[PATCH 6/7] kprobes/ftrace: Use ftrace_location() when [dis]arming probes
From: Naveen N. Rao <hidden>
Date: 2019-06-18 14:49:15
Also in:
lkml
Subsystem:
kprobes, the rest · Maintainers:
Naveen N Rao, "David S. Miller", Masami Hiramatsu, Linus Torvalds
Ftrace location could include more than a single instruction in case of some architectures (powerpc64, for now). In this case, kprobe is permitted on any of those instructions, and uses ftrace infrastructure for functioning. However, [dis]arm_kprobe_ftrace() uses the kprobe address when setting up ftrace filter IP. This won't work if the address points to any instruction apart from the one that has a branch to _mcount(). To resolve this, have [dis]arm_kprobe_ftrace() use ftrace_function() to identify the filter IP. Signed-off-by: Naveen N. Rao <redacted> --- kernel/kprobes.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 445337c107e0..282ee704e2d8 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c@@ -978,10 +978,10 @@ static int prepare_kprobe(struct kprobe *p) /* Caller must lock kprobe_mutex */ static int arm_kprobe_ftrace(struct kprobe *p) { + unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr); int ret = 0; - ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, - (unsigned long)p->addr, 0, 0); + ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, ftrace_ip, 0, 0); if (ret) { pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n", p->addr, ret);
@@ -1005,13 +1005,14 @@ static int arm_kprobe_ftrace(struct kprobe *p) * non-empty filter_hash for IPMODIFY ops, we're safe from an accidental * empty filter_hash which would undesirably trace all functions. */ - ftrace_set_filter_ip(&kprobe_ftrace_ops, (unsigned long)p->addr, 1, 0); + ftrace_set_filter_ip(&kprobe_ftrace_ops, ftrace_ip, 1, 0); return ret; } /* Caller must lock kprobe_mutex */ static int disarm_kprobe_ftrace(struct kprobe *p) { + unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr); int ret = 0; if (kprobe_ftrace_enabled == 1) {
@@ -1022,8 +1023,7 @@ static int disarm_kprobe_ftrace(struct kprobe *p) kprobe_ftrace_enabled--; - ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, - (unsigned long)p->addr, 1, 0); + ret = ftrace_set_filter_ip(&kprobe_ftrace_ops, ftrace_ip, 1, 0); WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n", p->addr, ret); return ret;
--
2.22.0