[RFC PATCH 2/4] core: Support fetching TARGET_OBJECT_X86_XSAVE_OFFSETS from architectures.

[John Baldwin]

Add gdbarch_core_xfer_x86_xsave_offsets to fetch the x86 XSAVE offsets
structure from a core file.
---
 gdb/corelow.c             | 22 ++++++++++++++++++++++
 gdb/gdbarch-components.py | 13 +++++++++++++
 gdb/gdbarch-gen.h         | 10 ++++++++++
 gdb/gdbarch.c             | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 77 insertions(+)

diff --git a/gdb/corelow.c b/gdb/corelow.c
index f7f2bd3f318..c945d47df29 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -987,6 +987,28 @@ core_target::xfer_partial (enum target_object object, const char *annex,
 	}
       return TARGET_XFER_E_IO;
 
+    case TARGET_OBJECT_X86_XSAVE_OFFSETS:
+      if (readbuf)
+	{
+	  if (m_core_gdbarch != nullptr
+	      && gdbarch_core_xfer_x86_xsave_offsets_p (m_core_gdbarch))
+	    {
+	      LONGEST l = gdbarch_core_xfer_x86_xsave_offsets  (m_core_gdbarch,
+								readbuf, offset,
+								len);
+
+	      if (l >= 0)
+		{
+		  *xfered_len = l;
+		  if (l == 0)
+		    return TARGET_XFER_EOF;
+		  else
+		    return TARGET_XFER_OK;
+		}
+	    }
+	}
+      return TARGET_XFER_E_IO;
+
     default:
     fallthrough:
       return this->beneath ()->xfer_partial (object, annex, readbuf,
diff --git a/gdb/gdbarch-components.py b/gdb/gdbarch-components.py
index 4987f8a5fef..9c88433f02f 100644
--- a/gdb/gdbarch-components.py
+++ b/gdb/gdbarch-components.py
@@ -1585,6 +1585,19 @@ of bytes read (zero indicates EOF, a negative value indicates failure).
     invalid=True,
 )
 
+Method(
+    comment="""
+Read offset OFFSET of TARGET_OBJECT_X86_XSAVE_OFFSETS from core file
+into buffer READBUF with length LEN.  Return the number of bytes read
+(zero indicates EOF, a negative value indicates failure).
+""",
+    type="LONGEST",
+    name="core_xfer_x86_xsave_offsets",
+    params=[("gdb_byte *", "readbuf"), ("ULONGEST", "offset"), ("ULONGEST", "len")],
+    predicate=True,
+    invalid=True,
+)
+
 Value(
     comment="""
 BFD target to use when generating a core file.
diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
index b7beb73d36d..9dca81b9c85 100644
--- a/gdb/gdbarch-gen.h
+++ b/gdb/gdbarch-gen.h
@@ -923,6 +923,16 @@ typedef LONGEST (gdbarch_core_xfer_siginfo_ftype) (struct gdbarch *gdbarch, gdb_
 extern LONGEST gdbarch_core_xfer_siginfo (struct gdbarch *gdbarch, gdb_byte *readbuf, ULONGEST offset, ULONGEST len);
 extern void set_gdbarch_core_xfer_siginfo (struct gdbarch *gdbarch, gdbarch_core_xfer_siginfo_ftype *core_xfer_siginfo);
 
+/* Read offset OFFSET of TARGET_OBJECT_X86_XSAVE_OFFSETS from core file
+   into buffer READBUF with length LEN.  Return the number of bytes read
+   (zero indicates EOF, a negative value indicates failure). */
+
+extern bool gdbarch_core_xfer_x86_xsave_offsets_p (struct gdbarch *gdbarch);
+
+typedef LONGEST (gdbarch_core_xfer_x86_xsave_offsets_ftype) (struct gdbarch *gdbarch, gdb_byte *readbuf, ULONGEST offset, ULONGEST len);
+extern LONGEST gdbarch_core_xfer_x86_xsave_offsets (struct gdbarch *gdbarch, gdb_byte *readbuf, ULONGEST offset, ULONGEST len);
+extern void set_gdbarch_core_xfer_x86_xsave_offsets (struct gdbarch *gdbarch, gdbarch_core_xfer_x86_xsave_offsets_ftype *core_xfer_x86_xsave_offsets);
+
 /* BFD target to use when generating a core file. */
 
 extern bool gdbarch_gcore_bfd_target_p (struct gdbarch *gdbarch);
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 55dd602b27f..7d2d8dbdb4b 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -176,6 +176,7 @@ struct gdbarch
   gdbarch_core_pid_to_str_ftype *core_pid_to_str;
   gdbarch_core_thread_name_ftype *core_thread_name;
   gdbarch_core_xfer_siginfo_ftype *core_xfer_siginfo;
+  gdbarch_core_xfer_x86_xsave_offsets_ftype *core_xfer_x86_xsave_offsets;
   const char * gcore_bfd_target;
   int vtable_function_descriptors;
   int vbit_in_delta;
@@ -527,6 +528,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of core_pid_to_str, has predicate.  */
   /* Skip verify of core_thread_name, has predicate.  */
   /* Skip verify of core_xfer_siginfo, has predicate.  */
+  /* Skip verify of core_xfer_x86_xsave_offsets, has predicate.  */
   /* Skip verify of gcore_bfd_target, has predicate.  */
   /* Skip verify of vtable_function_descriptors, invalid_p == 0 */
   /* Skip verify of vbit_in_delta, invalid_p == 0 */
@@ -1122,6 +1124,12 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
   fprintf_filtered (file,
                       "gdbarch_dump: core_xfer_siginfo = <%s>\n",
                       host_address_to_string (gdbarch->core_xfer_siginfo));
+  fprintf_filtered (file,
+                      "gdbarch_dump: gdbarch_core_xfer_x86_xsave_offsets_p() = %d\n",
+                      gdbarch_core_xfer_x86_xsave_offsets_p (gdbarch));
+  fprintf_filtered (file,
+                      "gdbarch_dump: core_xfer_x86_xsave_offsets = <%s>\n",
+                      host_address_to_string (gdbarch->core_xfer_x86_xsave_offsets));
   fprintf_filtered (file,
                       "gdbarch_dump: gdbarch_gcore_bfd_target_p() = %d\n",
                       gdbarch_gcore_bfd_target_p (gdbarch));
@@ -3865,6 +3873,30 @@ set_gdbarch_core_xfer_siginfo (struct gdbarch *gdbarch,
   gdbarch->core_xfer_siginfo = core_xfer_siginfo;
 }
 
+bool
+gdbarch_core_xfer_x86_xsave_offsets_p (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  return gdbarch->core_xfer_x86_xsave_offsets != NULL;
+}
+
+LONGEST
+gdbarch_core_xfer_x86_xsave_offsets (struct gdbarch *gdbarch, gdb_byte *readbuf, ULONGEST offset, ULONGEST len)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->core_xfer_x86_xsave_offsets != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_core_xfer_x86_xsave_offsets called\n");
+  return gdbarch->core_xfer_x86_xsave_offsets (gdbarch, readbuf, offset, len);
+}
+
+void
+set_gdbarch_core_xfer_x86_xsave_offsets (struct gdbarch *gdbarch,
+                                         gdbarch_core_xfer_x86_xsave_offsets_ftype core_xfer_x86_xsave_offsets)
+{
+  gdbarch->core_xfer_x86_xsave_offsets = core_xfer_x86_xsave_offsets;
+}
+
 bool
 gdbarch_gcore_bfd_target_p (struct gdbarch *gdbarch)
 {
-- 
2.34.1