fbsd-nat: Add helper functions to fetch and store register sets.

In particular, this supports register sets described by a regcache_map
which are fetched and stored with dedicated ptrace operations.  These
functions are intended to be used in architecture-specific
fetch_registers and store_registers target methods.

gdb/fbsd-nat.c

@@ -1601,6 +1601,52 @@ fbsd_nat_target::supports_disable_randomization ()
 #endif
 }
 
+/* See fbsd-nat.h.  */
+
+void
+fbsd_nat_target::fetch_register_set (struct regcache *regcache, int regnum,
+				     int fetch_op, const struct regset *regset,
+				     void *regs, size_t size)
+{
+  const struct regcache_map_entry *map
+    = (const struct regcache_map_entry *) regset->regmap;
+  pid_t pid = get_ptrace_pid (regcache->ptid ());
+
+  if (regnum == -1 || regcache_map_supplies (map, regnum, regcache->arch(),
+					     size))
+    {
+      if (ptrace (fetch_op, pid, (PTRACE_TYPE_ARG3) regs, 0) == -1)
+	perror_with_name (_("Couldn't get registers"));
+
+      regcache->supply_regset (regset, regnum, regs, size);
+    }
+}
+
+/* See fbsd-nat.h.  */
+
+void
+fbsd_nat_target::store_register_set (struct regcache *regcache, int regnum,
+				     int fetch_op, int store_op,
+				     const struct regset *regset, void *regs,
+				     size_t size)
+{
+  const struct regcache_map_entry *map
+    = (const struct regcache_map_entry *) regset->regmap;
+  pid_t pid = get_ptrace_pid (regcache->ptid ());
+
+  if (regnum == -1 || regcache_map_supplies (map, regnum, regcache->arch(),
+					     size))
+    {
+      if (ptrace (fetch_op, pid, (PTRACE_TYPE_ARG3) regs, 0) == -1)
+	perror_with_name (_("Couldn't get registers"));
+
+      regcache->collect_regset (regset, regnum, regs, size);
+
+      if (ptrace (store_op, pid, (PTRACE_TYPE_ARG3) regs, 0) == -1)
+	perror_with_name (_("Couldn't write registers"));
+    }
+}
+
 void _initialize_fbsd_nat ();
 void
 _initialize_fbsd_nat ()

gdb/fbsd-nat.h

@@ -21,6 +21,8 @@
 #define FBSD_NAT_H
 
 #include "inf-ptrace.h"
+#include "regcache.h"
+#include "regset.h"
 #include <osreldate.h>
 #include <sys/proc.h>
 
@@ -103,6 +105,47 @@ class fbsd_nat_target : public inf_ptrace_target
   bool supports_multi_process () override;
 
   bool supports_disable_randomization () override;
+
+private:
+  /* Helper routines for use in fetch_registers and store_registers in
+     subclasses.  These routines fetch and store a single set of
+     registers described by REGSET.  The REGSET's 'regmap' field must
+     point to an array of 'struct regcache_map_entry'.
+
+     FETCH_OP is a ptrace operation to fetch the set of registers from
+     a native thread.  STORE_OP is a ptrace operation to store the set
+     of registers to a native thread.
+
+     The caller must provide storage for the set of registers in REGS,
+     and SIZE is the size of the storage.  */
+
+  void fetch_register_set (struct regcache *regcache, int regnum, int fetch_op,
+			   const struct regset *regset, void *regs, size_t size);
+
+  void store_register_set (struct regcache *regcache, int regnum, int fetch_op,
+			   int store_op, const struct regset *regset,
+			   void *regs, size_t size);
+protected:
+  /* Wrapper versions of the above helpers which accept a register set
+     type such as 'struct reg' or 'struct fpreg'.  */
+
+  template <class Regset>
+  void fetch_register_set (struct regcache *regcache, int regnum, int fetch_op,
+			   const struct regset *regset)
+  {
+    Regset regs;
+    fetch_register_set (regcache, regnum, fetch_op, regset, &regs,
+			sizeof (regs));
+  }
+
+  template <class Regset>
+  void store_register_set (struct regcache *regcache, int regnum, int fetch_op,
+			   int store_op, const struct regset *regset)
+  {
+    Regset regs;
+    store_register_set (regcache, regnum, fetch_op, store_op, regset, &regs,
+			sizeof (regs));
+  }
 };
 
 #endif /* fbsd-nat.h */