diff --git a/contrib/elftoolchain/readelf/readelf.c b/contrib/elftoolchain/readelf/readelf.c
--- a/contrib/elftoolchain/readelf/readelf.c
+++ b/contrib/elftoolchain/readelf/readelf.c
@@ -1197,6 +1197,7 @@
 	case 0x102: return "NT_PPC_VSX (ppc VSX registers)";
 	case 0x202: return "NT_X86_XSTATE (x86 XSAVE extended state)";
 	case 0x400: return "NT_ARM_VFP (arm VFP registers)";
+	case 0x401: return "NT_ARM_TLS (arm TLS register)";
 	case 0x406: return "NT_ARM_ADDR_MASK (arm address mask)";
 	default: return (note_type_unknown(nt));
 	}
diff --git a/sys/arm/arm/ptrace_machdep.c b/sys/arm/arm/ptrace_machdep.c
--- a/sys/arm/arm/ptrace_machdep.c
+++ b/sys/arm/arm/ptrace_machdep.c
@@ -67,6 +67,28 @@
 ELF_REGSET(regset_arm_vfp);
 #endif
 
+static bool
+get_arm_tls(struct regset *rs, struct thread *td, void *buf,
+    size_t *sizep)
+{
+	if (buf != NULL) {
+		KASSERT(*sizep == sizeof(td->td_pcb->pcb_regs.sf_tpidrurw),
+		    ("%s: invalid size", __func__));
+		memcpy(buf, &td->td_pcb->pcb_regs.sf_tpidrurw,
+		    sizeof(td->td_pcb->pcb_regs.sf_tpidrurw));
+	}
+	*sizep = sizeof(td->td_pcb->pcb_regs.sf_tpidrurw);
+
+	return (true);
+}
+
+static struct regset regset_arm_tls = {
+	.note = NT_ARM_TLS,
+	.size = sizeof(uint32_t),
+	.get = get_arm_tls,
+};
+ELF_REGSET(regset_arm_tls);
+
 int
 cpu_ptrace(struct thread *td, int req, void *addr, int data)
 {
diff --git a/sys/arm64/arm64/ptrace_machdep.c b/sys/arm64/arm64/ptrace_machdep.c
--- a/sys/arm64/arm64/ptrace_machdep.c
+++ b/sys/arm64/arm64/ptrace_machdep.c
@@ -81,6 +81,54 @@
 ELF32_REGSET(regset_arm_vfp);
 #endif
 
+static bool
+get_arm64_tls(struct regset *rs, struct thread *td, void *buf,
+    size_t *sizep)
+{
+	if (buf != NULL) {
+		KASSERT(*sizep == sizeof(td->td_pcb->pcb_tpidr_el0),
+		    ("%s: invalid size", __func__));
+		memcpy(buf, &td->td_pcb->pcb_tpidr_el0,
+		    sizeof(td->td_pcb->pcb_tpidr_el0));
+	}
+	*sizep = sizeof(td->td_pcb->pcb_tpidr_el0);
+
+	return (true);
+}
+
+static struct regset regset_arm64_tls = {
+	.note = NT_ARM_TLS,
+	.size = sizeof(uint64_t),
+	.get = get_arm64_tls,
+};
+ELF_REGSET(regset_arm64_tls);
+
+#ifdef COMPAT_FREEBSD32
+static bool
+get_arm_tls(struct regset *rs, struct thread *td, void *buf,
+    size_t *sizep)
+{
+	if (buf != NULL) {
+		uint32_t tp;
+
+		KASSERT(*sizep == sizeof(uint32_t),
+		    ("%s: invalid size", __func__));
+		tp = (uint32_t)td->td_pcb->pcb_tpidr_el0;
+		memcpy(buf, &tp, sizeof(tp));
+	}
+	*sizep = sizeof(uint32_t);
+
+	return (true);
+}
+
+static struct regset regset_arm_tls = {
+	.note = NT_ARM_TLS,
+	.size = sizeof(uint32_t),
+	.get = get_arm_tls,
+};
+ELF32_REGSET(regset_arm_tls);
+#endif
+
 int
 ptrace_set_pc(struct thread *td, u_long addr)
 {
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -825,6 +825,7 @@
 #define	NT_PPC_VSX	0x102	/* PowerPC VSX registers */
 #define	NT_X86_XSTATE	0x202	/* x86 XSAVE extended state. */
 #define	NT_ARM_VFP	0x400	/* ARM VFP registers */
+#define	NT_ARM_TLS	0x401	/* ARM TLS register */
 #define	NT_ARM_ADDR_MASK	0x406	/* arm64 address mask (e.g. for TBI) */
 
 /* GNU note types. */
diff --git a/usr.bin/gcore/elfcore.c b/usr.bin/gcore/elfcore.c
--- a/usr.bin/gcore/elfcore.c
+++ b/usr.bin/gcore/elfcore.c
@@ -372,6 +372,9 @@
 		elf_putregnote(NT_FPREGSET, tids[i], sb);
 		elf_putnote(NT_THRMISC, elf_note_thrmisc, tids + i, sb);
 		elf_putnote(NT_PTLWPINFO, elf_note_ptlwpinfo, tids + i, sb);
+#if defined(__aarch64__) || defined(__arm__)
+		elf_putregnote(NT_ARM_TLS, tids[i], sb);
+#endif
 #if (defined(ELFCORE_COMPAT_32) && defined(__aarch64__)) || defined(__arm__)
 		elf_putregnote(NT_ARM_VFP, tids[i], sb);
 #endif