[v5] Implement basic threading support in the NetBSD target

Message ID 20200402192431.2111-1-n54@gmx.com
State New
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  • [v5] Implement basic threading support in the NetBSD target
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Commit Message

Kamil Rytarowski April 2, 2020, 7:24 p.m.
Use sysctl(3) as the portable interface to prompt NetBSD threads on
all supported NetBSD versions. In future newer versions could switch
to PT_LWPSTATUS ptrace(2) API that will be supported on NetBSD 10.0
and newer.

Implement as part of nbsd_nat_target:
 - thread_name()         - read descriptive thread name
 - thread_alive()        - check whether a thread is alive
 - post_attach()         - updates the list of threads after attach
 - update_thread_list()  - updates the list of threads
 - pid_to_str()          - translates ptid to a descriptive string

There are two local static functions:
 - nbsd_thread_lister()  - generic LWP lister for a specified pid
 - nbsd_add_threads()    - utility to update the list of threads

Now, GDB on NetBSD can attach to a multithreaded process, spawn
a multithreaded process, list threads, print their LWP+PID numbers
and descriptive thread names.

gdb/ChangeLog:

       * nbsd-nat.h (struct thread_info): Add forward declaration.
       (nbsd_nat_target::thread_alive): Add.
       (nbsd_nat_target::thread_name): Likewise.
       (nbsd_nat_target::update_thread_list): Likewise.
       (update_thread_list::post_attach): Likewise.
       (post_attach::pid_to_str): Likewise.
       * nbsd-nat.c: Include "gdbthread.h" and "inferior.h".
       (nbsd_thread_lister): Add.
       (nbsd_nat_target::thread_alive): Likewise.
       (nbsd_nat_target::thread_name): Likewise.
       (nbsd_add_threads): Likewise.
       (update_thread_list::post_attach): Likewise.
       (nbsd_nat_target::update_thread_list): Likewise.
       (post_attach::pid_to_str): Likewise.
---
 gdb/ChangeLog  |  17 ++++++
 gdb/nbsd-nat.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/nbsd-nat.h |   8 +++
 3 files changed, 185 insertions(+)

--
2.25.0

Comments

Kamil Rytarowski April 6, 2020, 7:26 a.m. | #1
Ping?

On 02.04.2020 21:24, Kamil Rytarowski wrote:
> Use sysctl(3) as the portable interface to prompt NetBSD threads on

> all supported NetBSD versions. In future newer versions could switch

> to PT_LWPSTATUS ptrace(2) API that will be supported on NetBSD 10.0

> and newer.

>

> Implement as part of nbsd_nat_target:

>  - thread_name()         - read descriptive thread name

>  - thread_alive()        - check whether a thread is alive

>  - post_attach()         - updates the list of threads after attach

>  - update_thread_list()  - updates the list of threads

>  - pid_to_str()          - translates ptid to a descriptive string

>

> There are two local static functions:

>  - nbsd_thread_lister()  - generic LWP lister for a specified pid

>  - nbsd_add_threads()    - utility to update the list of threads

>

> Now, GDB on NetBSD can attach to a multithreaded process, spawn

> a multithreaded process, list threads, print their LWP+PID numbers

> and descriptive thread names.

>

> gdb/ChangeLog:

>

>        * nbsd-nat.h (struct thread_info): Add forward declaration.

>        (nbsd_nat_target::thread_alive): Add.

>        (nbsd_nat_target::thread_name): Likewise.

>        (nbsd_nat_target::update_thread_list): Likewise.

>        (update_thread_list::post_attach): Likewise.

>        (post_attach::pid_to_str): Likewise.

>        * nbsd-nat.c: Include "gdbthread.h" and "inferior.h".

>        (nbsd_thread_lister): Add.

>        (nbsd_nat_target::thread_alive): Likewise.

>        (nbsd_nat_target::thread_name): Likewise.

>        (nbsd_add_threads): Likewise.

>        (update_thread_list::post_attach): Likewise.

>        (nbsd_nat_target::update_thread_list): Likewise.

>        (post_attach::pid_to_str): Likewise.

> ---

>  gdb/ChangeLog  |  17 ++++++

>  gdb/nbsd-nat.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++++

>  gdb/nbsd-nat.h |   8 +++

>  3 files changed, 185 insertions(+)

>

> diff --git a/gdb/ChangeLog b/gdb/ChangeLog

> index ef62216e0ad..764b65d872d 100644

> --- a/gdb/ChangeLog

> +++ b/gdb/ChangeLog

> @@ -1,3 +1,20 @@

> +2020-04-01  Kamil Rytarowski  <n54@gmx.com>

> +

> +	* nbsd-nat.h (struct thread_info): Add forward declaration.

> +	(nbsd_nat_target::thread_alive): Add.

> +	(nbsd_nat_target::thread_name): Likewise.

> +	(nbsd_nat_target::update_thread_list): Likewise.

> +	(update_thread_list::post_attach): Likewise.

> +	(post_attach::pid_to_str): Likewise.

> +	* nbsd-nat.c: Include "gdbthread.h" and "inferior.h".

> +	(nbsd_thread_lister): Add.

> +	(nbsd_nat_target::thread_alive): Likewise.

> +	(nbsd_nat_target::thread_name): Likewise.

> +	(nbsd_add_threads): Likewise.

> +	(update_thread_list::post_attach): Likewise.

> +	(nbsd_nat_target::update_thread_list): Likewise.

> +	(post_attach::pid_to_str): Likewise.

> +

>  2020-04-01  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

>

>  	* infrun.c (stop_all_threads): Update assertion, plus when

> diff --git a/gdb/nbsd-nat.c b/gdb/nbsd-nat.c

> index 326bbe3aec3..4423e19428d 100644

> --- a/gdb/nbsd-nat.c

> +++ b/gdb/nbsd-nat.c

> @@ -20,6 +20,8 @@

>  #include "defs.h"

>

>  #include "nbsd-nat.h"

> +#include "gdbthread.h"

> +#include "inferior.h"

>

>  #include <sys/types.h>

>  #include <sys/ptrace.h>

> @@ -39,3 +41,161 @@ nbsd_nat_target::pid_to_exec_file (int pid)

>      return NULL;

>    return buf;

>  }

> +

> +/* Generic thread (LWP) lister within a specified process.  The callback

> +   parameters is a C++ function that is called for each detected thread.  */

> +

> +static bool

> +nbsd_thread_lister (const pid_t pid,

> +		    gdb::function_view<bool (const struct kinfo_lwp *)>

> +		    callback)

> +{

> +  int mib[5] = {CTL_KERN, KERN_LWP, pid, sizeof (struct kinfo_lwp), 0};

> +  size_t size;

> +

> +  if (sysctl (mib, ARRAY_SIZE (mib), NULL, &size, NULL, 0) == -1 || size == 0)

> +    perror_with_name (("sysctl"));

> +

> +  mib[4] = size / sizeof (size_t);

> +

> +  gdb::unique_xmalloc_ptr<struct kinfo_lwp[]> kl

> +    ((struct kinfo_lwp *) xcalloc (size, 1));

> +

> +  if (sysctl (mib, ARRAY_SIZE (mib), kl.get (), &size, NULL, 0) == -1

> +      || size == 0)

> +    perror_with_name (("sysctl"));

> +

> +  for (size_t i = 0; i < size / sizeof (struct kinfo_lwp); i++)

> +    {

> +      struct kinfo_lwp *l = &kl[i];

> +

> +      /* Return true if the specified thread is alive.  */

> +      auto lwp_alive

> +	= [] (struct kinfo_lwp *lwp)

> +	  {

> +	    switch (lwp->l_stat)

> +	      {

> +	      case LSSLEEP:

> +	      case LSRUN:

> +	      case LSONPROC:

> +	      case LSSTOP:

> +	      case LSSUSPENDED:

> +		return true;

> +	      default:

> +		return false;

> +	      }

> +	  };

> +

> +      /* Ignore embryonic or demised threads.  */

> +      if (!lwp_alive (l))

> +	continue;

> +

> +      if (callback (l))

> +	return true;

> +    }

> +

> +  return false;

> +}

> +

> +/* Return true if PTID is still active in the inferior.  */

> +

> +bool

> +nbsd_nat_target::thread_alive (ptid_t ptid)

> +{

> +  pid_t pid = ptid.pid ();

> +  int lwp = ptid.lwp ();

> +

> +  auto fn

> +    = [&lwp] (const struct kinfo_lwp *kl)

> +      {

> +        return kl->l_lid == lwp;

> +      };

> +

> +  return nbsd_thread_lister (pid, fn);

> +}

> +

> +/* Return the name assigned to a thread by an application.  Returns

> +   the string in a static buffer.  */

> +

> +const char *

> +nbsd_nat_target::thread_name (struct thread_info *thr)

> +{

> +  ptid_t ptid = thr->ptid;

> +  pid_t pid = ptid.pid ();

> +  int lwp = ptid.lwp ();

> +

> +  static char buf[KI_LNAMELEN] = {};

> +

> +  auto fn

> +    = [&lwp] (const struct kinfo_lwp *kl)

> +      {

> +	if (kl->l_lid == lwp)

> +	  {

> +	    xsnprintf (buf, sizeof buf, "%s", kl->l_name);

> +	    return true;

> +	  }

> +	return false;

> +      };

> +

> +  if (nbsd_thread_lister (pid, fn))

> +    return buf;

> +  else

> +    return NULL;

> +}

> +

> +/* Implement the "post_attach" target_ops method.  */

> +

> +static void

> +nbsd_add_threads (nbsd_nat_target *target, pid_t pid)

> +{

> +  auto fn

> +    = [&target, &pid] (const struct kinfo_lwp *kl)

> +      {

> +	ptid_t ptid = ptid_t (pid, kl->l_lid, 0);

> +	if (!in_thread_list (target, ptid))

> +	  {

> +	    if (inferior_ptid.lwp () == 0)

> +	      thread_change_ptid (target, inferior_ptid, ptid);

> +	    else

> +	      add_thread (target, ptid);

> +	  }

> +	return false;

> +      };

> +

> +  nbsd_thread_lister (pid, fn);

> +}

> +

> +/* Implement the "post_attach" target_ops method.  */

> +

> +void

> +nbsd_nat_target::post_attach (int pid)

> +{

> +  nbsd_add_threads (this, pid);

> +}

> +

> +/* Implement the "update_thread_list" target_ops method.  */

> +

> +void

> +nbsd_nat_target::update_thread_list ()

> +{

> +  prune_threads ();

> +

> +  nbsd_add_threads (this, inferior_ptid.pid ());

> +}

> +

> +/* Convert PTID to a string.  */

> +

> +std::string

> +nbsd_nat_target::pid_to_str (ptid_t ptid)

> +{

> +  int lwp = ptid.lwp ();

> +

> +  if (lwp != 0)

> +    {

> +      pid_t pid = ptid.pid ();

> +

> +      return string_printf ("LWP %d of process %d", lwp, pid);

> +    }

> +

> +  return normal_pid_to_str (ptid);

> +}

> diff --git a/gdb/nbsd-nat.h b/gdb/nbsd-nat.h

> index a752fbe572d..3606048cd07 100644

> --- a/gdb/nbsd-nat.h

> +++ b/gdb/nbsd-nat.h

> @@ -22,11 +22,19 @@

>

>  #include "inf-ptrace.h"

>

> +struct thread_info;

> +

>  /* A prototype NetBSD target.  */

>

>  struct nbsd_nat_target : public inf_ptrace_target

>  {

>    char *pid_to_exec_file (int pid) override;

> +

> +  bool thread_alive (ptid_t ptid) override;

> +  const char *thread_name (struct thread_info *thr) override;

> +  void post_attach (int pid) override;

> +  void update_thread_list () override;

> +  std::string pid_to_str (ptid_t ptid) override;

>  };

>

>  #endif /* nbsd-nat.h */

> --

> 2.25.0

>
Tom Tromey April 6, 2020, 8:50 p.m. | #2
>>>>> "Kamil" == Kamil Rytarowski <n54@gmx.com> writes:


Kamil> gdb/ChangeLog:

Kamil>        * nbsd-nat.h (struct thread_info): Add forward declaration.
Kamil>        (nbsd_nat_target::thread_alive): Add.
Kamil>        (nbsd_nat_target::thread_name): Likewise.
Kamil>        (nbsd_nat_target::update_thread_list): Likewise.
Kamil>        (update_thread_list::post_attach): Likewise.
Kamil>        (post_attach::pid_to_str): Likewise.
Kamil>        * nbsd-nat.c: Include "gdbthread.h" and "inferior.h".
Kamil>        (nbsd_thread_lister): Add.
Kamil>        (nbsd_nat_target::thread_alive): Likewise.
Kamil>        (nbsd_nat_target::thread_name): Likewise.
Kamil>        (nbsd_add_threads): Likewise.
Kamil>        (update_thread_list::post_attach): Likewise.
Kamil>        (nbsd_nat_target::update_thread_list): Likewise.
Kamil>        (post_attach::pid_to_str): Likewise.

Thanks, this is ok.

vTom

Patch

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ef62216e0ad..764b65d872d 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,20 @@ 
+2020-04-01  Kamil Rytarowski  <n54@gmx.com>
+
+	* nbsd-nat.h (struct thread_info): Add forward declaration.
+	(nbsd_nat_target::thread_alive): Add.
+	(nbsd_nat_target::thread_name): Likewise.
+	(nbsd_nat_target::update_thread_list): Likewise.
+	(update_thread_list::post_attach): Likewise.
+	(post_attach::pid_to_str): Likewise.
+	* nbsd-nat.c: Include "gdbthread.h" and "inferior.h".
+	(nbsd_thread_lister): Add.
+	(nbsd_nat_target::thread_alive): Likewise.
+	(nbsd_nat_target::thread_name): Likewise.
+	(nbsd_add_threads): Likewise.
+	(update_thread_list::post_attach): Likewise.
+	(nbsd_nat_target::update_thread_list): Likewise.
+	(post_attach::pid_to_str): Likewise.
+
 2020-04-01  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

 	* infrun.c (stop_all_threads): Update assertion, plus when
diff --git a/gdb/nbsd-nat.c b/gdb/nbsd-nat.c
index 326bbe3aec3..4423e19428d 100644
--- a/gdb/nbsd-nat.c
+++ b/gdb/nbsd-nat.c
@@ -20,6 +20,8 @@ 
 #include "defs.h"

 #include "nbsd-nat.h"
+#include "gdbthread.h"
+#include "inferior.h"

 #include <sys/types.h>
 #include <sys/ptrace.h>
@@ -39,3 +41,161 @@  nbsd_nat_target::pid_to_exec_file (int pid)
     return NULL;
   return buf;
 }
+
+/* Generic thread (LWP) lister within a specified process.  The callback
+   parameters is a C++ function that is called for each detected thread.  */
+
+static bool
+nbsd_thread_lister (const pid_t pid,
+		    gdb::function_view<bool (const struct kinfo_lwp *)>
+		    callback)
+{
+  int mib[5] = {CTL_KERN, KERN_LWP, pid, sizeof (struct kinfo_lwp), 0};
+  size_t size;
+
+  if (sysctl (mib, ARRAY_SIZE (mib), NULL, &size, NULL, 0) == -1 || size == 0)
+    perror_with_name (("sysctl"));
+
+  mib[4] = size / sizeof (size_t);
+
+  gdb::unique_xmalloc_ptr<struct kinfo_lwp[]> kl
+    ((struct kinfo_lwp *) xcalloc (size, 1));
+
+  if (sysctl (mib, ARRAY_SIZE (mib), kl.get (), &size, NULL, 0) == -1
+      || size == 0)
+    perror_with_name (("sysctl"));
+
+  for (size_t i = 0; i < size / sizeof (struct kinfo_lwp); i++)
+    {
+      struct kinfo_lwp *l = &kl[i];
+
+      /* Return true if the specified thread is alive.  */
+      auto lwp_alive
+	= [] (struct kinfo_lwp *lwp)
+	  {
+	    switch (lwp->l_stat)
+	      {
+	      case LSSLEEP:
+	      case LSRUN:
+	      case LSONPROC:
+	      case LSSTOP:
+	      case LSSUSPENDED:
+		return true;
+	      default:
+		return false;
+	      }
+	  };
+
+      /* Ignore embryonic or demised threads.  */
+      if (!lwp_alive (l))
+	continue;
+
+      if (callback (l))
+	return true;
+    }
+
+  return false;
+}
+
+/* Return true if PTID is still active in the inferior.  */
+
+bool
+nbsd_nat_target::thread_alive (ptid_t ptid)
+{
+  pid_t pid = ptid.pid ();
+  int lwp = ptid.lwp ();
+
+  auto fn
+    = [&lwp] (const struct kinfo_lwp *kl)
+      {
+        return kl->l_lid == lwp;
+      };
+
+  return nbsd_thread_lister (pid, fn);
+}
+
+/* Return the name assigned to a thread by an application.  Returns
+   the string in a static buffer.  */
+
+const char *
+nbsd_nat_target::thread_name (struct thread_info *thr)
+{
+  ptid_t ptid = thr->ptid;
+  pid_t pid = ptid.pid ();
+  int lwp = ptid.lwp ();
+
+  static char buf[KI_LNAMELEN] = {};
+
+  auto fn
+    = [&lwp] (const struct kinfo_lwp *kl)
+      {
+	if (kl->l_lid == lwp)
+	  {
+	    xsnprintf (buf, sizeof buf, "%s", kl->l_name);
+	    return true;
+	  }
+	return false;
+      };
+
+  if (nbsd_thread_lister (pid, fn))
+    return buf;
+  else
+    return NULL;
+}
+
+/* Implement the "post_attach" target_ops method.  */
+
+static void
+nbsd_add_threads (nbsd_nat_target *target, pid_t pid)
+{
+  auto fn
+    = [&target, &pid] (const struct kinfo_lwp *kl)
+      {
+	ptid_t ptid = ptid_t (pid, kl->l_lid, 0);
+	if (!in_thread_list (target, ptid))
+	  {
+	    if (inferior_ptid.lwp () == 0)
+	      thread_change_ptid (target, inferior_ptid, ptid);
+	    else
+	      add_thread (target, ptid);
+	  }
+	return false;
+      };
+
+  nbsd_thread_lister (pid, fn);
+}
+
+/* Implement the "post_attach" target_ops method.  */
+
+void
+nbsd_nat_target::post_attach (int pid)
+{
+  nbsd_add_threads (this, pid);
+}
+
+/* Implement the "update_thread_list" target_ops method.  */
+
+void
+nbsd_nat_target::update_thread_list ()
+{
+  prune_threads ();
+
+  nbsd_add_threads (this, inferior_ptid.pid ());
+}
+
+/* Convert PTID to a string.  */
+
+std::string
+nbsd_nat_target::pid_to_str (ptid_t ptid)
+{
+  int lwp = ptid.lwp ();
+
+  if (lwp != 0)
+    {
+      pid_t pid = ptid.pid ();
+
+      return string_printf ("LWP %d of process %d", lwp, pid);
+    }
+
+  return normal_pid_to_str (ptid);
+}
diff --git a/gdb/nbsd-nat.h b/gdb/nbsd-nat.h
index a752fbe572d..3606048cd07 100644
--- a/gdb/nbsd-nat.h
+++ b/gdb/nbsd-nat.h
@@ -22,11 +22,19 @@ 

 #include "inf-ptrace.h"

+struct thread_info;
+
 /* A prototype NetBSD target.  */

 struct nbsd_nat_target : public inf_ptrace_target
 {
   char *pid_to_exec_file (int pid) override;
+
+  bool thread_alive (ptid_t ptid) override;
+  const char *thread_name (struct thread_info *thr) override;
+  void post_attach (int pid) override;
+  void update_thread_list () override;
+  std::string pid_to_str (ptid_t ptid) override;
 };

 #endif /* nbsd-nat.h */