binutils-gdb/gdb/arm-fbsd-tdep.c

/* Target-dependent code for FreeBSD/arm.

   Copyright (C) 2017-2025 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/>.  */


#include "elf/common.h"
#include "target-descriptions.h"
#include "aarch32-tdep.h"
#include "arm-tdep.h"
#include "arm-fbsd-tdep.h"
#include "auxv.h"
#include "fbsd-tdep.h"
#include "gdbcore.h"
#include "inferior.h"
#include "osabi.h"
#include "solib-svr4.h"
#include "trad-frame.h"
#include "tramp-frame.h"

/* Register maps.  */

static const struct regcache_map_entry arm_fbsd_gregmap[] =
  {
    { 13, ARM_A1_REGNUM, 4 }, /* r0 ... r12 */
    { 1, ARM_SP_REGNUM, 4 },
    { 1, ARM_LR_REGNUM, 4 },
    { 1, ARM_PC_REGNUM, 4 },
    { 1, ARM_PS_REGNUM, 4 },
    { 0 }
  };

static const struct regcache_map_entry arm_fbsd_vfpregmap[] =
  {
    { 32, ARM_D0_REGNUM, 8 }, /* d0 ... d31 */
    { 1, ARM_FPSCR_REGNUM, 4 },
    { 0 }
  };

/* Register numbers are relative to tdep->tls_regnum.  */

static const struct regcache_map_entry arm_fbsd_tls_regmap[] =
  {
    { 1, 0, 4 },	/* tpidruro  */
    { 0 }
  };

/* In a signal frame, sp points to a 'struct sigframe' which is
   defined as:

   struct sigframe {
	   siginfo_t	sf_si;
	   ucontext_t	sf_uc;
	   mcontext_vfp_t sf_vfp;
   };

   ucontext_t is defined as:

   struct __ucontext {
	   sigset_t	uc_sigmask;
	   mcontext_t	uc_mcontext;
	   ...
   };

   mcontext_t is defined as:

   struct {
	   unsigned int __gregs[17];
	   size_t       mc_vfp_size;
	   void         *mc_vfp_ptr;
	   ...
   };

   mcontext_vfp_t is defined as:

   struct {
	  uint64_t      mcv_reg[32];
	  uint32_t      mcv_fpscr;
   };

   If the VFP state is valid, then mc_vfp_ptr will point to sf_vfp in
   the sigframe, otherwise it is NULL.  There is no non-VFP floating
   point register state saved in the signal frame.  */

#define ARM_SIGFRAME_UCONTEXT_OFFSET	64
#define ARM_UCONTEXT_MCONTEXT_OFFSET	16
#define ARM_MCONTEXT_VFP_PTR_OFFSET	72

/* Implement the "init" method of struct tramp_frame.  */

static void
arm_fbsd_sigframe_init (const struct tramp_frame *self,
			const frame_info_ptr &this_frame,
			struct trad_frame_cache *this_cache,
			CORE_ADDR func)
{
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
  CORE_ADDR mcontext_addr = (sp
			     + ARM_SIGFRAME_UCONTEXT_OFFSET
			     + ARM_UCONTEXT_MCONTEXT_OFFSET);
  ULONGEST mcontext_vfp_addr;

  trad_frame_set_reg_regmap (this_cache, arm_fbsd_gregmap, mcontext_addr,
			     regcache_map_entry_size (arm_fbsd_gregmap));

  if (safe_read_memory_unsigned_integer (mcontext_addr
					 + ARM_MCONTEXT_VFP_PTR_OFFSET, 4,
					 byte_order,
					 &mcontext_vfp_addr)
      && mcontext_vfp_addr != 0)
    trad_frame_set_reg_regmap (this_cache, arm_fbsd_vfpregmap, mcontext_vfp_addr,
			       regcache_map_entry_size (arm_fbsd_vfpregmap));

  trad_frame_set_id (this_cache, frame_id_build (sp, func));
}

static const struct tramp_frame arm_fbsd_sigframe =
{
  SIGTRAMP_FRAME,
  4,
  {
    {0xe1a0000d, ULONGEST_MAX},		/* mov  r0, sp  */
    {0xe2800040, ULONGEST_MAX},		/* add  r0, r0, #SIGF_UC  */
    {0xe59f700c, ULONGEST_MAX},		/* ldr  r7, [pc, #12]  */
    {0xef0001a1, ULONGEST_MAX},		/* swi  SYS_sigreturn  */
    {TRAMP_SENTINEL_INSN, ULONGEST_MAX}
  },
  arm_fbsd_sigframe_init
};

/* Register set definitions.  */

const struct regset arm_fbsd_gregset =
  {
    arm_fbsd_gregmap,
    regcache_supply_regset, regcache_collect_regset
  };

const struct regset arm_fbsd_vfpregset =
  {
    arm_fbsd_vfpregmap,
    regcache_supply_regset, regcache_collect_regset
  };

static void
arm_fbsd_supply_tls_regset (const struct regset *regset,
			    struct regcache *regcache,
			    int regnum, const void *buf, size_t size)
{
  struct gdbarch *gdbarch = regcache->arch ();
  arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);

  regcache->supply_regset (regset, tdep->tls_regnum, regnum, buf, size);
}

static void
arm_fbsd_collect_tls_regset (const struct regset *regset,
			     const struct regcache *regcache,
			     int regnum, void *buf, size_t size)
{
  struct gdbarch *gdbarch = regcache->arch ();
  arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);

  regcache->collect_regset (regset, tdep->tls_regnum, regnum, buf, size);
}

const struct regset arm_fbsd_tls_regset =
  {
    arm_fbsd_tls_regmap,
    arm_fbsd_supply_tls_regset, arm_fbsd_collect_tls_regset
  };

/* Implement the "iterate_over_regset_sections" gdbarch method.  */

static void
arm_fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
				       iterate_over_regset_sections_cb *cb,
				       void *cb_data,
				       const struct regcache *regcache)
{
  arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);

  cb (".reg", ARM_FBSD_SIZEOF_GREGSET, ARM_FBSD_SIZEOF_GREGSET,
      &arm_fbsd_gregset, NULL, cb_data);

  if (tdep->tls_regnum > 0)
    cb (".reg-aarch-tls", ARM_FBSD_SIZEOF_TLSREGSET, ARM_FBSD_SIZEOF_TLSREGSET,
	&arm_fbsd_tls_regset, NULL, cb_data);

  /* While FreeBSD/arm cores do contain a NT_FPREGSET / ".reg2"
     register set, it is not populated with register values by the
     kernel but just contains all zeroes.  */
  if (tdep->vfp_register_count > 0)
    cb (".reg-arm-vfp", ARM_FBSD_SIZEOF_VFPREGSET, ARM_FBSD_SIZEOF_VFPREGSET,
	&arm_fbsd_vfpregset, "VFP floating-point", cb_data);
}

/* See arm-fbsd-tdep.h.  */

const struct target_desc *
arm_fbsd_read_description_auxv (const std::optional<gdb::byte_vector> &auxv,
				target_ops *target, gdbarch *gdbarch, bool tls)
{
  CORE_ADDR arm_hwcap = 0;

  if (!auxv.has_value ()
      || target_auxv_search (*auxv, target, gdbarch, AT_FREEBSD_HWCAP,
			     &arm_hwcap) != 1)
    return arm_read_description (ARM_FP_TYPE_NONE, tls);

  if (arm_hwcap & HWCAP_VFP)
    {
      if (arm_hwcap & HWCAP_NEON)
	return aarch32_read_description (tls);
      else if ((arm_hwcap & (HWCAP_VFPv3 | HWCAP_VFPD32))
	       == (HWCAP_VFPv3 | HWCAP_VFPD32))
	return arm_read_description (ARM_FP_TYPE_VFPV3, tls);
      else
	return arm_read_description (ARM_FP_TYPE_VFPV2, tls);
    }

  return arm_read_description (ARM_FP_TYPE_NONE, tls);
}

/* See arm-fbsd-tdep.h.  */

const struct target_desc *
arm_fbsd_read_description_auxv (bool tls)
{
  const std::optional<gdb::byte_vector> &auxv = target_read_auxv ();
  return arm_fbsd_read_description_auxv (auxv,
					 current_inferior ()->top_target (),
					 current_inferior ()->arch (),
					 tls);
}

/* Implement the "core_read_description" gdbarch method.  */

static const struct target_desc *
arm_fbsd_core_read_description (struct gdbarch *gdbarch,
				struct target_ops *target,
				bfd *abfd)
{
  asection *tls = bfd_get_section_by_name (abfd, ".reg-aarch-tls");

  std::optional<gdb::byte_vector> auxv = target_read_auxv_raw (target);
  return arm_fbsd_read_description_auxv (auxv, target, gdbarch, tls != nullptr);
}

/* Implement the get_thread_local_address gdbarch method.  */

static CORE_ADDR
arm_fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
				   CORE_ADDR lm_addr, CORE_ADDR offset)
{
  arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);
  regcache *regcache
    = get_thread_arch_regcache (current_inferior (), ptid, gdbarch);

  target_fetch_registers (regcache, tdep->tls_regnum);

  ULONGEST tpidruro;
  if (regcache->cooked_read (tdep->tls_regnum, &tpidruro) != REG_VALID)
    error (_("Unable to fetch %%tpidruro"));

  /* %tpidruro points to the TCB whose first member is the dtv
      pointer.  */
  CORE_ADDR dtv_addr = tpidruro;
  return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
}

/* Implement the 'init_osabi' method of struct gdb_osabi_handler.  */

static void
arm_fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  arm_gdbarch_tdep *tdep = gdbarch_tdep<arm_gdbarch_tdep> (gdbarch);

  /* Generic FreeBSD support.  */
  fbsd_init_abi (info, gdbarch);

  if (tdep->fp_model == ARM_FLOAT_AUTO)
    tdep->fp_model = ARM_FLOAT_SOFT_VFP;

  tramp_frame_prepend_unwinder (gdbarch, &arm_fbsd_sigframe);

  set_solib_svr4_ops (gdbarch, make_svr4_ilp32_solib_ops);

  tdep->jb_pc = 24;
  tdep->jb_elt_size = 4;

  set_gdbarch_iterate_over_regset_sections
    (gdbarch, arm_fbsd_iterate_over_regset_sections);
  set_gdbarch_core_read_description (gdbarch, arm_fbsd_core_read_description);

  if (tdep->tls_regnum > 0)
    {
      set_gdbarch_fetch_tls_load_module_address (gdbarch,
						 svr4_fetch_objfile_link_map);
      set_gdbarch_get_thread_local_address (gdbarch,
					    arm_fbsd_get_thread_local_address);
    }

  /* Single stepping.  */
  set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
}

INIT_GDB_FILE (arm_fbsd_tdep)
{
  gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_FREEBSD,
			  arm_fbsd_init_abi);
}