Remove use of deprecated core functions (in NetBSD/ARM)

This is in preparation for deleting deprecated_add_core_fns and
related code.

As a side-effect, this makes it possible to read NetBSD/ARM
core files on non-NetBSD/ARM platforms, subject to PR corefiles/25638.

I have removed this comment:
-  /* This is ok: we're running native...  */
Since we are using the gdbarch from the regcache, we should be
guaranteed to be calling the right function here, so it shouldn't
matter whether we are running native.

Tested by reading a NetBSD/ARM core file on Linux/x86-64 and NetBSD/ARM;
the "info registers" output matches the one from the system GDB.

gdb/ChangeLog:

2020-03-05  Christian Biesinger  <cbiesinger@google.com>

	* Makefile.in (HFILES_NO_SRCDIR): Add new arm-nbsd-tdep.h file.
	* arm-nbsd-nat.c (arm_supply_gregset): Moved to arm-nbsd-tdep and
	renamed to arm_nbsd_supply_gregset.
	(fetch_register): Update to call arm_nbsd_supply_gregset.
	(fetch_regs): Remove in favor of fetch_register with a -1 regno.
	(arm_netbsd_nat_target::fetch_registers): Update.
	(fetch_elfcore_registers): Removed.
	(_initialize_arm_netbsd_nat): Removed call to deprecated_add_core_fns.
	* arm-nbsd-tdep.c (struct arm_nbsd_reg): New struct.
	(arm_nbsd_supply_gregset): Moved from arm-nbsd-nat.c and updated to
	not require NetBSD system headers.
	(arm_nbsd_regset): New struct.
	(arm_nbsd_iterate_over_regset_sections): New function.
	(arm_netbsd_init_abi_common): Updated to call
	set_gdbarch_iterate_over_regset_sections.
	* arm-nbsd-tdep.h: New file.

gdb/Makefile.in

@@ -1205,6 +1205,7 @@ HFILES_NO_SRCDIR = \
 	arc-tdep.h \
 	arch-utils.h \
 	arm-linux-tdep.h \
+	arm-nbsd-tdep.h \
 	arm-tdep.h \
 	auto-load.h \
 	auxv.h \

gdb/arm-nbsd-nat.c

@@ -31,6 +31,7 @@
 #include <machine/frame.h>
 
 #include "arm-tdep.h"
+#include "arm-nbsd-tdep.h"
 #include "aarch32-tdep.h"
 #include "inf-ptrace.h"
 
@@ -45,28 +46,6 @@ public:
 
 static arm_netbsd_nat_target the_arm_netbsd_nat_target;
 
-static void
-arm_supply_gregset (struct regcache *regcache, struct reg *gregset)
-{
-  int regno;
-  CORE_ADDR r_pc;
-
-  /* Integer registers.  */
-  for (regno = ARM_A1_REGNUM; regno < ARM_SP_REGNUM; regno++)
-    regcache->raw_supply (regno, (char *) &gregset->r[regno]);
-
-  regcache->raw_supply (ARM_SP_REGNUM, (char *) &gregset->r_sp);
-  regcache->raw_supply (ARM_LR_REGNUM, (char *) &gregset->r_lr);
-  /* This is ok: we're running native...  */
-  r_pc = gdbarch_addr_bits_remove (regcache->arch (), gregset->r_pc);
-  regcache->raw_supply (ARM_PC_REGNUM, (char *) &r_pc);
-
-  if (arm_apcs_32)
-    regcache->raw_supply (ARM_PS_REGNUM, (char *) &gregset->r_cpsr);
-  else
-    regcache->raw_supply (ARM_PS_REGNUM, (char *) &gregset->r_pc);
-}
-
 static void
 arm_supply_vfpregset (struct regcache *regcache, struct fpreg *fpregset)
 {
@@ -95,57 +74,8 @@ fetch_register (struct regcache *regcache, int regno)
       warning (_("unable to fetch general register"));
       return;
     }
-
-  switch (regno)
-    {
-    case ARM_SP_REGNUM:
-      regcache->raw_supply (ARM_SP_REGNUM, (char *) &inferior_registers.r_sp);
-      break;
-
-    case ARM_LR_REGNUM:
-      regcache->raw_supply (ARM_LR_REGNUM, (char *) &inferior_registers.r_lr);
-      break;
-
-    case ARM_PC_REGNUM:
-      /* This is ok: we're running native...  */
-      inferior_registers.r_pc = gdbarch_addr_bits_remove
-				  (regcache->arch (),
-				   inferior_registers.r_pc);
-      regcache->raw_supply (ARM_PC_REGNUM, (char *) &inferior_registers.r_pc);
-      break;
-
-    case ARM_PS_REGNUM:
-      if (arm_apcs_32)
-	regcache->raw_supply (ARM_PS_REGNUM,
-			      (char *) &inferior_registers.r_cpsr);
-      else
-	regcache->raw_supply (ARM_PS_REGNUM,
-			      (char *) &inferior_registers.r_pc);
-      break;
-
-    default:
-      regcache->raw_supply (regno, (char *) &inferior_registers.r[regno]);
-      break;
-    }
-}
-
-static void
-fetch_regs (struct regcache *regcache)
-{
-  struct reg inferior_registers;
-  int ret;
-  int regno;
-
-  ret = ptrace (PT_GETREGS, regcache->ptid ().pid (),
-		(PTRACE_TYPE_ARG3) &inferior_registers, 0);
-
-  if (ret < 0)
-    {
-      warning (_("unable to fetch general registers"));
-      return;
-    }
-
-  arm_supply_gregset (regcache, &inferior_registers);
+  arm_nbsd_supply_gregset (nullptr, regcache, regno, &inferior_registers,
+			   sizeof (inferior_registers));
 }
 
 static void
@@ -207,7 +137,7 @@ arm_netbsd_nat_target::fetch_registers (struct regcache *regcache, int regno)
     }
   else
     {
-      fetch_regs (regcache);
+      fetch_register (regcache, -1);
       fetch_fp_regs (regcache);
     }
 }
@@ -416,56 +346,9 @@ arm_netbsd_nat_target::read_description ()
   return arm_read_description (ARM_FP_TYPE_VFPV3);
 }
 
-static void
-fetch_elfcore_registers (struct regcache *regcache,
-			 gdb_byte *core_reg_sect, unsigned core_reg_size,
-			 int which, CORE_ADDR ignore)
-{
-  struct reg gregset;
-  struct fpreg fparegset;
-
-  switch (which)
-    {
-    case 0:	/* Integer registers.  */
-      if (core_reg_size != sizeof (struct reg))
-	warning (_("wrong size of register set in core file"));
-      else
-	{
-	  /* The memcpy may be unnecessary, but we can't really be sure
-	     of the alignment of the data in the core file.  */
-	  memcpy (&gregset, core_reg_sect, sizeof (gregset));
-	  arm_supply_gregset (regcache, &gregset);
-	}
-      break;
-
-    case 2:
-      /* cbiesinger/2020-02-12 -- as far as I can tell, ARM/NetBSD does
-         not write any floating point registers into the core file (tested
-	 with NetBSD 9.1_RC1).  When it does, this block will need to read them,
-	 and the arm-netbsd gdbarch will need a core_read_description function
-	 to return the right description for them.  */
-      break;
-
-    default:
-      /* Don't know what kind of register request this is; just ignore it.  */
-      break;
-    }
-}
-
-static struct core_fns arm_netbsd_elfcore_fns =
-{
-  bfd_target_elf_flavour,		/* core_flavour.  */
-  default_check_format,			/* check_format.  */
-  default_core_sniffer,			/* core_sniffer.  */
-  fetch_elfcore_registers,		/* core_read_registers.  */
-  NULL
-};
-
 void _initialize_arm_netbsd_nat ();
 void
 _initialize_arm_netbsd_nat ()
 {
   add_inf_child_target (&the_arm_netbsd_nat_target);
-
-  deprecated_add_core_fns (&arm_netbsd_elfcore_fns);
 }

gdb/arm-nbsd-tdep.c

@@ -21,7 +21,9 @@
 #include "osabi.h"
 
 #include "arch/arm.h"
+#include "arm-nbsd-tdep.h"
 #include "arm-tdep.h"
+#include "regset.h"
 #include "solib-svr4.h"
 
 /* Description of the longjmp buffer.  */
@@ -35,6 +37,70 @@ static const gdb_byte arm_nbsd_arm_be_breakpoint[] = {0xe6, 0x00, 0x00, 0x11};
 static const gdb_byte arm_nbsd_thumb_le_breakpoint[] = {0xfe, 0xde};
 static const gdb_byte arm_nbsd_thumb_be_breakpoint[] = {0xde, 0xfe};
 
+/* This matches struct reg from NetBSD's sys/arch/arm/include/reg.h */
+struct arm_nbsd_reg {
+  uint32_t reg[13];
+  uint32_t sp;
+  uint32_t lr;
+  uint32_t pc;
+  uint32_t cpsr;
+};
+
+void
+arm_nbsd_supply_gregset (const struct regset *regset, struct regcache *regcache,
+			 int regnum, const void *gregs, size_t len)
+{
+  const arm_nbsd_reg *gregset = static_cast<const arm_nbsd_reg *>(gregs);
+  gdb_assert (len >= sizeof (arm_nbsd_reg));
+
+  /* Integer registers.  */
+  for (int i = ARM_A1_REGNUM; i < ARM_SP_REGNUM; i++)
+    if (regnum == -1 || regnum == i)
+      regcache->raw_supply (i, (char *) &gregset->reg[i]);
+
+  if (regnum == -1 || regnum == ARM_SP_REGNUM)
+    regcache->raw_supply (ARM_SP_REGNUM, (char *) &gregset->sp);
+  if (regnum == -1 || regnum == ARM_LR_REGNUM)
+    regcache->raw_supply (ARM_LR_REGNUM, (char *) &gregset->lr);
+  if (regnum == -1 || regnum == ARM_PC_REGNUM)
+    {
+      CORE_ADDR r_pc = gdbarch_addr_bits_remove (regcache->arch (), gregset->pc);
+      regcache->raw_supply (ARM_PC_REGNUM, (char *) &r_pc);
+    }
+
+  if (regnum == -1 || regnum == ARM_PS_REGNUM)
+    {
+      if (arm_apcs_32)
+	regcache->raw_supply (ARM_PS_REGNUM, (char *) &gregset->cpsr);
+      else
+	regcache->raw_supply (ARM_PS_REGNUM, (char *) &gregset->pc);
+    }
+}
+
+static const struct regset arm_nbsd_regset = {
+  nullptr,
+  arm_nbsd_supply_gregset,
+  /* We don't need a collect function because we only use this reading registers
+     (via iterate_over_regset_sections and fetch_regs/fetch_register).  */
+  nullptr,
+  0
+};
+
+static void
+arm_nbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
+				       iterate_over_regset_sections_cb *cb,
+				       void *cb_data,
+				       const struct regcache *regcache)
+{
+  cb (".reg", sizeof (arm_nbsd_reg), sizeof (arm_nbsd_reg), &arm_nbsd_regset,
+      NULL, cb_data);
+  /* cbiesinger/2020-02-12 -- as far as I can tell, ARM/NetBSD does
+     not write any floating point registers into the core file (tested
+     with NetBSD 9.1_RC1).  When it does, this function will need to read them,
+     and the arm-netbsd gdbarch will need a core_read_description function
+     to return the right description for them.  */
+}
+
 static void
 arm_netbsd_init_abi_common (struct gdbarch_info info,
 			    struct gdbarch *gdbarch)
@@ -66,10 +132,12 @@ arm_netbsd_init_abi_common (struct gdbarch_info info,
   tdep->jb_pc = ARM_NBSD_JB_PC;
   tdep->jb_elt_size = ARM_NBSD_JB_ELEMENT_SIZE;
 
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, arm_nbsd_iterate_over_regset_sections);
   /* Single stepping.  */
   set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
 }
-  
+
 static void
 arm_netbsd_elf_init_abi (struct gdbarch_info info,
 			 struct gdbarch *gdbarch)

gdb/arm-nbsd-tdep.h

@@ -0,0 +1,27 @@
+/* NetBSD/ARM support.
+
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef ARM_NBSD_TDEP_H
+#define ARM_NBSD_TDEP_H
+
+void arm_nbsd_supply_gregset
+  (const struct regset *regset, struct regcache *regcache,
+   int regnum, const void *gregs, size_t len);
+
+#endif