[PATCH v2] Avoid get_ptrace_pid() usage on NetBSD in x86-bsd-nat.c

[Kamil Rytarowski]

Add gdb_ptrace() that wraps the ptrace(2) API and correctly passes
the pid,lwp pair to the calls on NetBSD; and the result of
get_ptrace_pid() on other BSD Operating Systems.

gdb/ChangeLog:

	* x86-bsd-nat.c (gdb_ptrace): New.
	* (x86bsd_dr_get, x86bsd_dr_set): Use gdb_ptrace.
---
 gdb/ChangeLog     |  5 +++++
 gdb/x86-bsd-nat.c | 38 ++++++++++++++++++--------------------
 2 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7f87eceaf70..23a5932489f 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-19  Kamil Rytarowski  <n54@gmx.com>
+
+	* x86-bsd-nat.c (gdb_ptrace): New.
+	* (x86bsd_dr_get, x86bsd_dr_set): Use gdb_ptrace.
+
 2020-03-19  Andrew Burgess  <andrew.burgess@embecosm.com>

 	* remote.c (remote_target::process_stop_reply): Handle events for
diff --git a/gdb/x86-bsd-nat.c b/gdb/x86-bsd-nat.c
index 640a3c28110..c1da7d6ce30 100644
--- a/gdb/x86-bsd-nat.c
+++ b/gdb/x86-bsd-nat.c
@@ -33,6 +33,19 @@
 #include "inf-ptrace.h"
 

+static int
+gdb_ptrace (PTRACE_TYPE_ARG1 request, ptid_t ptid, PTRACE_TYPE_ARG3 addr)
+{
+#ifdef __NetBSD__
+  /* Support for NetBSD threads: unlike other ptrace implementations in this
+     file, NetBSD requires that we pass both the pid and lwp.  */
+  return ptrace (request, ptid.pid (), addr, ptid.lwp ());
+#else
+  pid_t pid = get_ptrace_pid (ptid);
+  return ptrace (request, pid, addr, 0);
+#endif
+}
+
 #ifdef PT_GETXSTATE_INFO
 size_t x86bsd_xsave_len;
 #endif
@@ -56,14 +69,8 @@ static unsigned long
 x86bsd_dr_get (ptid_t ptid, int regnum)
 {
   struct dbreg dbregs;
-#ifdef __NetBSD__
-  int lwp = inferior_ptid.lwp ();
-#else
-  int lwp = 0;
-#endif

-  if (ptrace (PT_GETDBREGS, get_ptrace_pid (inferior_ptid),
-	      (PTRACE_TYPE_ARG3) &dbregs, lwp) == -1)
+  if (gdb_ptrace (PT_GETDBREGS, ptid, (PTRACE_TYPE_ARG3) &dbregs, lwp) == -1)
     perror_with_name (_("Couldn't read debug registers"));

   return DBREG_DRX ((&dbregs), regnum);
@@ -73,14 +80,9 @@ static void
 x86bsd_dr_set (int regnum, unsigned long value)
 {
   struct dbreg dbregs;
-#ifdef __NetBSD__
-  int lwp = inferior_ptid.lwp ();
-#else
-  int lwp = 0;
-#endif

-  if (ptrace (PT_GETDBREGS, get_ptrace_pid (inferior_ptid),
-              (PTRACE_TYPE_ARG3) &dbregs, lwp) == -1)
+  if (gdb_ptrace (PT_GETDBREGS, inferior_ptid,
+		  (PTRACE_TYPE_ARG3) &dbregs, lwp) == -1)
     perror_with_name (_("Couldn't get debug registers"));

   /* For some mysterious reason, some of the reserved bits in the
@@ -92,12 +94,8 @@ x86bsd_dr_set (int regnum, unsigned long value)

   for (thread_info *thread : current_inferior ()->non_exited_threads ())
     {
-#ifdef __NetBSD__
-      lwp = thread->ptid.lwp ();
-#endif
-
-      if (ptrace (PT_SETDBREGS, get_ptrace_pid (thread->ptid),
-		  (PTRACE_TYPE_ARG3) &dbregs, lwp) == -1)
+      if (gdb_ptrace (PT_SETDBREGS, thread->ptid,
+		      (PTRACE_TYPE_ARG3) &dbregs, lwp) == -1)
 	perror_with_name (_("Couldn't write debug registers"));
     }
 }
--
2.25.0