bpf: minor cleanups on fd maps and helpers

Some minor cleanups: i) Remove the unlikely() from fd array map lookups
and let the CPU branch predictor do its job, scenarios where there is not
always a map entry are very well valid. ii) Move the attribute type check
in the bpf_perf_event_read() helper a bit earlier so it's consistent wrt
checks with bpf_perf_event_output() helper as well. iii) remove some
comments that are self-documenting in kprobe_prog_is_valid_access() and
therefore make it consistent to tp_prog_is_valid_access() as well.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index b94a365..d638062 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -719,14 +719,13 @@ select_insn:
 
                if (unlikely(index >= array->map.max_entries))
                        goto out;
-
                if (unlikely(tail_call_cnt > MAX_TAIL_CALL_CNT))
                        goto out;
 
                tail_call_cnt++;
 
                prog = READ_ONCE(array->ptrs[index]);
-               if (unlikely(!prog))
+               if (!prog)
                        goto out;
 
                /* ARG1 at this point is guaranteed to point to CTX from

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3de25fb..4e61f74 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -199,19 +199,19 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
                return -E2BIG;
 
        ee = READ_ONCE(array->ptrs[index]);
-       if (unlikely(!ee))
+       if (!ee)
                return -ENOENT;
 
        event = ee->event;
+       if (unlikely(event->attr.type != PERF_TYPE_HARDWARE &&
+                    event->attr.type != PERF_TYPE_RAW))
+               return -EINVAL;
+
        /* make sure event is local and doesn't have pmu::count */
        if (event->oncpu != smp_processor_id() ||
            event->pmu->count)
                return -EINVAL;
 
-       if (unlikely(event->attr.type != PERF_TYPE_HARDWARE &&
-                    event->attr.type != PERF_TYPE_RAW))
-               return -EINVAL;
-
        /*
         * we don't know if the function is run successfully by the
         * return value. It can be judged in other places, such as
@@ -251,7 +251,7 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
                return -E2BIG;
 
        ee = READ_ONCE(array->ptrs[index]);
-       if (unlikely(!ee))
+       if (!ee)
                return -ENOENT;
 
        event = ee->event;
@@ -354,18 +354,12 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func
 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
                                        enum bpf_reg_type *reg_type)
 {
-       /* check bounds */
        if (off < 0 || off >= sizeof(struct pt_regs))
                return false;
-
-       /* only read is allowed */
        if (type != BPF_READ)
                return false;
-
-       /* disallow misaligned access */
        if (off % size != 0)
                return false;
-
        return true;
 }