Add feature check for uprobe_multi

Signed-off-by: Jiri Olsa <[email protected]>
olsajiri · Oct 22, 2023 · ff11848 · ff11848
1 parent 713f170
commit ff11848
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Showing 3 changed files with 83 additions and 0 deletions.
diff --git a/src/bpffeature.cpp b/src/bpffeature.cpp
@@ -1,7 +1,9 @@
 #include "bpffeature.h"
 
+#include <bcc/bcc_syms.h>
 #include <bcc/libbpf.h>
 #include <bpf/bpf.h>
+#include <bpf/libbpf.h>
 #include <cstddef>
 #include <cstdio>
 #include <fcntl.h>
@@ -401,6 +403,74 @@ bool BPFfeature::has_kprobe_multi()
   return *has_kprobe_multi_;
 }
 
+extern "C" __attribute__((noinline)) __attribute__((unused)) void uprobe_multi_test_func(
+    void)
+{
+}
+
+bool BPFfeature::has_uprobe_multi()
+{
+  if (has_uprobe_multi_.has_value())
+    return *has_uprobe_multi_;
+
+  LIBBPF_OPTS(bpf_prog_load_opts,
+              load_opts,
+              .expected_attach_type = static_cast<enum ::bpf_attach_type>(
+                  libbpf::BPF_TRACE_UPROBE_MULTI), );
+
+  const char* sym = "uprobe_multi_test_func";
+  const char* path = "/proc/self/exe";
+  int err, progfd, linkfd = -1;
+  struct bcc_symbol bsym;
+
+  err = bcc_resolve_symname(path, sym, 0, -1, NULL, &bsym);
+  if (err)
+  {
+    has_uprobe_multi_ = false;
+    return *has_uprobe_multi_;
+  }
+
+  struct bpf_insn insns[] = {
+    BPF_MOV64_IMM(BPF_REG_0, 0),
+    BPF_EXIT_INSN(),
+  };
+
+  progfd = bpf_prog_load(::BPF_PROG_TYPE_KPROBE,
+                         "uprobe_multi",
+                         "GPL",
+                         reinterpret_cast<struct bpf_insn*>(insns),
+                         ARRAY_SIZE(insns),
+                         &load_opts);
+
+  if (progfd >= 0)
+  {
+    LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+    const unsigned long offset = (unsigned long)bsym.offset;
+
+    link_opts.uprobe_multi.path = path;
+    link_opts.uprobe_multi.offsets = &offset;
+    link_opts.uprobe_multi.cnt = 1;
+
+    linkfd = bpf_link_create(progfd,
+                             0,
+                             static_cast<enum ::bpf_attach_type>(
+                                 libbpf::BPF_TRACE_UPROBE_MULTI),
+                             &link_opts);
+  }
+
+  has_uprobe_multi_ = linkfd >= 0;
+
+  if (linkfd >= 0)
+  {
+    close(linkfd);
+  }
+  if (progfd >= 0)
+  {
+    close(progfd);
+  }
+  return *has_uprobe_multi_;
+}
+
 bool BPFfeature::has_skb_output(void)
 {
   if (!has_kfunc())
@@ -530,6 +600,7 @@ std::string BPFfeature::report(void)
       << "  perf_event: " << to_str(has_prog_perf_event())
       << "  kfunc: " << to_str(has_kfunc())
       << "  kprobe_multi: " << to_str(has_kprobe_multi())
+      << "  uprobe_multi: " << to_str(has_uprobe_multi())
       << "  raw_tp_special: " << to_str(has_raw_tp_special())
       << "  iter: " << to_str(has_iter("task")) << std::endl;
 

diff --git a/src/bpffeature.h b/src/bpffeature.h
@@ -77,6 +77,7 @@ class BPFfeature
   bool has_d_path();
   bool has_uprobe_refcnt();
   bool has_kprobe_multi();
+  bool has_uprobe_multi();
   bool has_kfunc();
   bool has_skb_output();
   bool has_raw_tp_special();
@@ -117,6 +118,7 @@ class BPFfeature
   std::optional<bool> has_map_batch_;
   std::optional<bool> has_uprobe_refcnt_;
   std::optional<bool> has_kprobe_multi_;
+  std::optional<bool> has_uprobe_multi_;
   std::optional<bool> has_skb_output_;
   std::optional<bool> has_raw_tp_special_;
   std::optional<bool> has_prog_kfunc_;

diff --git a/src/libbpf/bpf.h b/src/libbpf/bpf.h
@@ -12,6 +12,10 @@
 #define BPF_F_KPROBE_MULTI_RETURN (1U << 0)
 #endif
 
+#ifndef BPF_F_UPROBE_MULTI_RETURN
+#define BPF_F_UPROBE_MULTI_RETURN (1U << 0)
+#endif
+
 // clang-format off
 enum bpf_map_type {
 	BPF_MAP_TYPE_UNSPEC,
@@ -126,6 +130,12 @@ enum bpf_attach_type {
 	BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
 	BPF_PERF_EVENT,
 	BPF_TRACE_KPROBE_MULTI,
+	BPF_LSM_CGROUP,
+	BPF_STRUCT_OPS,
+	BPF_NETFILTER,
+	BPF_TCX_INGRESS,
+	BPF_TCX_EGRESS,
+	BPF_TRACE_UPROBE_MULTI,
 };
 
 #ifdef __BPF_FUNC_MAPPER