Add FreeBSD/mips architecture.

This has been tested for the n64 and o32 ABIs.  Signal frame unwinders for
both ABIs are provided.  FreeBSD/mips requires custom linkmap offsets since
it contains an additional l_off member in 'struct link_map' that other
FreeBSD platforms do not have.  Support for collecting and supplying
general purpose and floating point register sets are provided.  Common
routines for working with native format register sets are exported for
use by the native target.

gdb/ChangeLog:

	* Makefile.in (ALL_TARGET_OBS): Add mips-fbsd-tdep.o.
	(ALLDEPFILES): Add mips-fbsd-tdep.c.
	* NEWS: Mention new FreeBSD/mips target.
	* configure.tgt: Add mips*-*-freebsd*.
	* mips-fbsd-tdep.c: New file.
	* mips-fbsd-tdep.h: New file.

gdb/doc/ChangeLog:

	* gdb.texinfo (Contributors): Add SRI International and University
	of Cambridge for FreeBSD/mips.

1 files changed, 560 insertions, 0 deletions

diff --git a/gdb/mips-fbsd-tdep.c b/gdb/mips-fbsd-tdep.c
new file mode 100644
index 0000000..733534d
--- /dev/null
+++ b/gdb/mips-fbsd-tdep.c
@@ -0,0 +1,560 @@
+/* Target-dependent code for FreeBSD/mips.
+
+   Copyright (C) 2017 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 "defs.h"
+#include "osabi.h"
+#include "regset.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
+
+#include "fbsd-tdep.h"
+#include "mips-tdep.h"
+#include "mips-fbsd-tdep.h"
+
+#include "solib-svr4.h"
+
+/* Shorthand for some register numbers used below.  */
+#define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
+#define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
+#define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
+
+/* Core file support. */
+
+/* Number of registers in `struct reg' from <machine/reg.h>.  The
+   first 38 follow the standard MIPS layout.  The 39th holds
+   IC_INT_REG on RM7K and RM9K processors.  The 40th is a dummy for
+   padding.  */
+#define MIPS_FBSD_NUM_GREGS	40
+
+/* Number of registers in `struct fpreg' from <machine/reg.h>.  The
+   first 32 hold floating point registers.  33 holds the FSR.  The
+   34th is a dummy for padding.  */
+#define MIPS_FBSD_NUM_FPREGS	34
+
+/* Supply a single register.  If the source register size matches the
+   size the regcache expects, this can use regcache_raw_supply().  If
+   they are different, this copies the source register into a buffer
+   that can be passed to regcache_raw_supply().  */
+
+static void
+mips_fbsd_supply_reg (struct regcache *regcache, int regnum, const void *addr,
+		      size_t len)
+{
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+
+  if (register_size (gdbarch, regnum) == len)
+    regcache_raw_supply (regcache, regnum, addr);
+  else
+    {
+      enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+      gdb_byte buf[MAX_REGISTER_SIZE];
+      LONGEST val;
+
+      val = extract_signed_integer ((const gdb_byte *) addr, len, byte_order);
+      store_signed_integer (buf, register_size (gdbarch, regnum), byte_order,
+			    val);
+      regcache_raw_supply (regcache, regnum, buf);
+    }
+}
+
+/* Collect a single register.  If the destination register size
+   matches the size the regcache expects, this can use
+   regcache_raw_supply().  If they are different, this fetches the
+   register via regcache_raw_supply() into a buffer and then copies it
+   into the final destination.  */
+
+static void
+mips_fbsd_collect_reg (const struct regcache *regcache, int regnum, void *addr,
+		       size_t len)
+{
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+
+  if (register_size (gdbarch, regnum) == len)
+    regcache_raw_collect (regcache, regnum, addr);
+  else
+    {
+      enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+      gdb_byte buf[MAX_REGISTER_SIZE];
+      LONGEST val;
+
+      regcache_raw_collect (regcache, regnum, buf);
+      val = extract_signed_integer (buf, register_size (gdbarch, regnum),
+				    byte_order);
+      store_signed_integer ((gdb_byte *) addr, len, byte_order, val);
+    }
+}
+
+/* Supply the floating-point registers stored in FPREGS to REGCACHE.
+   Each floating-point register in FPREGS is REGSIZE bytes in
+   length.  */
+
+void
+mips_fbsd_supply_fpregs (struct regcache *regcache, int regnum,
+			 const void *fpregs, size_t regsize)
+{
+  const gdb_byte *regs = (const gdb_byte *) fpregs;
+  int i;
+
+  for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
+    if (regnum == i || regnum == -1)
+      mips_fbsd_supply_reg (regcache, i,
+			    regs + (i - MIPS_FP0_REGNUM) * regsize, regsize);
+}
+
+/* Supply the general-purpose registers stored in GREGS to REGCACHE.
+   Each general-purpose register in GREGS is REGSIZE bytes in
+   length.  */
+
+void
+mips_fbsd_supply_gregs (struct regcache *regcache, int regnum,
+			const void *gregs, size_t regsize)
+{
+  const gdb_byte *regs = (const gdb_byte *) gregs;
+  int i;
+
+  for (i = 0; i <= MIPS_PC_REGNUM; i++)
+    if (regnum == i || regnum == -1)
+      mips_fbsd_supply_reg (regcache, i, regs + i * regsize, regsize);
+}
+
+/* Collect the floating-point registers from REGCACHE and store them
+   in FPREGS.  Each floating-point register in FPREGS is REGSIZE bytes
+   in length.  */
+
+void
+mips_fbsd_collect_fpregs (const struct regcache *regcache, int regnum,
+			  void *fpregs, size_t regsize)
+{
+  gdb_byte *regs = (gdb_byte *) fpregs;
+  int i;
+
+  for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
+    if (regnum == i || regnum == -1)
+      mips_fbsd_collect_reg (regcache, i,
+			     regs + (i - MIPS_FP0_REGNUM) * regsize, regsize);
+}
+
+/* Collect the general-purpose registers from REGCACHE and store them
+   in GREGS.  Each general-purpose register in GREGS is REGSIZE bytes
+   in length.  */
+
+void
+mips_fbsd_collect_gregs (const struct regcache *regcache, int regnum,
+			 void *gregs, size_t regsize)
+{
+  gdb_byte *regs = (gdb_byte *) gregs;
+  int i;
+
+  for (i = 0; i <= MIPS_PC_REGNUM; i++)
+    if (regnum == i || regnum == -1)
+      mips_fbsd_collect_reg (regcache, i, regs + i * regsize, regsize);
+}
+
+/* Supply register REGNUM from the buffer specified by FPREGS and LEN
+   in the floating-point register set REGSET to register cache
+   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
+
+static void
+mips_fbsd_supply_fpregset (const struct regset *regset,
+			   struct regcache *regcache,
+			   int regnum, const void *fpregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPS_FBSD_NUM_FPREGS * regsize);
+
+  mips_fbsd_supply_fpregs (regcache, regnum, fpregs, regsize);
+}
+
+/* Collect register REGNUM from the register cache REGCACHE and store
+   it in the buffer specified by FPREGS and LEN in the floating-point
+   register set REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+static void
+mips_fbsd_collect_fpregset (const struct regset *regset,
+			    const struct regcache *regcache,
+			    int regnum, void *fpregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPS_FBSD_NUM_FPREGS * regsize);
+
+  mips_fbsd_collect_fpregs (regcache, regnum, fpregs, regsize);
+}
+
+/* Supply register REGNUM from the buffer specified by GREGS and LEN
+   in the general-purpose register set REGSET to register cache
+   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
+
+static void
+mips_fbsd_supply_gregset (const struct regset *regset,
+			  struct regcache *regcache, int regnum,
+			  const void *gregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPS_FBSD_NUM_GREGS * regsize);
+
+  mips_fbsd_supply_gregs (regcache, regnum, gregs, regsize);
+}
+
+/* Collect register REGNUM from the register cache REGCACHE and store
+   it in the buffer specified by GREGS and LEN in the general-purpose
+   register set REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+static void
+mips_fbsd_collect_gregset (const struct regset *regset,
+			   const struct regcache *regcache,
+			   int regnum, void *gregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPS_FBSD_NUM_GREGS * regsize);
+
+  mips_fbsd_collect_gregs (regcache, regnum, gregs, regsize);
+}
+
+/* FreeBSD/mips register sets.  */
+
+static const struct regset mips_fbsd_gregset =
+{
+  NULL,
+  mips_fbsd_supply_gregset,
+  mips_fbsd_collect_gregset,
+};
+
+static const struct regset mips_fbsd_fpregset =
+{
+  NULL,
+  mips_fbsd_supply_fpregset,
+  mips_fbsd_collect_fpregset,
+};
+
+/* Iterate over core file register note sections.  */
+
+static void
+mips_fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
+					iterate_over_regset_sections_cb *cb,
+					void *cb_data,
+					const struct regcache *regcache)
+{
+  size_t regsize = mips_abi_regsize (gdbarch);
+
+  cb (".reg", MIPS_FBSD_NUM_GREGS * regsize, &mips_fbsd_gregset,
+      NULL, cb_data);
+  cb (".reg2", MIPS_FBSD_NUM_FPREGS * regsize, &mips_fbsd_fpregset,
+      NULL, cb_data);
+}
+
+/* Signal trampoline support.  */
+
+#define FBSD_SYS_sigreturn	417
+
+#define MIPS_INST_LI_V0_SIGRETURN 0x24020000 + FBSD_SYS_sigreturn
+#define MIPS_INST_SYSCALL	0x0000000c
+#define MIPS_INST_BREAK		0x0000000d
+
+#define O32_SIGFRAME_UCONTEXT_OFFSET	(16)
+#define O32_SIGSET_T_SIZE	(16)
+
+#define O32_UCONTEXT_ONSTACK	(O32_SIGSET_T_SIZE)
+#define O32_UCONTEXT_PC		(O32_UCONTEXT_ONSTACK + 4)
+#define O32_UCONTEXT_REGS	(O32_UCONTEXT_PC + 4)
+#define O32_UCONTEXT_SR		(O32_UCONTEXT_REGS + 4 * 32)
+#define O32_UCONTEXT_LO		(O32_UCONTEXT_SR + 4)
+#define O32_UCONTEXT_HI		(O32_UCONTEXT_LO + 4)
+#define O32_UCONTEXT_FPUSED	(O32_UCONTEXT_HI + 4)
+#define O32_UCONTEXT_FPREGS	(O32_UCONTEXT_FPUSED + 4)
+
+#define O32_UCONTEXT_REG_SIZE	4
+
+static void
+mips_fbsd_sigframe_init (const struct tramp_frame *self,
+			 struct frame_info *this_frame,
+			 struct trad_frame_cache *cache,
+			 CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR sp, ucontext_addr, addr;
+  int regnum;
+  gdb_byte buf[4];
+
+  /* We find the appropriate instance of `ucontext_t' at a
+     fixed offset in the signal frame.  */
+  sp = get_frame_register_signed (this_frame,
+				  MIPS_SP_REGNUM + gdbarch_num_regs (gdbarch));
+  ucontext_addr = sp + O32_SIGFRAME_UCONTEXT_OFFSET;
+
+  /* PC.  */
+  regnum = mips_regnum (gdbarch)->pc;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + O32_UCONTEXT_PC);
+
+  /* GPRs.  */
+  for (regnum = MIPS_ZERO_REGNUM, addr = ucontext_addr + O32_UCONTEXT_REGS;
+       regnum <= MIPS_RA_REGNUM; regnum++, addr += O32_UCONTEXT_REG_SIZE)
+    trad_frame_set_reg_addr (cache,
+			     regnum + gdbarch_num_regs (gdbarch),
+			     addr);
+
+  regnum = MIPS_PS_REGNUM;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + O32_UCONTEXT_SR);
+
+  /* HI and LO.  */
+  regnum = mips_regnum (gdbarch)->lo;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + O32_UCONTEXT_LO);
+  regnum = mips_regnum (gdbarch)->hi;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + O32_UCONTEXT_HI);
+
+  if (target_read_memory (ucontext_addr + O32_UCONTEXT_FPUSED, buf, 4) == 0 &&
+      extract_unsigned_integer (buf, 4, byte_order) != 0)
+    {
+      for (regnum = 0, addr = ucontext_addr + O32_UCONTEXT_FPREGS;
+	   regnum < 32; regnum++, addr += O32_UCONTEXT_REG_SIZE)
+	trad_frame_set_reg_addr (cache,
+				 regnum + gdbarch_fp0_regnum (gdbarch),
+				 addr);
+      trad_frame_set_reg_addr (cache, mips_regnum (gdbarch)->fp_control_status,
+			       addr);
+    }
+
+  trad_frame_set_id (cache, frame_id_build (sp, func));
+}
+
+#define MIPS_INST_ADDIU_A0_SP_O32 (0x27a40000 \
+				   + O32_SIGFRAME_UCONTEXT_OFFSET)
+
+static const struct tramp_frame mips_fbsd_sigframe =
+{
+  SIGTRAMP_FRAME,
+  MIPS_INSN32_SIZE,
+  {
+    { MIPS_INST_ADDIU_A0_SP_O32, -1 },	/* addiu   a0, sp, SIGF_UC */
+    { MIPS_INST_LI_V0_SIGRETURN, -1 },	/* li      v0, SYS_sigreturn */
+    { MIPS_INST_SYSCALL, -1 },		/* syscall */
+    { MIPS_INST_BREAK, -1 },		/* break */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  mips_fbsd_sigframe_init
+};
+
+#define N64_SIGFRAME_UCONTEXT_OFFSET	(32)
+#define N64_SIGSET_T_SIZE	(16)
+
+#define N64_UCONTEXT_ONSTACK	(N64_SIGSET_T_SIZE)
+#define N64_UCONTEXT_PC		(N64_UCONTEXT_ONSTACK + 8)
+#define N64_UCONTEXT_REGS	(N64_UCONTEXT_PC + 8)
+#define N64_UCONTEXT_SR		(N64_UCONTEXT_REGS + 8 * 32)
+#define N64_UCONTEXT_LO		(N64_UCONTEXT_SR + 8)
+#define N64_UCONTEXT_HI		(N64_UCONTEXT_LO + 8)
+#define N64_UCONTEXT_FPUSED	(N64_UCONTEXT_HI + 8)
+#define N64_UCONTEXT_FPREGS	(N64_UCONTEXT_FPUSED + 8)
+
+#define N64_UCONTEXT_REG_SIZE	8
+
+static void
+mips64_fbsd_sigframe_init (const struct tramp_frame *self,
+			   struct frame_info *this_frame,
+			   struct trad_frame_cache *cache,
+			   CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR sp, ucontext_addr, addr;
+  int regnum;
+  gdb_byte buf[4];
+
+  /* We find the appropriate instance of `ucontext_t' at a
+     fixed offset in the signal frame.  */
+  sp = get_frame_register_signed (this_frame,
+				  MIPS_SP_REGNUM + gdbarch_num_regs (gdbarch));
+  ucontext_addr = sp + N64_SIGFRAME_UCONTEXT_OFFSET;
+
+  /* PC.  */
+  regnum = mips_regnum (gdbarch)->pc;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + N64_UCONTEXT_PC);
+
+  /* GPRs.  */
+  for (regnum = MIPS_ZERO_REGNUM, addr = ucontext_addr + N64_UCONTEXT_REGS;
+       regnum <= MIPS_RA_REGNUM; regnum++, addr += N64_UCONTEXT_REG_SIZE)
+    trad_frame_set_reg_addr (cache,
+			     regnum + gdbarch_num_regs (gdbarch),
+			     addr);
+
+  regnum = MIPS_PS_REGNUM;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + N64_UCONTEXT_SR);
+
+  /* HI and LO.  */
+  regnum = mips_regnum (gdbarch)->lo;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + N64_UCONTEXT_LO);
+  regnum = mips_regnum (gdbarch)->hi;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + N64_UCONTEXT_HI);
+
+  if (target_read_memory (ucontext_addr + N64_UCONTEXT_FPUSED, buf, 4) == 0 &&
+      extract_unsigned_integer (buf, 4, byte_order) != 0)
+    {
+      for (regnum = 0, addr = ucontext_addr + N64_UCONTEXT_FPREGS;
+	   regnum < 32; regnum++, addr += N64_UCONTEXT_REG_SIZE)
+	trad_frame_set_reg_addr (cache,
+				 regnum + gdbarch_fp0_regnum (gdbarch),
+				 addr);
+      trad_frame_set_reg_addr (cache, mips_regnum (gdbarch)->fp_control_status,
+			       addr);
+    }
+
+  trad_frame_set_id (cache, frame_id_build (sp, func));
+}
+
+#define MIPS_INST_DADDIU_A0_SP_N64 (0x67a40000 \
+				    + N64_SIGFRAME_UCONTEXT_OFFSET)
+
+static const struct tramp_frame mips64_fbsd_sigframe =
+{
+  SIGTRAMP_FRAME,
+  MIPS_INSN32_SIZE,
+  {
+    { MIPS_INST_DADDIU_A0_SP_N64, -1 },	/* daddiu  a0, sp, SIGF_UC */
+    { MIPS_INST_LI_V0_SIGRETURN, -1 },	/* li      v0, SYS_sigreturn */
+    { MIPS_INST_SYSCALL, -1 },		/* syscall */
+    { MIPS_INST_BREAK, -1 },		/* break */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  mips64_fbsd_sigframe_init
+};
+
+/* Shared library support.  */
+
+/* FreeBSD/mips uses a slightly different `struct link_map' than the
+   other FreeBSD platforms as it includes an additional `l_off'
+   member.  */
+
+static struct link_map_offsets *
+mips_fbsd_ilp32_fetch_link_map_offsets (void)
+{
+  static struct link_map_offsets lmo;
+  static struct link_map_offsets *lmp = NULL;
+
+  if (lmp == NULL)
+    {
+      lmp = &lmo;
+
+      lmo.r_version_offset = 0;
+      lmo.r_version_size = 4;
+      lmo.r_map_offset = 4;
+      lmo.r_brk_offset = 8;
+      lmo.r_ldsomap_offset = -1;
+
+      lmo.link_map_size = 24;
+      lmo.l_addr_offset = 0;
+      lmo.l_name_offset = 8;
+      lmo.l_ld_offset = 12;
+      lmo.l_next_offset = 16;
+      lmo.l_prev_offset = 20;
+    }
+
+  return lmp;
+}
+
+static struct link_map_offsets *
+mips_fbsd_lp64_fetch_link_map_offsets (void)
+{
+  static struct link_map_offsets lmo;
+  static struct link_map_offsets *lmp = NULL;
+
+  if (lmp == NULL)
+    {
+      lmp = &lmo;
+
+      lmo.r_version_offset = 0;
+      lmo.r_version_size = 4;
+      lmo.r_map_offset = 8;
+      lmo.r_brk_offset = 16;
+      lmo.r_ldsomap_offset = -1;
+
+      lmo.link_map_size = 48;
+      lmo.l_addr_offset = 0;
+      lmo.l_name_offset = 16;
+      lmo.l_ld_offset = 24;
+      lmo.l_next_offset = 32;
+      lmo.l_prev_offset = 40;
+    }
+
+  return lmp;
+}
+
+static void
+mips_fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  enum mips_abi abi = mips_abi (gdbarch);
+
+  /* Generic FreeBSD support.  */
+  fbsd_init_abi (info, gdbarch);
+
+  set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
+
+  switch (abi)
+    {
+      case MIPS_ABI_O32:
+	tramp_frame_prepend_unwinder (gdbarch, &mips_fbsd_sigframe);
+	break;
+      case MIPS_ABI_N32:
+	break;
+      case MIPS_ABI_N64:
+	tramp_frame_prepend_unwinder (gdbarch, &mips64_fbsd_sigframe);
+	break;
+    }
+
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, mips_fbsd_iterate_over_regset_sections);
+
+  /* FreeBSD/mips has SVR4-style shared libraries.  */
+  set_solib_svr4_fetch_link_map_offsets
+    (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
+	       mips_fbsd_ilp32_fetch_link_map_offsets :
+	       mips_fbsd_lp64_fetch_link_map_offsets));
+}
+
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+void _initialize_mips_fbsd_tdep (void);
+
+void
+_initialize_mips_fbsd_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_FREEBSD_ELF,
+			  mips_fbsd_init_abi);
+}