Add common write_memory and read_memory NetBSD routines

Instead of sharing the native-only code with all BSDs with slightly
different semantics of the kernels, share the NetBSD-only behavior beteen
the NetBSD native and gdbserver setup.

NetBSD does not differentiate the address space I and D in the
operations (contrary to OpenBSD). NetBSD handles EACCES that integrates
with NetBSD specific PaX MPROTECT error handling.

Add a verbose message in the native client that an operation could be
cancelled due to PaX MPROTECT setup.

gdb/ChangeLog:

       * nat/netbsd-nat.c (write_memory, read_memory): Add.
       * nat/netbsd-nat.h (write_memory, read_memory): Likewise.
       * nbsd-nat.c (nbsd_nat_target::xfer_partial): Update.

gdbserver/ChangeLog:

       * netbsd-low.cc (netbsd_process_target::read_memory)
       (netbsd_process_target::write_memory): Update.

2 files changed, 7 insertions, 59 deletions

diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog
index 1571719..1709f3f 100644
--- a/gdbserver/ChangeLog
+++ b/gdbserver/ChangeLog
@@ -1,5 +1,10 @@
 2020-10-07  Kamil Rytarowski  <n54@gmx.com>
 
+	* netbsd-low.cc (netbsd_process_target::read_memory)
+	(netbsd_process_target::write_memory): Update.
+
+2020-10-07  Kamil Rytarowski  <n54@gmx.com>
+
 	* netbsd-aarch64-low.cc: Add.
 	* Makefile.in (SFILES): Register "netbsd-aarch64-low.c".
 	* configure.srv: Add aarch64*-*-netbsd*.
diff --git a/gdbserver/netbsd-low.cc b/gdbserver/netbsd-low.cc
index 7bec55a..e5ea823 100644
--- a/gdbserver/netbsd-low.cc
+++ b/gdbserver/netbsd-low.cc
@@ -556,36 +556,8 @@ int
 netbsd_process_target::read_memory (CORE_ADDR memaddr, unsigned char *myaddr,
 				    int size)
 {
-  struct ptrace_io_desc io;
-  io.piod_op = PIOD_READ_D;
-  io.piod_len = size;
-
   pid_t pid = current_process ()->pid;
-
-  int bytes_read = 0;
-
-  if (size == 0)
-    {
-      /* Zero length write always succeeds.  */
-      return 0;
-    }
-  do
-    {
-      io.piod_offs = (void *)(memaddr + bytes_read);
-      io.piod_addr = myaddr + bytes_read;
-
-      int rv = ptrace (PT_IO, pid, &io, 0);
-      if (rv == -1)
-	return errno;
-      if (io.piod_len == 0)
-	return 0;
-
-      bytes_read += io.piod_len;
-      io.piod_len = size - bytes_read;
-    }
-  while (bytes_read < size);
-
-  return 0;
+  return netbsd_nat::read_memory (pid, myaddr, memaddr, size, nullptr);
 }
 
 /* Implement the write_memory target_ops method.  */
@@ -594,37 +566,8 @@ int
 netbsd_process_target::write_memory (CORE_ADDR memaddr,
 				     const unsigned char *myaddr, int size)
 {
-  struct ptrace_io_desc io;
-  io.piod_op = PIOD_WRITE_D;
-  io.piod_len = size;
-
   pid_t pid = current_process ()->pid;
-
-  int bytes_written = 0;
-
-  if (size == 0)
-    {
-      /* Zero length write always succeeds.  */
-      return 0;
-    }
-
-  do
-    {
-      io.piod_addr = (void *)(myaddr + bytes_written);
-      io.piod_offs = (void *)(memaddr + bytes_written);
-
-      int rv = ptrace (PT_IO, pid, &io, 0);
-      if (rv == -1)
-	return errno;
-      if (io.piod_len == 0)
-	return 0;
-
-      bytes_written += io.piod_len;
-      io.piod_len = size - bytes_written;
-    }
-  while (bytes_written < size);
-
-  return 0;
+  return netbsd_nat::write_memory (pid, myaddr, memaddr, size, nullptr);
 }
 
 /* Implement the request_interrupt target_ops method.  */