[PROF-13913] Ensure opentelemetry-ebpf-profiler support for JDK 26

interpreter/hotspot/data.go

@@ -166,17 +166,18 @@ type hotspotVMData struct {
 			ConstMethod uint `name:"_constMethod"`
 		} `name:"Method,methodOopDesc"`
 		Nmethod struct { // .Sizeof >256
-			Sizeof             uint
-			CompileID          uint `name:"_compile_id"`
-			MetadataOffset     uint `name:"_metadata_offset,_oops_offset"`
-			ScopesPcsOffset    uint `name:"_scopes_pcs_offset"`
-			DependenciesOffset uint `name:"_dependencies_offset"` // JDK -22 only
-			ImmutableData      uint `name:"_immutable_data"`      // JDK 23+ only
-			ImmutableDataSize  uint `name:"_immutable_data_size"` // JDK 23+ only
-			OrigPcOffset       uint `name:"_orig_pc_offset"`
-			DeoptimizeOffset   uint `name:"_deoptimize_offset,_deopt_handler_offset,_deopt_handler_begin"`
-			Method             uint `name:"_method"`
-			ScopesDataOffset   uint `name:"_scopes_data_offset,_scopes_data_begin"`
+			Sizeof                   uint
+			CompileID                uint `name:"_compile_id"`
+			MetadataOffset           uint `name:"_metadata_offset,_oops_offset"`
+			ScopesPcsOffset          uint `name:"_scopes_pcs_offset"`
+			DependenciesOffset       uint `name:"_dependencies_offset"`             // JDK -22 only
+			ImmutableData            uint `name:"_immutable_data"`                  // JDK 23+ only
+			ImmutableDataSize        uint `name:"_immutable_data_size"`             // JDK 23+ only
+			ImmutableDataRefCountOff uint `name:"_immutable_data_ref_count_offset"` // JDK 26+ only
+			OrigPcOffset             uint `name:"_orig_pc_offset"`
+			DeoptimizeOffset         uint `name:"_deoptimize_offset,_deopt_handler_offset,_deopt_handler_begin,_deopt_handler_entry_offset"`
+			Method                   uint `name:"_method"`
+			ScopesDataOffset         uint `name:"_scopes_data_offset,_scopes_data_begin"`
 		} `name:"nmethod,CompiledMethod"`
 		OopDesc struct {
 			Sizeof uint
@@ -601,6 +602,11 @@ func (d *hotspotData) newVMData(rm remotememory.RemoteMemory, bias libpf.Address
 		vms.CodeBlob.RelocationSize = 0
 	}
 
+	// JDK26+: immutable data has a ref count trailer; not present prior to JDK26
+	if vms.Nmethod.ImmutableDataRefCountOff == ^uint(0) {
+		vms.Nmethod.ImmutableDataRefCountOff = 0
+	}
+
 	// Check that all symbols got loaded from JVM introspection data
 	err := forEachItem("", reflect.ValueOf(&vmd.vmStructs).Elem(),
 		func(item reflect.Value, name string) error {

interpreter/hotspot/hotspot.go

@@ -78,6 +78,9 @@ package hotspot // import "go.opentelemetry.io/ebpf-profiler/interpreter/hotspot
 //  JDK24 - Tested ok
 //   - nmethod metadata moved to codeblob mutable data area
 //  JDK25 - Tested ok
+//  JDK26 - Tested ok
+//   - nmethod._deopt_handler_offset renamed to _deopt_handler_entry_offset
+//   - immutable_data now has ref count trailer (_immutable_data_ref_count_offset)
 //
 // NOTE: Ahead-Of-Time compilation (AOT) is NOT SUPPORTED. The main complication is that, the AOT
 // ELF files are mapped directly to the program virtual space, and contain the code to execute.

interpreter/hotspot/instance.go

@@ -511,7 +511,8 @@ func (d *hotspotInstance) getJITInfo(addr libpf.Address, addrCheck uint32) (
 		// [scopes_data]	@ _immutable_data + nmethod._scopes_data_begin	\ arrays we need
 		// [scopes_pcs]		@ _immutable_data + nmethod._scopes_pcs_offset	/ for inlining info
 		// [speculations]	@ _immutable_data + nmethod._speculations_offset
-		// [end]		@ _immutable_Data + nmethod._immutable_data_size
+		// [end]		    @ _immutable_data + nmethod._immutable_data_size
+		// [end]            @ _immutable_data + min(_immutable_data_size, _immutable_data_ref_count_offset)  (JDK 26+)
 		// ...
 		// speculations presence depends on JDK build, and is not used. Instead the scopes
 		// end is determined from immutable data size.
@@ -535,6 +536,15 @@ func (d *hotspotInstance) getJITInfo(addr libpf.Address, addrCheck uint32) (
 		scopesDataOff := npsr.PtrDiff32(nmethod, vms.Nmethod.ScopesDataOffset)
 		immutableDataPtr := npsr.Ptr(nmethod, vms.Nmethod.ImmutableData)
 		immutableDataSize := npsr.Uint32(nmethod, vms.Nmethod.ImmutableDataSize)
+
+		// JDK26+: immutable data ends at ref_count offset, not at immutable_data_size
+		if vms.Nmethod.ImmutableDataRefCountOff != 0 {
+			immutableDataRefCountOff := npsr.Uint32(nmethod, vms.Nmethod.ImmutableDataRefCountOff)
+			if immutableDataRefCountOff < immutableDataSize {
+				immutableDataSize = immutableDataRefCountOff
+			}
+		}
+
 		if immutableDataSize >= maxMetadataSize {
 			return nil, fmt.Errorf("unreasonably large immutable data region: %d bytes",
 				immutableDataSize)