Add support for the x86 XSAVE extended state on FreeBSD/x86.

Recognize NT_X86_XSTATE notes in FreeBSD process cores.  Recent
FreeBSD versions include a note containing the XSAVE state for each
thread in the process when XSAVE is in use.  The note stores a copy of
the current XSAVE mask in a reserved section of the machine-defined
XSAVE state at the same offset as Linux's NT_X86_XSTATE note.

For native processes, use the PT_GETXSTATE_INFO ptrace request to
determine if XSAVE is enabled, and if so the active XSAVE state mask
(that is, the value of %xcr0 for the target process) as well as the
size of XSAVE state area.  Use the PT_GETXSTATE and PT_SETXSTATE requests
to fetch and store the XSAVE state, respectively, in the BSD x86
native targets.

In addition, the FreeBSD amd64 and i386 native targets now include
"read_description" target methods to determine the correct x86 target
description for the current XSAVE mask.  On FreeBSD amd64 this also
properly returns an i386 target description for 32-bit binaries which
allows the 64-bit GDB to run 32-bit binaries.

Note that the ptrace changes are in the BSD native targets, not the
FreeBSD-specific native targets since that is where the other ptrace
register accesses occur.  Of the other BSDs, NetBSD and DragonFly use
XSAVE in the kernel but do not currently export the extended state via
ptrace(2).  OpenBSD does not currently support XSAVE.

bfd/ChangeLog:

	* elf.c (elfcore_grok_note): Recognize NT_X86_XSTATE on
	FreeBSD.
	(elfcore_write_xstatereg): Use correct note name on FreeBSD.

gdb/ChangeLog:

	* amd64-tdep.c (amd64_target_description): New function.
	* amd64-tdep.h: Export amd64_target_description and tdesc_amd64.
	* amd64bsd-nat.c [PT_GETXSTATE_INFO]: New variable amd64bsd_xsave_len.
	(amd64bsd_fetch_inferior_registers) [PT_GETXSTATE_INFO]: Handle
	x86 extended save area.
	(amd64bsd_store_inferior_registers) [PT_GETXSTATE_INFO]: Likewise.
	* amd64bsd-nat.h: Export amd64bsd_xsave_len.
	* amd64fbsd-nat.c (amd64fbsd_read_description): New function.
	(_initialize_amd64fbsd_nat): Set "to_read_description" to
	"amd64fbsd_read_description".
	* amd64fbsd-tdep.c (amd64fbsd_core_read_description): New function.
	(amd64fbsd_supply_xstateregset): New function.
	(amd64fbsd_collect_xstateregset): New function.
	Add "amd64fbsd_xstateregset".
	(amd64fbsd_iterate_over_regset_sections): New function.
	(amd64fbsd_init_abi): Set "xsave_xcr0_offset" to
	"I386_FBSD_XSAVE_XCR0_OFFSET".
	Add "iterate_over_regset_sections" gdbarch method.
	Add "core_read_description" gdbarch method.
	* i386-tdep.c (i386_target_description): New function.
	* i386-tdep.h: Export i386_target_description and tdesc_i386.
	* i386bsd-nat.c [PT_GETXSTATE_INFO]: New variable i386bsd_xsave_len.
	(i386bsd_fetch_inferior_registers) [PT_GETXSTATE_INFO]: Handle
	x86 extended save area.
	(i386bsd_store_inferior_registers) [PT_GETXSTATE_INFO]: Likewise.
	* i386bsd-nat.h: Export i386bsd_xsave_len.
	* i386fbsd-nat.c (i386fbsd_read_description): New function.
	(_initialize_i386fbsd_nat): Set "to_read_description" to
	"i386fbsd_read_description".
	* i386fbsd-tdep.c (i386fbsd_core_read_xcr0): New function.
	(i386fbsd_core_read_description): New function.
	(i386fbsd_supply_xstateregset): New function.
	(i386fbsd_collect_xstateregset): New function.
	Add "i386fbsd_xstateregset".
	(i386fbsd_iterate_over_regset_sections): New function.
	(i386fbsd4_init_abi): Set "xsave_xcr0_offset" to
	"I386_FBSD_XSAVE_XCR0_OFFSET".
	Add "iterate_over_regset_sections" gdbarch method.
	Add "core_read_description" gdbarch method.
	* i386fbsd-tdep.h: New file.

1 files changed, 106 insertions, 0 deletions

diff --git a/gdb/i386fbsd-tdep.c b/gdb/i386fbsd-tdep.c
index ed41706..99e08cb 100644
--- a/gdb/i386fbsd-tdep.c
+++ b/gdb/i386fbsd-tdep.c
@@ -22,6 +22,9 @@
 #include "gdbcore.h"
 #include "osabi.h"
 #include "regcache.h"
+#include "regset.h"
+#include "i386fbsd-tdep.h"
+#include "x86-xstate.h"
 
 #include "i386-tdep.h"
 #include "i387-tdep.h"
@@ -235,6 +238,100 @@ static int i386fbsd_jmp_buf_reg_offset[] =
   0 * 4				/* %eip */
 };
 
+/* Get XSAVE extended state xcr0 from core dump.  */
+
+uint64_t
+i386fbsd_core_read_xcr0 (bfd *abfd)
+{
+  asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
+  uint64_t xcr0;
+
+  if (xstate)
+    {
+      size_t size = bfd_section_size (abfd, xstate);
+
+      /* Check extended state size.  */
+      if (size < X86_XSTATE_AVX_SIZE)
+	xcr0 = X86_XSTATE_SSE_MASK;
+      else
+	{
+	  char contents[8];
+
+	  if (! bfd_get_section_contents (abfd, xstate, contents,
+					  I386_FBSD_XSAVE_XCR0_OFFSET,
+					  8))
+	    {
+	      warning (_("Couldn't read `xcr0' bytes from "
+			 "`.reg-xstate' section in core file."));
+	      return 0;
+	    }
+
+	  xcr0 = bfd_get_64 (abfd, contents);
+	}
+    }
+  else
+    xcr0 = 0;
+
+  return xcr0;
+}
+
+/* Implement the core_read_description gdbarch method.  */
+
+static const struct target_desc *
+i386fbsd_core_read_description (struct gdbarch *gdbarch,
+				struct target_ops *target,
+				bfd *abfd)
+{
+  return i386_target_description (i386fbsd_core_read_xcr0 (abfd));
+}
+
+/* Similar to i386_supply_fpregset, but use XSAVE extended state.  */
+
+static void
+i386fbsd_supply_xstateregset (const struct regset *regset,
+			      struct regcache *regcache, int regnum,
+			      const void *xstateregs, size_t len)
+{
+  i387_supply_xsave (regcache, regnum, xstateregs);
+}
+
+/* Similar to i386_collect_fpregset, but use XSAVE extended state.  */
+
+static void
+i386fbsd_collect_xstateregset (const struct regset *regset,
+			       const struct regcache *regcache,
+			       int regnum, void *xstateregs, size_t len)
+{
+  i387_collect_xsave (regcache, regnum, xstateregs, 1);
+}
+
+/* Register set definitions.  */
+
+static const struct regset i386fbsd_xstateregset =
+  {
+    NULL,
+    i386fbsd_supply_xstateregset,
+    i386fbsd_collect_xstateregset
+  };
+
+/* Iterate over core file register note sections.  */
+
+static void
+i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
+				       iterate_over_regset_sections_cb *cb,
+				       void *cb_data,
+				       const struct regcache *regcache)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  cb (".reg", tdep->sizeof_gregset, &i386_gregset, NULL, cb_data);
+  cb (".reg2", tdep->sizeof_fpregset, &i386_fpregset, NULL, cb_data);
+
+  if (tdep->xcr0 & X86_XSTATE_AVX)
+    cb (".reg-xstate", X86_XSTATE_SIZE(tdep->xcr0),
+	&i386fbsd_xstateregset, "XSAVE extended state", cb_data);
+}
+
 static void
 i386fbsd_supply_uthread (struct regcache *regcache,
 			 int regnum, CORE_ADDR addr)
@@ -376,6 +473,15 @@ i386fbsd4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* FreeBSD 4.0 introduced a new `struct sigcontext'.  */
   tdep->sc_reg_offset = i386fbsd4_sc_reg_offset;
   tdep->sc_num_regs = ARRAY_SIZE (i386fbsd4_sc_reg_offset);
+
+  tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
+
+  /* Iterate over core file register note sections.  */
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, i386fbsd_iterate_over_regset_sections);
+
+  set_gdbarch_core_read_description (gdbarch,
+				     i386fbsd_core_read_description);
 }