Add support for NetBSD threads in sparc-nat.c

NetBSD ptrace(2) accepts thread id (LWP) as the 4th argument for threads.

Define gdb_ptrace() a wrapper function for ptrace(2) that properly passes
the pid,lwp pair on NetBSD and the result of get_ptrace_pid() for others.

gdb/ChangeLog:

	* sparc-nat.c (gdb_ptrace): New.
	* sparc-nat.c (sparc_fetch_inferior_registers)
	(sparc_store_inferior_registers) Remove obsolete comment.
	* sparc-nat.c (sparc_fetch_inferior_registers)
	(sparc_store_inferior_registers) Switch from pid_t to ptid_t.
	* sparc-nat.c (sparc_fetch_inferior_registers)
	(sparc_store_inferior_registers) Use gdb_ptrace.

2 files changed, 32 insertions, 28 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e418e43..abf3346 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,15 @@
 2020-03-17  Kamil Rytarowski  <n54@gmx.com>
 
+	* sparc-nat.c (gdb_ptrace): New.
+	* sparc-nat.c (sparc_fetch_inferior_registers)
+	(sparc_store_inferior_registers) Remove obsolete comment.
+	* sparc-nat.c (sparc_fetch_inferior_registers)
+	(sparc_store_inferior_registers) Switch from pid_t to ptid_t.
+	* sparc-nat.c (sparc_fetch_inferior_registers)
+	(sparc_store_inferior_registers) Use gdb_ptrace.
+
+2020-03-17  Kamil Rytarowski  <n54@gmx.com>
+
 	* sh-nbsd-nat.c (fetch_registers): New variable lwp and pass
 	it to the ptrace call.
 	* sh-nbsd-nat.c (store_registers): Likewise.
diff --git a/gdb/sparc-nat.c b/gdb/sparc-nat.c
index dff0f52..fadcfd3 100644
--- a/gdb/sparc-nat.c
+++ b/gdb/sparc-nat.c
@@ -78,6 +78,19 @@ typedef struct fp_status fpregset_t;
 #define PTRACE_SETFPREGS PT_SETFPREGS
 #endif
 
+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
+}
+
 /* Register set description.  */
 const struct sparc_gregmap *sparc_gregmap;
 const struct sparc_fpregmap *sparc_fpregmap;
@@ -137,22 +150,7 @@ void
 sparc_fetch_inferior_registers (struct regcache *regcache, int regnum)
 {
   struct gdbarch *gdbarch = regcache->arch ();
-  pid_t pid;
-
-  /* NOTE: cagney/2002-12-03: This code assumes that the currently
-     selected light weight processes' registers can be written
-     directly into the selected thread's register cache.  This works
-     fine when given an 1:1 LWP:thread model (such as found on
-     GNU/Linux) but will, likely, have problems when used on an N:1
-     (userland threads) or N:M (userland multiple LWP) model.  In the
-     case of the latter two, the LWP's registers do not necessarily
-     belong to the selected thread (the LWP could be in the middle of
-     executing the thread switch code).
-
-     These functions should instead be parameterized with an explicit
-     object (struct regcache, struct thread_info?) into which the LWPs
-     registers can be written.  */
-  pid = get_ptrace_pid (regcache->ptid ());
+  ptid_t ptid = regcache->ptid ();
 
   if (regnum == SPARC_G0_REGNUM)
     {
@@ -166,7 +164,7 @@ sparc_fetch_inferior_registers (struct regcache *regcache, int regnum)
     {
       gregset_t regs;
 
-      if (ptrace (PTRACE_GETREGS, pid, (PTRACE_TYPE_ARG3) &regs, 0) == -1)
+      if (gdb_ptrace (PTRACE_GETREGS, ptid, (PTRACE_TYPE_ARG3) &regs) == -1)
 	perror_with_name (_("Couldn't get registers"));
 
       sparc_supply_gregset (sparc_gregmap, regcache, -1, &regs);
@@ -178,7 +176,7 @@ sparc_fetch_inferior_registers (struct regcache *regcache, int regnum)
     {
       fpregset_t fpregs;
 
-      if (ptrace (PTRACE_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
+      if (gdb_ptrace (PTRACE_GETFPREGS, ptid, (PTRACE_TYPE_ARG3) &fpregs) == -1)
 	perror_with_name (_("Couldn't get floating point status"));
 
       sparc_supply_fpregset (sparc_fpregmap, regcache, -1, &fpregs);
@@ -189,22 +187,18 @@ void
 sparc_store_inferior_registers (struct regcache *regcache, int regnum)
 {
   struct gdbarch *gdbarch = regcache->arch ();
-  pid_t pid;
-
-  /* NOTE: cagney/2002-12-02: See comment in fetch_inferior_registers
-     about threaded assumptions.  */
-  pid = get_ptrace_pid (regcache->ptid ());
+  ptid_t ptid = regcache->ptid ();
 
   if (regnum == -1 || sparc_gregset_supplies_p (gdbarch, regnum))
     {
       gregset_t regs;
 
-      if (ptrace (PTRACE_GETREGS, pid, (PTRACE_TYPE_ARG3) &regs, 0) == -1)
+      if (gdb_ptrace (PTRACE_GETREGS, ptid, (PTRACE_TYPE_ARG3) &regs) == -1)
 	perror_with_name (_("Couldn't get registers"));
 
       sparc_collect_gregset (sparc_gregmap, regcache, regnum, &regs);
 
-      if (ptrace (PTRACE_SETREGS, pid, (PTRACE_TYPE_ARG3) &regs, 0) == -1)
+      if (gdb_ptrace (PTRACE_SETREGS, ptid, (PTRACE_TYPE_ARG3) &regs) == -1)
 	perror_with_name (_("Couldn't write registers"));
 
       /* Deal with the stack regs.  */
@@ -225,7 +219,7 @@ sparc_store_inferior_registers (struct regcache *regcache, int regnum)
     {
       fpregset_t fpregs, saved_fpregs;
 
-      if (ptrace (PTRACE_GETFPREGS, pid, (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
+      if (gdb_ptrace (PTRACE_GETFPREGS, ptid, (PTRACE_TYPE_ARG3) &fpregs) == -1)
 	perror_with_name (_("Couldn't get floating-point registers"));
 
       memcpy (&saved_fpregs, &fpregs, sizeof (fpregs));
@@ -237,8 +231,8 @@ sparc_store_inferior_registers (struct regcache *regcache, int regnum)
 	 to write the registers if nothing changed.  */
       if (memcmp (&saved_fpregs, &fpregs, sizeof (fpregs)) != 0)
 	{
-	  if (ptrace (PTRACE_SETFPREGS, pid,
-		      (PTRACE_TYPE_ARG3) &fpregs, 0) == -1)
+	  if (gdb_ptrace (PTRACE_SETFPREGS, ptid,
+			  (PTRACE_TYPE_ARG3) &fpregs) == -1)
 	    perror_with_name (_("Couldn't write floating-point registers"));
 	}