[binutils-gdb] gdb: LoongArch: Add internal TLS support

https://sourceware.org/git/gitweb.cgi?p=3Dbinutils-gdb.git;h=3D0fb12bd362c3=
87d1d8ad19616a8c4fba562a5ae3

commit 0fb12bd362c387d1d8ad19616a8c4fba562a5ae3
Author: Hui Li <[email protected]>
Date:   Mon Jul 13 18:37:24 2026 +0800

    gdb: LoongArch: Add internal TLS support
   =20
    Implements the LoongArch-specific get_tls_dtv_addr() and uses
    svr4_tls_register_tls_methods() to register it, together with
    svr4_tls_get_thread_local_address as the get_thread_local_address
    gdbarch method, to support internal TLS address lookup.
   =20
    LoongArch doesn't need get_tls_dtp_offset since musl's DTP_OFFSET
    is defined as 0.
   =20
    This is the LoongArch version of commit c34309bea22
    ("Internal TLS support for aarch64, x86_64, riscv, ppc64, and s390x").
   =20
    Depends-On: bfc3ac0d13b
    ("LoongArch: Support R_LARCH_TLS_DTPREL32/64 used in debug section")
   =20
    Before:
   =20
    make check-gdb TESTS=3D"gdb.base/tls-nothreads.exp"
    =3D=3D=3D gdb Summary =3D=3D=3D
   =20
      # of expected passes          101
      # of known failures           48
   =20
    make check-gdb TESTS=3D"gdb.base/tls-dlobj.exp"
    =3D=3D=3D gdb Summary =3D=3D=3D
   =20
      # of expected passes          261
   =20
    After:
   =20
    make check-gdb TESTS=3D"gdb.base/tls-nothreads.exp"
    =3D=3D=3D gdb Summary =3D=3D=3D
   =20
      # of expected passes          302
   =20
    make check-gdb TESTS=3D"gdb.base/tls-dlobj.exp"
    =3D=3D=3D gdb Summary =3D=3D=3D
   =20
      # of expected passes          523
   =20
    Signed-off-by: Hui Li <[email protected]>
    Approved-By: Simon Marchi <[email protected]>
    Signed-off-by: Tiezhu Yang <[email protected]>

Diff:
---
 gdb/arch/loongarch.h                      |  1 +
 gdb/configure.tgt                         |  2 +-
 gdb/loongarch-linux-tdep.c                | 53 +++++++++++++++++++++++++++=
++++
 gdb/testsuite/gdb.base/tls-common.exp.tcl |  2 +-
 4 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/gdb/arch/loongarch.h b/gdb/arch/loongarch.h
index ee9d378afd6..ec3d0d195c9 100644
--- a/gdb/arch/loongarch.h
+++ b/gdb/arch/loongarch.h
@@ -26,6 +26,7 @@
 enum loongarch_regnum
 {
   LOONGARCH_RA_REGNUM =3D 1,		/* Return Address.  */
+  LOONGARCH_TP_REGNUM =3D 2,		/* Thread Pointer.  */
   LOONGARCH_SP_REGNUM =3D 3,		/* Stack Pointer.  */
   LOONGARCH_A0_REGNUM =3D 4,		/* First Argument/Return Value.  */
   LOONGARCH_A7_REGNUM =3D 11,		/* Seventh Argument/Syscall Number.  */
diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index 362de60065c..7313b31e42a 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -374,7 +374,7 @@ loongarch*-*-linux*)
 	# Target: LoongArch running Linux
 	gdb_target_obs=3D"loongarch-linux-tdep.o glibc-tdep.o \
 			linux-tdep.o solib-svr4.o solib-svr4-linux.o \
-			linux-record.o"
+			linux-record.o svr4-tls-tdep.o"
 	;;
=20
 m32c-*-*)
diff --git a/gdb/loongarch-linux-tdep.c b/gdb/loongarch-linux-tdep.c
index bab84fd126a..4879fe1954d 100644
--- a/gdb/loongarch-linux-tdep.c
+++ b/gdb/loongarch-linux-tdep.c
@@ -26,6 +26,7 @@
 #include "linux-record.h"
 #include "linux-tdep.h"
 #include "solib-svr4-linux.h"
+#include "svr4-tls-tdep.h"
 #include "loongarch-tdep.h"
 #include "record-full.h"
 #include "regset.h"
@@ -1137,6 +1138,56 @@ init_loongarch_linux_record_tdep (struct gdbarch *gd=
barch)
   loongarch_linux_record_tdep.arg7 =3D LOONGARCH_A0_REGNUM + 6;
 }
=20
+/* Fetch and return the TLS DTV (dynamic thread vector) address for PTID.
+   Throw a suitable TLS error if something goes wrong.  */
+
+static CORE_ADDR
+loongarch_linux_get_tls_dtv_addr (struct gdbarch *gdbarch, ptid_t ptid,
+				  svr4_tls_libc libc)
+{
+  /* On LoongArch, the thread pointer is found in TP.  */
+  regcache *regcache
+    =3D get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
+  target_fetch_registers (regcache, LOONGARCH_TP_REGNUM);
+  ULONGEST thr_ptr;
+  if (regcache->cooked_read (LOONGARCH_TP_REGNUM, &thr_ptr) !=3D REG_VALID)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch thread pointer"));
+
+  CORE_ADDR dtv_ptr_addr;
+  switch (libc)
+    {
+      case svr4_tls_libc_musl:
+	/* MUSL: The DTV pointer is found at the very end of the pthread
+	   struct which is located *before* the thread pointer.  I.e.
+	   the thread pointer will be just beyond the end of the struct,
+	   so the address of the DTV pointer is found one pointer-size
+	   before the thread pointer.  */
+	dtv_ptr_addr =3D thr_ptr - (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+	break;
+      case svr4_tls_libc_glibc:
+	/* GLIBC:  The thread pointer (TP) points just beyond the end of
+	   the TCB (thread control block).  On LoongArch, this struct
+	   (tcbhead_t) is defined to contain two pointers.  The first is
+	   a pointer to the DTV and the second is a pointer to private
+	   data.  So the DTV pointer address is found two pointer-size
+	   before thread pointer.  */
+	dtv_ptr_addr =3D thr_ptr - 2 * (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_B=
IT);
+	break;
+      default:
+	throw_error (TLS_GENERIC_ERROR, _("Unknown LoongArch C library"));
+	break;
+    }
+
+  gdb::byte_vector buf (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+  if (target_read_memory (dtv_ptr_addr, buf.data (), buf.size ()) !=3D 0)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch DTV address"));
+
+  const struct builtin_type *builtin =3D builtin_type (gdbarch);
+  CORE_ADDR dtv_addr =3D gdbarch_pointer_to_address
+			 (gdbarch, builtin->builtin_data_ptr, buf.data ());
+  return dtv_addr;
+}
+
 /* Initialize LoongArch Linux ABI info.  */
=20
 static void
@@ -1158,6 +1209,8 @@ loongarch_linux_init_abi (struct gdbarch_info info, s=
truct gdbarch *gdbarch)
=20
   /* Enable TLS support.  */
   set_gdbarch_fetch_tls_load_module_address (gdbarch, svr4_fetch_objfile_l=
ink_map);
+  set_gdbarch_get_thread_local_address (gdbarch, svr4_tls_get_thread_local=
_address);
+  svr4_tls_register_tls_methods (info, gdbarch, loongarch_linux_get_tls_dt=
v_addr);
=20
   /* Prepend tramp frame unwinder for signal.  */
   tramp_frame_prepend_unwinder (gdbarch, &loongarch_linux_rt_sigframe);
diff --git a/gdb/testsuite/gdb.base/tls-common.exp.tcl b/gdb/testsuite/gdb.=
base/tls-common.exp.tcl
index 06cab649519..53ed1ca4d8a 100644
--- a/gdb/testsuite/gdb.base/tls-common.exp.tcl
+++ b/gdb/testsuite/gdb.base/tls-common.exp.tcl
@@ -26,7 +26,7 @@ require {is_any_target "*-*-linux*"}
=20
 set internal_tls_linux_targets {"x86_64-*-linux*" "aarch64-*-linux*"
 				"riscv*-*-linux*" "powerpc64*-*-linux*"
-				"s390x*-*-linux*"}
+				"s390x*-*-linux*" "loongarch*-*-linux*"}
=20
 # The "maint set force-internal-tls-address-lookup" command is only
 # available for certain Linux architectures.  Don't attempt to force