* regcache.c (struct regcache): Add ptid_t member.

(regcache_xmalloc): Initialize it.
	(regcache_cpy_no_passthrough): Do not refer to current_regcache.
	(regcache_dup): Likewise.
	(regcache_dup_no_passthrough): Likewise.
	(current_regcache): Make static.
	(registers_ptid): Remove variable.
	(get_thread_regcache): New function.
	(get_current_regcache): New function.
	(registers_changed): Implement by freeing current regcache.
	(regcache_raw_read): Do not refer to current_regcache.  Set
	inferior_ptid to regcache->ptid while calling target routines.
	(regcache_raw_write): Likewise.
	(regcache_raw_supply): Do not refer to current_regcache.
	(read_pc_pid): Use thread regcache.  Do not modify inferior_ptid.
	(write_pc_pid): Likewise.
	(build_regcache): Remove.
	(_initialize_regcache): Do not call DEPRECATED_REGISTER_GDBARCH_SWAP
	or deprecated_register_gdbarch_swap.  Do not initialize
	registers_ptid.
	* regcache.h (get_current_regcache): Add prototype.
	(get_thread_regcache): Likewise.
	(current_regcache): Remove declaration.

	* corelow.c (core_open): Replace current_regcache by
	get_current_regcache ().
	* frame.c (frame_pop): Likewise.
	(put_frame_register): Likewise.
	(get_current_frame, create_new_frame): Likewise.
	* mi/mi-main.c (mi_cmd_data_write_register_values): Likewise.
	* stack.c (return_command): Likewise.
	* infcall.c (call_function_by_hand): Likewise.
	* infrun.c (resume): Likewise.
	(save_inferior_status, restore_inferior_status): Likewise.
	* linux-fork.c (fork_load_infrun_state): Likewise.
	(fork_save_infrun_state): Likewise.
	* win32-nat.c (win32_resume): Likewise.
	* i386fbsd-nat.c (i386fbsd_resume): Likewise.
	* monitor.c (monitor_wait): Likewise.
	* remote.c (remote_wait): Likewise.
	* remote-mips.c (mips_wait): Likewise.

	* bsd-kvm.c (bsd_kvm_open): Likewise
	(bsd_kvm_proc_cmd, bsd_kvm_pcb_cmd): Likewise.
	* fbsd-nat.c (fbsd_make_corefile_notes): Likewise.
	* i386-linux-nat.c (i386_linux_resume): Likewise.
	* ia64-linux-nat.c (ia64_linux_insert_watchpoint): Likewise.
	(ia64_linux_stopped_data_address): Likewise.

	* frv-tdep.c (frv_fdpic_loadmap_addresses): Likewise.
	* m32c-tdep.c (m32c_virtual_frame_pointer): Likewise.
	* mep-tdep.c (current_me_module, current_options): Likewise.
	* mips-tdep.c (deprecated_mips_set_processor_regs_hack): Likewise.

	* linux-nat.c (linux_nat_do_thread_registers): Use thread
	regcache instead of current_regcache.  Call target_fetch_registers.
	(linux_nat_corefile_thread_callback): Update call site.
	(linux_nat_do_registers): Likewise.
	* procfs.c (procfs_do_thread_registers): Use thread regcache instead
	of current_regcache.
	(procfs_make_note_section): Likewise.
	* proc-service.c (ps_lgetregs, ps_lsetregs): Likewise.
	(ps_lgetfpregs, ps_lsetfpregs): Likewise.
	* sol-thread.c (ps_lgetregs, ps_lsetregs): Likewise.
	(ps_lgetfpregs, ps_lsetfpregs): Likewise.

gdb/linux-nat.c

@@ -2583,19 +2583,26 @@ linux_nat_do_thread_registers (bfd *obfd, ptid_t ptid,
   gdb_fpxregset_t fpxregs;
 #endif
   unsigned long lwp = ptid_get_lwp (ptid);
-  struct gdbarch *gdbarch = current_gdbarch;
+  struct regcache *regcache = get_thread_regcache (ptid);
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
   const struct regset *regset;
   int core_regset_p;
+  struct cleanup *old_chain;
+
+  old_chain = save_inferior_ptid ();
+  inferior_ptid = ptid;
+  target_fetch_registers (regcache, -1);
+  do_cleanups (old_chain);
 
   core_regset_p = gdbarch_regset_from_core_section_p (gdbarch);
   if (core_regset_p
       && (regset = gdbarch_regset_from_core_section (gdbarch, ".reg",
 						     sizeof (gregs))) != NULL
       && regset->collect_regset != NULL)
-    regset->collect_regset (regset, current_regcache, -1,
+    regset->collect_regset (regset, regcache, -1,
 			    &gregs, sizeof (gregs));
   else
-    fill_gregset (current_regcache, &gregs, -1);
+    fill_gregset (regcache, &gregs, -1);
 
   note_data = (char *) elfcore_write_prstatus (obfd,
 					       note_data,
@@ -2607,10 +2614,10 @@ linux_nat_do_thread_registers (bfd *obfd, ptid_t ptid,
       && (regset = gdbarch_regset_from_core_section (gdbarch, ".reg2",
 						     sizeof (fpregs))) != NULL
       && regset->collect_regset != NULL)
-    regset->collect_regset (regset, current_regcache, -1,
+    regset->collect_regset (regset, regcache, -1,
 			    &fpregs, sizeof (fpregs));
   else
-    fill_fpregset (current_regcache, &fpregs, -1);
+    fill_fpregset (regcache, &fpregs, -1);
 
   note_data = (char *) elfcore_write_prfpreg (obfd,
 					      note_data,
@@ -2622,10 +2629,10 @@ linux_nat_do_thread_registers (bfd *obfd, ptid_t ptid,
       && (regset = gdbarch_regset_from_core_section (gdbarch, ".reg-xfp",
 						     sizeof (fpxregs))) != NULL
       && regset->collect_regset != NULL)
-    regset->collect_regset (regset, current_regcache, -1,
+    regset->collect_regset (regset, regcache, -1,
 			    &fpxregs, sizeof (fpxregs));
   else
-    fill_fpxregset (current_regcache, &fpxregs, -1);
+    fill_fpxregset (regcache, &fpxregs, -1);
 
   note_data = (char *) elfcore_write_prxfpreg (obfd,
 					       note_data,
@@ -2650,21 +2657,12 @@ static int
 linux_nat_corefile_thread_callback (struct lwp_info *ti, void *data)
 {
   struct linux_nat_corefile_thread_data *args = data;
-  ptid_t saved_ptid = inferior_ptid;
 
-  inferior_ptid = ti->ptid;
-  registers_changed ();
-  /* FIXME should not be necessary; fill_gregset should do it automatically. */
-  target_fetch_registers (current_regcache, -1);
   args->note_data = linux_nat_do_thread_registers (args->obfd,
 						   ti->ptid,
 						   args->note_data,
 						   args->note_size);
   args->num_notes++;
-  inferior_ptid = saved_ptid;
-  registers_changed ();
-  /* FIXME should not be necessary; fill_gregset should do it automatically. */
-  target_fetch_registers (current_regcache, -1);
 
   return 0;
 }
@@ -2675,15 +2673,11 @@ static char *
 linux_nat_do_registers (bfd *obfd, ptid_t ptid,
 			char *note_data, int *note_size)
 {
-  registers_changed ();
-  /* FIXME should not be necessary; fill_gregset should do it automatically. */
-  target_fetch_registers (current_regcache, -1);
   return linux_nat_do_thread_registers (obfd,
 					ptid_build (ptid_get_pid (inferior_ptid),
 						    ptid_get_pid (inferior_ptid),
 						    0),
 					note_data, note_size);
-  return note_data;
 }
 
 /* Fills the "to_make_corefile_note" target vector.  Builds the note