[RFC 08/13] x86-fbsd-nat: Support fetching TARGET_OBJECT_X86_CPUID objects

[John Baldwin <jhb@FreeBSD.org>]

When probing for the cached XSAVE layout, fetch the CPUID note data
and cache it until needed for a future fetch via ::xfer_partial.
---
 gdb/configure.nat  |  6 ++++--
 gdb/x86-fbsd-nat.c | 37 +++++++++++++++++++++++++++++++++++++
 gdb/x86-fbsd-nat.h |  9 +++++++++
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/gdb/configure.nat b/gdb/configure.nat
index 1dc4206b69c..4ed71d8619d 100644
--- a/gdb/configure.nat
+++ b/gdb/configure.nat
@@ -165,7 +165,8 @@ case ${gdb_host} in
 		;;
 	    i386)
 		# Host: FreeBSD/i386
-		NATDEPFILES="${NATDEPFILES} x86-nat.o nat/x86-dregs.o \
+		NATDEPFILES="${NATDEPFILES} x86-nat.o nat/x86-cpuid.o \
+		nat/x86-dregs.o
 		nat/x86-xstate.o x86-bsd-nat.o x86-fbsd-nat.o i386-fbsd-nat.o \
 		bsd-kvm.o"
 		;;
@@ -195,7 +196,8 @@ case ${gdb_host} in
 	    i386)
 		# Host: FreeBSD/amd64
 		NATDEPFILES="${NATDEPFILES} amd64-nat.o \
-		amd64-fbsd-nat.o bsd-kvm.o x86-nat.o nat/x86-dregs.o \
+		amd64-fbsd-nat.o bsd-kvm.o x86-nat.o nat/x86-cpuid.o \
+		nat/x86-dregs.o \
 		nat/x86-xstate.o x86-bsd-nat.o x86-fbsd-nat.o"
 		;;
 	esac
diff --git a/gdb/x86-fbsd-nat.c b/gdb/x86-fbsd-nat.c
index 240e228976c..14fd323a7fb 100644
--- a/gdb/x86-fbsd-nat.c
+++ b/gdb/x86-fbsd-nat.c
@@ -20,6 +20,7 @@
 #include "defs.h"
 #include "x86-fbsd-nat.h"
 #ifdef PT_GETXSTATE_INFO
+#include "nat/x86-cpuid.h"
 #include "nat/x86-xstate.h"
 #endif
 
@@ -48,6 +49,40 @@ x86_fbsd_nat_target::low_new_fork (ptid_t parent, pid_t child)
 }
 
 #ifdef PT_GETXSTATE_INFO
+enum target_xfer_status
+x86_fbsd_nat_target::xfer_partial (enum target_object object,
+				   const char *annex, gdb_byte *readbuf,
+				   const gdb_byte *writebuf,
+				   ULONGEST offset, ULONGEST len,
+				   ULONGEST *xfered_len)
+{
+  switch (object)
+    {
+    case TARGET_OBJECT_X86_CPUID:
+      if (readbuf)
+	{
+	  size_t size = m_cpuid_note_len;
+	  if (offset >= size)
+	    return TARGET_XFER_EOF;
+	  size -= offset;
+	  if (size > len)
+	    size = len;
+
+	  if (size == 0)
+	    return TARGET_XFER_EOF;
+
+	  memcpy (readbuf, m_cpuid_note.get () + offset, size);
+	  *xfered_len = size;
+	  return TARGET_XFER_OK;
+	}
+      return TARGET_XFER_E_IO;
+    default:
+      return fbsd_nat_target::xfer_partial (object, annex, readbuf,
+					    writebuf, offset, len,
+					    xfered_len);
+    }
+}
+
 void
 x86_fbsd_nat_target::probe_xsave_layout (pid_t pid)
 {
@@ -56,6 +91,8 @@ x86_fbsd_nat_target::probe_xsave_layout (pid_t pid)
 
   m_xsave_probed = true;
 
+  x86_cpuid_note (m_cpuid_note, m_cpuid_note_len);
+
   if (ptrace (PT_GETXSTATE_INFO, pid, (PTRACE_TYPE_ARG3) &m_xsave_info,
 	      sizeof (m_xsave_info)) != 0)
     return;
diff --git a/gdb/x86-fbsd-nat.h b/gdb/x86-fbsd-nat.h
index 723bb6cf305..71b6ad09916 100644
--- a/gdb/x86-fbsd-nat.h
+++ b/gdb/x86-fbsd-nat.h
@@ -42,6 +42,13 @@ class x86_fbsd_nat_target : public x86bsd_nat_target<fbsd_nat_target>
   x86_xsave_layout fetch_x86_xsave_layout () override
   { return m_xsave_layout; }
 
+  enum target_xfer_status xfer_partial (enum target_object object,
+					const char *annex,
+					gdb_byte *readbuf,
+					const gdb_byte *writebuf,
+					ULONGEST offset, ULONGEST len,
+					ULONGEST *xfered_len) override;
+
 protected:
   void probe_xsave_layout (pid_t pid);
 
@@ -49,6 +56,8 @@ class x86_fbsd_nat_target : public x86bsd_nat_target<fbsd_nat_target>
   x86_xsave_layout m_xsave_layout;
 
 private:
+  gdb::unique_xmalloc_ptr<gdb_byte> m_cpuid_note;
+  size_t m_cpuid_note_len;
   bool m_xsave_probed;
 #endif
 };
-- 
2.41.0