.5
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