[PATCH RFC v7 net-next 19/28] tracing: allow eBPF programs to be attached to kprobe/kretprobe

From: Alexei Starovoitov
Date: Tue Aug 26 2014 - 22:34:48 EST


Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
---
kernel/trace/trace_kprobe.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 282f6e4e5539..b6db92207c99 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -19,6 +19,7 @@

#include <linux/module.h>
#include <linux/uaccess.h>
+#include <trace/bpf_trace.h>

#include "trace_probe.h"

@@ -930,6 +931,22 @@ __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
if (ftrace_trigger_soft_disabled(ftrace_file))
return;

+ if (call->flags & TRACE_EVENT_FL_BPF) {
+ struct bpf_context ctx = {};
+ unsigned long args[3];
+ /* get first 3 arguments of the function. x64 syscall ABI uses
+ * the same 3 registers as x64 calling convention.
+ * todo: implement it cleanly via arch specific
+ * regs_get_argument_nth() helper
+ */
+ syscall_get_arguments(current, regs, 0, 3, args);
+ ctx.arg1 = args[0];
+ ctx.arg2 = args[1];
+ ctx.arg3 = args[2];
+ trace_filter_call_bpf(ftrace_file->filter, &ctx);
+ return;
+ }
+
local_save_flags(irq_flags);
pc = preempt_count();

@@ -978,6 +995,17 @@ __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
if (ftrace_trigger_soft_disabled(ftrace_file))
return;

+ if (call->flags & TRACE_EVENT_FL_BPF) {
+ struct bpf_context ctx = {};
+ /* assume that register used to return a value from syscall is
+ * the same as register used to return a value from a function
+ * todo: provide arch specific helper
+ */
+ ctx.ret = syscall_get_return_value(current, regs);
+ trace_filter_call_bpf(ftrace_file->filter, &ctx);
+ return;
+ }
+
local_save_flags(irq_flags);
pc = preempt_count();

--
1.7.9.5

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