Add features, semantic analyzer and runtime tests for jiffies builtin

bpftrace · Sep 19, 2023 · e94a931 · e94a931
1 parent 0d931b4
commit e94a931
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Showing 11 changed files with 25 additions and 3 deletions.
diff --git a/docs/reference_guide.md b/docs/reference_guide.md
@@ -1943,7 +1943,7 @@ NetworkManager:1155 /var/lib/sss/mc/passwd (deleted)
 - `uid` - User ID
 - `gid` - Group ID
 - `nsecs` - Nanosecond timestamp. Alias of [`nsecs()`](#36-nsecs-timestamps-and-time-deltas)
-- `jiffies` - Jiffies in kernel
+- `jiffies` - Jiffies of the kernel. In 32-bit system, using this builtin might be slower.
 - `elapsed` - Nanoseconds since bpftrace initialization
 - `numaid` - NUMA Node ID
 - `cpu` - Processor ID

diff --git a/man/adoc/bpftrace.adoc b/man/adoc/bpftrace.adoc
@@ -1047,9 +1047,9 @@ For string arguments use the `str()` call to retrieve the value.
 
 | jiffies
 | uint64
-| 5.6
+| 5.9
 | get_jiffies_64
-| Jiffies in kernel
+| Jiffies of the kernel. In 32-bit system, using this builtin might be slower.
 
 | pid
 | uint64

diff --git a/src/ast/irbuilderbpf.cpp b/src/ast/irbuilderbpf.cpp
@@ -1001,6 +1001,8 @@ CallInst *IRBuilderBPF::CreateGetNs(TimestampMode ts, const location &loc)
 
 CallInst *IRBuilderBPF::CreateJiffies64(const location &loc)
 {
+  // u64 bpf_jiffies64()
+  // Return: jiffies (BITS_PER_LONG == 64) or jiffies_64 (otherwise)
   FunctionType *jiffies64_func_type = FunctionType::get(getInt64Ty(), false);
   return CreateHelperCall(libbpf::BPF_FUNC_jiffies64,
                           jiffies64_func_type,

diff --git a/src/ast/passes/semantic_analyser.cpp b/src/ast/passes/semantic_analyser.cpp
@@ -316,6 +316,12 @@ void SemanticAnalyser::visit(Builtin &builtin)
           << "BPF_FUNC_get_current_cgroup_id is not available for your kernel "
              "version";
     }
+    else if (builtin.ident == "jiffies" &&
+        !bpftrace_.feature_->has_helper_jiffies64())
+    {
+      LOG(ERROR, builtin.loc, err_)
+          << "BPF_FUNC_jiffies64 is not available for your kernel version";
+    }
   }
   else if (builtin.ident == "curtask")
   {

diff --git a/src/bpffeature.cpp b/src/bpffeature.cpp
@@ -502,6 +502,7 @@ std::string BPFfeature::report(void)
       << "  skboutput: " << to_str(has_skb_output())
       << "  get_tai_ns: " << to_str(has_helper_ktime_get_tai_ns())
       << "  get_func_ip: " << to_str(has_helper_get_func_ip())
+      << "  jiffies64: " << to_str(has_helper_jiffies64())
 
       << std::endl;
 

diff --git a/src/bpffeature.h b/src/bpffeature.h
@@ -105,6 +105,7 @@ class BPFfeature
   DEFINE_HELPER_TEST(ktime_get_boot_ns, libbpf::BPF_PROG_TYPE_KPROBE);
   DEFINE_HELPER_TEST(ktime_get_tai_ns, libbpf::BPF_PROG_TYPE_KPROBE);
   DEFINE_HELPER_TEST(get_func_ip, libbpf::BPF_PROG_TYPE_TRACING);
+  DEFINE_HELPER_TEST(jiffies64, libbpf::BPF_PROG_TYPE_KPROBE);
   DEFINE_PROG_TEST(kprobe, libbpf::BPF_PROG_TYPE_KPROBE);
   DEFINE_PROG_TEST(tracepoint, libbpf::BPF_PROG_TYPE_TRACEPOINT);
   DEFINE_PROG_TEST(perf_event, libbpf::BPF_PROG_TYPE_PERF_EVENT);

diff --git a/tests/mocks.h b/tests/mocks.h
@@ -118,6 +118,7 @@ class MockBPFfeature : public BPFfeature
     map_ringbuf_ = std::make_optional<bool>(has_features);
     has_ktime_get_tai_ns_ = std::make_optional<bool>(has_features);
     has_get_func_ip_ = std::make_optional<bool>(has_features);
+    has_jiffies64_ = std::make_optional<bool>(has_features);
   };
 
   void has_loop(bool has)

diff --git a/tests/runtime/builtin b/tests/runtime/builtin
@@ -276,3 +276,10 @@ EXPECT @[{.n=0x[0-9a-f]+,.c=120}]: 1
 REQUIRES_FEATURE dwarf
 TIMEOUT 5
 BEFORE ./testprogs/uprobe_test
+
+NAME jiffies
+PROG i:ms:1 { printf("SUCCESS %d\n", jiffies); exit(); }
+EXPECT SUCCESS -?[0-9][0-9]*
+REQUIRES_FEATURE jiffies64
+TIMEOUT 5
+MIN_KERNEL 5.9
diff --git a/tests/runtime/engine/parser.py b/tests/runtime/engine/parser.py
@@ -166,6 +166,7 @@ def __read_test_struct(test, test_suite):
                     "skboutput",
                     "get_tai_ns",
                     "get_func_ip",
+                    "jiffies64",
                 }
 
                 for f in line.split(" "):

diff --git a/tests/runtime/engine/runner.py b/tests/runtime/engine/runner.py
@@ -134,6 +134,7 @@ def __get_bpffeature():
         bpffeature["skboutput"] = output.find("skboutput: yes") != -1
         bpffeature["get_tai_ns"] = output.find("get_ktime_ns: yes") != -1
         bpffeature["get_func_ip"] = output.find("get_func_ip: yes") != -1
+        bpffeature["jiffies64"] = output.find("jiffies64: yes") != -1
         return bpffeature
 
     @staticmethod

diff --git a/tests/semantic_analyser.cpp b/tests/semantic_analyser.cpp
@@ -189,9 +189,11 @@ TEST(semantic_analyser, builtin_variables)
   test("kprobe:f { probe }", 0);
   test("tracepoint:a:b { args }", 0);
   test("kprobe:f { fake }", 1);
+  test("kprobe:f { jiffies }", 0);
 
   MockBPFfeature feature(false);
   test(feature, "k:f { cgroup }", 1);
+  test(feature, "k:f { jiffies }", 1);
 }
 
 TEST(semantic_analyser, builtin_cpid)