Add 'regset' parameter to 'iterate_over_regset_sections_cb'

This adds the 'regset' parameter to the iterator callback.
Consequently the 'regset_from_core_section' method is dropped for all
targets that provide the iterator method.

This change prepares for replacing regset_from_core_section
everywhere, thereby eliminating one gdbarch interface.  Since the
iterator is usually no more complex than regset_from_core_section
alone, targets that previously didn't define core_regset_sections will
then gain multi-arch capable core file generation support without
increased complexity.

gdb/ChangeLog:

	* gdbarch.sh (iterate_over_regset_sections_cb): Add regset
	parameter.
	* gdbarch.h: Regenerate.
	* corelow.c (sniff_core_bfd): Don't sniff if gdbarch has a regset
	iterator.
	(get_core_register_section): Add parameter 'regset' and use it, if
	set.  Add parameter 'min_size' and verify the bfd section size
	against it.
	(get_core_registers_cb): Add parameter 'regset' and pass it to
	get_core_register section.  For the "standard" register sections
	".reg" and ".reg2", set an appropriate default for human_name.
	(get_core_registers): Don't abort when the gdbarch has an iterator
	but no regset_from_core_section.  Add NULL/0 for parameters
	'regset'/'min_size' in calls to get_core_register_section.
	* linux-tdep.c (linux_collect_regset_section_cb): Add parameter
	'regset' and use it instead of calling the
	regset_from_core_section gdbarch method.
	* i386-tdep.h (struct gdbarch_tdep): Add field 'fpregset'.
	* i386-tdep.c (i386_supply_xstateregset)
	(i386_collect_xstateregset, i386_xstateregset): Moved to
	i386-linux-tdep.c.
	(i386_regset_from_core_section): Drop handling for .reg-xfp and
	.reg-xstate.
	(i386_gdbarch_init): Set tdep field 'fpregset'.  Enable generic
	core file support only if the regset iterator hasn't been set.
	* i386-linux-tdep.c (i386_linux_supply_xstateregset)
	(i386_linux_collect_xstateregset, i386_linux_xstateregset): New.
	Moved from i386-tdep.c and renamed to *_linux*.
	(i386_linux_iterate_over_regset_sections): Add regset parameter to
	each callback invocation.  Allow any .reg-xstate size when reading
	from a core file.
	* amd64-tdep.c (amd64_supply_xstateregset)
	(amd64_collect_xstateregset, amd64_xstateregset): Moved to
	amd64-linux-tdep.c.
	(amd64_regset_from_core_section): Remove.
	(amd64_init_abi): Set new tdep field 'fpregset'.  No longer
	install an amd64-specific regset_from_core_section gdbarch method.
	* amd64-linux-tdep.c (amd64_linux_supply_xstateregset)
	(amd64_linux_collect_xstateregset, amd64_linux_xstateregset): New.
	Moved from amd64-tdep.c and renamed to *_linux*.
	(amd64_linux_iterate_over_regset_sections): Add regset parameter
	to each callback invocation.  Allow any .reg-xstate size when
	reading from a core file.
	* arm-linux-tdep.c (arm_linux_regset_from_core_section): Remove.
	(arm_linux_iterate_over_regset_sections): Add regset parameter to
	each callback invocation.
	(arm_linux_init_abi): No longer set the regset_from_core_section
	gdbarch method.
	* ppc-linux-tdep.c (ppc_linux_regset_from_core_section): Remove.
	(ppc_linux_iterate_over_regset_sections): Add regset parameter to
	each callback invocation.
	(ppc_linux_init_abi): No longer set the regset_from_core_section
	gdbarch method.
	* s390-linux-tdep.c (struct gdbarch_tdep): Remove the fields
	gregset, sizeof_gregset, fpregset, and sizeof_fpregset.
	(s390_regset_from_core_section): Remove.
	(s390_iterate_over_regset_sections): Add regset parameter to each
	callback invocation.
	(s390_gdbarch_init): No longer set the regset_from_core_section
	gdbarch method.  Drop initialization of deleted tdep fields.

gdb/i386-tdep.c

@@ -3806,26 +3806,6 @@ i386_collect_fpregset (const struct regset *regset,
   i387_collect_fsave (regcache, regnum, fpregs);
 }
 
-/* Similar to i386_supply_fpregset, but use XSAVE extended state.  */
-
-static void
-i386_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
-i386_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.  */
 
 const struct regset i386_gregset =
@@ -3833,16 +3813,11 @@ const struct regset i386_gregset =
     NULL, i386_supply_gregset, i386_collect_gregset
   };
 
-static const struct regset i386_fpregset =
+const struct regset i386_fpregset =
   {
     NULL, i386_supply_fpregset, i386_collect_fpregset
   };
 
-static const struct regset i386_xstateregset =
-  {
-    NULL, i386_supply_xstateregset, i386_collect_xstateregset
-  };
-
 /* Return the appropriate register set for the core section identified
    by SECT_NAME and SECT_SIZE.  */
 
@@ -3853,15 +3828,10 @@ i386_regset_from_core_section (struct gdbarch *gdbarch,
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 
   if (strcmp (sect_name, ".reg") == 0 && sect_size == tdep->sizeof_gregset)
-      return &i386_gregset;
+    return &i386_gregset;
 
-  if ((strcmp (sect_name, ".reg2") == 0 && sect_size == tdep->sizeof_fpregset)
-      || (strcmp (sect_name, ".reg-xfp") == 0
-	  && sect_size == I387_SIZEOF_FXSAVE))
-    return &i386_fpregset;
-
-  if (strcmp (sect_name, ".reg-xstate") == 0)
-    return &i386_xstateregset;
+  if (strcmp (sect_name, ".reg2") == 0 && sect_size == tdep->sizeof_fpregset)
+    return tdep->fpregset;
 
   return NULL;
 }
@@ -8291,6 +8261,7 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 
   /* Floating-point registers.  */
   tdep->sizeof_fpregset = I387_SIZEOF_FSAVE;
+  tdep->fpregset = &i386_fpregset;
 
   /* The default settings include the FPU registers, the MMX registers
      and the SSE registers.  This can be overridden for a specific ABI
@@ -8595,7 +8566,8 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   /* If we have a register mapping, enable the generic core file
      support, unless it has already been enabled.  */
   if (tdep->gregset_reg_offset
-      && !gdbarch_regset_from_core_section_p (gdbarch))
+      && !gdbarch_regset_from_core_section_p (gdbarch)
+      && !gdbarch_iterate_over_regset_sections_p (gdbarch))
     set_gdbarch_regset_from_core_section (gdbarch,
 					  i386_regset_from_core_section);