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authorAndrii Nakryiko2020-02-29 15:11:11 -0800
committerAlexei Starovoitov2020-03-02 16:25:14 -0800
commit396f544ed5e5a9c40de5663b774f643644cba059 (patch)
tree33208526d4177af87a61d5f2fdc6fdc521ccc8b9 /tools
parentfd56e0058412fb542db0e9556f425747cf3f8366 (diff)
selftests/bpf: Fix BPF_KRETPROBE macro and use it in attach_probe test
For kretprobes, there is no point in capturing input arguments from pt_regs, as they are going to be, most probably, clobbered by the time probed kernel function returns. So switch BPF_KRETPROBE to accept zero or one argument (optional return result). Fixes: ac065870d928 ("selftests/bpf: Add BPF_PROG, BPF_KPROBE, and BPF_KRETPROBE macros") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200229231112.1240137-4-andriin@fb.com
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/bpf_trace_helpers.h13
-rw-r--r--tools/testing/selftests/bpf/progs/test_attach_probe.c3
-rw-r--r--tools/testing/selftests/bpf/progs/test_overhead.c6
3 files changed, 11 insertions, 11 deletions
diff --git a/tools/testing/selftests/bpf/bpf_trace_helpers.h b/tools/testing/selftests/bpf/bpf_trace_helpers.h
index c6f1354d93fb..83b8e02f5ee9 100644
--- a/tools/testing/selftests/bpf/bpf_trace_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_trace_helpers.h
@@ -96,15 +96,16 @@ typeof(name(0)) name(struct pt_regs *ctx) \
static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args)
#define ___bpf_kretprobe_args0() ctx
-#define ___bpf_kretprobe_argsN(x, args...) \
- ___bpf_kprobe_args(args), (void *)PT_REGS_RET(ctx)
+#define ___bpf_kretprobe_args1(x) \
+ ___bpf_kretprobe_args0(), (void *)PT_REGS_RET(ctx)
#define ___bpf_kretprobe_args(args...) \
- ___bpf_apply(___bpf_kretprobe_args, ___bpf_empty(args))(args)
+ ___bpf_apply(___bpf_kretprobe_args, ___bpf_narg(args))(args)
/*
- * BPF_KRETPROBE is similar to BPF_KPROBE, except, in addition to listing all
- * input kprobe arguments, one last extra argument has to be specified, which
- * captures kprobe return value.
+ * BPF_KRETPROBE is similar to BPF_KPROBE, except, it only provides optional
+ * return value (in addition to `struct pt_regs *ctx`), but no input
+ * arguments, because they will be clobbered by the time probed function
+ * returns.
*/
#define BPF_KRETPROBE(name, args...) \
name(struct pt_regs *ctx); \
diff --git a/tools/testing/selftests/bpf/progs/test_attach_probe.c b/tools/testing/selftests/bpf/progs/test_attach_probe.c
index dd8fae6660ab..38ed8c3bf922 100644
--- a/tools/testing/selftests/bpf/progs/test_attach_probe.c
+++ b/tools/testing/selftests/bpf/progs/test_attach_probe.c
@@ -4,6 +4,7 @@
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
+#include "bpf_trace_helpers.h"
int kprobe_res = 0;
int kretprobe_res = 0;
@@ -18,7 +19,7 @@ int handle_kprobe(struct pt_regs *ctx)
}
SEC("kretprobe/sys_nanosleep")
-int handle_kretprobe(struct pt_regs *ctx)
+int BPF_KRETPROBE(handle_kretprobe)
{
kretprobe_res = 2;
return 0;
diff --git a/tools/testing/selftests/bpf/progs/test_overhead.c b/tools/testing/selftests/bpf/progs/test_overhead.c
index bfe9fbcb9684..f43714c69cc8 100644
--- a/tools/testing/selftests/bpf/progs/test_overhead.c
+++ b/tools/testing/selftests/bpf/progs/test_overhead.c
@@ -17,11 +17,9 @@ int BPF_KPROBE(prog1, struct task_struct *tsk, const char *buf, bool exec)
}
SEC("kretprobe/__set_task_comm")
-int BPF_KRETPROBE(prog2,
- struct task_struct *tsk, const char *buf, bool exec,
- int ret)
+int BPF_KRETPROBE(prog2, int ret)
{
- return !PT_REGS_PARM1(ctx) && ret;
+ return ret;
}
SEC("raw_tp/task_rename")