diff options
| author | Andrii Nakryiko <andriin@fb.com> | 2020-02-29 15:11:11 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-03-02 16:25:14 -0800 |
| commit | 396f544ed5e5a9c40de5663b774f643644cba059 (patch) | |
| tree | 33208526d4177af87a61d5f2fdc6fdc521ccc8b9 | |
| parent | fd56e0058412fb542db0e9556f425747cf3f8366 (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
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_trace_helpers.h | 13 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_attach_probe.c | 3 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_overhead.c | 6 |
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") |