bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs

needs two wrapper functions to fetch 'struct pt_regs *' to convert
tracepoint bpf context into kprobe bpf context to reuse existing
helper functions

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

3 files changed, 43 insertions, 2 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 21ee41b92e8a..198f6ace70ec 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -160,6 +160,7 @@ struct bpf_array {
 #define MAX_TAIL_CALL_CNT 32
 
 u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
+u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 void bpf_fd_array_map_clear(struct bpf_map *map);
 bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
 const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 499d9e933f8e..35114725cf30 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -116,7 +116,7 @@ free_smap:
         return ERR_PTR(err);
 }
 
-static u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5)
+u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5)
 {
         struct pt_regs *regs = (struct pt_regs *) (long) r1;
         struct bpf_map *map = (struct bpf_map *) (long) r2;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3e5ebe3254d2..413ec5614180 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -340,12 +340,52 @@ static struct bpf_prog_type_list kprobe_tl = {
         .type   = BPF_PROG_TYPE_KPROBE,
 };
 
+static u64 bpf_perf_event_output_tp(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
+{
+        /*
+         * r1 points to perf tracepoint buffer where first 8 bytes are hidden
+         * from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
+         * from there and call the same bpf_perf_event_output() helper
+         */
+        u64 ctx = *(long *)r1;
+
+        return bpf_perf_event_output(ctx, r2, index, r4, size);
+}
+
+static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
+        .func           = bpf_perf_event_output_tp,
+        .gpl_only       = true,
+        .ret_type       = RET_INTEGER,
+        .arg1_type      = ARG_PTR_TO_CTX,
+        .arg2_type      = ARG_CONST_MAP_PTR,
+        .arg3_type      = ARG_ANYTHING,
+        .arg4_type      = ARG_PTR_TO_STACK,
+        .arg5_type      = ARG_CONST_STACK_SIZE,
+};
+
+static u64 bpf_get_stackid_tp(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+        u64 ctx = *(long *)r1;
+
+        return bpf_get_stackid(ctx, r2, r3, r4, r5);
+}
+
+static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
+        .func           = bpf_get_stackid_tp,
+        .gpl_only       = true,
+        .ret_type       = RET_INTEGER,
+        .arg1_type      = ARG_PTR_TO_CTX,
+        .arg2_type      = ARG_CONST_MAP_PTR,
+        .arg3_type      = ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
 {
         switch (func_id) {
         case BPF_FUNC_perf_event_output:
+                return &bpf_perf_event_output_proto_tp;
         case BPF_FUNC_get_stackid:
-                return NULL;
+                return &bpf_get_stackid_proto_tp;
         default:
                 return tracing_func_proto(func_id);
         }