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authorMasami Hiramatsu <mhiramat@kernel.org>2019-07-25 15:24:37 +0900
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-08-31 12:19:10 -0400
commit0bc11ed5ab60c135aa764a62c02cd5ea68289de4 (patch)
tree503be167bf756a0f32c4fbe11da3c41895697049
parentc68c9ec1c52e5bcd221eb09bc5344ad4f407b204 (diff)
kprobes: Allow kprobes coexist with livepatch
Allow kprobes which do not modify regs->ip, coexist with livepatch by dropping FTRACE_OPS_FL_IPMODIFY from ftrace_ops. User who wants to modify regs->ip (e.g. function fault injection) must set a dummy post_handler to its kprobes when registering. However, if such regs->ip modifying kprobes is set on a function, that function can not be livepatched. Link: http://lkml.kernel.org/r/156403587671.30117.5233558741694155985.stgit@devnote2 Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-rw-r--r--kernel/kprobes.c56
1 files changed, 40 insertions, 16 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d9770a5393c8..f57deec96ba1 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -962,8 +962,15 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
#ifdef CONFIG_KPROBES_ON_FTRACE
static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
.func = kprobe_ftrace_handler,
+ .flags = FTRACE_OPS_FL_SAVE_REGS,
+};
+
+static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
+ .func = kprobe_ftrace_handler,
.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
};
+
+static int kprobe_ipmodify_enabled;
static int kprobe_ftrace_enabled;
/* Must ensure p->addr is really on ftrace */
@@ -976,58 +983,75 @@ static int prepare_kprobe(struct kprobe *p)
}
/* Caller must lock kprobe_mutex */
-static int arm_kprobe_ftrace(struct kprobe *p)
+static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
+ int *cnt)
{
int ret = 0;
- ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
- (unsigned long)p->addr, 0, 0);
+ ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
if (ret) {
pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
p->addr, ret);
return ret;
}
- if (kprobe_ftrace_enabled == 0) {
- ret = register_ftrace_function(&kprobe_ftrace_ops);
+ if (*cnt == 0) {
+ ret = register_ftrace_function(ops);
if (ret) {
pr_debug("Failed to init kprobe-ftrace (%d)\n", ret);
goto err_ftrace;
}
}
- kprobe_ftrace_enabled++;
+ (*cnt)++;
return ret;
err_ftrace:
/*
- * Note: Since kprobe_ftrace_ops has IPMODIFY set, and ftrace requires a
- * non-empty filter_hash for IPMODIFY ops, we're safe from an accidental
- * empty filter_hash which would undesirably trace all functions.
+ * At this point, sinec ops is not registered, we should be sefe from
+ * registering empty filter.
*/
- ftrace_set_filter_ip(&kprobe_ftrace_ops, (unsigned long)p->addr, 1, 0);
+ ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
return ret;
}
+static int arm_kprobe_ftrace(struct kprobe *p)
+{
+ bool ipmodify = (p->post_handler != NULL);
+
+ return __arm_kprobe_ftrace(p,
+ ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
+ ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
+}
+
/* Caller must lock kprobe_mutex */
-static int disarm_kprobe_ftrace(struct kprobe *p)
+static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
+ int *cnt)
{
int ret = 0;
- if (kprobe_ftrace_enabled == 1) {
- ret = unregister_ftrace_function(&kprobe_ftrace_ops);
+ if (*cnt == 1) {
+ ret = unregister_ftrace_function(ops);
if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (%d)\n", ret))
return ret;
}
- kprobe_ftrace_enabled--;
+ (*cnt)--;
- ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
- (unsigned long)p->addr, 1, 0);
+ ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
p->addr, ret);
return ret;
}
+
+static int disarm_kprobe_ftrace(struct kprobe *p)
+{
+ bool ipmodify = (p->post_handler != NULL);
+
+ return __disarm_kprobe_ftrace(p,
+ ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
+ ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
+}
#else /* !CONFIG_KPROBES_ON_FTRACE */
#define prepare_kprobe(p) arch_prepare_kprobe(p)
#define arm_kprobe_ftrace(p) (-ENODEV)