Re: [PATCH] 0001-Fix-multi-thread-debug-bug-in-AIX.patch

[Aditya Kamath1 <Aditya.Kamath1@ibm.com>]

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Hi Ulrich and community,

Thank you for the feedback for the fix of this bug. Please find attached the patch. {See: 0001-Fix-multi-thread-debug-bug-in-AIX.patch}

So, I have fixed the bug and it works alright. Please find the test program, output with patch and without patch pasted below this email.

>+      if (s.find (member_name) != std::string::npos)
>+      {
>+       return object_bfd;
>+      }

>This matches the member name *anywhere* in the full >filename,
>which could lead to spurious matches, I think.  The test
>should be more specific.

This I have taken care in the patch.

There are a few changes for which I want to explain below.

We now have all variables {pd_able, pd_active and pd_session} now in a map of process ID and structure. This will help us make AIX GDB code easy to manage them per process in the aix-thread.c file.

Secondly, in the function pid_to_str () there is a beneath () call, which is why I had to put this function in rs6000-aix-nat.c file.

Third thing is previously if there was no object file, we would use pd_disable () to disable thread debugging. This is incorrect now that we support multiple inferiors. Since we rely on inferior_ptid with new object file function till a point, we must disable only when we mourn the inferior or a process dies. Otherwise, there is every chance we will disable thread debugging for a wrong inferior that can be currently inferior_ptid. It also creates a mess disabling the pd_active for the wrong inferior in cases where a new inferior is born who object file is being loaded. This change can be seen in the patch.

I have written comments for the remaining changes in the patch.

Kindly give me feedback if we can do anything better or is incorrect. If not, kindly push this patch so that AIX folks can have a better debugging experience.

Have a nice day ahead.

Thanks and regards,
Aditya.

-------------------------------------------
Code:-


#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <pthread.h>

#include <assert.h>


pthread_barrier_t barrier;


#define NUM_THREADS 2


void *

thread_function (void *arg)

{

  /* This ensures that the breakpoint is only hit after both threads

     are created, so the test can always switch to the non-event

     thread when the breakpoint triggers.  */


  pthread_barrier_wait (&barrier);

  pid_t child;


  child = fork ();

  if (child > 0)

    printf ("I am parent \n");

  else

  {

    child = fork ();

    if (child > 0)

      printf ("I am child \n");

    else

      printf ("I am grandchild \n");

  }

  while (1); /* break here */

}


int

main (void)

{

  int i;

  pthread_t thread[NUM_THREADS];


  alarm (300);


  pthread_barrier_init (&barrier, NULL, NUM_THREADS);


  for (i = 0; i < NUM_THREADS; i++)

    {

      int res;


      res = pthread_create (&thread[i], NULL,

                            thread_function, NULL);

      assert (res == 0);

    }


  while (1)

  {

    sleep (15);

  }


  return 0;

}


---------------------------------------------------
Output with patch applied:-


Reading symbols from /home/aditya/gdb_tests/ultimate-multi-thread-fork...

(gdb) set detach-on-fork off

(gdb) r

Starting program: /home/aditya/gdb_tests/ultimate-multi-thread-fork

[New Thread 258]

[New Thread 515]

[New inferior 2 (Process 17498448)]

I am parent

[New inferior 3 (Process 11731454)]

I am parent

^C

Thread 1.1 received signal SIGINT, Interrupt.

[Switching to Thread 1]

0xd0595fb0 in _p_nsleep () from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) inferior 2

[Switching to inferior 2 [Process 17498448] (/home/aditya/gdb_tests/ultimate-multi-thread-fork)]

[Switching to thread 2.1 (Process 17498448)]

#0  0xd0594fc8 in _sigsetmask () from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) info threads

  Id   Target Id                          Frame

  1.1  Thread 1 (tid 25231849, running)   0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.2  Thread 258 (tid 33227061, running) thread_function (arg=0x0)

    at /home/aditya/gdb_tests/ultimate-multi-thread-fork.c:32

  1.3  Thread 515 (tid 23069149, running) thread_function (arg=warning: (Internal error: pc 0x0 in read in psymtab, but not in symtab.)


0x0)

    at /home/aditya/gdb_tests/ultimate-multi-thread-fork.c:32

* 2.1  Process 17498448                   0xd0594fc8 in _sigsetmask ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  3.1  Process 11731454                   0xd0594fc8 in _sigsetmask ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) info sharedlibrary

From        To          Syms Read   Shared Object Library

0xd05bc124  0xd05bf194  Yes (*)     /usr/lib/libpthreads.a(shr_comm.o)

0xd05bb240  0xd05bb9a1  Yes (*)     /usr/lib/libcrypt.a(shr.o)

0xd0576180  0xd05ba731  Yes (*)     /usr/lib/libpthread.a(shr_xpg5.o)

0xd0100e00  0xd0575123  Yes (*)     /usr/lib/libc.a(shr.o)

(*): Shared library is missing debugging information.


--------------------------------------------------------

Output without patch:-


Reading symbols from /home/aditya/gdb_tests/ultimate-multi-thread-fork...

(gdb) set detach-on-fork off

(gdb) r

Starting program: /home/aditya/gdb_tests/ultimate-multi-thread-fork

[New Thread 1]

[New Thread 258]

[New Thread 515]

[New inferior 2 (process 11731200)]

I am parent

[New inferior 3 (process 16843200)]

I am parent

^C

Thread 1.1 received signal SIGINT, Interrupt.

0xd0595fb0 in _p_nsleep () from /usr/lib/libpthread.a(shr_xpg5.o)

(gdb) inferior 2

[Switching to inferior 2 [process 11731200] (/home/aditya/gdb_tests/ultimate-multi-thread-fork)]

[Switching to thread 2.1 (process 11731200)]

#0  0xd0594fc8 in ?? ()

(gdb) info threads

  Id   Target Id         Frame

  1.1  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.2  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.3  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

  1.4  process 15270316  0xd0595fb0 in _p_nsleep ()

   from /usr/lib/libpthread.a(shr_xpg5.o)

* 2.1  process 11731200  0xd0594fc8 in ?? ()

  3.1  process 16843200  0xd0594fc8 in ?? ()

(gdb) info sharedlibrary

warning: "/usr/lib/libpthreads.a": member "shr_comm.o" missing.

warning: "/usr/lib/libcrypt.a": member "shr.o" missing.

warning: "/usr/lib/libpthread.a": member "shr_xpg5.o" missing.

warning: "/usr/lib/libc.a": member "shr.o" missing.

warning: Could not load shared library symbols for 4 libraries, e.g. /usr/lib/libpthreads.a(shr_comm.o).

Use the "info sharedlibrary" command to see the complete listing.

Do you need "set solib-search-path" or "set sysroot"?

From        To          Syms Read   Shared Object Library

                        No          /usr/lib/libpthreads.a(shr_comm.o)

                        No          /usr/lib/libcrypt.a(shr.o)

                        No          /usr/lib/libpthread.a(shr_xpg5.o)

                        No          /usr/lib/libc.a(shr.o)

(gdb)



________________________________
From: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Sent: 20 January 2023 20:14
To: simark@simark.ca <simark@simark.ca>; Aditya Kamath1 <Aditya.Kamath1@ibm.com>; gdb-patches@sourceware.org <gdb-patches@sourceware.org>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
Subject: Re: [PATCH] 0001-Fix-multi-thread-debug-bug-in-AIX.patch

Aditya Kamath1 <Aditya.Kamath1@ibm.com> wrote:

>Inorder to resolve the same I request for one information. How can we iterate_over_threads
>of a particular process. What is that function. Is there any built-in available??
>Kindly let me know and that should solve this issue.

Instead of iterate_over_threads you could use the all_threads() iterator directly;
this can be specialized to only return threads of one inferior like this:

       for (thread_info *tp : all_threads (proc_target, ptid_t (pid)))
       {
            ...
       }

>Also kindly give me feedback on this patch if I need to change anything.

I think this change in solib-aix.c is not quite correct:
+      std::string s = bfd_get_filename (object_bfd.get ());
+      if (s.find (member_name) != std::string::npos)
+      {
+       return object_bfd;
+      }

This matches the member name *anywhere* in the full filename,
which could lead to spurious matches, I think.  The test
should be more specific.

Bye,
Ulrich


[-- Attachment #2: 0001-Fix-multi-thread-debug-bug-in-AIX.patch --]
[-- Type: application/octet-stream, Size: 17098 bytes --]

From 1783be1c9161479a158a4e52dd0663f45e6b92e9 Mon Sep 17 00:00:00 2001
From: Aditya Vidyadhar Kamath <Aditya.Kamath1@ibm.com>
Date: Fri, 27 Jan 2023 08:19:56 -0600
Subject: [PATCH] Fix multi-thread debug bug in AIX

---
 gdb/aix-thread.c     | 189 ++++++++++++++++++++++++++-----------------
 gdb/rs6000-aix-nat.c |  10 +++
 gdb/solib-aix.c      |  15 ++++
 3 files changed, 141 insertions(+), 73 deletions(-)

diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index e556c153576..c6231e92f91 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -55,6 +55,7 @@
 #include <sys/reg.h>
 #include <sched.h>
 #include <sys/pthdebug.h>
+#include <map>
 
 #if !HAVE_DECL_GETTHRDS
 extern int getthrds (pid_t, struct thrdsinfo64 *, int, tid_t *, int);
@@ -70,7 +71,7 @@ static bool debug_aix_thread;
 
 /* Return whether to treat PID as a debuggable thread id.  */
 
-#define PD_TID(ptid)	(pd_active && ptid.tid () != 0)
+#define PD_TID(ptid)	(tmap[ptid.pid ()].pd_active && ptid.tid () != 0)
 
 /* Success and failure values returned by pthdb callbacks.  */
 
@@ -149,14 +150,6 @@ static aix_thread_target aix_thread_ops;
 
 static CORE_ADDR pd_brk_addr;
 
-/* Whether the current application is debuggable by pthdb.  */
-
-static int pd_able = 0;
-
-/* Whether a threaded application is being debugged.  */
-
-static int pd_active = 0;
-
 /* Whether the current architecture is 64-bit.  
    Only valid when pd_able is true.  */
 
@@ -191,9 +184,21 @@ static pthdb_callbacks_t pd_callbacks = {
   NULL
 };
 
-/* Current pthdb session.  */
+/* Aix variable structure.  */
+struct aix_thread_variables 
+{
+  /* Whether the current application is debuggable by pthdb.  */
+  int pd_able;
 
-static pthdb_session_t pd_session;
+  /* Whether a threaded application is being debugged.  */
+  int pd_active;
+
+  /* Current pthdb session.  */
+  pthdb_session_t pd_session;
+};
+
+/* Collection of Aix variables per inferior.  */
+static std::map<pid_t, aix_thread_variables> tmap;
 
 /* Return a printable representation of pthdebug function return
    STATUS.  */
@@ -508,14 +513,13 @@ pdc_read_data (pthdb_user_t user_current_pid, void *buf,
   /* This is needed to eliminate the dependency of current thread
      which is null so that thread reads the correct target memory.  */
   {
-    scoped_restore_current_thread restore_current_thread;
+    scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
     /* Before the first inferior is added, we pass inferior_ptid.pid ()
        from pd_enable () which is 0.  There is no need to switch threads
        during first initialisation.  In the rest of the callbacks the
        current thread needs to be correct.  */
     if (user_current_pid != 0)
-      switch_to_thread (current_inferior ()->process_target (),
-			ptid_t (user_current_pid));
+      inferior_ptid = ptid_t (user_current_pid);
     status = target_read_memory (addr, (gdb_byte *) buf, len);
   }
   ret = status == 0 ? PDC_SUCCESS : PDC_FAILURE;
@@ -639,36 +643,32 @@ pcmp (const void *p1v, const void *p2v)
   return p1->pthid < p2->pthid ? -1 : p1->pthid > p2->pthid;
 }
 
-/* iterate_over_threads() callback for counting GDB threads.
-
-   Do not count the main thread (whose tid is zero).  This matches
-   the list of threads provided by the pthreaddebug library, which
-   does not include that main thread either, and thus allows us
-   to compare the two lists.  */
+/* Callback for counting GDB threads for process pid.  */
 
 static int
-giter_count (struct thread_info *thread, void *countp)
+giter_count (pid_t pid)
 {
-  if (PD_TID (thread->ptid))
-    (*(int *) countp)++;
-  return 0;
+  int gcount = 0;
+  process_stratum_target *proc_target
+    = current_inferior ()->process_target ();
+  for (thread_info *tp : all_threads (proc_target, ptid_t (pid)))
+    gcount++;
+  return gcount;
 }
 
-/* iterate_over_threads() callback for accumulating GDB thread pids.
-
-   Do not include the main thread (whose tid is zero).  This matches
-   the list of threads provided by the pthreaddebug library, which
-   does not include that main thread either, and thus allows us
-   to compare the two lists.  */
+/* Callback for accumulating GDB thread pids.  */
 
 static int
-giter_accum (struct thread_info *thread, void *bufp)
+giter_accum (void *bufp, pid_t pid)
 {
-  if (PD_TID (thread->ptid))
-    {
-      **(struct thread_info ***) bufp = thread;
-      (*(struct thread_info ***) bufp)++;
-    }
+  process_stratum_target *proc_target
+    = current_inferior ()->process_target ();
+  for (thread_info *tp : all_threads (proc_target, ptid_t (pid)))
+  {
+    **(struct thread_info ***) bufp = tp;
+    (*(struct thread_info ***) bufp)++;
+  }
+
   return 0;
 }
 
@@ -719,7 +719,10 @@ get_signaled_thread (int pid)
 		    sizeof (thrinf), &ktid, 1) != 1)
 	break;
 
-      if (thrinf.ti_cursig == SIGTRAP)
+      /* We also need to keep in mind Trap and interrupt or any
+         signal that needs to be handled in pd_update ().  */
+
+      if (thrinf.ti_cursig)
 	return thrinf.ti_tid;
     }
 
@@ -750,6 +753,9 @@ sync_threadlists (int pid)
   pthdb_pthread_t pdtid;
   pthread_t pthid;
   pthdb_tid_t tid;
+  process_stratum_target *proc_target
+            = current_inferior ()->process_target ();
+  thread_info  *tp;
 
   /* Accumulate an array of libpthdebug threads sorted by pthread id.  */
 
@@ -759,11 +765,11 @@ sync_threadlists (int pid)
 
   for (cmd = PTHDB_LIST_FIRST;; cmd = PTHDB_LIST_NEXT)
     {
-      status = pthdb_pthread (pd_session, &pdtid, cmd);
+      status = pthdb_pthread (tmap[pid].pd_session, &pdtid, cmd);
       if (status != PTHDB_SUCCESS || pdtid == PTHDB_INVALID_PTHREAD)
 	break;
 
-      status = pthdb_pthread_ptid (pd_session, pdtid, &pthid);
+      status = pthdb_pthread_ptid (tmap[pid].pd_session, pdtid, &pthid);
       if (status != PTHDB_SUCCESS || pthid == PTHDB_INVALID_PTID)
 	continue;
 
@@ -780,7 +786,7 @@ sync_threadlists (int pid)
 
   for (pi = 0; pi < pcount; pi++)
     {
-      status = pthdb_pthread_tid (pd_session, pbuf[pi].pdtid, &tid);
+      status = pthdb_pthread_tid (tmap[pid].pd_session, pbuf[pi].pdtid, &tid);
       if (status != PTHDB_SUCCESS)
 	tid = PTHDB_INVALID_TID;
       pbuf[pi].tid = tid;
@@ -790,10 +796,11 @@ sync_threadlists (int pid)
 
   /* Accumulate an array of GDB threads sorted by pid.  */
 
-  gcount = 0;
-  iterate_over_threads (giter_count, &gcount);
+  /* gcount is GDB thread count and pcount is pthreadlib thread count.  */
+
+  gcount = giter_count (pid);
   g = gbuf = XNEWVEC (struct thread_info *, gcount);
-  iterate_over_threads (giter_accum, &g);
+  giter_accum (&g, pid);
   qsort (gbuf, gcount, sizeof *gbuf, gcmp);
 
   /* Apply differences between the two arrays to GDB's thread list.  */
@@ -810,8 +817,6 @@ sync_threadlists (int pid)
 	  priv->pdtid = pbuf[pi].pdtid;
 	  priv->tid = pbuf[pi].tid;
 
-	  process_stratum_target *proc_target
-	    = current_inferior ()->process_target ();
 	  thread = add_thread_with_info (proc_target,
 					 ptid_t (pid, 0, pbuf[pi].pthid),
 					 priv);
@@ -830,6 +835,23 @@ sync_threadlists (int pid)
 
 	  cmp_result = ptid_cmp (pptid, gptid);
 
+	  /* If there is only one thread then we need not make the main 
+	     thread look like a thread.  It can stay as a process. This
+	     is useful when we have multiple inferiors, but only one is
+	     threaded.  So we need not make the other inferiors with only
+	     main thread, look like a threaded one.  For example, Thread
+	     1.1, 1.2, 2.1, 3.1 exists then it is useful to skip this for
+	     loop for 2.1 and 3.1 leaving them as main process thread with
+	     a dummy priv set.  */
+
+	  if (pcount == 1 && gcount == 1)
+	  {
+	    aix_thread_info *priv = new aix_thread_info;
+	    tp = find_thread_ptid (proc_target, gptid);
+	    tp->priv.reset (priv);
+	    break;
+	  }
+
 	  if (cmp_result == 0)
 	    {
 	      aix_thread_info *priv = get_aix_thread_info (gbuf[gi]);
@@ -841,8 +863,25 @@ sync_threadlists (int pid)
 	    }
 	  else if (cmp_result > 0)
 	    {
-	      delete_thread (gbuf[gi]);
-	      gi++;
+	      /* This is to make the main process thread now look
+		 like a thread.  */
+
+	      if (gptid.is_pid () && gptid.pid () == pptid.pid ())
+	      {
+		thread_change_ptid (proc_target, gptid, pptid);
+		aix_thread_info *priv = new aix_thread_info;
+		priv->pdtid = pbuf[pi].pdtid;
+		priv->tid = pbuf[pi].tid;
+		tp = find_thread_ptid (proc_target, pptid);
+		tp->priv.reset (priv);
+		pi++;
+		gi++;
+	      }
+	      else
+	      {
+		delete_thread (gbuf[gi]);
+		gi++;
+	      }
 	    }
 	  else
 	    {
@@ -888,10 +927,10 @@ pd_update (int pid)
   pthdb_tid_t tid;
   struct thread_info *thread = NULL;
 
-  if (!pd_active)
+  if (!tmap[pid].pd_active)
     return ptid_t (pid);
 
-  status = pthdb_session_update (pd_session);
+  status = pthdb_session_update (tmap[pid].pd_session);
   if (status != PTHDB_SUCCESS)
     return ptid_t (pid);
 
@@ -921,12 +960,12 @@ pd_activate (int pid)
 		
   status = pthdb_session_init (pid, arch64 ? PEM_64BIT : PEM_32BIT,
 			       PTHDB_FLAG_REGS, &pd_callbacks, 
-			       &pd_session);
+			       &tmap[pid].pd_session);
   if (status != PTHDB_SUCCESS)
     {
       return ptid_t (pid);
     }
-  pd_active = 1;
+  tmap[pid].pd_active = 1;
   return pd_update (pid);
 }
 
@@ -935,12 +974,12 @@ pd_activate (int pid)
 static void
 pd_deactivate (void)
 {
-  if (!pd_active)
+  if (!tmap[inferior_ptid.pid ()].pd_active)
     return;
-  pthdb_session_destroy (pd_session);
+  pthdb_session_destroy (tmap[inferior_ptid.pid ()].pd_session);
   
   pid_to_prc (&inferior_ptid);
-  pd_active = 0;
+  tmap[inferior_ptid.pid ()].pd_active = 0;
 }
 
 /* An object file has just been loaded.  Check whether the current
@@ -953,8 +992,15 @@ pd_enable (void)
   char *stub_name;
   struct bound_minimal_symbol ms;
 
+  /* Create set of variables for this inferior.  */
+  if (tmap.find (inferior_ptid.pid ()) == tmap.end ())
+  {
+    struct aix_thread_variables z = {0, 0};
+    tmap.insert ({inferior_ptid.pid (), z});
+  }
+
   /* Don't initialize twice.  */
-  if (pd_able)
+  if (tmap[inferior_ptid.pid ()].pd_able)
     return;
 
   /* Check application word size.  */
@@ -978,7 +1024,7 @@ pd_enable (void)
 
   /* Prepare for thread debugging.  */
   current_inferior ()->push_target (&aix_thread_ops);
-  pd_able = 1;
+  tmap[inferior_ptid.pid ()].pd_able = 1; 
 
   /* If we're debugging a core file or an attached inferior, the
      pthread library may already have been initialized, so try to
@@ -991,28 +1037,25 @@ pd_enable (void)
 static void
 pd_disable (void)
 {
-  if (!pd_able)
+  if (!tmap[inferior_ptid.pid ()].pd_able)
     return;
-  if (pd_active)
+  if (tmap[inferior_ptid.pid ()].pd_active)
     pd_deactivate ();
-  pd_able = 0;
+  tmap[inferior_ptid.pid ()].pd_able = 0;
   current_inferior ()->unpush_target (&aix_thread_ops);
+  tmap.erase (inferior_ptid.pid ());
 }
 
 /* new_objfile observer callback.
 
    If OBJFILE is non-null, check whether a threaded application is
-   being debugged, and if so, prepare for thread debugging.
-
-   If OBJFILE is null, stop debugging threads.  */
+   being debugged, and if so, prepare for thread debugging.  */
 
 static void
 new_objfile (struct objfile *objfile)
 {
   if (objfile)
     pd_enable ();
-  else
-    pd_disable ();
 }
 
 /* Attach to process specified by ARGS.  */
@@ -1096,7 +1139,7 @@ aix_thread_target::wait (ptid_t ptid, struct target_waitstatus *status,
   gdb_assert (ptid.is_pid ());
 
   /* Check whether libpthdebug might be ready to be initialized.  */
-  if (!pd_active && status->kind () == TARGET_WAITKIND_STOPPED
+  if (!tmap[ptid.pid ()].pd_active && status->kind () == TARGET_WAITKIND_STOPPED
       && status->sig () == GDB_SIGNAL_TRAP)
     {
       process_stratum_target *proc_target
@@ -1233,7 +1276,7 @@ fetch_regs_user_thread (struct regcache *regcache, pthdb_pthread_t pdtid)
   if (debug_aix_thread)
     gdb_printf (gdb_stdlog, 
 		"fetch_regs_user_thread %lx\n", (long) pdtid);
-  status = pthdb_pthread_context (pd_session, pdtid, &ctx);
+  status = pthdb_pthread_context (tmap[inferior_ptid.pid ()].pd_session, pdtid, &ctx);
   if (status != PTHDB_SUCCESS)
     error (_("aix-thread: fetch_registers: pthdb_pthread_context returned %s"),
 	   pd_status2str (status));
@@ -1518,7 +1561,7 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
 
   /* Retrieve the thread's current context for its non-register
      values.  */
-  status = pthdb_pthread_context (pd_session, pdtid, &ctx);
+  status = pthdb_pthread_context (tmap[inferior_ptid.pid ()].pd_session, pdtid, &ctx);
   if (status != PTHDB_SUCCESS)
     error (_("aix-thread: store_registers: pthdb_pthread_context returned %s"),
 	   pd_status2str (status));
@@ -1576,7 +1619,7 @@ store_regs_user_thread (const struct regcache *regcache, pthdb_pthread_t pdtid)
 	ctx.fpscr = tmp_fpscr;
     }
 
-  status = pthdb_pthread_setcontext (pd_session, pdtid, &ctx);
+  status = pthdb_pthread_setcontext (tmap[inferior_ptid.pid ()].pd_session, pdtid, &ctx);
   if (status != PTHDB_SUCCESS)
     error (_("aix-thread: store_registers: "
 	     "pthdb_pthread_setcontext returned %s"),
@@ -1741,7 +1784,7 @@ aix_thread_target::mourn_inferior ()
 {
   target_ops *beneath = this->beneath ();
 
-  pd_deactivate ();
+  pd_disable ();
   beneath->mourn_inferior ();
 }
 
@@ -1800,24 +1843,24 @@ aix_thread_target::extra_thread_info (struct thread_info *thread)
     /* i18n: Like "thread-identifier %d, [state] running, suspended" */
     buf.printf (_("tid %d"), (int)tid);
 
-  status = pthdb_pthread_state (pd_session, pdtid, &state);
+  status = pthdb_pthread_state (tmap[inferior_ptid.pid ()].pd_session, pdtid, &state);
   if (status != PTHDB_SUCCESS)
     state = PST_NOTSUP;
   buf.printf (", %s", state2str (state));
 
-  status = pthdb_pthread_suspendstate (pd_session, pdtid, 
+  status = pthdb_pthread_suspendstate (tmap[inferior_ptid.pid ()].pd_session, pdtid, 
 				       &suspendstate);
   if (status == PTHDB_SUCCESS && suspendstate == PSS_SUSPENDED)
     /* i18n: Like "Thread-Id %d, [state] running, suspended" */
     buf.printf (_(", suspended"));
 
-  status = pthdb_pthread_detachstate (pd_session, pdtid, 
+  status = pthdb_pthread_detachstate (tmap[inferior_ptid.pid ()].pd_session, pdtid, 
 				      &detachstate);
   if (status == PTHDB_SUCCESS && detachstate == PDS_DETACHED)
     /* i18n: Like "Thread-Id %d, [state] running, detached" */
     buf.printf (_(", detached"));
 
-  pthdb_pthread_cancelpend (pd_session, pdtid, &cancelpend);
+  pthdb_pthread_cancelpend (tmap[inferior_ptid.pid ()].pd_session, pdtid, &cancelpend);
   if (status == PTHDB_SUCCESS && cancelpend)
     /* i18n: Like "Thread-Id %d, [state] running, cancel pending" */
     buf.printf (_(", cancel pending"));
diff --git a/gdb/rs6000-aix-nat.c b/gdb/rs6000-aix-nat.c
index 2ac1f6e70b6..d1fece6faa7 100644
--- a/gdb/rs6000-aix-nat.c
+++ b/gdb/rs6000-aix-nat.c
@@ -95,6 +95,8 @@ class rs6000_nat_target final : public inf_ptrace_target
 
   ptid_t wait (ptid_t, struct target_waitstatus *, target_wait_flags) override;
 
+  std::string pid_to_str (ptid_t) override;
+
   /* Fork detection related functions, For adding multi process debugging
      support.  */
   void follow_fork (inferior *, ptid_t, target_waitkind, bool, bool) override;
@@ -619,6 +621,14 @@ rs6000_nat_target::xfer_partial (enum target_object object,
     }
 }
 
+std::string 
+rs6000_nat_target::pid_to_str (ptid_t ptid)
+{
+  if (!ptid.tid ())
+    return string_printf (_("Process %s"), pulongest (ptid.pid ())); 
+
+  return string_printf (_("Thread %s"), pulongest (ptid.tid ()));
+}
 /* Wait for the child specified by PTID to do something.  Return the
    process ID of the child, or MINUS_ONE_PTID in case of error; store
    the status in *OURSTATUS.  */
diff --git a/gdb/solib-aix.c b/gdb/solib-aix.c
index f483f54de13..74676cbfa50 100644
--- a/gdb/solib-aix.c
+++ b/gdb/solib-aix.c
@@ -550,6 +550,10 @@ solib_aix_in_dynsym_resolve_code (CORE_ADDR pc)
   return 0;
 }
 
+/* For multi inferiors, post object file name change
+   we store the new names in this vector.  */
+std::vector<std::string> aix_slib_name;
+
 /* Implement the "bfd_open" target_so_ops method.  */
 
 static gdb_bfd_ref_ptr
@@ -618,6 +622,16 @@ solib_aix_bfd_open (const char *pathname)
       if (member_name == bfd_get_filename (object_bfd.get ()))
 	break;
 
+      std::string s = bfd_get_filename (object_bfd.get ());
+      auto it = aix_slib_name.begin ();
+      while (it != aix_slib_name.end ())
+      {
+	std::string s1 = *it;
+	if (s1.compare(s) == 0)
+	  return object_bfd;
+	it++;
+      }
+
       object_bfd = gdb_bfd_openr_next_archived_file (archive_bfd.get (),
 						     object_bfd.get ());
     }
@@ -644,6 +658,7 @@ solib_aix_bfd_open (const char *pathname)
   std::string fname = string_printf ("%s%s",
 				     bfd_get_filename (archive_bfd.get ()),
 				     sep);
+  aix_slib_name.push_back (fname);
   bfd_set_filename (object_bfd.get (), fname.c_str ());
 
   return object_bfd;
-- 
2.31.1