From: Masami Hiramatsu <mhiramat@kernel.org>
To: Alexei Starovoitov <ast@fb.com>, Josef Bacik <jbacik@fb.com>
Cc: rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
ast@kernel.org, kernel-team@fb.com, daniel@iogearbox.net,
linux-btrfs@vger.kernel.org, darrick.wong@oracle.com,
mhiramat@kernel.org, Josef Bacik <josef@toxicpanda.com>
Subject: [RFC PATCH bpf-next 1/3] tracing/kprobe: bpf: Check error injectable event is on function entry
Date: Fri, 22 Dec 2017 20:38:43 +0900 [thread overview]
Message-ID: <151394272357.5598.4199197920812849350.stgit@devbox> (raw)
In-Reply-To: <151394269314.5598.6344820223613246849.stgit@devbox>
Check whether error injectable event is on function entry or not.
Currently it checks the event is ftrace-based kprobes or not,
but that is wrong. It should check if the event is on the entry
of target function. Since error injection will override a function
to just return with modified return value, that operation must
be done before the target function starts making stackframe.
As a side effect, bpf error injection is no need to depend on
function-tracer. It can work with sw-breakpoint based kprobe
events too.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/trace/Kconfig | 2 --
kernel/trace/bpf_trace.c | 6 +++---
kernel/trace/trace_kprobe.c | 8 +++++---
kernel/trace/trace_probe.h | 12 ++++++------
4 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index ae3a2d519e50..6400e1bf97c5 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -533,9 +533,7 @@ config FUNCTION_PROFILER
config BPF_KPROBE_OVERRIDE
bool "Enable BPF programs to override a kprobed function"
depends on BPF_EVENTS
- depends on KPROBES_ON_FTRACE
depends on HAVE_KPROBE_OVERRIDE
- depends on DYNAMIC_FTRACE_WITH_REGS
default n
help
Allows BPF to override the execution of a probed function and
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f6d2327ecb59..d663660f8392 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -800,11 +800,11 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
int ret = -EEXIST;
/*
- * Kprobe override only works for ftrace based kprobes, and only if they
- * are on the opt-in list.
+ * Kprobe override only works if they are on the function entry,
+ * and only if they are on the opt-in list.
*/
if (prog->kprobe_override &&
- (!trace_kprobe_ftrace(event->tp_event) ||
+ (!trace_kprobe_on_func_entry(event->tp_event) ||
!trace_kprobe_error_injectable(event->tp_event)))
return -EINVAL;
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 91f4b57dab82..265e3e27e8dc 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -88,13 +88,15 @@ static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
return nhit;
}
-int trace_kprobe_ftrace(struct trace_event_call *call)
+bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
- return kprobe_ftrace(&tk->rp.kp);
+
+ return kprobe_on_func_entry(tk->rp.kp.addr, tk->rp.kp.symbol_name,
+ tk->rp.kp.offset);
}
-int trace_kprobe_error_injectable(struct trace_event_call *call)
+bool trace_kprobe_error_injectable(struct trace_event_call *call)
{
struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
unsigned long addr;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 5e54d748c84c..e101c5bb9eda 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -252,8 +252,8 @@ struct symbol_cache;
unsigned long update_symbol_cache(struct symbol_cache *sc);
void free_symbol_cache(struct symbol_cache *sc);
struct symbol_cache *alloc_symbol_cache(const char *sym, long offset);
-int trace_kprobe_ftrace(struct trace_event_call *call);
-int trace_kprobe_error_injectable(struct trace_event_call *call);
+bool trace_kprobe_on_func_entry(struct trace_event_call *call);
+bool trace_kprobe_error_injectable(struct trace_event_call *call);
#else
/* uprobes do not support symbol fetch methods */
#define fetch_symbol_u8 NULL
@@ -280,14 +280,14 @@ alloc_symbol_cache(const char *sym, long offset)
return NULL;
}
-static inline int trace_kprobe_ftrace(struct trace_event_call *call)
+static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
- return 0;
+ return false;
}
-static inline int trace_kprobe_error_injectable(struct trace_event_call *call)
+static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
{
- return 0;
+ return false;
}
#endif /* CONFIG_KPROBE_EVENTS */
next prev parent reply other threads:[~2017-12-22 11:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-22 11:38 [RFC PATCH bpf-next 0/3] Separate error injection framework from kprobes Masami Hiramatsu
2017-12-22 11:38 ` Masami Hiramatsu [this message]
2017-12-22 11:39 ` [RFC PATCH bpf-next 2/3] tracing/kprobe: bpf: Compare instruction pointer with original one Masami Hiramatsu
2017-12-22 11:39 ` [RFC PATCH bpf-next 3/3] error-injection: Separate error-injection from kprobe Masami Hiramatsu
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