[PATCH v7 1/3] kprobes/ftrace: Use ftrace_location() when [dis]arming probes
From: Jisheng Zhang <hidden>
Date: 2019-12-25 09:42:12
Also in:
linux-doc, 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> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> --- kernel/kprobes.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 53534aa258a6..5c630b424e3a 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c@@ -986,9 +986,10 @@ static int prepare_kprobe(struct kprobe *p) static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, int *cnt) { + unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr); int ret = 0; - ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0); + ret = ftrace_set_filter_ip(ops, ftrace_ip, 0, 0); if (ret) { pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n", p->addr, ret);
@@ -1011,7 +1012,7 @@ static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, * At this point, sinec ops is not registered, we should be sefe from * registering empty filter. */ - ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0); + ftrace_set_filter_ip(ops, ftrace_ip, 1, 0); return ret; }
@@ -1028,6 +1029,7 @@ static int arm_kprobe_ftrace(struct kprobe *p) static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, int *cnt) { + unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr); int ret = 0; if (*cnt == 1) {
@@ -1038,7 +1040,7 @@ static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops, (*cnt)--; - ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0); + ret = ftrace_set_filter_ip(ops, ftrace_ip, 1, 0); WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n", p->addr, ret); return ret;
--
2.24.1
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