[PATCH v4 05/11] Internal TLS support for aarch64, x86_64, riscv, ppc64, and s390x

[Kevin Buettner <kevinb@redhat.com>]

For each architecture, aarch64, x86_64, riscv, ppc64, and s390x,
this commit defines a suitable 'get_tls_dtv_addr' method and,
when necessary, a 'get_tls_dtp_offset' method.

It also registers linux_get_thread_local_address, defined in
linux-tdep.c (in an earlier commit), as the get_thread_local_address
gdbarch method.  It also registers its architecture specific code
using linux_register_tls_methods().

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=24548
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31563

Reviewed-By: Luis Machado <luis.machado@arm.com>
---
 gdb/aarch64-linux-tdep.c | 55 ++++++++++++++++++++++++++++
 gdb/amd64-linux-tdep.c   | 37 +++++++++++++++++++
 gdb/ppc-linux-tdep.c     | 62 ++++++++++++++++++++++++++++++++
 gdb/riscv-linux-tdep.c   | 78 ++++++++++++++++++++++++++++++++++++++++
 gdb/s390-linux-tdep.c    | 43 ++++++++++++++++++++++
 5 files changed, 275 insertions(+)

diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index c608a84bc71..89423a233f2 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -35,6 +35,7 @@
 #include "target/target.h"
 #include "expop.h"
 #include "auxv.h"
+#include "inferior.h"
 
 #include "regcache.h"
 #include "regset.h"
@@ -2693,6 +2694,57 @@ aarch64_use_target_description_from_corefile_notes (gdbarch *gdbarch,
   return true;
 }
 
+/* Fetch and return the TLS DTV (dynamic thread vector) address for PTID.
+   Throw a suitable TLS error if something goes wrong.  */
+
+static CORE_ADDR
+aarch64_linux_get_tls_dtv_addr (struct gdbarch *gdbarch, ptid_t ptid,
+				linux_libc libc)
+{
+  /* On aarch64, the thread pointer is found in the TPIDR register. 
+     Note that this is the first register in the TLS feature - see
+     features/aarch64-tls.c - and it will always be present.  */
+  regcache *regcache
+    = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
+  aarch64_gdbarch_tdep *tdep = gdbarch_tdep<aarch64_gdbarch_tdep> (gdbarch);
+  target_fetch_registers (regcache, tdep->tls_regnum_base);
+  ULONGEST thr_ptr;
+  if (regcache->cooked_read (tdep->tls_regnum_base, &thr_ptr) != REG_VALID)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch thread pointer"));
+
+  CORE_ADDR dtv_ptr_addr;
+  switch (libc)
+    {
+    case linux_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 = thr_ptr - (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+      break;
+    case linux_libc_glibc:
+      /* GLIBC: The thread pointer (tpidr) points at the TCB (thread control
+	 block).  On aarch64, 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 the same as the thread pointer.  */
+      dtv_ptr_addr = thr_ptr;
+      break;
+    default:
+      throw_error (TLS_GENERIC_ERROR, _("Unknown aarch64 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 ()) != 0)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch DTV address"));
+
+  const struct builtin_type *builtin = builtin_type (gdbarch);
+  CORE_ADDR dtv_addr = gdbarch_pointer_to_address
+			 (gdbarch, builtin->builtin_data_ptr, buf.data ());
+  return dtv_addr;
+}
+
 static void
 aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -2714,6 +2766,9 @@ aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* Enable TLS support.  */
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 					     svr4_fetch_objfile_link_map);
+  set_gdbarch_get_thread_local_address (gdbarch,
+					linux_get_thread_local_address);
+  linux_register_tls_methods (info, gdbarch, aarch64_linux_get_tls_dtv_addr);
 
   /* Shared library handling.  */
   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
index 77de8211d86..7512448d987 100644
--- a/gdb/amd64-linux-tdep.c
+++ b/gdb/amd64-linux-tdep.c
@@ -34,6 +34,7 @@
 #include "i386-linux-tdep.h"
 #include "linux-tdep.h"
 #include "gdbsupport/x86-xstate.h"
+#include "inferior.h"
 
 #include "amd64-tdep.h"
 #include "solib-svr4.h"
@@ -1767,6 +1768,39 @@ amd64_dtrace_parse_probe_argument (struct gdbarch *gdbarch,
     }
 }
 
+/* Fetch and return the TLS DTV (dynamic thread vector) address for PTID.
+   Throw a suitable TLS error if something goes wrong.  */
+
+static CORE_ADDR
+amd64_linux_get_tls_dtv_addr (struct gdbarch *gdbarch, ptid_t ptid,
+			      enum linux_libc libc)
+{
+  /* On x86-64, the thread pointer is found in the fsbase register.  */
+  regcache *regcache
+    = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
+  target_fetch_registers (regcache, AMD64_FSBASE_REGNUM);
+  ULONGEST fsbase;
+  if (regcache->cooked_read (AMD64_FSBASE_REGNUM, &fsbase) != REG_VALID)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch thread pointer"));
+
+  /* The thread pointer (fsbase) points at the TCB (thread control
+     block).  The first two members of this struct are both pointers,
+     where the first will be a pointer to the TCB (i.e. it points at
+     itself) and the second will be a pointer to the DTV (dynamic
+     thread vector).  There are many other fields too, but the one
+     we care about here is the DTV pointer.  Compute the address
+     of the DTV pointer, fetch it, and convert it to an address.  */
+  CORE_ADDR dtv_ptr_addr = fsbase + gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
+  gdb::byte_vector buf (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+  if (target_read_memory (dtv_ptr_addr, buf.data (), buf.size ()) != 0)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch DTV address"));
+
+  const struct builtin_type *builtin = builtin_type (gdbarch);
+  CORE_ADDR dtv_addr = gdbarch_pointer_to_address
+			 (gdbarch, builtin->builtin_data_ptr, buf.data ());
+  return dtv_addr;
+}
+
 static void
 amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch,
 			    int num_disp_step_buffers)
@@ -1797,6 +1831,9 @@ amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch,
   /* Enable TLS support.  */
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 					     svr4_fetch_objfile_link_map);
+  set_gdbarch_get_thread_local_address (gdbarch,
+					linux_get_thread_local_address);
+  linux_register_tls_methods (info, gdbarch, amd64_linux_get_tls_dtv_addr);
 
   /* GNU/Linux uses SVR4-style shared libraries.  */
   set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index 8a5eea765c2..42a4bc71263 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -2070,6 +2070,63 @@ ppc64_linux_gcc_target_options (struct gdbarch *gdbarch)
   return "";
 }
 
+/* Fetch and return the TLS DTV (dynamic thread vector) address for PTID.
+   Throw a suitable TLS error if something goes wrong.  */
+
+static CORE_ADDR
+ppc64_linux_get_tls_dtv_addr (struct gdbarch *gdbarch, ptid_t ptid,
+			      enum linux_libc libc)
+{
+  /* On ppc64, the thread pointer is found in r13.  Fetch this
+     register.  */
+  regcache *regcache
+    = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
+  int thread_pointer_regnum = PPC_R0_REGNUM + 13;
+  target_fetch_registers (regcache, thread_pointer_regnum);
+  ULONGEST thr_ptr;
+  if (regcache->cooked_read (thread_pointer_regnum, &thr_ptr) != REG_VALID)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch thread pointer"));
+
+  /* The thread pointer (r13) is an address that is 0x7000 ahead of
+     the *end* of the TCB (thread control block).  The field
+     holding the DTV address is at the very end of the TCB. 
+     Therefore, the DTV pointer address can be found by
+     subtracting (0x7000+8) from the thread pointer.  Compute the
+     address of the DTV pointer, fetch it, and convert it to an
+     address.  */
+  CORE_ADDR dtv_ptr_addr = thr_ptr - 0x7000 - 8;
+  gdb::byte_vector buf (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+  if (target_read_memory (dtv_ptr_addr, buf.data (), buf.size ()) != 0)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch DTV address"));
+
+  const struct builtin_type *builtin = builtin_type (gdbarch);
+  CORE_ADDR dtv_addr = gdbarch_pointer_to_address
+			 (gdbarch, builtin->builtin_data_ptr, buf.data ());
+  return dtv_addr;
+}
+
+/* For internal TLS lookup, return the DTP offset, which is the offset
+   to subtract from a DTV entry, in order to obtain the address of the
+   TLS block.  */
+
+static ULONGEST
+ppc_linux_get_tls_dtp_offset (struct gdbarch *gdbarch, ptid_t ptid,
+			      linux_libc libc)
+{
+  if (libc == linux_libc_musl)
+    {
+      /* This value is DTP_OFFSET, which represents the value to
+	 subtract from the DTV entry.  For PPC, it can be found in
+	 MUSL's arch/powerpc64/pthread_arch.h and
+	 arch/powerpc32/pthread_arch.h.  (Both values are the same.)
+	 It represents the value to subtract from the DTV entry, once
+	 it has been fetched from the DTV array.  */
+      return 0x8000;
+    }
+  else
+    return 0;
+}
+
 static displaced_step_prepare_status
 ppc_linux_displaced_step_prepare  (gdbarch *arch, thread_info *thread,
 				   CORE_ADDR &displaced_pc)
@@ -2283,6 +2340,11 @@ ppc_linux_init_abi (struct gdbarch_info info,
 	set_gdbarch_gnu_triplet_regexp (gdbarch, ppc64_gnu_triplet_regexp);
       /* Set GCC target options.  */
       set_gdbarch_gcc_target_options (gdbarch, ppc64_linux_gcc_target_options);
+      /* Internal thread local address support.  */
+      set_gdbarch_get_thread_local_address (gdbarch,
+					    linux_get_thread_local_address);
+      linux_register_tls_methods (info, gdbarch, ppc64_linux_get_tls_dtv_addr,
+				  ppc_linux_get_tls_dtp_offset);
     }
 
   set_gdbarch_core_read_description (gdbarch, ppc_linux_core_read_description);
diff --git a/gdb/riscv-linux-tdep.c b/gdb/riscv-linux-tdep.c
index ff478cf4c28..31d90a32ce4 100644
--- a/gdb/riscv-linux-tdep.c
+++ b/gdb/riscv-linux-tdep.c
@@ -25,6 +25,7 @@
 #include "tramp-frame.h"
 #include "trad-frame.h"
 #include "gdbarch.h"
+#include "inferior.h"
 
 /* The following value is derived from __NR_rt_sigreturn in
    <include/uapi/asm-generic/unistd.h> from the Linux source tree.  */
@@ -173,6 +174,79 @@ riscv_linux_syscall_next_pc (const frame_info_ptr &frame)
   return pc + 4 /* Length of the ECALL insn.  */;
 }
 
+/* Fetch and return the TLS DTV (dynamic thread vector) address for PTID.
+   Throw a suitable TLS error if something goes wrong.  */
+
+static CORE_ADDR
+riscv_linux_get_tls_dtv_addr (struct gdbarch *gdbarch, ptid_t ptid,
+			      linux_libc libc)
+{
+  /* On RISC-V, the thread pointer is found in TP.  */
+  regcache *regcache
+    = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
+  int thread_pointer_regnum = RISCV_TP_REGNUM;
+  target_fetch_registers (regcache, thread_pointer_regnum);
+  ULONGEST thr_ptr;
+  if (regcache->cooked_read (thread_pointer_regnum, &thr_ptr) != REG_VALID)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch thread pointer"));
+
+  CORE_ADDR dtv_ptr_addr;
+  switch (libc)
+    {
+      case linux_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
+	  = thr_ptr - (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+	break;
+      case linux_libc_glibc:
+	/* GLIBC:  The thread pointer (TP) points just beyond the end of
+	   the TCB (thread control block).  On RISC-V, 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 16 bytes (i.e. the size of
+	   two pointers) before thread pointer.  */
+
+	dtv_ptr_addr
+	  = thr_ptr - 2 * (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+	break;
+      default:
+	throw_error (TLS_GENERIC_ERROR, _("Unknown RISC-V 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 ()) != 0)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch DTV address"));
+
+  const struct builtin_type *builtin = builtin_type (gdbarch);
+  CORE_ADDR dtv_addr = gdbarch_pointer_to_address
+			 (gdbarch, builtin->builtin_data_ptr, buf.data ());
+  return dtv_addr;
+}
+
+/* For internal TLS lookup, return the DTP offset, which is the offset
+   to subtract from a DTV entry, in order to obtain the address of the
+   TLS block.  */
+
+static ULONGEST
+riscv_linux_get_tls_dtp_offset (struct gdbarch *gdbarch, ptid_t ptid,
+				linux_libc libc)
+{
+  if (libc == linux_libc_musl)
+    {
+      /* This value is DTP_OFFSET in MUSL's arch/riscv64/pthread_arch.h.
+	 It represents the value to subtract from the DTV entry, once
+	 it has been loaded.  */
+      return 0x800;
+    }
+  else
+    return 0;
+}
+
 /* Initialize RISC-V Linux ABI info.  */
 
 static void
@@ -198,6 +272,10 @@ riscv_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* Enable TLS support.  */
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 					     svr4_fetch_objfile_link_map);
+  set_gdbarch_get_thread_local_address (gdbarch,
+					linux_get_thread_local_address);
+  linux_register_tls_methods (info, gdbarch, riscv_linux_get_tls_dtv_addr,
+			      riscv_linux_get_tls_dtp_offset);
 
   set_gdbarch_iterate_over_regset_sections
     (gdbarch, riscv_linux_iterate_over_regset_sections);
diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c
index bc1db550d2e..17055d9f7b5 100644
--- a/gdb/s390-linux-tdep.c
+++ b/gdb/s390-linux-tdep.c
@@ -40,6 +40,7 @@
 #include "target.h"
 #include "trad-frame.h"
 #include "xml-syscall.h"
+#include "inferior.h"
 
 #include "features/s390-linux32v1.c"
 #include "features/s390-linux32v2.c"
@@ -1123,6 +1124,45 @@ s390_init_linux_record_tdep (struct linux_record_tdep *record_tdep,
   record_tdep->ioctl_FIOQSIZE = 0x545e;
 }
 
+/* Fetch and return the TLS DTV (dynamic thread vector) address for PTID.
+   Throw a suitable TLS error if something goes wrong.  */
+
+static CORE_ADDR
+s390_linux_get_tls_dtv_addr (struct gdbarch *gdbarch, ptid_t ptid,
+			     enum linux_libc libc)
+{
+  /* On S390, the thread pointer is found in two registers A0 and A1
+     (or, using gdb naming, acr0 and acr1) A0 contains the top 32
+     bits of the address and A1 contains the bottom 32 bits.  */
+  regcache *regcache
+    = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);
+  target_fetch_registers (regcache, S390_A0_REGNUM);
+  target_fetch_registers (regcache, S390_A1_REGNUM);
+  ULONGEST thr_ptr_lo, thr_ptr_hi, thr_ptr;
+  if (regcache->cooked_read (S390_A0_REGNUM, &thr_ptr_hi) != REG_VALID
+      || regcache->cooked_read (S390_A1_REGNUM, &thr_ptr_lo) != REG_VALID)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch thread pointer"));
+  thr_ptr = (thr_ptr_hi << 32) + thr_ptr_lo;
+
+  /* The thread pointer points at the TCB (thread control block).  The
+     first two members of this struct are both pointers, where the
+     first will be a pointer to the TCB (i.e.  it points at itself)
+     and the second will be a pointer to the DTV (dynamic thread
+     vector).  There are many other fields too, but the one we care
+     about here is the DTV pointer.  Compute the address of the DTV
+     pointer, fetch it, and convert it to an address.  */
+  CORE_ADDR dtv_ptr_addr
+    = thr_ptr + gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
+  gdb::byte_vector buf (gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT);
+  if (target_read_memory (dtv_ptr_addr, buf.data (), buf.size ()) != 0)
+    throw_error (TLS_GENERIC_ERROR, _("Unable to fetch DTV address"));
+
+  const struct builtin_type *builtin = builtin_type (gdbarch);
+  CORE_ADDR dtv_addr = gdbarch_pointer_to_address
+			 (gdbarch, builtin->builtin_data_ptr, buf.data ());
+  return dtv_addr;
+}
+
 /* Initialize OSABI common for GNU/Linux on 31- and 64-bit systems.  */
 
 static void
@@ -1151,6 +1191,9 @@ s390_linux_init_abi_any (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* Enable TLS support.  */
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 					     svr4_fetch_objfile_link_map);
+  set_gdbarch_get_thread_local_address (gdbarch,
+					linux_get_thread_local_address);
+  linux_register_tls_methods (info, gdbarch, s390_linux_get_tls_dtv_addr);
 
   /* Support reverse debugging.  */
   set_gdbarch_process_record_signal (gdbarch, s390_linux_record_signal);
-- 
2.46.2