diff --git a/src/hotspot/cpu/aarch64/aarch64.ad b/src/hotspot/cpu/aarch64/aarch64.ad
index 75baef153f875..a6d037dba554f 100644
--- a/src/hotspot/cpu/aarch64/aarch64.ad
+++ b/src/hotspot/cpu/aarch64/aarch64.ad
@@ -1765,10 +1765,6 @@ void MachPrologNode::emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const {
   // n.b. frame size includes space for return pc and rfp
   const int framesize = C->output()->frame_size_in_bytes();
 
-  // insert a nop at the start of the prolog so we can patch in a
-  // branch if we need to invalidate the method later
-  __ nop();
-
   if (C->clinit_barrier_on_entry()) {
     assert(!C->method()->holder()->is_not_initialized(), "initialization should have been started");
 
diff --git a/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp b/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp
index 33158d6b97a91..6d7c758939e2d 100644
--- a/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp
+++ b/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp
@@ -212,11 +212,6 @@ void NativeMovRegMem::verify() {
 
 void NativeJump::verify() { ; }
 
-
-void NativeJump::check_verified_entry_alignment(address entry, address verified_entry) {
-}
-
-
 address NativeJump::jump_destination() const          {
   address dest = MacroAssembler::target_addr_for_insn_or_null(instruction_address());
 
@@ -345,10 +340,6 @@ bool NativeInstruction::is_movk() {
   return Instruction_aarch64::extract(int_at(0), 30, 23) == 0b11100101;
 }
 
-bool NativeInstruction::is_sigill_not_entrant() {
-  return uint_at(0) == 0xd4bbd5a1; // dcps1 #0xdead
-}
-
 void NativeIllegalInstruction::insert(address code_pos) {
   *(juint*)code_pos = 0xd4bbd5a1; // dcps1 #0xdead
 }
@@ -359,31 +350,6 @@ bool NativeInstruction::is_stop() {
 
 //-------------------------------------------------------------------
 
-// MT-safe inserting of a jump over a jump or a nop (used by
-// nmethod::make_not_entrant)
-
-void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {
-
-  assert(dest == SharedRuntime::get_handle_wrong_method_stub(), "expected fixed destination of patch");
-  assert(nativeInstruction_at(verified_entry)->is_jump_or_nop()
-         || nativeInstruction_at(verified_entry)->is_sigill_not_entrant(),
-         "Aarch64 cannot replace non-jump with jump");
-
-  // Patch this nmethod atomically.
-  if (Assembler::reachable_from_branch_at(verified_entry, dest)) {
-    ptrdiff_t disp = dest - verified_entry;
-    guarantee(disp < 1 << 27 && disp > - (1 << 27), "branch overflow");
-
-    unsigned int insn = (0b000101 << 26) | ((disp >> 2) & 0x3ffffff);
-    *(unsigned int*)verified_entry = insn;
-  } else {
-    // We use an illegal instruction for marking a method as not_entrant.
-    NativeIllegalInstruction::insert(verified_entry);
-  }
-
-  ICache::invalidate_range(verified_entry, instruction_size);
-}
-
 void NativeGeneralJump::verify() {  }
 
 void NativeGeneralJump::insert_unconditional(address code_pos, address entry) {
diff --git a/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp b/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp
index 0eb5ff815be1d..915e33fe56a7f 100644
--- a/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp
+++ b/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, 2108, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -83,7 +83,6 @@ class NativeInstruction {
   bool is_safepoint_poll();
   bool is_movz();
   bool is_movk();
-  bool is_sigill_not_entrant();
   bool is_stop();
 
 protected:
@@ -360,9 +359,6 @@ class NativeJump: public NativeInstruction {
 
   // Insertion of native jump instruction
   static void insert(address code_pos, address entry);
-  // MT-safe insertion of native jump at verified method entry
-  static void check_verified_entry_alignment(address entry, address verified_entry);
-  static void patch_verified_entry(address entry, address verified_entry, address dest);
 };
 
 inline NativeJump* nativeJump_at(address address) {
diff --git a/src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.cpp b/src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.cpp
index 4492c9da33e1f..029e5131a846e 100644
--- a/src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.cpp
+++ b/src/hotspot/cpu/arm/gc/shared/barrierSetAssembler_arm.cpp
@@ -193,10 +193,7 @@ void BarrierSetAssembler::nmethod_entry_barrier(MacroAssembler* masm) {
   __ bind(guard);
 
   // nmethod guard value. Skipped over in common case.
-  //
-  // Put a debug value to make any offsets skew
-  // clearly visible in coredump
-  __ emit_int32(0xDEADBEAF);
+  __ emit_int32(0); // initial armed value, will be reset later
 
   __ bind(skip);
   __ block_comment("nmethod_barrier end");
diff --git a/src/hotspot/cpu/arm/nativeInst_arm_32.cpp b/src/hotspot/cpu/arm/nativeInst_arm_32.cpp
index 2caf2d7587e53..232294b246a12 100644
--- a/src/hotspot/cpu/arm/nativeInst_arm_32.cpp
+++ b/src/hotspot/cpu/arm/nativeInst_arm_32.cpp
@@ -282,16 +282,6 @@ void NativeMovConstReg::set_pc_relative_offset(address addr, address pc) {
   }
 }
 
-void RawNativeJump::check_verified_entry_alignment(address entry, address verified_entry) {
-}
-
-void RawNativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {
-  assert(dest == SharedRuntime::get_handle_wrong_method_stub(), "should be");
-  int *a = (int *)verified_entry;
-  a[0] = not_entrant_illegal_instruction; // always illegal
-  ICache::invalidate_range((address)&a[0], sizeof a[0]);
-}
-
 void NativeGeneralJump::insert_unconditional(address code_pos, address entry) {
   int offset = (int)(entry - code_pos - 8);
   assert(offset < 0x2000000 && offset > -0x2000000, "encoding constraint");
diff --git a/src/hotspot/cpu/arm/nativeInst_arm_32.hpp b/src/hotspot/cpu/arm/nativeInst_arm_32.hpp
index e26c23cd9836c..ee856bcfe6049 100644
--- a/src/hotspot/cpu/arm/nativeInst_arm_32.hpp
+++ b/src/hotspot/cpu/arm/nativeInst_arm_32.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -61,10 +61,6 @@ class RawNativeInstruction {
     instr_fld_fst    = 0xd0
   };
 
-  // illegal instruction used by NativeJump::patch_verified_entry
-  // permanently undefined (UDF): 0xe << 28 | 0b1111111 << 20 | 0b1111 << 4
-  static const int not_entrant_illegal_instruction = 0xe7f000f0;
-
   static int decode_rotated_imm12(int encoding) {
     int base = encoding & 0xff;
     int right_rotation = (encoding & 0xf00) >> 7;
@@ -274,10 +270,6 @@ class RawNativeJump: public NativeInstruction {
     }
   }
 
-  static void check_verified_entry_alignment(address entry, address verified_entry);
-
-  static void patch_verified_entry(address entry, address verified_entry, address dest);
-
 };
 
 inline RawNativeJump* rawNativeJump_at(address address) {
diff --git a/src/hotspot/cpu/ppc/c1_MacroAssembler_ppc.cpp b/src/hotspot/cpu/ppc/c1_MacroAssembler_ppc.cpp
index 77d3653aefdb8..02e069b6be16d 100644
--- a/src/hotspot/cpu/ppc/c1_MacroAssembler_ppc.cpp
+++ b/src/hotspot/cpu/ppc/c1_MacroAssembler_ppc.cpp
@@ -46,7 +46,6 @@ void C1_MacroAssembler::explicit_null_check(Register base) {
 
 
 void C1_MacroAssembler::build_frame(int frame_size_in_bytes, int bang_size_in_bytes) {
-  // Avoid stack bang as first instruction. It may get overwritten by patch_verified_entry.
   const Register return_pc = R20;
   mflr(return_pc);
 
diff --git a/src/hotspot/cpu/ppc/nativeInst_ppc.cpp b/src/hotspot/cpu/ppc/nativeInst_ppc.cpp
index 1114da60d2bb6..ca492329729c0 100644
--- a/src/hotspot/cpu/ppc/nativeInst_ppc.cpp
+++ b/src/hotspot/cpu/ppc/nativeInst_ppc.cpp
@@ -39,18 +39,6 @@
 #include "c1/c1_Runtime1.hpp"
 #endif
 
-// We use an illtrap for marking a method as not_entrant
-// Work around a C++ compiler bug which changes 'this'
-bool NativeInstruction::is_sigill_not_entrant_at(address addr) {
-  if (!Assembler::is_illtrap(addr)) return false;
-  CodeBlob* cb = CodeCache::find_blob(addr);
-  if (cb == nullptr || !cb->is_nmethod()) return false;
-  nmethod *nm = (nmethod *)cb;
-  // This method is not_entrant iff the illtrap instruction is
-  // located at the verified entry point.
-  return nm->verified_entry_point() == addr;
-}
-
 #ifdef ASSERT
 void NativeInstruction::verify() {
   // Make sure code pattern is actually an instruction address.
@@ -331,25 +319,6 @@ void NativeMovConstReg::verify() {
 }
 #endif // ASSERT
 
-void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {
-  ResourceMark rm;
-  int code_size = 1 * BytesPerInstWord;
-  CodeBuffer cb(verified_entry, code_size + 1);
-  MacroAssembler* a = new MacroAssembler(&cb);
-#ifdef COMPILER2
-  assert(dest == SharedRuntime::get_handle_wrong_method_stub(), "expected fixed destination of patch");
-#endif
-  // Patch this nmethod atomically. Always use illtrap/trap in debug build.
-  if (DEBUG_ONLY(false &&) a->is_within_range_of_b(dest, a->pc())) {
-    a->b(dest);
-  } else {
-    // The signal handler will continue at dest=OptoRuntime::handle_wrong_method_stub().
-    // We use an illtrap for marking a method as not_entrant.
-    a->illtrap();
-  }
-  ICache::ppc64_flush_icache_bytes(verified_entry, code_size);
-}
-
 #ifdef ASSERT
 void NativeJump::verify() {
   address addr = addr_at(0);
@@ -462,9 +431,7 @@ bool NativeDeoptInstruction::is_deopt_at(address code_pos) {
   if (!Assembler::is_illtrap(code_pos)) return false;
   CodeBlob* cb = CodeCache::find_blob(code_pos);
   if (cb == nullptr || !cb->is_nmethod()) return false;
-  nmethod *nm = (nmethod *)cb;
-  // see NativeInstruction::is_sigill_not_entrant_at()
-  return nm->verified_entry_point() != code_pos;
+  return true;
 }
 
 // Inserts an instruction which is specified to cause a SIGILL at a given pc
diff --git a/src/hotspot/cpu/ppc/nativeInst_ppc.hpp b/src/hotspot/cpu/ppc/nativeInst_ppc.hpp
index f4d570116a8c1..38126ec858dc9 100644
--- a/src/hotspot/cpu/ppc/nativeInst_ppc.hpp
+++ b/src/hotspot/cpu/ppc/nativeInst_ppc.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2025, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2024 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -69,13 +69,6 @@ class NativeInstruction {
     return MacroAssembler::tdi_get_si16(long_at(0), Assembler::traptoUnconditional, 0);
   }
 
-  // We use an illtrap for marking a method as not_entrant.
-  bool is_sigill_not_entrant() {
-    // Work around a C++ compiler bug which changes 'this'.
-    return NativeInstruction::is_sigill_not_entrant_at(addr_at(0));
-  }
-  static bool is_sigill_not_entrant_at(address addr);
-
 #ifdef COMPILER2
   // SIGTRAP-based implicit range checks
   bool is_sigtrap_range_check() {
@@ -328,15 +321,7 @@ class NativeJump: public NativeInstruction {
     }
   }
 
-  // MT-safe insertion of native jump at verified method entry
-  static void patch_verified_entry(address entry, address verified_entry, address dest);
-
   void verify() NOT_DEBUG_RETURN;
-
-  static void check_verified_entry_alignment(address entry, address verified_entry) {
-    // We just patch one instruction on ppc64, so the jump doesn't have to
-    // be aligned. Nothing to do here.
-  }
 };
 
 // Instantiates a NativeJump object starting at the given instruction
diff --git a/src/hotspot/cpu/ppc/ppc.ad b/src/hotspot/cpu/ppc/ppc.ad
index d8e00cfef8957..c9e10d71a10a9 100644
--- a/src/hotspot/cpu/ppc/ppc.ad
+++ b/src/hotspot/cpu/ppc/ppc.ad
@@ -1686,12 +1686,7 @@ void MachPrologNode::emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const {
   const Register toc_temp             = R23;
   assert_different_registers(R11, return_pc, callers_sp, push_frame_temp, toc_temp);
 
-  if (method_is_frameless) {
-    // Add nop at beginning of all frameless methods to prevent any
-    // oop instructions from getting overwritten by make_not_entrant
-    // (patching attempt would fail).
-    __ nop();
-  } else {
+  if (!method_is_frameless) {
     // Get return pc.
     __ mflr(return_pc);
   }
diff --git a/src/hotspot/cpu/riscv/nativeInst_riscv.cpp b/src/hotspot/cpu/riscv/nativeInst_riscv.cpp
index 31947b520d056..3834a0d3d3d14 100644
--- a/src/hotspot/cpu/riscv/nativeInst_riscv.cpp
+++ b/src/hotspot/cpu/riscv/nativeInst_riscv.cpp
@@ -356,18 +356,6 @@ void NativeMovRegMem::verify() {
 
 void NativeJump::verify() { }
 
-
-void NativeJump::check_verified_entry_alignment(address entry, address verified_entry) {
-  // Patching to not_entrant can happen while activations of the method are
-  // in use. The patching in that instance must happen only when certain
-  // alignment restrictions are true. These guarantees check those
-  // conditions.
-
-  // Must be 4 bytes aligned
-  MacroAssembler::assert_alignment(verified_entry);
-}
-
-
 address NativeJump::jump_destination() const {
   address dest = MacroAssembler::target_addr_for_insn(instruction_address());
 
@@ -420,12 +408,6 @@ bool NativeInstruction::is_safepoint_poll() {
   return MacroAssembler::is_lwu_to_zr(address(this));
 }
 
-// A 16-bit instruction with all bits ones is permanently reserved as an illegal instruction.
-bool NativeInstruction::is_sigill_not_entrant() {
-  // jvmci
-  return uint_at(0) == 0xffffffff;
-}
-
 void NativeIllegalInstruction::insert(address code_pos) {
   assert_cond(code_pos != nullptr);
   Assembler::sd_instr(code_pos, 0xffffffff);   // all bits ones is permanently reserved as an illegal instruction
@@ -437,45 +419,6 @@ bool NativeInstruction::is_stop() {
 
 //-------------------------------------------------------------------
 
-// MT-safe inserting of a jump over a jump or a nop (used by
-// nmethod::make_not_entrant)
-
-void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {
-
-  assert(dest == SharedRuntime::get_handle_wrong_method_stub(), "expected fixed destination of patch");
-
-  assert(nativeInstruction_at(verified_entry)->is_jump_or_nop() ||
-         nativeInstruction_at(verified_entry)->is_sigill_not_entrant(),
-         "riscv cannot replace non-jump with jump");
-
-  check_verified_entry_alignment(entry, verified_entry);
-
-  // Patch this nmethod atomically.
-  if (Assembler::reachable_from_branch_at(verified_entry, dest)) {
-    ptrdiff_t offset = dest - verified_entry;
-    guarantee(Assembler::is_simm21(offset) && ((offset % 2) == 0),
-              "offset is too large to be patched in one jal instruction."); // 1M
-
-    uint32_t insn = 0;
-    address pInsn = (address)&insn;
-    Assembler::patch(pInsn, 31, 31, (offset >> 20) & 0x1);
-    Assembler::patch(pInsn, 30, 21, (offset >> 1) & 0x3ff);
-    Assembler::patch(pInsn, 20, 20, (offset >> 11) & 0x1);
-    Assembler::patch(pInsn, 19, 12, (offset >> 12) & 0xff);
-    Assembler::patch(pInsn, 11, 7, 0); // zero, no link jump
-    Assembler::patch(pInsn, 6, 0, 0b1101111); // j, (jal x0 offset)
-    Assembler::sd_instr(verified_entry, insn);
-  } else {
-    // We use an illegal instruction for marking a method as
-    // not_entrant.
-    NativeIllegalInstruction::insert(verified_entry);
-  }
-
-  ICache::invalidate_range(verified_entry, instruction_size);
-}
-
-//-------------------------------------------------------------------
-
 void NativeGeneralJump::insert_unconditional(address code_pos, address entry) {
   CodeBuffer cb(code_pos, instruction_size);
   MacroAssembler a(&cb);
diff --git a/src/hotspot/cpu/riscv/nativeInst_riscv.hpp b/src/hotspot/cpu/riscv/nativeInst_riscv.hpp
index d8f5fa57816f3..1598dfb839807 100644
--- a/src/hotspot/cpu/riscv/nativeInst_riscv.hpp
+++ b/src/hotspot/cpu/riscv/nativeInst_riscv.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2014, 2018, Red Hat Inc. All rights reserved.
  * Copyright (c) 2020, 2023, Huawei Technologies Co., Ltd. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
@@ -74,7 +74,6 @@ class NativeInstruction {
   bool is_nop() const;
   bool is_jump_or_nop();
   bool is_safepoint_poll();
-  bool is_sigill_not_entrant();
   bool is_stop();
 
  protected:
@@ -274,9 +273,6 @@ class NativeJump: public NativeInstruction {
 
   // Insertion of native jump instruction
   static void insert(address code_pos, address entry);
-  // MT-safe insertion of native jump at verified method entry
-  static void check_verified_entry_alignment(address entry, address verified_entry);
-  static void patch_verified_entry(address entry, address verified_entry, address dest);
 };
 
 inline NativeJump* nativeJump_at(address addr) {
diff --git a/src/hotspot/cpu/riscv/riscv.ad b/src/hotspot/cpu/riscv/riscv.ad
index 0d44acc803f32..634e5fd506394 100644
--- a/src/hotspot/cpu/riscv/riscv.ad
+++ b/src/hotspot/cpu/riscv/riscv.ad
@@ -1368,14 +1368,6 @@ void MachPrologNode::emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const {
   // n.b. frame size includes space for return pc and fp
   const int framesize = C->output()->frame_size_in_bytes();
 
-  // insert a nop at the start of the prolog so we can patch in a
-  // branch if we need to invalidate the method later
-  {
-    Assembler::IncompressibleScope scope(masm); // keep the nop as 4 bytes for patching.
-    MacroAssembler::assert_alignment(__ pc());
-    __ nop();  // 4 bytes
-  }
-
   assert_cond(C != nullptr);
 
   if (C->clinit_barrier_on_entry()) {
@@ -1804,7 +1796,6 @@ void MachUEPNode::emit(C2_MacroAssembler* masm, PhaseRegAlloc* ra_) const
   // This is the unverified entry point.
   __ ic_check(CodeEntryAlignment);
 
-  // Verified entry point must be properly 4 bytes aligned for patching by NativeJump::patch_verified_entry().
   // ic_check() aligns to CodeEntryAlignment >= InteriorEntryAlignment(min 16) > NativeInstruction::instruction_size(4).
   assert(((__ offset()) % CodeEntryAlignment) == 0, "Misaligned verified entry point");
 }
@@ -8199,7 +8190,7 @@ instruct unnecessary_membar_volatile_rvtso() %{
   ins_cost(0);
 
   size(0);
-  
+ 
   format %{ "#@unnecessary_membar_volatile_rvtso (unnecessary so empty encoding)" %}
   ins_encode %{
     __ block_comment("unnecessary_membar_volatile_rvtso");
diff --git a/src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.cpp b/src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.cpp
index e78906708afd7..2d663061aec9c 100644
--- a/src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.cpp
+++ b/src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.cpp
@@ -180,7 +180,7 @@ void BarrierSetAssembler::nmethod_entry_barrier(MacroAssembler* masm) {
     __ z_lg(Z_R0_scratch, in_bytes(bs_nm->thread_disarmed_guard_value_offset()), Z_thread); // 6 bytes
 
     // Compare to current patched value:
-    __ z_cfi(Z_R0_scratch, /* to be patched */ -1); // 6 bytes (2 + 4 byte imm val)
+    __ z_cfi(Z_R0_scratch, /* to be patched */ 0); // 6 bytes (2 + 4 byte imm val)
 
     // Conditional Jump
     __ z_larl(Z_R14, (Assembler::instr_len((unsigned long)LARL_ZOPC) + Assembler::instr_len((unsigned long)BCR_ZOPC)) / 2); // 6 bytes
diff --git a/src/hotspot/cpu/s390/nativeInst_s390.cpp b/src/hotspot/cpu/s390/nativeInst_s390.cpp
index 9990c225a8986..546f8b133975d 100644
--- a/src/hotspot/cpu/s390/nativeInst_s390.cpp
+++ b/src/hotspot/cpu/s390/nativeInst_s390.cpp
@@ -167,27 +167,6 @@ bool NativeInstruction::is_illegal() {
   return halfword_at(-2) == illegal_instruction();
 }
 
-// We use an illtrap for marking a method as not_entrant.
-bool NativeInstruction::is_sigill_not_entrant() {
-  if (!is_illegal()) return false; // Just a quick path.
-
-  // One-sided error of is_illegal tolerable here
-  // (see implementation of is_illegal() for details).
-
-  CodeBlob* cb = CodeCache::find_blob(addr_at(0));
-  if (cb == nullptr || !cb->is_nmethod()) {
-    return false;
-  }
-
-  nmethod *nm = (nmethod *)cb;
-  // This method is not_entrant if the illtrap instruction
-  // is located at the verified entry point.
-  // BE AWARE: the current pc (this) points to the instruction after the
-  // "illtrap" location.
-  address sig_addr = ((address) this) - 2;
-  return nm->verified_entry_point() == sig_addr;
-}
-
 bool NativeInstruction::is_jump() {
   unsigned long inst;
   Assembler::get_instruction((address)this, &inst);
@@ -620,19 +599,6 @@ void NativeJump::verify() {
   fatal("this is not a `NativeJump' site");
 }
 
-// Patch atomically with an illtrap.
-void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {
-  ResourceMark rm;
-  int code_size = 2;
-  CodeBuffer cb(verified_entry, code_size + 1);
-  MacroAssembler* a = new MacroAssembler(&cb);
-#ifdef COMPILER2
-  assert(dest == SharedRuntime::get_handle_wrong_method_stub(), "expected fixed destination of patch");
-#endif
-  a->z_illtrap();
-  ICache::invalidate_range(verified_entry, code_size);
-}
-
 #undef LUCY_DBG
 
 //-------------------------------------
diff --git a/src/hotspot/cpu/s390/nativeInst_s390.hpp b/src/hotspot/cpu/s390/nativeInst_s390.hpp
index fcae833769f74..16400df3f2686 100644
--- a/src/hotspot/cpu/s390/nativeInst_s390.hpp
+++ b/src/hotspot/cpu/s390/nativeInst_s390.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2025, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2016, 2024 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -85,9 +85,6 @@ class NativeInstruction {
   // Bcrl is currently the only accepted instruction here.
   bool is_jump();
 
-  // We use an illtrap for marking a method as not_entrant.
-  bool is_sigill_not_entrant();
-
   bool is_safepoint_poll() {
     // Is the current instruction a POTENTIAL read access to the polling page?
     // The instruction's current arguments are not checked!
@@ -609,11 +606,6 @@ class NativeJump: public NativeInstruction {
 
   // Insertion of native jump instruction.
   static void insert(address code_pos, address entry);
-
-  // MT-safe insertion of native jump at verified method entry.
-  static void check_verified_entry_alignment(address entry, address verified_entry) { }
-
-  static void patch_verified_entry(address entry, address verified_entry, address dest);
 };
 
 //-------------------------------------
diff --git a/src/hotspot/cpu/s390/stubGenerator_s390.cpp b/src/hotspot/cpu/s390/stubGenerator_s390.cpp
index d3f6540a3ea83..bb1d9ce603793 100644
--- a/src/hotspot/cpu/s390/stubGenerator_s390.cpp
+++ b/src/hotspot/cpu/s390/stubGenerator_s390.cpp
@@ -3197,7 +3197,7 @@ class StubGenerator: public StubCodeGenerator {
 
     // VM-Call: BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr)
     __ call_VM_leaf(CAST_FROM_FN_PTR(address, BarrierSetNMethod::nmethod_stub_entry_barrier));
-    __ z_ltr(Z_R0_scratch, Z_RET);
+    __ z_ltr(Z_RET, Z_RET);
 
     // VM-Call Epilogue
     __ restore_volatile_regs(Z_SP, frame::z_abi_160_size, true, false);
diff --git a/src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp b/src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp
index 684347e35fa40..cde429b03832b 100644
--- a/src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp
+++ b/src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp
@@ -325,16 +325,6 @@ void C1_MacroAssembler::remove_frame(int frame_size_in_bytes) {
 
 
 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
-  if (breakAtEntry) {
-    // Verified Entry first instruction should be 5 bytes long for correct
-    // patching by patch_verified_entry().
-    //
-    // Breakpoint has one byte first instruction.
-    // Also first instruction will be one byte "push(rbp)" if stack banging
-    // code is not generated (see build_frame() above).
-    // For all these cases generate long instruction first.
-    fat_nop();
-  }
   if (breakAtEntry) int3();
   // build frame
 }
diff --git a/src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp b/src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp
index 177be6e59f74a..a0ff36df2ea97 100644
--- a/src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp
+++ b/src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp
@@ -50,13 +50,6 @@
 
 // C2 compiled method's prolog code.
 void C2_MacroAssembler::verified_entry(int framesize, int stack_bang_size, bool fp_mode_24b, bool is_stub) {
-
-  // WARNING: Initial instruction MUST be 5 bytes or longer so that
-  // NativeJump::patch_verified_entry will be able to patch out the entry
-  // code safely. The push to verify stack depth is ok at 5 bytes,
-  // the frame allocation can be either 3 or 6 bytes. So if we don't do
-  // stack bang then we must use the 6 byte frame allocation even if
-  // we have no frame. :-(
   assert(stack_bang_size >= framesize || stack_bang_size <= 0, "stack bang size incorrect");
 
   assert((framesize & (StackAlignmentInBytes-1)) == 0, "frame size not aligned");
@@ -87,8 +80,7 @@ void C2_MacroAssembler::verified_entry(int framesize, int stack_bang_size, bool
       subptr(rsp, framesize);
     }
   } else {
-    // Create frame (force generation of a 4 byte immediate value)
-    subptr_imm32(rsp, framesize);
+    subptr(rsp, framesize);
 
     // Save RBP register now.
     framesize -= wordSize;
diff --git a/src/hotspot/cpu/x86/macroAssembler_x86.cpp b/src/hotspot/cpu/x86/macroAssembler_x86.cpp
index 803bce4894589..c401863d7cdc8 100644
--- a/src/hotspot/cpu/x86/macroAssembler_x86.cpp
+++ b/src/hotspot/cpu/x86/macroAssembler_x86.cpp
@@ -1621,19 +1621,6 @@ void MacroAssembler::post_call_nop() {
   emit_int32(0x00);
 }
 
-// A 5 byte nop that is safe for patching (see patch_verified_entry)
-void MacroAssembler::fat_nop() {
-  if (UseAddressNop) {
-    addr_nop_5();
-  } else {
-    emit_int8((uint8_t)0x26); // es:
-    emit_int8((uint8_t)0x2e); // cs:
-    emit_int8((uint8_t)0x64); // fs:
-    emit_int8((uint8_t)0x65); // gs:
-    emit_int8((uint8_t)0x90);
-  }
-}
-
 void MacroAssembler::mulpd(XMMRegister dst, AddressLiteral src, Register rscratch) {
   assert(rscratch != noreg || always_reachable(src), "missing");
   if (reachable(src)) {
diff --git a/src/hotspot/cpu/x86/macroAssembler_x86.hpp b/src/hotspot/cpu/x86/macroAssembler_x86.hpp
index f7ac6fb4297ea..d75c9b624fd3a 100644
--- a/src/hotspot/cpu/x86/macroAssembler_x86.hpp
+++ b/src/hotspot/cpu/x86/macroAssembler_x86.hpp
@@ -209,8 +209,6 @@ class MacroAssembler: public Assembler {
   void align(uint modulus, uint target);
 
   void post_call_nop();
-  // A 5 byte nop that is safe for patching (see patch_verified_entry)
-  void fat_nop();
 
   // Stack frame creation/removal
   void enter();
diff --git a/src/hotspot/cpu/x86/nativeInst_x86.cpp b/src/hotspot/cpu/x86/nativeInst_x86.cpp
index c3345be2172f1..aad1f77e17346 100644
--- a/src/hotspot/cpu/x86/nativeInst_x86.cpp
+++ b/src/hotspot/cpu/x86/nativeInst_x86.cpp
@@ -336,55 +336,6 @@ void NativeJump::insert(address code_pos, address entry) {
   ICache::invalidate_range(code_pos, instruction_size);
 }
 
-void NativeJump::check_verified_entry_alignment(address entry, address verified_entry) {
-  // Patching to not_entrant can happen while activations of the method are
-  // in use. The patching in that instance must happen only when certain
-  // alignment restrictions are true. These guarantees check those
-  // conditions.
-  const int linesize = 64;
-
-  // Must be wordSize aligned
-  guarantee(((uintptr_t) verified_entry & (wordSize -1)) == 0,
-            "illegal address for code patching 2");
-  // First 5 bytes must be within the same cache line - 4827828
-  guarantee((uintptr_t) verified_entry / linesize ==
-            ((uintptr_t) verified_entry + 4) / linesize,
-            "illegal address for code patching 3");
-}
-
-
-// MT safe inserting of a jump over an unknown instruction sequence (used by nmethod::make_not_entrant)
-// The problem: jmp <dest> is a 5-byte instruction. Atomic write can be only with 4 bytes.
-// First patches the first word atomically to be a jump to itself.
-// Then patches the last byte  and then atomically patches the first word (4-bytes),
-// thus inserting the desired jump
-// This code is mt-safe with the following conditions: entry point is 4 byte aligned,
-// entry point is in same cache line as unverified entry point, and the instruction being
-// patched is >= 5 byte (size of patch).
-//
-// In C2 the 5+ byte sized instruction is enforced by code in MachPrologNode::emit.
-// In C1 the restriction is enforced by CodeEmitter::method_entry
-// In JVMCI, the restriction is enforced by HotSpotFrameContext.enter(...)
-//
-void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) {
-  // complete jump instruction (to be inserted) is in code_buffer;
-  union {
-    jlong cb_long;
-    unsigned char code_buffer[8];
-  } u;
-
-  u.cb_long = *(jlong *)verified_entry;
-
-  intptr_t disp = (intptr_t)dest - ((intptr_t)verified_entry + 1 + 4);
-  guarantee(disp == (intptr_t)(int32_t)disp, "must be 32-bit offset");
-
-  u.code_buffer[0] = instruction_code;
-  *(int32_t*)(u.code_buffer + 1) = (int32_t)disp;
-
-  Atomic::store((jlong *) verified_entry, u.cb_long);
-  ICache::invalidate_range(verified_entry, 8);
-}
-
 void NativeIllegalInstruction::insert(address code_pos) {
   assert(NativeIllegalInstruction::instruction_size == sizeof(short), "right address unit for update");
   *(short *)code_pos = instruction_code;
diff --git a/src/hotspot/cpu/x86/nativeInst_x86.hpp b/src/hotspot/cpu/x86/nativeInst_x86.hpp
index b2448cb99fdb0..3e76700648010 100644
--- a/src/hotspot/cpu/x86/nativeInst_x86.hpp
+++ b/src/hotspot/cpu/x86/nativeInst_x86.hpp
@@ -445,9 +445,6 @@ class NativeJump: public NativeInstruction {
 
   // Insertion of native jump instruction
   static void insert(address code_pos, address entry);
-  // MT-safe insertion of native jump at verified method entry
-  static void check_verified_entry_alignment(address entry, address verified_entry);
-  static void patch_verified_entry(address entry, address verified_entry, address dest);
 };
 
 inline NativeJump* nativeJump_at(address address) {
diff --git a/src/hotspot/cpu/zero/nativeInst_zero.cpp b/src/hotspot/cpu/zero/nativeInst_zero.cpp
deleted file mode 100644
index 0d2747f7fa698..0000000000000
--- a/src/hotspot/cpu/zero/nativeInst_zero.cpp
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2008 Red Hat, Inc.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#include "asm/assembler.inline.hpp"
-#include "entry_zero.hpp"
-#include "interpreter/zero/zeroInterpreter.hpp"
-#include "nativeInst_zero.hpp"
-#include "runtime/sharedRuntime.hpp"
-
-// This method is called by nmethod::make_not_entrant to
-// insert a jump to SharedRuntime::get_handle_wrong_method_stub()
-// (dest) at the start of a compiled method (verified_entry) to avoid
-// a race where a method is invoked while being made non-entrant.
-
-void NativeJump::patch_verified_entry(address entry,
-                                      address verified_entry,
-                                      address dest) {
-  assert(dest == SharedRuntime::get_handle_wrong_method_stub(), "should be");
-
-  ((ZeroEntry*) verified_entry)->set_entry_point(
-    (address) ZeroInterpreter::normal_entry);
-}
diff --git a/src/hotspot/cpu/zero/nativeInst_zero.hpp b/src/hotspot/cpu/zero/nativeInst_zero.hpp
index fd8f03f1a59bf..399a8e96bc3bf 100644
--- a/src/hotspot/cpu/zero/nativeInst_zero.hpp
+++ b/src/hotspot/cpu/zero/nativeInst_zero.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2007 Red Hat, Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -177,14 +177,6 @@ class NativeJump : public NativeInstruction {
   void set_jump_destination(address dest) {
     ShouldNotCallThis();
   }
-
-  static void check_verified_entry_alignment(address entry,
-                                             address verified_entry) {
-  }
-
-  static void patch_verified_entry(address entry,
-                                   address verified_entry,
-                                   address dest);
 };
 
 inline NativeJump* nativeJump_at(address address) {
diff --git a/src/hotspot/os/windows/os_windows.cpp b/src/hotspot/os/windows/os_windows.cpp
index 9e536d2df97aa..24969683a1fab 100644
--- a/src/hotspot/os/windows/os_windows.cpp
+++ b/src/hotspot/os/windows/os_windows.cpp
@@ -2752,19 +2752,6 @@ LONG WINAPI topLevelExceptionFilter(struct _EXCEPTION_POINTERS* exceptionInfo) {
       }
     }
 
-#ifdef _M_ARM64
-    if (in_java &&
-        (exception_code == EXCEPTION_ILLEGAL_INSTRUCTION ||
-          exception_code == EXCEPTION_ILLEGAL_INSTRUCTION_2)) {
-      if (nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant");
-        }
-        return Handle_Exception(exceptionInfo, SharedRuntime::get_handle_wrong_method_stub());
-      }
-    }
-#endif
-
     if (in_java) {
       switch (exception_code) {
       case EXCEPTION_INT_DIVIDE_BY_ZERO:
diff --git a/src/hotspot/os_cpu/aix_ppc/os_aix_ppc.cpp b/src/hotspot/os_cpu/aix_ppc/os_aix_ppc.cpp
index 3dbb8adddd62e..98b17aaacfcde 100644
--- a/src/hotspot/os_cpu/aix_ppc/os_aix_ppc.cpp
+++ b/src/hotspot/os_cpu/aix_ppc/os_aix_ppc.cpp
@@ -229,16 +229,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
 
       CodeBlob *cb = nullptr;
       int stop_type = -1;
-      // Handle signal from NativeJump::patch_verified_entry().
-      if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant");
-        }
-        stub = SharedRuntime::get_handle_wrong_method_stub();
-        goto run_stub;
-      }
-
-      else if ((sig == (USE_POLL_BIT_ONLY ? SIGTRAP : SIGSEGV)) &&
+      if ((sig == (USE_POLL_BIT_ONLY ? SIGTRAP : SIGSEGV)) &&
                ((NativeInstruction*)pc)->is_safepoint_poll() &&
                CodeCache::contains((void*) pc) &&
                ((cb = CodeCache::find_blob(pc)) != nullptr) &&
diff --git a/src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp b/src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp
index ad32ee150e8a3..b7556ca69da79 100644
--- a/src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp
+++ b/src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp
@@ -271,14 +271,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
       // Java thread running in Java code => find exception handler if any
       // a fault inside compiled code, the interpreter, or a stub
 
-      // Handle signal from NativeJump::patch_verified_entry().
-      if ((sig == SIGILL)
-          && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant");
-        }
-        stub = SharedRuntime::get_handle_wrong_method_stub();
-      } else if ((sig == SIGSEGV || sig == SIGBUS) && SafepointMechanism::is_poll_address((address)info->si_addr)) {
+      if ((sig == SIGSEGV || sig == SIGBUS) && SafepointMechanism::is_poll_address((address)info->si_addr)) {
         stub = SharedRuntime::get_poll_stub(pc);
 #if defined(__APPLE__)
       // 32-bit Darwin reports a SIGBUS for nearly all memory access exceptions.
diff --git a/src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp b/src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp
index 6900283418d58..e565f353382e2 100644
--- a/src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp
+++ b/src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp
@@ -232,14 +232,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
       // Java thread running in Java code => find exception handler if any
       // a fault inside compiled code, the interpreter, or a stub
 
-      // Handle signal from NativeJump::patch_verified_entry().
-      if ((sig == SIGILL || sig == SIGTRAP)
-          && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
-        }
-        stub = SharedRuntime::get_handle_wrong_method_stub();
-      } else if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
+      if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
         stub = SharedRuntime::get_poll_stub(pc);
       } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
         // BugId 4454115: A read from a MappedByteBuffer can fault
diff --git a/src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp b/src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp
index 6c245f8f1a6e0..28b47877264a7 100644
--- a/src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp
+++ b/src/hotspot/os_cpu/linux_arm/os_linux_arm.cpp
@@ -359,11 +359,6 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
           stub = SharedRuntime::continuation_for_implicit_exception(
               thread, pc, SharedRuntime::IMPLICIT_NULL);
         }
-      } else if (sig == SIGILL &&
-                 *(int*)pc ==
-                     NativeInstruction::not_entrant_illegal_instruction) {
-        // Not entrant
-        stub = SharedRuntime::get_handle_wrong_method_stub();
       }
     } else if ((thread->thread_state() == _thread_in_vm ||
                 thread->thread_state() == _thread_in_native) &&
diff --git a/src/hotspot/os_cpu/linux_ppc/os_linux_ppc.cpp b/src/hotspot/os_cpu/linux_ppc/os_linux_ppc.cpp
index 5fe37be0d2012..556189471436a 100644
--- a/src/hotspot/os_cpu/linux_ppc/os_linux_ppc.cpp
+++ b/src/hotspot/os_cpu/linux_ppc/os_linux_ppc.cpp
@@ -258,15 +258,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
 
       CodeBlob *cb = nullptr;
       int stop_type = -1;
-      // Handle signal from NativeJump::patch_verified_entry().
-      if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant");
-        }
-        stub = SharedRuntime::get_handle_wrong_method_stub();
-      }
-
-      else if ((sig == (USE_POLL_BIT_ONLY ? SIGTRAP : SIGSEGV)) &&
+      if ((sig == (USE_POLL_BIT_ONLY ? SIGTRAP : SIGSEGV)) &&
                // A linux-ppc64 kernel before 2.6.6 doesn't set si_addr on some segfaults
                // in 64bit mode (cf. http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.6),
                // especially when we try to read from the safepoint polling page. So the check
diff --git a/src/hotspot/os_cpu/linux_riscv/os_linux_riscv.cpp b/src/hotspot/os_cpu/linux_riscv/os_linux_riscv.cpp
index 8366a7249fa4f..7a5929b0f412b 100644
--- a/src/hotspot/os_cpu/linux_riscv/os_linux_riscv.cpp
+++ b/src/hotspot/os_cpu/linux_riscv/os_linux_riscv.cpp
@@ -223,14 +223,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
       // Java thread running in Java code => find exception handler if any
       // a fault inside compiled code, the interpreter, or a stub
 
-      // Handle signal from NativeJump::patch_verified_entry().
-      if ((sig == SIGILL || sig == SIGTRAP)
-          && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant (%s)", (sig == SIGTRAP) ? "SIGTRAP" : "SIGILL");
-        }
-        stub = SharedRuntime::get_handle_wrong_method_stub();
-      } else if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
+      if (sig == SIGSEGV && SafepointMechanism::is_poll_address((address)info->si_addr)) {
         stub = SharedRuntime::get_poll_stub(pc);
       } else if (sig == SIGBUS /* && info->si_code == BUS_OBJERR */) {
         // BugId 4454115: A read from a MappedByteBuffer can fault
diff --git a/src/hotspot/os_cpu/linux_s390/os_linux_s390.cpp b/src/hotspot/os_cpu/linux_s390/os_linux_s390.cpp
index 7e4d72fc0667c..4e074512e34ad 100644
--- a/src/hotspot/os_cpu/linux_s390/os_linux_s390.cpp
+++ b/src/hotspot/os_cpu/linux_s390/os_linux_s390.cpp
@@ -257,15 +257,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
       // Java thread running in Java code => find exception handler if any
       // a fault inside compiled code, the interpreter, or a stub
 
-      // Handle signal from NativeJump::patch_verified_entry().
-      if (sig == SIGILL && nativeInstruction_at(pc)->is_sigill_not_entrant()) {
-        if (TraceTraps) {
-          tty->print_cr("trap: not_entrant (SIGILL)");
-        }
-        stub = SharedRuntime::get_handle_wrong_method_stub();
-      }
-
-      else if (sig == SIGSEGV &&
+      if (sig == SIGSEGV &&
                SafepointMechanism::is_poll_address((address)info->si_addr)) {
         if (TraceTraps) {
           tty->print_cr("trap: safepoint_poll at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
diff --git a/src/hotspot/share/code/nmethod.cpp b/src/hotspot/share/code/nmethod.cpp
index acebaae6ba4f8..4e7e091311967 100644
--- a/src/hotspot/share/code/nmethod.cpp
+++ b/src/hotspot/share/code/nmethod.cpp
@@ -28,7 +28,6 @@
 #include "code/dependencies.hpp"
 #include "code/nativeInst.hpp"
 #include "code/nmethod.inline.hpp"
-#include "code/relocInfo.hpp"
 #include "code/scopeDesc.hpp"
 #include "compiler/abstractCompiler.hpp"
 #include "compiler/compilationLog.hpp"
@@ -692,13 +691,6 @@ address nmethod::oops_reloc_begin() const {
   }
 
   address low_boundary = verified_entry_point();
-  if (!is_in_use()) {
-    low_boundary += NativeJump::instruction_size;
-    // %%% Note:  On SPARC we patch only a 4-byte trap, not a full NativeJump.
-    // This means that the low_boundary is going to be a little too high.
-    // This shouldn't matter, since oops of non-entrant methods are never used.
-    // In fact, why are we bothering to look at oops in a non-entrant method??
-  }
   return low_boundary;
 }
 
@@ -1653,10 +1645,6 @@ void nmethod::maybe_print_nmethod(const DirectiveSet* directive) {
 }
 
 void nmethod::print_nmethod(bool printmethod) {
-  // Enter a critical section to prevent a race with deopts that patch code and updates the relocation info.
-  // Unfortunately, we have to lock the NMethodState_lock before the tty lock due to the deadlock rules and
-  // cannot lock in a more finely grained manner.
-  ConditionalMutexLocker ml(NMethodState_lock, !NMethodState_lock->owned_by_self(), Mutex::_no_safepoint_check_flag);
   ttyLocker ttyl;  // keep the following output all in one block
   if (xtty != nullptr) {
     xtty->begin_head("print_nmethod");
@@ -2040,19 +2028,7 @@ bool nmethod::make_not_entrant(ChangeReason change_reason) {
     } else {
       // The caller can be calling the method statically or through an inline
       // cache call.
-      NativeJump::patch_verified_entry(entry_point(), verified_entry_point(),
-                                       SharedRuntime::get_handle_wrong_method_stub());
-
-      // Update the relocation info for the patched entry.
-      // First, get the old relocation info...
-      RelocIterator iter(this, verified_entry_point(), verified_entry_point() + 8);
-      if (iter.next() && iter.addr() == verified_entry_point()) {
-        Relocation* old_reloc = iter.reloc();
-        // ...then reset the iterator to update it.
-        RelocIterator iter(this, verified_entry_point(), verified_entry_point() + 8);
-        relocInfo::change_reloc_info_for_address(&iter, verified_entry_point(), old_reloc->type(),
-                                                 relocInfo::relocType::runtime_call_type);
-      }
+      BarrierSet::barrier_set()->barrier_set_nmethod()->make_not_entrant(this);
     }
 
     if (update_recompile_counts()) {
@@ -2942,9 +2918,6 @@ void nmethod::verify() {
   if (is_not_entrant())
     return;
 
-  // Make sure all the entry points are correctly aligned for patching.
-  NativeJump::check_verified_entry_alignment(entry_point(), verified_entry_point());
-
   // assert(oopDesc::is_oop(method()), "must be valid");
 
   ResourceMark rm;
diff --git a/src/hotspot/share/gc/shared/barrierSetNMethod.cpp b/src/hotspot/share/gc/shared/barrierSetNMethod.cpp
index 41eb0a24b625a..522000e0a99e6 100644
--- a/src/hotspot/share/gc/shared/barrierSetNMethod.cpp
+++ b/src/hotspot/share/gc/shared/barrierSetNMethod.cpp
@@ -72,11 +72,25 @@ bool BarrierSetNMethod::supports_entry_barrier(nmethod* nm) {
 }
 
 void BarrierSetNMethod::disarm(nmethod* nm) {
-  set_guard_value(nm, disarmed_guard_value());
+  guard_with(nm, disarmed_guard_value());
+}
+
+void BarrierSetNMethod::guard_with(nmethod* nm, int value) {
+  assert((value & not_entrant) == 0, "not_entrant bit is reserved");
+  // Enter critical section.  Does not block for safepoint.
+  ConditionalMutexLocker ml(NMethodEntryBarrier_lock, !NMethodEntryBarrier_lock->owned_by_self(), Mutex::_no_safepoint_check_flag);
+  // Do not undo sticky bit
+  if (is_not_entrant(nm)) {
+    value |= not_entrant;
+  }
+  if (guard_value(nm) != value) {
+    // Patch the code only if needed.
+    set_guard_value(nm, value);
+  }
 }
 
 bool BarrierSetNMethod::is_armed(nmethod* nm) {
-  return guard_value(nm) != disarmed_guard_value();
+  return (guard_value(nm) & ~not_entrant) != disarmed_guard_value();
 }
 
 bool BarrierSetNMethod::nmethod_entry_barrier(nmethod* nm) {
@@ -152,7 +166,7 @@ void BarrierSetNMethod::arm_all_nmethods() {
   // seriously wrong.
   ++_current_phase;
   if (_current_phase == INT_MAX) {
-    _current_phase = 1;
+    _current_phase = initial;
   }
   BarrierSetNMethodArmClosure cl(_current_phase);
   Threads::threads_do(&cl);
@@ -178,23 +192,25 @@ int BarrierSetNMethod::nmethod_stub_entry_barrier(address* return_address_ptr) {
   BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
 
   // Called upon first entry after being armed
-  bool may_enter = bs_nm->nmethod_entry_barrier(nm);
+  bool may_enter = !bs_nm->is_not_entrant(nm) && bs_nm->nmethod_entry_barrier(nm);
   assert(!nm->is_osr_method() || may_enter, "OSR nmethods should always be entrant after migration");
 
-  // In case a concurrent thread disarmed the nmethod, we need to ensure the new instructions
-  // are made visible, by using a cross modify fence. Note that this is synchronous cross modifying
-  // code, where the existence of new instructions is communicated via data (the guard value).
-  // This cross modify fence is only needed when the nmethod entry barrier modifies the
-  // instructions. Not all platforms currently do that, so if this check becomes expensive,
-  // it can be made conditional on the nmethod_patching_type.
-  OrderAccess::cross_modify_fence();
-
-  // Diagnostic option to force deoptimization 1 in 10 times. It is otherwise
-  // a very rare event.
-  if (DeoptimizeNMethodBarriersALot && !nm->is_osr_method()) {
-    static volatile uint32_t counter=0;
-    if (Atomic::add(&counter, 1u) % 10 == 0) {
-      may_enter = false;
+  if (may_enter) {
+    // In case a concurrent thread disarmed the nmethod, we need to ensure the new instructions
+    // are made visible, by using a cross modify fence. Note that this is synchronous cross modifying
+    // code, where the existence of new instructions is communicated via data (the guard value).
+    // This cross modify fence is only needed when the nmethod entry barrier modifies the
+    // instructions. Not all platforms currently do that, so if this check becomes expensive,
+    // it can be made conditional on the nmethod_patching_type.
+    OrderAccess::cross_modify_fence();
+
+    // Diagnostic option to force deoptimization 1 in 10 times. It is otherwise
+    // a very rare event.
+    if (DeoptimizeNMethodBarriersALot && !nm->is_osr_method()) {
+      static volatile uint32_t counter=0;
+      if (Atomic::add(&counter, 1u) % 10 == 0) {
+        may_enter = false;
+      }
     }
   }
 
@@ -220,3 +236,22 @@ oop BarrierSetNMethod::oop_load_no_keepalive(const nmethod* nm, int index) {
 oop BarrierSetNMethod::oop_load_phantom(const nmethod* nm, int index) {
   return NativeAccess<ON_PHANTOM_OOP_REF>::oop_load(nm->oop_addr_at(index));
 }
+
+// Make the nmethod permanently not-entrant, so that nmethod_stub_entry_barrier() will call
+// deoptimize() to redirect the caller to SharedRuntime::get_handle_wrong_method_stub().
+// A sticky armed bit is set and other bits are preserved.  As a result, a call to
+// nmethod_stub_entry_barrier() may appear to be spurious, because is_armed() still returns
+// false and nmethod_entry_barrier() is not called.
+void BarrierSetNMethod::make_not_entrant(nmethod* nm) {
+  // Enter critical section.  Does not block for safepoint.
+  ConditionalMutexLocker ml(NMethodEntryBarrier_lock, !NMethodEntryBarrier_lock->owned_by_self(), Mutex::_no_safepoint_check_flag);
+  int value = guard_value(nm) | not_entrant;
+  if (guard_value(nm) != value) {
+    // Patch the code only if needed.
+    set_guard_value(nm, value);
+  }
+}
+
+bool BarrierSetNMethod::is_not_entrant(nmethod* nm) {
+  return (guard_value(nm) & not_entrant) != 0;
+}
diff --git a/src/hotspot/share/gc/shared/barrierSetNMethod.hpp b/src/hotspot/share/gc/shared/barrierSetNMethod.hpp
index 756dc43b3f1da..b905e8869b576 100644
--- a/src/hotspot/share/gc/shared/barrierSetNMethod.hpp
+++ b/src/hotspot/share/gc/shared/barrierSetNMethod.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,10 +36,20 @@ class nmethod;
 class BarrierSetNMethod: public CHeapObj<mtGC> {
 private:
   int _current_phase;
+  enum {
+    not_entrant = 1 << 31, // armed sticky bit, see make_not_entrant
+    armed = 0,
+    initial = 1,
+  };
+
   void deoptimize(nmethod* nm, address* return_addr_ptr);
 
+protected:
+  virtual int guard_value(nmethod* nm);
+  void set_guard_value(nmethod* nm, int value);
+
 public:
-  BarrierSetNMethod() : _current_phase(1) {}
+  BarrierSetNMethod() : _current_phase(initial) {}
   bool supports_entry_barrier(nmethod* nm);
 
   virtual bool nmethod_entry_barrier(nmethod* nm);
@@ -50,13 +60,15 @@ class BarrierSetNMethod: public CHeapObj<mtGC> {
 
   static int nmethod_stub_entry_barrier(address* return_address_ptr);
   bool nmethod_osr_entry_barrier(nmethod* nm);
-  bool is_armed(nmethod* nm);
+  virtual bool is_armed(nmethod* nm);
+  void arm(nmethod* nm) { guard_with(nm, armed); }
   void disarm(nmethod* nm);
+  virtual void make_not_entrant(nmethod* nm);
+  virtual bool is_not_entrant(nmethod* nm);
 
-  int guard_value(nmethod* nm);
-  void set_guard_value(nmethod* nm, int value);
+  virtual void guard_with(nmethod* nm, int value);
 
-  void arm_all_nmethods();
+  virtual void arm_all_nmethods();
 
   virtual oop oop_load_no_keepalive(const nmethod* nm, int index);
   virtual oop oop_load_phantom(const nmethod* nm, int index);
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
index 49d2df0cc936c..0d9077be2265b 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.cpp
@@ -150,7 +150,7 @@ class ShenandoahNMethodUnlinkClosure : public NMethodClosure {
         ShenandoahNMethod::heal_nmethod_metadata(nm_data);
         // Code cache unloading needs to know about on-stack nmethods. Arm the nmethods to get
         // mark_as_maybe_on_stack() callbacks when they are used again.
-        _bs->set_guard_value(nm, 0);
+        _bs->arm(nm);
       }
     }
 
diff --git a/src/hotspot/share/gc/z/zBarrierSetNMethod.cpp b/src/hotspot/share/gc/z/zBarrierSetNMethod.cpp
index 0d6be2b789f77..392d194a65bee 100644
--- a/src/hotspot/share/gc/z/zBarrierSetNMethod.cpp
+++ b/src/hotspot/share/gc/z/zBarrierSetNMethod.cpp
@@ -105,3 +105,36 @@ oop ZBarrierSetNMethod::oop_load_no_keepalive(const nmethod* nm, int index) {
 oop ZBarrierSetNMethod::oop_load_phantom(const nmethod* nm, int index) {
   return ZNMethod::oop_load_phantom(nm, index);
 }
+
+void ZBarrierSetNMethod::guard_with(nmethod* nm, int value) {
+  assert((value & not_entrant) == 0, "not_entrant bit is reserved");
+  ZLocker<ZReentrantLock> locker(ZNMethod::lock_for_nmethod(nm));
+  // Preserve the sticky bit
+  if (is_not_entrant(nm)) {
+    value |= not_entrant;
+  }
+  if (guard_value(nm) != value) {
+    // Patch the code only if needed.
+    set_guard_value(nm, value);
+  }
+}
+
+bool ZBarrierSetNMethod::is_armed(nmethod* nm) {
+  int value = guard_value(nm) & ~not_entrant;
+  return value != disarmed_guard_value();
+}
+
+void ZBarrierSetNMethod::make_not_entrant(nmethod* nm) {
+  ZLocker<ZReentrantLock> locker(ZNMethod::lock_for_nmethod(nm));
+  int value = guard_value(nm) | not_entrant; // permanent sticky value
+  set_guard_value(nm, value);
+}
+
+bool ZBarrierSetNMethod::is_not_entrant(nmethod* nm) {
+  return (guard_value(nm) & not_entrant) != 0;
+}
+
+uintptr_t ZBarrierSetNMethod::color(nmethod* nm) {
+  // color is stored at low order bits of int; conversion to uintptr_t is fine
+  return uintptr_t(guard_value(nm) & ~not_entrant);
+}
diff --git a/src/hotspot/share/gc/z/zBarrierSetNMethod.hpp b/src/hotspot/share/gc/z/zBarrierSetNMethod.hpp
index 780d3772123e3..e0b7ba6c773aa 100644
--- a/src/hotspot/share/gc/z/zBarrierSetNMethod.hpp
+++ b/src/hotspot/share/gc/z/zBarrierSetNMethod.hpp
@@ -30,15 +30,27 @@
 class nmethod;
 
 class ZBarrierSetNMethod : public BarrierSetNMethod {
+  enum : int {
+    not_entrant = 1 << 31, // armed sticky bit, see make_not_entrant
+  };
+
 protected:
   virtual bool nmethod_entry_barrier(nmethod* nm);
 
 public:
+  uintptr_t color(nmethod* nm);
+
   virtual ByteSize thread_disarmed_guard_value_offset() const;
   virtual int* disarmed_guard_value_address() const;
 
   virtual oop oop_load_no_keepalive(const nmethod* nm, int index);
   virtual oop oop_load_phantom(const nmethod* nm, int index);
+
+  virtual void make_not_entrant(nmethod* nm);
+  virtual bool is_not_entrant(nmethod* nm);
+  virtual void guard_with(nmethod* nm, int value);
+  virtual bool is_armed(nmethod* nm);
+  virtual void arm_all_nmethods() { ShouldNotCallThis(); }
 };
 
 #endif // SHARE_GC_Z_ZBARRIERSETNMETHOD_HPP
diff --git a/src/hotspot/share/gc/z/zMark.cpp b/src/hotspot/share/gc/z/zMark.cpp
index 9846f1244ecea..cc153bc925ad3 100644
--- a/src/hotspot/share/gc/z/zMark.cpp
+++ b/src/hotspot/share/gc/z/zMark.cpp
@@ -769,7 +769,7 @@ class ZMarkYoungNMethodClosure : public NMethodClosure {
         ZNMethod::nmethod_patch_barriers(nm);
       }
 
-      _bs_nm->set_guard_value(nm, (int)untype(new_disarm_value_ptr));
+      _bs_nm->guard_with(nm, (int)untype(new_disarm_value_ptr));
 
       if (complete_disarm) {
         log_trace(gc, nmethod)("nmethod: " PTR_FORMAT " visited by young (complete) [" PTR_FORMAT " -> " PTR_FORMAT "]", p2i(nm), prev_color, untype(new_disarm_value_ptr));
diff --git a/src/hotspot/share/gc/z/zNMethod.cpp b/src/hotspot/share/gc/z/zNMethod.cpp
index bf592c20fa296..3f65d2eea973e 100644
--- a/src/hotspot/share/gc/z/zNMethod.cpp
+++ b/src/hotspot/share/gc/z/zNMethod.cpp
@@ -241,7 +241,7 @@ void ZNMethod::disarm(nmethod* nm) {
 
 void ZNMethod::set_guard_value(nmethod* nm, int value) {
   BarrierSetNMethod* const bs = BarrierSet::barrier_set()->barrier_set_nmethod();
-  bs->set_guard_value(nm, value);
+  bs->guard_with(nm, value);
 }
 
 void ZNMethod::nmethod_patch_barriers(nmethod* nm) {
@@ -300,9 +300,8 @@ void ZNMethod::nmethods_do(bool secondary, NMethodClosure* cl) {
 }
 
 uintptr_t ZNMethod::color(nmethod* nm) {
-  BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
-  // color is stored at low order bits of int; conversion to uintptr_t is fine
-  return (uintptr_t)bs_nm->guard_value(nm);
+  ZBarrierSetNMethod* bs_nm = static_cast<ZBarrierSetNMethod*>(BarrierSet::barrier_set()->barrier_set_nmethod());
+  return bs_nm->color(nm);
 }
 
 oop ZNMethod::oop_load_no_keepalive(const nmethod* nm, int index) {
diff --git a/src/hotspot/share/runtime/mutexLocker.cpp b/src/hotspot/share/runtime/mutexLocker.cpp
index 36e0cfe112581..b90f8c23a6dca 100644
--- a/src/hotspot/share/runtime/mutexLocker.cpp
+++ b/src/hotspot/share/runtime/mutexLocker.cpp
@@ -36,6 +36,7 @@
 // Mutexes used in the VM (see comment in mutexLocker.hpp):
 
 Mutex*   NMethodState_lock            = nullptr;
+Mutex*   NMethodEntryBarrier_lock     = nullptr;
 Monitor* SystemDictionary_lock        = nullptr;
 Mutex*   InvokeMethodTypeTable_lock   = nullptr;
 Monitor* InvokeMethodIntrinsicTable_lock = nullptr;
@@ -205,6 +206,8 @@ void assert_lock_strong(const Mutex* lock) {
 void mutex_init() {
   MUTEX_DEFN(tty_lock                        , PaddedMutex  , tty);      // allow to lock in VM
 
+  MUTEX_DEFN(NMethodEntryBarrier_lock        , PaddedMutex  , service-1);
+
   MUTEX_DEFN(STS_lock                        , PaddedMonitor, nosafepoint);
 
   if (UseG1GC) {
diff --git a/src/hotspot/share/runtime/mutexLocker.hpp b/src/hotspot/share/runtime/mutexLocker.hpp
index 6baa93b257933..640747c3fe91c 100644
--- a/src/hotspot/share/runtime/mutexLocker.hpp
+++ b/src/hotspot/share/runtime/mutexLocker.hpp
@@ -34,6 +34,7 @@ class Thread;
 // Mutexes used in the VM.
 
 extern Mutex*   NMethodState_lock;               // a lock used to guard a compiled method state
+extern Mutex*   NMethodEntryBarrier_lock;        // protects nmethod entry barrier
 extern Monitor* SystemDictionary_lock;           // a lock on the system dictionary
 extern Mutex*   InvokeMethodTypeTable_lock;
 extern Monitor* InvokeMethodIntrinsicTable_lock;