Replace 'core_regset_sections' by iterator method

The core_regset_sections list in gdbarch (needed for multi-arch
capable core file generation support) is replaced by an iterator
method.  Overall, this reduces the code a bit, and it allows for more
flexibility.

gdb/ChangeLog:

	* amd64-linux-tdep.c (amd64_linux_regset_sections): Remove.
	(amd64_linux_iterate_over_regset_sections): New.
	(amd64_linux_init_abi_common): Don't install the regset section
	list, but the new iterator in gdbarch.
	* arm-linux-tdep.c (arm_linux_fpa_regset_sections)
	(arm_linux_vfp_regset_sections): Remove.  Move combined logic...
	(arm_linux_iterate_over_regset_sections): ...here.  New function.
	(arm_linux_init_abi): Set iterator instead of section list.
	* corelow.c (get_core_registers_cb): New function, logic moved
	from...
	(get_core_registers): ...loop body here.  Use new iterator method
	instead of walking through the regset section list.
	* gdbarch.sh: Remove 'core_regset_sections'.  New method
	'iterate_over_regset_sections'.  New typedef
	'iterate_over_regset_sections_cb'.
	* gdbarch.c: Regenerate.
	* gdbarch.h: Likewise.
	* i386-linux-tdep.c (i386_linux_regset_sections)
	(i386_linux_sse_regset_sections, i386_linux_avx_regset_sections):
	Remove.
	(i386_linux_iterate_over_regset_sections): New.
	(i386_linux_init_abi): Don't choose a regset section list, but
	install new iterator in gdbarch.
	* linux-tdep.c (struct linux_collect_regset_section_cb_data): New.
	(linux_collect_regset_section_cb): New function, logic moved
	from...
	(linux_collect_thread_registers): ...loop body here.  Use iterator
	method instead of walking through list.
	(linux_make_corefile_notes_1): Check for presence of iterator
	method instead of regset section list.
	* ppc-linux-tdep.c (ppc_linux_vsx_regset_sections)
	(ppc_linux_vmx_regset_sections, ppc_linux_fp_regset_sections)
	(ppc64_linux_vsx_regset_sections, ppc64_linux_vmx_regset_sections)
	(ppc64_linux_fp_regset_sections): Remove.  Move combined logic...
	(ppc_linux_iterate_over_regset_sections): ...here.  New function.
	(ppc_linux_init_abi): Don't choose from above regset section
	lists, but install new iterator in gdbarch.
	* regset.h (struct core_regset_section): Remove.
	* s390-linux-tdep.c (struct gdbarch_tdep): Add new fields
	have_linux_v1, have_linux_v2, and have_tdb.
	(s390_linux32_regset_sections, s390_linux32v1_regset_sections)
	(s390_linux32v2_regset_sections, s390_linux64_regset_sections)
	(s390_linux64v1_regset_sections, s390_linux64v2_regset_sections)
	(s390x_linux64_regset_sections, s390x_linux64v1_regset_sections)
	(s390x_linux64v2_regset_sections): Remove.  Move combined logic...
	(s390_iterate_over_regset_sections): ...here.  New function.  Use
	new tdep fields.
	(s390_gdbarch_init): Set new tdep fields.  Don't choose from above
	regset section lists, but install new iterator.

12 files changed, 312 insertions, 328 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index afaf056..589c601 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,55 @@
+2014-09-30  Andreas Arnez  <arnez@linux.vnet.ibm.com>
+
+	* amd64-linux-tdep.c (amd64_linux_regset_sections): Remove.
+	(amd64_linux_iterate_over_regset_sections): New.
+	(amd64_linux_init_abi_common): Don't install the regset section
+	list, but the new iterator in gdbarch.
+	* arm-linux-tdep.c (arm_linux_fpa_regset_sections)
+	(arm_linux_vfp_regset_sections): Remove.  Move combined logic...
+	(arm_linux_iterate_over_regset_sections): ...here.  New function.
+	(arm_linux_init_abi): Set iterator instead of section list.
+	* corelow.c (get_core_registers_cb): New function, logic moved
+	from...
+	(get_core_registers): ...loop body here.  Use new iterator method
+	instead of walking through the regset section list.
+	* gdbarch.sh: Remove 'core_regset_sections'.  New method
+	'iterate_over_regset_sections'.  New typedef
+	'iterate_over_regset_sections_cb'.
+	* gdbarch.c: Regenerate.
+	* gdbarch.h: Likewise.
+	* i386-linux-tdep.c (i386_linux_regset_sections)
+	(i386_linux_sse_regset_sections, i386_linux_avx_regset_sections):
+	Remove.
+	(i386_linux_iterate_over_regset_sections): New.
+	(i386_linux_init_abi): Don't choose a regset section list, but
+	install new iterator in gdbarch.
+	* linux-tdep.c (struct linux_collect_regset_section_cb_data): New.
+	(linux_collect_regset_section_cb): New function, logic moved
+	from...
+	(linux_collect_thread_registers): ...loop body here.  Use iterator
+	method instead of walking through list.
+	(linux_make_corefile_notes_1): Check for presence of iterator
+	method instead of regset section list.
+	* ppc-linux-tdep.c (ppc_linux_vsx_regset_sections)
+	(ppc_linux_vmx_regset_sections, ppc_linux_fp_regset_sections)
+	(ppc64_linux_vsx_regset_sections, ppc64_linux_vmx_regset_sections)
+	(ppc64_linux_fp_regset_sections): Remove.  Move combined logic...
+	(ppc_linux_iterate_over_regset_sections): ...here.  New function.
+	(ppc_linux_init_abi): Don't choose from above regset section
+	lists, but install new iterator in gdbarch.
+	* regset.h (struct core_regset_section): Remove.
+	* s390-linux-tdep.c (struct gdbarch_tdep): Add new fields
+	have_linux_v1, have_linux_v2, and have_tdb.
+	(s390_linux32_regset_sections, s390_linux32v1_regset_sections)
+	(s390_linux32v2_regset_sections, s390_linux64_regset_sections)
+	(s390_linux64v1_regset_sections, s390_linux64v2_regset_sections)
+	(s390x_linux64_regset_sections, s390x_linux64v1_regset_sections)
+	(s390x_linux64v2_regset_sections): Remove.  Move combined logic...
+	(s390_iterate_over_regset_sections): ...here.  New function.  Use
+	new tdep fields.
+	(s390_gdbarch_init): Set new tdep fields.  Don't choose from above
+	regset section lists, but install new iterator.
+
 2014-09-29  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* solib-svr4.c (svr4_parse_libraries): Use "library-list-svr4.dtd".
diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
index 850ca20..2432bae 100644
--- a/gdb/amd64-linux-tdep.c
+++ b/gdb/amd64-linux-tdep.c
@@ -53,15 +53,6 @@
 #include "record-full.h"
 #include "linux-record.h"
 
-/* Supported register note sections.  */
-static struct core_regset_section amd64_linux_regset_sections[] =
-{
-  { ".reg", 27 * 8, "general-purpose" },
-  { ".reg2", 512, "floating-point" },
-  { ".reg-xstate", X86_XSTATE_MAX_SIZE, "XSAVE extended state" },
-  { NULL, 0 }
-};
-
 /* Mapping between the general-purpose registers in `struct user'
    format and GDB's register cache layout.  */
 
@@ -1609,6 +1600,19 @@ amd64_linux_core_read_description (struct gdbarch *gdbarch,
     }
 }
 
+/* Iterate over core file register note sections.  */
+
+static void
+amd64_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
+					  iterate_over_regset_sections_cb *cb,
+					  void *cb_data,
+					  const struct regcache *regcache)
+{
+  cb (".reg", 27 * 8, "general-purpose", cb_data);
+  cb (".reg2", 512, "floating-point", cb_data);
+  cb (".reg-xstate", X86_XSTATE_MAX_SIZE, "XSAVE extended state", cb_data);
+}
+
 static void
 amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -1643,8 +1647,9 @@ amd64_linux_init_abi_common(struct gdbarch_info info, struct gdbarch *gdbarch)
   /* GNU/Linux uses the dynamic linker included in the GNU C Library.  */
   set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
 
-  /* Install supported register note sections.  */
-  set_gdbarch_core_regset_sections (gdbarch, amd64_linux_regset_sections);
+  /* Iterate over core file register note sections.  */
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, amd64_linux_iterate_over_regset_sections);
 
   set_gdbarch_core_read_description (gdbarch,
 				     amd64_linux_core_read_description);
diff --git a/gdb/arm-linux-tdep.c b/gdb/arm-linux-tdep.c
index 3d524c9..22decd5 100644
--- a/gdb/arm-linux-tdep.c
+++ b/gdb/arm-linux-tdep.c
@@ -753,21 +753,24 @@ arm_linux_regset_from_core_section (struct gdbarch *gdbarch,
   return NULL;
 }
 
-/* Core file register set sections.  */
+/* Iterate over core file register note sections.  */
 
-static struct core_regset_section arm_linux_fpa_regset_sections[] =
+static void
+arm_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
+					iterate_over_regset_sections_cb *cb,
+					void *cb_data,
+					const struct regcache *regcache)
 {
-  { ".reg", ARM_LINUX_SIZEOF_GREGSET, "general-purpose" },
-  { ".reg2", ARM_LINUX_SIZEOF_NWFPE, "FPA floating-point" },
-  { NULL, 0}
-};
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 
-static struct core_regset_section arm_linux_vfp_regset_sections[] =
-{
-  { ".reg", ARM_LINUX_SIZEOF_GREGSET, "general-purpose" },
-  { ".reg-arm-vfp", ARM_LINUX_SIZEOF_VFP, "VFP floating-point" },
-  { NULL, 0}
-};
+  cb (".reg", ARM_LINUX_SIZEOF_GREGSET, "general-purpose", cb_data);
+
+  if (tdep->have_vfp_registers)
+    cb (".reg-arm-vfp", ARM_LINUX_SIZEOF_VFP, "VFP floating-point",
+	cb_data);
+  else if (tdep->have_fpa_registers)
+    cb (".reg2", ARM_LINUX_SIZEOF_NWFPE, "FPA floating-point", cb_data);
+}
 
 /* Determine target description from core file.  */
 
@@ -1456,13 +1459,10 @@ arm_linux_init_abi (struct gdbarch_info info,
   /* Core file support.  */
   set_gdbarch_regset_from_core_section (gdbarch,
 					arm_linux_regset_from_core_section);
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, arm_linux_iterate_over_regset_sections);
   set_gdbarch_core_read_description (gdbarch, arm_linux_core_read_description);
 
-  if (tdep->have_vfp_registers)
-    set_gdbarch_core_regset_sections (gdbarch, arm_linux_vfp_regset_sections);
-  else if (tdep->have_fpa_registers)
-    set_gdbarch_core_regset_sections (gdbarch, arm_linux_fpa_regset_sections);
-
   set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type);
 
   /* Displaced stepping.  */
diff --git a/gdb/corelow.c b/gdb/corelow.c
index ecd99f6..7e64e1d 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -550,6 +550,22 @@ get_core_register_section (struct regcache *regcache,
 				  bfd_section_vma (core_bfd, section)));
 }
 
+/* Callback for get_core_registers that handles a single core file
+   register note section. */
+
+static void
+get_core_registers_cb (const char *sect_name, int size,
+		       const char *human_name, void *cb_data)
+{
+  struct regcache *regcache = (struct regcache *) cb_data;
+
+  if (strcmp (sect_name, ".reg") == 0)
+    get_core_register_section (regcache, sect_name, 0, human_name, 1);
+  else if (strcmp (sect_name, ".reg2") == 0)
+    get_core_register_section (regcache, sect_name, 2, human_name, 0);
+  else
+    get_core_register_section (regcache, sect_name, 3, human_name, 0);
+}
 
 /* Get the registers out of a core file.  This is the machine-
    independent part.  Fetch_core_registers is the machine-dependent
@@ -562,8 +578,8 @@ static void
 get_core_registers (struct target_ops *ops,
 		    struct regcache *regcache, int regno)
 {
-  struct core_regset_section *sect_list;
   int i;
+  struct gdbarch *gdbarch;
 
   if (!(core_gdbarch && gdbarch_regset_from_core_section_p (core_gdbarch))
       && (core_vec == NULL || core_vec->core_read_registers == NULL))
@@ -573,23 +589,11 @@ get_core_registers (struct target_ops *ops,
       return;
     }
 
-  sect_list = gdbarch_core_regset_sections (get_regcache_arch (regcache));
-  if (sect_list)
-    while (sect_list->sect_name != NULL)
-      {
-        if (strcmp (sect_list->sect_name, ".reg") == 0)
-	  get_core_register_section (regcache, sect_list->sect_name,
-				     0, sect_list->human_name, 1);
-        else if (strcmp (sect_list->sect_name, ".reg2") == 0)
-	  get_core_register_section (regcache, sect_list->sect_name,
-				     2, sect_list->human_name, 0);
-	else
-	  get_core_register_section (regcache, sect_list->sect_name,
-				     3, sect_list->human_name, 0);
-
-	sect_list++;
-      }
-
+  gdbarch = get_regcache_arch (regcache);
+  if (gdbarch_iterate_over_regset_sections_p (gdbarch))
+    gdbarch_iterate_over_regset_sections (gdbarch,
+					  get_core_registers_cb,
+					  (void *) regcache, NULL);
   else
     {
       get_core_register_section (regcache,
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index b0ee79d..be4bb78 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -260,7 +260,7 @@ struct gdbarch
   gdbarch_register_reggroup_p_ftype *register_reggroup_p;
   gdbarch_fetch_pointer_argument_ftype *fetch_pointer_argument;
   gdbarch_regset_from_core_section_ftype *regset_from_core_section;
-  struct core_regset_section * core_regset_sections;
+  gdbarch_iterate_over_regset_sections_ftype *iterate_over_regset_sections;
   gdbarch_make_corefile_notes_ftype *make_corefile_notes;
   gdbarch_elfcore_write_linux_prpsinfo_ftype *elfcore_write_linux_prpsinfo;
   gdbarch_find_memory_regions_ftype *find_memory_regions;
@@ -571,6 +571,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of register_reggroup_p, invalid_p == 0 */
   /* Skip verify of fetch_pointer_argument, has predicate.  */
   /* Skip verify of regset_from_core_section, has predicate.  */
+  /* Skip verify of iterate_over_regset_sections, has predicate.  */
   /* Skip verify of make_corefile_notes, has predicate.  */
   /* Skip verify of elfcore_write_linux_prpsinfo, has predicate.  */
   /* Skip verify of find_memory_regions, has predicate.  */
@@ -768,9 +769,6 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       "gdbarch_dump: core_read_description = <%s>\n",
                       host_address_to_string (gdbarch->core_read_description));
   fprintf_unfiltered (file,
-                      "gdbarch_dump: core_regset_sections = %s\n",
-                      host_address_to_string (gdbarch->core_regset_sections));
-  fprintf_unfiltered (file,
                       "gdbarch_dump: gdbarch_core_xfer_shared_libraries_p() = %d\n",
                       gdbarch_core_xfer_shared_libraries_p (gdbarch));
   fprintf_unfiltered (file,
@@ -987,6 +985,12 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       "gdbarch_dump: iterate_over_objfiles_in_search_order = <%s>\n",
                       host_address_to_string (gdbarch->iterate_over_objfiles_in_search_order));
   fprintf_unfiltered (file,
+                      "gdbarch_dump: gdbarch_iterate_over_regset_sections_p() = %d\n",
+                      gdbarch_iterate_over_regset_sections_p (gdbarch));
+  fprintf_unfiltered (file,
+                      "gdbarch_dump: iterate_over_regset_sections = <%s>\n",
+                      host_address_to_string (gdbarch->iterate_over_regset_sections));
+  fprintf_unfiltered (file,
                       "gdbarch_dump: long_bit = %s\n",
                       plongest (gdbarch->long_bit));
   fprintf_unfiltered (file,
@@ -3260,20 +3264,28 @@ set_gdbarch_regset_from_core_section (struct gdbarch *gdbarch,
   gdbarch->regset_from_core_section = regset_from_core_section;
 }
 
-struct core_regset_section *
-gdbarch_core_regset_sections (struct gdbarch *gdbarch)
+int
+gdbarch_iterate_over_regset_sections_p (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  return gdbarch->iterate_over_regset_sections != NULL;
+}
+
+void
+gdbarch_iterate_over_regset_sections (struct gdbarch *gdbarch, iterate_over_regset_sections_cb *cb, void *cb_data, const struct regcache *regcache)
 {
   gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->iterate_over_regset_sections != NULL);
   if (gdbarch_debug >= 2)
-    fprintf_unfiltered (gdb_stdlog, "gdbarch_core_regset_sections called\n");
-  return gdbarch->core_regset_sections;
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_iterate_over_regset_sections called\n");
+  gdbarch->iterate_over_regset_sections (gdbarch, cb, cb_data, regcache);
 }
 
 void
-set_gdbarch_core_regset_sections (struct gdbarch *gdbarch,
-                                  struct core_regset_section * core_regset_sections)
+set_gdbarch_iterate_over_regset_sections (struct gdbarch *gdbarch,
+                                          gdbarch_iterate_over_regset_sections_ftype iterate_over_regset_sections)
 {
-  gdbarch->core_regset_sections = core_regset_sections;
+  gdbarch->iterate_over_regset_sections = iterate_over_regset_sections;
 }
 
 int
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index 0303b2e..bbda3da 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -81,6 +81,9 @@ extern struct gdbarch *target_gdbarch (void);
 typedef int (iterate_over_objfiles_in_search_order_cb_ftype)
   (struct objfile *objfile, void *cb_data);
 
+typedef void (iterate_over_regset_sections_cb)
+  (const char *sect_name, int size, const char *human_name, void *cb_data);
+
 
 /* The following are pre-initialized by GDBARCH.  */
 
@@ -741,10 +744,18 @@ typedef const struct regset * (gdbarch_regset_from_core_section_ftype) (struct g
 extern const struct regset * gdbarch_regset_from_core_section (struct gdbarch *gdbarch, const char *sect_name, size_t sect_size);
 extern void set_gdbarch_regset_from_core_section (struct gdbarch *gdbarch, gdbarch_regset_from_core_section_ftype *regset_from_core_section);
 
-/* Supported register notes in a core file. */
+/* Iterate over all supported register notes in a core file.  For each
+   supported register note section, the iterator must call CB and pass
+   CB_DATA unchanged.  If REGCACHE is not NULL, the iterator can limit
+   the supported register note sections based on the current register
+   values.  Otherwise it should enumerate all supported register note
+   sections. */
+
+extern int gdbarch_iterate_over_regset_sections_p (struct gdbarch *gdbarch);
 
-extern struct core_regset_section * gdbarch_core_regset_sections (struct gdbarch *gdbarch);
-extern void set_gdbarch_core_regset_sections (struct gdbarch *gdbarch, struct core_regset_section * core_regset_sections);
+typedef void (gdbarch_iterate_over_regset_sections_ftype) (struct gdbarch *gdbarch, iterate_over_regset_sections_cb *cb, void *cb_data, const struct regcache *regcache);
+extern void gdbarch_iterate_over_regset_sections (struct gdbarch *gdbarch, iterate_over_regset_sections_cb *cb, void *cb_data, const struct regcache *regcache);
+extern void set_gdbarch_iterate_over_regset_sections (struct gdbarch *gdbarch, gdbarch_iterate_over_regset_sections_ftype *iterate_over_regset_sections);
 
 /* Create core file notes */
 
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 2a8bca8..80d3eec 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -655,8 +655,13 @@ F:CORE_ADDR:fetch_pointer_argument:struct frame_info *frame, int argi, struct ty
 # name SECT_NAME and size SECT_SIZE.
 M:const struct regset *:regset_from_core_section:const char *sect_name, size_t sect_size:sect_name, sect_size
 
-# Supported register notes in a core file.
-v:struct core_regset_section *:core_regset_sections:const char *name, int len::::::host_address_to_string (gdbarch->core_regset_sections)
+# Iterate over all supported register notes in a core file.  For each
+# supported register note section, the iterator must call CB and pass
+# CB_DATA unchanged.  If REGCACHE is not NULL, the iterator can limit
+# the supported register note sections based on the current register
+# values.  Otherwise it should enumerate all supported register note
+# sections.
+M:void:iterate_over_regset_sections:iterate_over_regset_sections_cb *cb, void *cb_data, const struct regcache *regcache:cb, cb_data, regcache
 
 # Create core file notes
 M:char *:make_corefile_notes:bfd *obfd, int *note_size:obfd, note_size
@@ -1169,6 +1174,9 @@ extern struct gdbarch *target_gdbarch (void);
 
 typedef int (iterate_over_objfiles_in_search_order_cb_ftype)
   (struct objfile *objfile, void *cb_data);
+
+typedef void (iterate_over_regset_sections_cb)
+  (const char *sect_name, int size, const char *human_name, void *cb_data);
 EOF
 
 # function typedef's
diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c
index b3707f7..4ee6874 100644
--- a/gdb/i386-linux-tdep.c
+++ b/gdb/i386-linux-tdep.c
@@ -52,28 +52,6 @@
 #include "features/i386/i386-avx-linux.c"
 #include "features/i386/i386-avx512-linux.c"
 
-/* Supported register note sections.  */
-static struct core_regset_section i386_linux_regset_sections[] =
-{
-  { ".reg", 68, "general-purpose" },
-  { ".reg2", 108, "floating-point" },
-  { NULL, 0 }
-};
-
-static struct core_regset_section i386_linux_sse_regset_sections[] =
-{
-  { ".reg", 68, "general-purpose" },
-  { ".reg-xfp", 512, "extended floating-point" },
-  { NULL, 0 }
-};
-
-static struct core_regset_section i386_linux_avx_regset_sections[] =
-{
-  { ".reg", 68, "general-purpose" },
-  { ".reg-xstate", X86_XSTATE_MAX_SIZE, "XSAVE extended state" },
-  { NULL, 0 }
-};
-
 /* Return non-zero, when the register is in the corresponding register
    group.  Put the LINUX_ORIG_EAX register in the system group.  */
 static int
@@ -670,6 +648,26 @@ i386_linux_core_read_description (struct gdbarch *gdbarch,
     return tdesc_i386_mmx_linux;
 }
 
+/* Iterate over core file register note sections.  */
+
+static void
+i386_linux_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", 68, "general-purpose", cb_data);
+
+  if (tdep->xcr0 & X86_XSTATE_AVX)
+    cb (".reg-xstate", X86_XSTATE_MAX_SIZE, "XSAVE extended state", cb_data);
+  else if (tdep->xcr0 & X86_XSTATE_SSE)
+    cb (".reg-xfp", 512, "extended floating-point", cb_data);
+  else
+    cb (".reg2", 108, "floating-point", cb_data);
+}
+
 /* Linux kernel shows PC value after the 'int $0x80' instruction even if
    inferior is still inside the syscall.  On next PTRACE_SINGLESTEP it will
    finish the syscall but PC will not change.
@@ -948,15 +946,9 @@ i386_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
                                              svr4_fetch_objfile_link_map);
 
-  /* Install supported register note sections.  */
-  if (tdesc_find_feature (tdesc, "org.gnu.gdb.i386.avx512")
-      || tdesc_find_feature (tdesc, "org.gnu.gdb.i386.avx"))
-    set_gdbarch_core_regset_sections (gdbarch, i386_linux_avx_regset_sections);
-  else if (tdesc_find_feature (tdesc, "org.gnu.gdb.i386.sse"))
-    set_gdbarch_core_regset_sections (gdbarch, i386_linux_sse_regset_sections);
-  else
-    set_gdbarch_core_regset_sections (gdbarch, i386_linux_regset_sections);
-
+  /* Core file support.  */
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, i386_linux_iterate_over_regset_sections);
   set_gdbarch_core_read_description (gdbarch,
 				     i386_linux_core_read_description);
 
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index dae59c5..3d8b1fc 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -1084,6 +1084,57 @@ linux_make_mappings_corefile_notes (struct gdbarch *gdbarch, bfd *obfd,
   return note_data;
 }
 
+/* Structure for passing information from
+   linux_collect_thread_registers via an iterator to
+   linux_collect_regset_section_cb. */
+
+struct linux_collect_regset_section_cb_data
+{
+  struct gdbarch *gdbarch;
+  const struct regcache *regcache;
+  bfd *obfd;
+  char *note_data;
+  int *note_size;
+  unsigned long lwp;
+  enum gdb_signal stop_signal;
+  int abort_iteration;
+};
+
+/* Callback for iterate_over_regset_sections that records a single
+   regset in the corefile note section.  */
+
+static void
+linux_collect_regset_section_cb (const char *sect_name, int size,
+				 const char *human_name, void *cb_data)
+{
+  const struct regset *regset;
+  char *buf;
+  struct linux_collect_regset_section_cb_data *data = cb_data;
+
+  if (data->abort_iteration)
+    return;
+
+  regset = gdbarch_regset_from_core_section (data->gdbarch, sect_name, size);
+  gdb_assert (regset && regset->collect_regset);
+
+  buf = xmalloc (size);
+  regset->collect_regset (regset, data->regcache, -1, buf, size);
+
+  /* PRSTATUS still needs to be treated specially.  */
+  if (strcmp (sect_name, ".reg") == 0)
+    data->note_data = (char *) elfcore_write_prstatus
+      (data->obfd, data->note_data, data->note_size, data->lwp,
+       gdb_signal_to_host (data->stop_signal), buf);
+  else
+    data->note_data = (char *) elfcore_write_register_note
+      (data->obfd, data->note_data, data->note_size,
+       sect_name, buf, size);
+  xfree (buf);
+
+  if (data->note_data == NULL)
+    data->abort_iteration = 1;
+}
+
 /* Records the thread's register state for the corefile note
    section.  */
 
@@ -1094,47 +1145,25 @@ linux_collect_thread_registers (const struct regcache *regcache,
 				enum gdb_signal stop_signal)
 {
   struct gdbarch *gdbarch = get_regcache_arch (regcache);
-  struct core_regset_section *sect_list;
-  unsigned long lwp;
+  struct linux_collect_regset_section_cb_data data;
 
-  sect_list = gdbarch_core_regset_sections (gdbarch);
-  gdb_assert (sect_list);
+  data.gdbarch = gdbarch;
+  data.regcache = regcache;
+  data.obfd = obfd;
+  data.note_data = note_data;
+  data.note_size = note_size;
+  data.stop_signal = stop_signal;
+  data.abort_iteration = 0;
 
   /* For remote targets the LWP may not be available, so use the TID.  */
-  lwp = ptid_get_lwp (ptid);
-  if (!lwp)
-    lwp = ptid_get_tid (ptid);
-
-  while (sect_list->sect_name != NULL)
-    {
-      const struct regset *regset;
-      char *buf;
-
-      regset = gdbarch_regset_from_core_section (gdbarch,
-						 sect_list->sect_name,
-						 sect_list->size);
-      gdb_assert (regset && regset->collect_regset);
-
-      buf = xmalloc (sect_list->size);
-      regset->collect_regset (regset, regcache, -1, buf, sect_list->size);
-
-      /* PRSTATUS still needs to be treated specially.  */
-      if (strcmp (sect_list->sect_name, ".reg") == 0)
-	note_data = (char *) elfcore_write_prstatus
-			       (obfd, note_data, note_size, lwp,
-				gdb_signal_to_host (stop_signal), buf);
-      else
-	note_data = (char *) elfcore_write_register_note
-			       (obfd, note_data, note_size,
-				sect_list->sect_name, buf, sect_list->size);
-      xfree (buf);
-      sect_list++;
-
-      if (!note_data)
-	return NULL;
-    }
-
-  return note_data;
+  data.lwp = ptid_get_lwp (ptid);
+  if (!data.lwp)
+    data.lwp = ptid_get_tid (ptid);
+
+  gdbarch_iterate_over_regset_sections (gdbarch,
+					linux_collect_regset_section_cb,
+					&data, regcache);
+  return data.note_data;
 }
 
 /* Fetch the siginfo data for the current thread, if it exists.  If
@@ -1524,7 +1553,7 @@ linux_make_corefile_notes_1 (struct gdbarch *gdbarch, bfd *obfd, int *note_size)
      converted to gdbarch_core_regset_sections, we no longer need to fall back
      to the target method at this point.  */
 
-  if (!gdbarch_core_regset_sections (gdbarch))
+  if (!gdbarch_iterate_over_regset_sections_p (gdbarch))
     return target_make_corefile_notes (obfd, note_size);
   else
     return linux_make_corefile_notes (gdbarch, obfd, note_size,
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index 316b254..7ab3255 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -257,54 +257,6 @@ ppc_linux_return_value (struct gdbarch *gdbarch, struct value *function,
 				      readbuf, writebuf);
 }
 
-static struct core_regset_section ppc_linux_vsx_regset_sections[] =
-{
-  { ".reg", 48 * 4, "general-purpose" },
-  { ".reg2", 264, "floating-point" },
-  { ".reg-ppc-vmx", 544, "ppc Altivec" },
-  { ".reg-ppc-vsx", 256, "POWER7 VSX" },
-  { NULL, 0}
-};
-
-static struct core_regset_section ppc_linux_vmx_regset_sections[] =
-{
-  { ".reg", 48 * 4, "general-purpose" },
-  { ".reg2", 264, "floating-point" },
-  { ".reg-ppc-vmx", 544, "ppc Altivec" },
-  { NULL, 0}
-};
-
-static struct core_regset_section ppc_linux_fp_regset_sections[] =
-{
-  { ".reg", 48 * 4, "general-purpose" },
-  { ".reg2", 264, "floating-point" },
-  { NULL, 0}
-};
-
-static struct core_regset_section ppc64_linux_vsx_regset_sections[] =
-{
-  { ".reg", 48 * 8, "general-purpose" },
-  { ".reg2", 264, "floating-point" },
-  { ".reg-ppc-vmx", 544, "ppc Altivec" },
-  { ".reg-ppc-vsx", 256, "POWER7 VSX" },
-  { NULL, 0}
-};
-
-static struct core_regset_section ppc64_linux_vmx_regset_sections[] =
-{
-  { ".reg", 48 * 8, "general-purpose" },
-  { ".reg2", 264, "floating-point" },
-  { ".reg-ppc-vmx", 544, "ppc Altivec" },
-  { NULL, 0}
-};
-
-static struct core_regset_section ppc64_linux_fp_regset_sections[] =
-{
-  { ".reg", 48 * 8, "general-purpose" },
-  { ".reg2", 264, "floating-point" },
-  { NULL, 0}
-};
-
 /* PLT stub in executable.  */
 static struct ppc_insn_pattern powerpc32_plt_stub[] =
   {
@@ -558,6 +510,28 @@ ppc_linux_regset_from_core_section (struct gdbarch *core_arch,
   return NULL;
 }
 
+/* Iterate over supported core file register note sections. */
+
+static void
+ppc_linux_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);
+  int have_altivec = tdep->ppc_vr0_regnum != -1;
+  int have_vsx = tdep->ppc_vsr0_upper_regnum != -1;
+
+  cb (".reg", 48 * tdep->wordsize, "general-purpose", cb_data);
+  cb (".reg2", 264, "floating-point", cb_data);
+
+  if (have_altivec)
+    cb (".reg-ppc-vmx", 544, "ppc Altivec", cb_data);
+
+  if (have_vsx)
+    cb (".reg-ppc-vsx", 256, "POWER7 VSX", cb_data);
+}
+
 static void
 ppc_linux_sigtramp_cache (struct frame_info *this_frame,
 			  struct trad_frame_cache *this_cache,
@@ -1352,19 +1326,6 @@ ppc_linux_init_abi (struct gdbarch_info info,
       else
 	set_gdbarch_gcore_bfd_target (gdbarch, "elf32-powerpc");
 
-      /* Supported register sections.  */
-      if (tdesc_find_feature (info.target_desc,
-			      "org.gnu.gdb.power.vsx"))
-	set_gdbarch_core_regset_sections (gdbarch,
-					  ppc_linux_vsx_regset_sections);
-      else if (tdesc_find_feature (info.target_desc,
-			       "org.gnu.gdb.power.altivec"))
-	set_gdbarch_core_regset_sections (gdbarch,
-					  ppc_linux_vmx_regset_sections);
-      else
-	set_gdbarch_core_regset_sections (gdbarch,
-					  ppc_linux_fp_regset_sections);
-
       if (powerpc_so_ops.in_dynsym_resolve_code == NULL)
 	{
 	  powerpc_so_ops = svr4_so_ops;
@@ -1416,19 +1377,6 @@ ppc_linux_init_abi (struct gdbarch_info info,
 	set_gdbarch_gcore_bfd_target (gdbarch, "elf64-powerpcle");
       else
 	set_gdbarch_gcore_bfd_target (gdbarch, "elf64-powerpc");
-
-      /* Supported register sections.  */
-      if (tdesc_find_feature (info.target_desc,
-			      "org.gnu.gdb.power.vsx"))
-	set_gdbarch_core_regset_sections (gdbarch,
-					  ppc64_linux_vsx_regset_sections);
-      else if (tdesc_find_feature (info.target_desc,
-			       "org.gnu.gdb.power.altivec"))
-	set_gdbarch_core_regset_sections (gdbarch,
-					  ppc64_linux_vmx_regset_sections);
-      else
-	set_gdbarch_core_regset_sections (gdbarch,
-					  ppc64_linux_fp_regset_sections);
     }
 
   /* PPC32 uses a different prpsinfo32 compared to most other Linux
@@ -1440,6 +1388,8 @@ ppc_linux_init_abi (struct gdbarch_info info,
   set_gdbarch_regset_from_core_section (gdbarch,
 					ppc_linux_regset_from_core_section);
   set_gdbarch_core_read_description (gdbarch, ppc_linux_core_read_description);
+  set_gdbarch_iterate_over_regset_sections (gdbarch,
+					    ppc_linux_iterate_over_regset_sections);
 
   /* Enable TLS support.  */
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
diff --git a/gdb/regset.h b/gdb/regset.h
index 37ed99a..68e19ee 100644
--- a/gdb/regset.h
+++ b/gdb/regset.h
@@ -23,14 +23,6 @@
 struct gdbarch;
 struct regcache;
 
-/* Data structure for the supported register notes in a core file.  */
-struct core_regset_section
-{
-  const char *sect_name;
-  int size;
-  const char *human_name;
-};
-
 /* Data structure describing a register set.  */
 
 typedef void (supply_regset_ftype) (const struct regset *, struct regcache *,
diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c
index ac8118b..840431d 100644
--- a/gdb/s390-linux-tdep.c
+++ b/gdb/s390-linux-tdep.c
@@ -88,6 +88,10 @@ struct gdbarch_tdep
 
   const struct regset *fpregset;
   int sizeof_fpregset;
+
+  int have_linux_v1;
+  int have_linux_v2;
+  int have_tdb;
 };
 
 
@@ -532,84 +536,6 @@ const struct regset s390_tdb_regset = {
   regcache_collect_regset
 };
 
-static struct core_regset_section s390_linux32_regset_sections[] =
-{
-  { ".reg", s390_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390_linux32v1_regset_sections[] =
-{
-  { ".reg", s390_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-last-break", 8, "s390 last-break address" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390_linux32v2_regset_sections[] =
-{
-  { ".reg", s390_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-last-break", 8, "s390 last-break address" },
-  { ".reg-s390-system-call", 4, "s390 system-call" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390_linux64_regset_sections[] =
-{
-  { ".reg", s390_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-high-gprs", 16*4, "s390 GPR upper halves" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390_linux64v1_regset_sections[] =
-{
-  { ".reg", s390_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-high-gprs", 16*4, "s390 GPR upper halves" },
-  { ".reg-s390-last-break", 8, "s930 last-break address" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390_linux64v2_regset_sections[] =
-{
-  { ".reg", s390_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-high-gprs", 16*4, "s390 GPR upper halves" },
-  { ".reg-s390-last-break", 8, "s930 last-break address" },
-  { ".reg-s390-system-call", 4, "s390 system-call" },
-  { ".reg-s390-tdb", s390_sizeof_tdbregset, "s390 TDB" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390x_linux64_regset_sections[] =
-{
-  { ".reg", s390x_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390x_linux64v1_regset_sections[] =
-{
-  { ".reg", s390x_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-last-break", 8, "s930 last-break address" },
-  { NULL, 0}
-};
-
-static struct core_regset_section s390x_linux64v2_regset_sections[] =
-{
-  { ".reg", s390x_sizeof_gregset, "general-purpose" },
-  { ".reg2", s390_sizeof_fpregset, "floating-point" },
-  { ".reg-s390-last-break", 8, "s930 last-break address" },
-  { ".reg-s390-system-call", 4, "s390 system-call" },
-  { ".reg-s390-tdb", s390_sizeof_tdbregset, "s390 TDB" },
-  { NULL, 0}
-};
-
-
 /* Return the appropriate register set for the core section identified
    by SECT_NAME and SECT_SIZE.  */
 static const struct regset *
@@ -640,6 +566,38 @@ s390_regset_from_core_section (struct gdbarch *gdbarch,
   return NULL;
 }
 
+/* Iterate over supported core file register note sections. */
+
+static void
+s390_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, "general-purpose", cb_data);
+  cb (".reg2", s390_sizeof_fpregset, "floating-point", cb_data);
+
+  if (tdep->abi == ABI_LINUX_S390 && tdep->gpr_full_regnum != -1)
+    cb (".reg-s390-high-gprs", 16 * 4, "s390 GPR upper halves", cb_data);
+
+  if (tdep->have_linux_v1)
+    cb (".reg-s390-last-break", 8, "s930 last-break address", cb_data);
+
+  if (tdep->have_linux_v2)
+    cb (".reg-s390-system-call", 4, "s390 system-call", cb_data);
+
+  /* If regcache is set, we are in "write" (gcore) mode.  In this
+     case, don't iterate over the TDB unless its registers are
+     available.  */
+  if (tdep->have_tdb
+      && (regcache == NULL
+	  || REG_VALID == regcache_register_status (regcache,
+						    S390_TDB_DWORD0_REGNUM)))
+    cb (".reg-s390-tdb", s390_sizeof_tdbregset, "s390 TDB", cb_data);
+}
+
 static const struct target_desc *
 s390_core_read_description (struct gdbarch *gdbarch,
 			    struct target_ops *target, bfd *abfd)
@@ -2904,6 +2862,7 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   int have_upper = 0;
   int have_linux_v1 = 0;
   int have_linux_v2 = 0;
+  int have_tdb = 0;
   int first_pseudo_reg, last_pseudo_reg;
   static const char *const stap_register_prefixes[] = { "%", NULL };
   static const char *const stap_register_indirection_prefixes[] = { "(",
@@ -3048,6 +3007,7 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
 						S390_TDB_DWORD0_REGNUM + i,
 						tdb_regs[i]);
+	  have_tdb = 1;
 	}
 
       if (!valid_p)
@@ -3077,6 +3037,9 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   /* Otherwise create a new gdbarch for the specified machine type.  */
   tdep = XCNEW (struct gdbarch_tdep);
   tdep->abi = tdep_abi;
+  tdep->have_linux_v1 = have_linux_v1;
+  tdep->have_linux_v2 = have_linux_v2;
+  tdep->have_tdb = have_tdb;
   gdbarch = gdbarch_alloc (&info, tdep);
 
   set_gdbarch_believe_pcc_promotion (gdbarch, 0);
@@ -3107,6 +3070,8 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   set_gdbarch_regset_from_core_section (gdbarch,
 					s390_regset_from_core_section);
   set_gdbarch_core_read_description (gdbarch, s390_core_read_description);
+  set_gdbarch_iterate_over_regset_sections (gdbarch,
+					    s390_iterate_over_regset_sections);
   set_gdbarch_cannot_store_register (gdbarch, s390_cannot_store_register);
   set_gdbarch_write_pc (gdbarch, s390_write_pc);
   set_gdbarch_pseudo_register_read (gdbarch, s390_pseudo_register_read);
@@ -3179,31 +3144,6 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 	(gdbarch, svr4_ilp32_fetch_link_map_offsets);
 
       set_xml_syscall_file_name (XML_SYSCALL_FILENAME_S390);
-
-      if (have_upper)
-	{
-	  if (have_linux_v2)
-	    set_gdbarch_core_regset_sections (gdbarch,
-					      s390_linux64v2_regset_sections);
-	  else if (have_linux_v1)
-	    set_gdbarch_core_regset_sections (gdbarch,
-					      s390_linux64v1_regset_sections);
-	  else
-	    set_gdbarch_core_regset_sections (gdbarch,
-					      s390_linux64_regset_sections);
-	}
-      else
-	{
-	  if (have_linux_v2)
-	    set_gdbarch_core_regset_sections (gdbarch,
-					      s390_linux32v2_regset_sections);
-	  else if (have_linux_v1)
-	    set_gdbarch_core_regset_sections (gdbarch,
-					      s390_linux32v1_regset_sections);
-	  else
-	    set_gdbarch_core_regset_sections (gdbarch,
-					      s390_linux32_regset_sections);
-	}
       break;
 
     case ABI_LINUX_ZSERIES:
@@ -3223,18 +3163,7 @@ s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 						    s390_address_class_type_flags_to_name);
       set_gdbarch_address_class_name_to_type_flags (gdbarch,
 						    s390_address_class_name_to_type_flags);
-
       set_xml_syscall_file_name (XML_SYSCALL_FILENAME_S390);
-
-      if (have_linux_v2)
-	set_gdbarch_core_regset_sections (gdbarch,
-					  s390x_linux64v2_regset_sections);
-      else if (have_linux_v1)
-	set_gdbarch_core_regset_sections (gdbarch,
-					  s390x_linux64v1_regset_sections);
-      else
-	set_gdbarch_core_regset_sections (gdbarch,
-					  s390x_linux64_regset_sections);
       break;
     }