fixup: generate perf_event and kprobe programs at compile time

Signed-off-by: Florian Lehner <florian.lehner@elastic.co>

support/ebpf/dotnet_tracer.ebpf.c

@@ -244,7 +244,7 @@ ErrorCode unwind_one_dotnet_frame(PerCPURecord *record, DotnetProcInfo *vi, bool
 // unwind_dotnet is the entry point for tracing when invoked from the native tracer
 // or interpreter dispatcher. It does not reset the trace object and will append the
 // dotnet stack frames to the trace object for the current CPU.
-SEC("perf_event/unwind_dotnet")
+static inline __attribute__((__always_inline__))
 int unwind_dotnet(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record) {
@@ -289,3 +289,4 @@ int unwind_dotnet(struct pt_regs *ctx) {
   DEBUG_PRINT("dotnet: tail call for next frame unwinder (%d) failed", unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_dotnet)

support/ebpf/hotspot_tracer.ebpf.c

@@ -890,7 +890,7 @@ static ErrorCode hotspot_unwind_one_frame(PerCPURecord *record, HotspotProcInfo
 // unwind_hotspot is the entry point for tracing when invoked from the native tracer
 // and it recursive unwinds all HotSpot frames and then jumps back to unwind further
 // native frames that follow.
-SEC("perf_event/unwind_hotspot")
+static inline __attribute__((__always_inline__))
 int unwind_hotspot(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record)
@@ -927,3 +927,4 @@ int unwind_hotspot(struct pt_regs *ctx) {
   DEBUG_PRINT("jvm: tail call for next frame unwinder (%d) failed", unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_hotspot)

support/ebpf/interpreter_dispatcher.ebpf.c

@@ -172,7 +172,8 @@ void maybe_add_apm_info(Trace *trace) {
               trace->apm_transaction_id.as_int, corr_buf.trace_flags);
 }
 
-SEC("perf_event/unwind_stop")
+// unwind_stop is the tail call destination for PROG_UNWIND_STOP.
+static inline __attribute__((__always_inline__))
 int unwind_stop(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record)
@@ -238,6 +239,7 @@ int unwind_stop(struct pt_regs *ctx) {
 
   return 0;
 }
+MULTI_USE_FUNC(unwind_stop)
 
 char _license[] SEC("license") = "GPL";
 // this number will be interpreted by the elf loader

support/ebpf/native_stack_trace.ebpf.c

@@ -571,7 +571,8 @@ static ErrorCode unwind_one_frame(u64 pid, u32 frame_idx, struct UnwindState *st
   #error unsupported architecture
 #endif
 
-SEC("perf_event/unwind_native")
+// unwind_native is the tail call destination for PROG_UNWIND_NATIVE.
+static inline __attribute__((__always_inline__))
 int unwind_native(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record)
@@ -632,3 +633,4 @@ int native_tracer_entry(struct bpf_perf_event_data *ctx) {
   u64 ts = bpf_ktime_get_ns();
   return collect_trace((struct pt_regs*) &ctx->regs, TRACE_SAMPLING, pid, tid, ts, 0);
 }
+MULTI_USE_FUNC(unwind_native)

support/ebpf/perl_tracer.ebpf.c

@@ -356,7 +356,7 @@ int walk_perl_stack(PerCPURecord *record, const PerlProcInfo *perlinfo) {
 // unwind_perl is the entry point for tracing when invoked from the native tracer
 // or interpreter dispatcher. It does not reset the trace object and will append the
 // Perl stack frames to the trace object for the current CPU.
-SEC("perf_event/unwind_perl")
+static inline __attribute__((__always_inline__))
 int unwind_perl(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record) {
@@ -426,3 +426,4 @@ int unwind_perl(struct pt_regs *ctx) {
   tail_call(ctx, unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_perl)

support/ebpf/php_tracer.ebpf.c

@@ -182,7 +182,8 @@ int walk_php_stack(PerCPURecord *record, PHPProcInfo *phpinfo, bool is_jitted) {
   return unwinder;
 }
 
-SEC("perf_event/unwind_php")
+// unwind_php is the tail call destination for PROG_UNWIND_PHP.
+static inline __attribute__((__always_inline__))
 int unwind_php(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record)
@@ -239,3 +240,4 @@ int unwind_php(struct pt_regs *ctx) {
   tail_call(ctx, unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_php)

support/ebpf/python_tracer.ebpf.c

@@ -276,7 +276,7 @@ ErrorCode get_PyFrame(const PyProcInfo *pyinfo, void **frame) {
 // unwind_python is the entry point for tracing when invoked from the native tracer
 // or interpreter dispatcher. It does not reset the trace object and will append the
 // Python stack frames to the trace object for the current CPU.
-SEC("perf_event/unwind_python")
+static inline __attribute__((__always_inline__))
 int unwind_python(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record)
@@ -318,3 +318,4 @@ int unwind_python(struct pt_regs *ctx) {
   tail_call(ctx, unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_python)

support/ebpf/ruby_tracer.ebpf.c

@@ -216,7 +216,8 @@ ErrorCode walk_ruby_stack(PerCPURecord *record, const RubyProcInfo *rubyinfo,
   return ERR_OK;
 }
 
-SEC("perf_event/unwind_ruby")
+// unwind_ruby is the tail call destination for PROG_UNWIND_RUBY.
+static inline __attribute__((__always_inline__))
 int unwind_ruby(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record)
@@ -273,3 +274,4 @@ int unwind_ruby(struct pt_regs *ctx) {
   tail_call(ctx, unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_ruby)

support/ebpf/tracemgmt.h

@@ -10,6 +10,20 @@
 #include "types.h"
 #include "errors.h"
 
+// MULTI_USE_FUNC generates perf event and kprobe eBPF programs
+// for a given function.
+#define MULTI_USE_FUNC(func_name) \
+    SEC("perf_event/"#func_name) \
+    int perf_##func_name(struct pt_regs *ctx) { \
+        return func_name(ctx); \
+    } \
+    \
+    SEC("kprobe/"#func_name) \
+    int kprobe_##func_name(struct pt_regs *ctx) { \
+        return func_name(ctx); \
+    }
+
+
 // increment_metric increments the value of the given metricID by 1
 static inline __attribute__((__always_inline__))
 void increment_metric(u32 metricID) {

support/ebpf/v8_tracer.ebpf.c

@@ -284,7 +284,7 @@ ErrorCode unwind_one_v8_frame(PerCPURecord *record, V8ProcInfo *vi, bool top) {
 // unwind_v8 is the entry point for tracing when invoked from the native tracer
 // or interpreter dispatcher. It does not reset the trace object and will append the
 // V8 stack frames to the trace object for the current CPU.
-SEC("perf_event/unwind_v8")
+static inline __attribute__((__always_inline__))
 int unwind_v8(struct pt_regs *ctx) {
   PerCPURecord *record = get_per_cpu_record();
   if (!record) {
@@ -328,3 +328,4 @@ int unwind_v8(struct pt_regs *ctx) {
   DEBUG_PRINT("v8: tail call for next frame unwinder (%d) failed", unwinder);
   return -1;
 }
+MULTI_USE_FUNC(unwind_v8)

tracer/tracer.go

@@ -602,9 +602,14 @@ func loadPerfUnwinders(coll *cebpf.CollectionSpec, ebpfProgs map[string]*cebpf.P
 			continue
 		}
 
-		progSpec, ok := coll.Programs[unwindProg.name]
+		unwindProgName := unwindProg.name
+		if !unwindProg.noTailCallTarget {
+			unwindProgName = "perf_" + unwindProg.name
+		}
+
+		progSpec, ok := coll.Programs[unwindProgName]
 		if !ok {
-			return fmt.Errorf("program %s does not exist", unwindProg.name)
+			return fmt.Errorf("program %s does not exist", unwindProgName)
 		}
 
 		if err := loadProgram(ebpfProgs, tailcallMap, unwindProg.progID, progSpec,
@@ -666,9 +671,14 @@ func loadKProbeUnwinders(coll *cebpf.CollectionSpec, ebpfProgs map[string]*cebpf
 			continue
 		}
 
-		progSpec, ok := coll.Programs[unwindProg.name]
+		unwindProgName := unwindProg.name
+		if !unwindProg.noTailCallTarget {
+			unwindProgName = "kprobe_" + unwindProg.name
+		}
+
+		progSpec, ok := coll.Programs[unwindProgName]
 		if !ok {
-			return fmt.Errorf("program %s does not exist", unwindProg.name)
+			return fmt.Errorf("program %s does not exist", unwindProgName)
 		}
 
 		// Replace the prog array for the tail calls.
@@ -679,15 +689,6 @@ func loadKProbeUnwinders(coll *cebpf.CollectionSpec, ebpfProgs map[string]*cebpf
 			}
 		}
 
-		// All the tail call targets are perf event programs. To be able to tail call them
-		// from a kprobe, adjust their specification.
-		if !unwindProg.noTailCallTarget {
-			// Adjust program type
-			progSpec.Type = cebpf.Kprobe
-
-			// Adjust program name for easier debugging
-			progSpec.Name = "kp_" + progSpec.Name
-		}
 		if err := loadProgram(ebpfProgs, tailcallMap, unwindProg.progID, progSpec,
 			programOptions, unwindProg.noTailCallTarget); err != nil {
 			return err