[GDBserver] Multi-process + multi-arch

This patch makes GDBserver support multi-process + biarch.

Currently, if you're debugging more than one process at once with a
single gdbserver (in extended-remote mode), then all processes must
have the same architecture (e.g., 64-bit vs 32-bit).  Otherwise, you
see this:

Added inferior 2
[Switching to inferior 2 [<null>] (<noexec>)]
Reading symbols from /home/pedro/gdb/tests/main32...done.
Temporary breakpoint 2 at 0x4004cf: main. (2 locations)
Starting program: /home/pedro/gdb/tests/main32
warning: Selected architecture i386 is not compatible with reported target architecture i386:x86-64
warning: Architecture rejected target-supplied description
Remote 'g' packet reply is too long: 000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000090cfffff0000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000000000000000b042f7460000000000020000230000002b0000002b0000002b000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000007f03000000000000ffff0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000801f00003b0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
... etc, etc ...

Even though the process was running a 32-bit program, GDBserver sent
back to GDB a register set in 64-bit layout.

A patch (http://sourceware.org/ml/gdb-patches/2012-11/msg00228.html) a
while ago made GDB track a target_gdbarch per inferior, and as
consequence, fetch a target description per-inferior.  This patch is
the GDBserver counterpart, that makes GDBserver keep track of each
process'es XML target description and register layout.  So in the
example above, GDBserver will send the correct register set in 32-bit
layout to GDB.

A new "struct target_desc" object (tdesc for short) is added, that
holds the target description and register layout information about
each process.  Each `struct process_info' holds a pointer to a target
description.  The regcache also gains a pointer to a target
description, mainly for convenience, and parallel with GDB (and
possible future support for programs that flip processor modes).

The low target's arch_setup routines are responsible for setting the
process'es correct tdesc.  This isn't that much different to how
things were done before, except that instead of detecting the inferior
process'es architecture and calling the corresponding
init_registers_FOO routine, which would change the regcache layout
globals and recreate the threads' regcaches, the regcache.c globals
are gone, and the init_registers_$BAR routines now each initialize a
separate global struct target_desc object (one for each arch variant
GDBserver supports), and so all the init_registers_$BAR routines that
are built into GDBserver are called early at GDBserver startup time
(similarly to how GDB handles its built-in target descriptions), and
then the arch_setup routine is responsible for making
process_info->tdesc point to one of these target description globals.
The regcache module is all parameterized to get the regcache's layout
from the tdesc object instead of the old register_bytes, etc. globals.

The threads' regcaches are now created lazily.  The old scheme where
we created each of them when we added a new thread doesn't work
anymore, because we add the main thread/lwp before we see it stop for
the first time, and it is only when we see the thread stop for the
first time that we have a chance of determining the inferior's
architecture (through the_low_target.arch_setup).  Therefore when we
add the main thread we don't know which architecture/tdesc its
regcache should have.

This patch makes the gdb.multi/multi-arch.exp test now pass against
(extended-remote) GDBserver.  It currently fails, without this patch.

The IPA also uses the regcache, so it gains a new global struct
target_desc pointer, which points at the description of the process it
is loaded in.

Re. the linux-low.c & friends changes.  Since the register map
etc. may differ between processes (64-bit vs 32-bit) etc., the
linux_target_ops num_regs, regmap and regset_bitmap data fields are no
longer sufficient.  A new method is added in their place that returns
a pointer to a new struct that includes all info linux-low.c needs to
access registers of the current inferior.

The patch/discussion that originally introduced
linux-low.c:disabled_regsets mentions that the disabled_regsets set
may be different per mode (in a biarch setup), and indeed that is
cleared whenever we start a new (first) inferior, so that global is
moved as well behind the new `struct regs_info'.

On the x86 side:

I simply replaced the i387-fp.c:num_xmm_registers global with a check
for 64-bit or 32-bit process, which is equivalent to how the global
was set.  This avoided coming up with some more general mechanism that
would work for all targets that use this module (GNU/Linux, Windows,
etc.).

Tested:

  GNU/Linux IA64
  GNU/Linux MIPS64
  GNU/Linux PowerPC (Fedora 16)
  GNU/Linux s390x (Fedora 16)
  GNU/Linux sparc64 (Debian)
  GNU/Linux x86_64, -m64 and -m32 (Fedora 17)

Cross built, and smoke tested:

  i686-w64-mingw32, under Wine.
  GNU/Linux TI C6x, by Yao Qi.

Cross built but otherwise not tested:

  aarch64-linux-gnu
  arm-linux-gnu
  m68k-linux
  nios2-linux-gnu
  sh-linux-gnu
  spu
  tilegx-unknown-linux-gnu

Completely untested:

  GNU/Linux Blackfin
  GNU/Linux CRIS
  GNU/Linux CRISv32
  GNU/Linux TI Xtensa
  GNU/Linux M32R
  LynxOS
  QNX NTO

gdb/gdbserver/
2013-06-07  Pedro Alves  <palves@redhat.com>

	* Makefile.in (OBS): Add tdesc.o.
	(IPA_OBJS): Add tdesc-ipa.o.
	(tdesc-ipa.o): New rule.
	* ax.c (gdb_eval_agent_expr): Adjust register_size call to new
	interface.
	* linux-low.c (new_inferior): Delete.
	(disabled_regsets, num_regsets): Delete.
	(linux_add_process): Adjust to set the new per-process
	new_inferior flag.
	(linux_detach_one_lwp): Adjust to call regcache_invalidate_thread.
	(linux_wait_for_lwp): Adjust.  Only call arch_setup if the event
	was a stop.  When calling arch_setup, switch the current inferior
	to the thread that got an event.
	(linux_resume_one_lwp): Adjust to call regcache_invalidate_thread.
	(regsets_fetch_inferior_registers)
	(regsets_store_inferior_registers): New regsets_info parameter.
	Adjust to use it.
	(linux_register_in_regsets): New regs_info parameter.  Adjust to
	use it.
	(register_addr, fetch_register, store_register): New usrregs_info
	parameter.  Adjust to use it.
	(usr_fetch_inferior_registers, usr_store_inferior_registers): New
	parameter regs_info.  Adjust to use it.
	(linux_fetch_registers): Get the current inferior's regs_info, and
	adjust to use it.
	(linux_store_registers): Ditto.
	[HAVE_LINUX_REGSETS] (initialize_regsets_info): New.
	(initialize_low): Don't initialize the target_regsets here.  Call
	initialize_low_arch.
	* linux-low.h (target_regsets): Delete declaration.
	(struct regsets_info): New.
	(struct usrregs_info): New.
	(struct regs_info): New.
	(struct process_info_private) <new_inferior>: New field.
	(struct linux_target_ops): Delete the num_regs, regmap, and
	regset_bitmap fields.  New field regs_info.
	[HAVE_LINUX_REGSETS] (initialize_regsets_info): Declare.
	* i387-fp.c (num_xmm_registers): Delete.
	(i387_cache_to_fsave, i387_fsave_to_cache): Adjust find_regno
	calls to new interface.
	(i387_cache_to_fxsave, i387_cache_to_xsave, i387_fxsave_to_cache)
	(i387_xsave_to_cache): Adjust find_regno calls to new interface.
	Infer the number of xmm registers from the regcache's target
	description.
	* i387-fp.h (num_xmm_registers): Delete.
	* inferiors.c (add_thread): Don't install the thread's regcache
	here.
	* proc-service.c (gregset_info): Fetch the current inferior's
	regs_info.  Adjust to use it.
	* regcache.c: Include tdesc.h.
	(register_bytes, reg_defs, num_registers)
	(gdbserver_expedite_regs): Delete.
	(get_thread_regcache): If the thread doesn't have a regcache yet,
	create one, instead of aborting gdbserver.
	(regcache_invalidate_one): Rename to ...
	(regcache_invalidate_thread): ... this.
	(regcache_invalidate_one): New.
	(regcache_invalidate): Only invalidate registers of the current
	process.
	(init_register_cache): Add target_desc parameter, and use it.
	(new_register_cache): Ditto.  Assert the target description has a
	non zero registers_size.
	(regcache_cpy): Add assertions.  Adjust.
	(realloc_register_cache, set_register_cache): Delete.
	(registers_to_string, registers_from_string): Adjust.
	(find_register_by_name, find_regno, find_register_by_number)
	(register_cache_size): Add target_desc parameter, and use it.
	(free_register_cache_thread, free_register_cache_thread_one)
	(regcache_release, register_cache_size): New.
	(register_size): Add target_desc parameter, and use it.
	(register_data, supply_register, supply_register_zeroed)
	(supply_regblock, supply_register_by_name, collect_register)
	(collect_register_as_string, collect_register_by_name): Adjust.
	* regcache.h (struct target_desc): Forward declare.
	(struct regcache) <tdesc>: New field.
	(init_register_cache, new_register_cache): Add target_desc
	parameter.
	(regcache_invalidate_thread): Declare.
	(regcache_invalidate_one): Delete declaration.
	(regcache_release): Declare.
	(find_register_by_number, register_cache_size, register_size)
	(find_regno): Add target_desc parameter.
	(gdbserver_expedite_regs, gdbserver_xmltarget): Delete
	declarations.
	* remote-utils.c: Include tdesc.h.
	(outreg, prepare_resume_reply): Adjust.
	* server.c: Include tdesc.h.
	(gdbserver_xmltarget): Delete declaration.
	(get_features_xml, process_serial_event): Adjust.
	* server.h [IN_PROCESS_AGENT] (struct target_desc): Forward
	declare.
	(struct process_info) <tdesc>: New field.
	(ipa_tdesc): Declare.
	* tdesc.c: New file.
	* tdesc.h: New file.
	* tracepoint.c: Include tdesc.h.
	[IN_PROCESS_AGENT] (ipa_tdesc): Define.
	(get_context_regcache): Adjust to pass ipa_tdesc down.
	(do_action_at_tracepoint): Adjust to get the register cache size
	from the context regcache's description.
	(traceframe_walk_blocks): Adjust to get the register cache size
	from the current trace frame's description.
	(traceframe_get_pc): Adjust to get current trace frame's
	description and pass it down.
	(gdb_collect): Adjust to get the register cache size from the
	IPA's description.
	* linux-amd64-ipa.c (tdesc_amd64_linux): Declare.
	(gdbserver_xmltarget): Delete.
	(initialize_low_tracepoint): Set the ipa's target description.
	* linux-i386-ipa.c (tdesc_i386_linux): Declare.
	(initialize_low_tracepoint): Set the ipa's target description.
	* linux-x86-low.c: Include tdesc.h.
	[__x86_64__] (is_64bit_tdesc): New.
	(ps_get_thread_area, x86_get_thread_area): Use it.
	(i386_cannot_store_register): Rename to ...
	(x86_cannot_store_register): ... this.  Use is_64bit_tdesc.
	(i386_cannot_fetch_register): Rename to ...
	(x86_cannot_fetch_register): ... this.  Use is_64bit_tdesc.
	(x86_fill_gregset, x86_store_gregset): Adjust register_size calls
	to new interface.
	(target_regsets): Rename to ...
	(x86_regsets): ... this.
	(x86_get_pc, x86_set_pc): Adjust register_size calls to new
	interface.
	(x86_siginfo_fixup): Use is_64bit_tdesc.
	[__x86_64__] (tdesc_amd64_linux, tdesc_amd64_avx_linux)
	(tdesc_x32_avx_linux, tdesc_x32_linux)
	(tdesc_i386_linux, tdesc_i386_mmx_linux, tdesc_i386_avx_linux):
	Declare.
	(x86_linux_update_xmltarget): Delete.
	(I386_LINUX_XSAVE_XCR0_OFFSET): Define.
	(have_ptrace_getfpxregs, have_ptrace_getregset): New.
	(AMD64_LINUX_USER64_CS): New.
	(x86_linux_read_description): New, based on
	x86_linux_update_xmltarget.
	(same_process_callback): New.
	(x86_arch_setup_process_callback): New.
	(x86_linux_update_xmltarget): New.
	(x86_regsets_info): New.
	(amd64_linux_regs_info): New.
	(i386_linux_usrregs_info): New.
	(i386_linux_regs_info): New.
	(x86_linux_regs_info): New.
	(x86_arch_setup): Reimplement.
	(x86_install_fast_tracepoint_jump_pad): Use is_64bit_tdesc.
	(x86_emit_ops): Ditto.
	(the_low_target): Adjust.  Install x86_linux_regs_info,
	x86_cannot_fetch_register, and x86_cannot_store_register.
	(initialize_low_arch): New.
	* linux-ia64-low.c (tdesc_ia64): Declare.
	(ia64_fetch_register): Adjust.
	(ia64_usrregs_info, regs_info): New globals.
	(ia64_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-sparc-low.c (tdesc_sparc64): Declare.
	(sparc_fill_gregset_to_stack, sparc_store_gregset_from_stack):
	Adjust.
	(sparc_arch_setup): New function.
	(sparc_regsets_info, sparc_usrregs_info, regs_info): New globals.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-ppc-low.c (tdesc_powerpc_32l, tdesc_powerpc_altivec32l)
	(tdesc_powerpc_cell32l, tdesc_powerpc_vsx32l)
	(tdesc_powerpc_isa205_32l, tdesc_powerpc_isa205_altivec32l)
	(tdesc_powerpc_isa205_vsx32l, tdesc_powerpc_e500l)
	(tdesc_powerpc_64l, tdesc_powerpc_altivec64l)
	(tdesc_powerpc_cell64l, tdesc_powerpc_vsx64l)
	(tdesc_powerpc_isa205_64l, tdesc_powerpc_isa205_altivec64l)
	(tdesc_powerpc_isa205_vsx64l): Declare.
	(ppc_cannot_store_register, ppc_collect_ptrace_register)
	(ppc_supply_ptrace_register, parse_spufs_run, ppc_get_pc)
	(ppc_set_pc, ppc_get_hwcap): Adjust.
	(ppc_usrregs_info): Forward declare.
	(!__powerpc64__) ppc_regmap_adjusted: New global.
	(ppc_arch_setup): Adjust to the current process'es target
	description.
	(ppc_fill_vsxregset, ppc_store_vsxregset, ppc_fill_vrregset)
	(ppc_store_vrregset, ppc_fill_evrregset, ppc_store_evrregse)
	(ppc_store_evrregset): Adjust.
	(target_regsets): Rename to ...
	(ppc_regsets): ... this, and make static.
	(ppc_usrregs_info, ppc_regsets_info, regs_info): New globals.
	(ppc_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-s390-low.c (tdesc_s390_linux32, tdesc_s390_linux32v1)
	(tdesc_s390_linux32v2, tdesc_s390_linux64, tdesc_s390_linux64v1)
	(tdesc_s390_linux64v2, tdesc_s390x_linux64, tdesc_s390x_linux64v1)
	(tdesc_s390x_linux64v2): Declare.
	(s390_collect_ptrace_register, s390_supply_ptrace_register)
	(s390_fill_gregset, s390_store_last_break): Adjust.
	(target_regsets): Rename to ...
	(s390_regsets): ... this, and make static.
	(s390_get_pc, s390_set_pc): Adjust.
	(s390_get_hwcap): New target_desc parameter, and use it.
	[__s390x__] (have_hwcap_s390_high_gprs): New global.
	(s390_arch_setup): Adjust to set the current process'es target
	description.  Don't adjust the regmap.
	(s390_usrregs_info, s390_regsets_info, regs_info): New globals.
	[__s390x__] (s390_usrregs_info_3264, s390_regsets_info_3264)
	(regs_info_3264): New globals.
	(s390_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-mips-low.c (tdesc_mips_linux, tdesc_mips_dsp_linux)
	(tdesc_mips64_linux, tdesc_mips64_dsp_linux): Declare.
	[__mips64] (init_registers_mips_linux)
	(init_registers_mips_dsp_linux): Delete defines.
	[__mips64] (tdesc_mips_linux, tdesc_mips_dsp_linux): New defines.
	(have_dsp): New global.
	(mips_read_description): New, based on mips_arch_setup.
	(mips_arch_setup): Reimplement.
	(get_usrregs_info): New function.
	(mips_cannot_fetch_register, mips_cannot_store_register)
	(mips_get_pc, mips_set_pc, mips_fill_gregset, mips_store_gregset)
	(mips_fill_fpregset, mips_store_fpregset): Adjust.
	(target_regsets): Rename to ...
	(mips_regsets): ... this, and make static.
	(mips_regsets_info, mips_dsp_usrregs_info, mips_usrregs_info)
	(dsp_regs_info, regs_info): New globals.
	(mips_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-arm-low.c (tdesc_arm, tdesc_arm_with_iwmmxt)
	(tdesc_arm_with_vfpv2, tdesc_arm_with_vfpv3, tdesc_arm_with_neon):
	Declare.
	(arm_fill_vfpregset, arm_store_vfpregset): Adjust.
	(arm_read_description): New, with bits factored from
	arm_arch_setup.
	(arm_arch_setup): Reimplement.
	(target_regsets): Rename to ...
	(arm_regsets): ... this, and make static.
	(arm_regsets_info, arm_usrregs_info, regs_info): New globals.
	(arm_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-m68k-low.c (tdesc_m68k): Declare.
	(target_regsets): Rename to ...
	(m68k_regsets): ... this, and make static.
	(m68k_regsets_info, m68k_usrregs_info, regs_info): New globals.
	(m68k_regs_info): New function.
	(m68k_arch_setup): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-sh-low.c (tdesc_sharch): Declare.
	(target_regsets): Rename to ...
	(sh_regsets): ... this, and make static.
	(sh_regsets_info, sh_usrregs_info, regs_info): New globals.
	(sh_regs_info, sh_arch_setup): New functions.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-bfin-low.c (tdesc_bfin): Declare.
	(bfin_arch_setup): New function.
	(bfin_usrregs_info, regs_info): New globals.
	(bfin_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-cris-low.c (tdesc_cris): Declare.
	(cris_arch_setup): New function.
	(cris_usrregs_info, regs_info): New globals.
	(cris_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-cris-low.c (tdesc_crisv32): Declare.
	(cris_arch_setup): New function.
	(cris_regsets_info, cris_usrregs_info, regs_info): New globals.
	(cris_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-m32r-low.c (tdesc_m32r): Declare.
	(m32r_arch_setup): New function.
	(m32r_usrregs_info, regs_info): New globals.
	(m32r_regs_info): Adjust.
	(initialize_low_arch): New function.
	* linux-tic6x-low.c (tdesc_tic6x_c64xp_linux)
	(tdesc_tic6x_c64x_linux, tdesc_tic6x_c62x_linux): Declare.
	(tic6x_usrregs_info): Forward declare.
	(tic6x_read_description): New function, based on ...
	(tic6x_arch_setup): ... this.  Reimplement.
	(target_regsets): Rename to ...
	(tic6x_regsets): ... this, and make static.
	(tic6x_regsets_info, tic6x_usrregs_info, regs_info): New globals.
	(tic6x_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-xtensa-low.c (tdesc_xtensa): Declare.
	(xtensa_fill_gregset, xtensa_store_gregset): Adjust.
	(target_regsets): Rename to ...
	(xtensa_regsets): ... this, and make static.
	(xtensa_regsets_info, xtensa_usrregs_info, regs_info): New
	globals.
	(xtensa_arch_setup, xtensa_regs_info): New functions.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* linux-nios2-low.c (tdesc_nios2_linux): Declare.
	(nios2_arch_setup): Set the current process'es tdesc.
	(target_regsets): Rename to ...
	(nios2_regsets): ... this.
	(nios2_regsets_info, nios2_usrregs_info, regs_info): New globals.
	(nios2_regs_info): New function.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
        * linux-aarch64-low.c (tdesc_aarch64): Declare.
        (aarch64_arch_setup): Set the current process'es tdesc.
        (target_regsets): Rename to ...
        (aarch64_regsets): ... this.
        (aarch64_regsets_info, aarch64_usrregs_info, regs_info): New globals.
        (aarch64_regs_info): New function.
        (the_low_target): Adjust.
        (initialize_low_arch): New function.
	* linux-tile-low.c (tdesc_tilegx, tdesc_tilegx32): Declare
	globals.
	(target_regsets): Rename to ...
	(tile_regsets): ... this.
	(tile_regsets_info, tile_usrregs_info, regs_info): New globals.
	(tile_regs_info): New function.
	(tile_arch_setup): Set the current process'es tdesc.
	(the_low_target): Adjust.
	(initialize_low_arch): New function.
	* spu-low.c (tdesc_spu): Declare.
	(spu_create_inferior, spu_attach): Set the new process'es tdesc.
	* win32-arm-low.c (tdesc_arm): Declare.
	(arm_arch_setup): New function.
	(the_low_target): Install arm_arch_setup instead of
	init_registers_arm.
	* win32-i386-low.c (tdesc_i386, tdesc_amd64): Declare.
	(init_windows_x86): Rename to ...
	(i386_arch_setup): ... this.  Set `win32_tdesc'.
	(the_low_target): Adjust.
	* win32-low.c (win32_tdesc): New global.
	(child_add_thread): Don't create the thread cache here.
	(do_initial_child_stuff): Set the new process'es tdesc.
	* win32-low.h (struct target_desc): Forward declare.
	(win32_tdesc): Declare.
	* lynx-i386-low.c (tdesc_i386): Declare global.
	(lynx_i386_arch_setup): Set `lynx_tdesc'.
	* lynx-low.c (lynx_tdesc): New global.
	(lynx_add_process): Set the new process'es tdesc.
	* lynx-low.h (struct target_desc): Forward declare.
	(lynx_tdesc): Declare global.
	* lynx-ppc-low.c (tdesc_powerpc_32): Declare global.
	(lynx_ppc_arch_setup): Set `lynx_tdesc'.
	* nto-low.c (nto_tdesc): New global.
	(do_attach): Set the new process'es tdesc.
	* nto-low.h (struct target_desc): Forward declare.
	(nto_tdesc): Declare.
	* nto-x86-low.c (tdesc_i386): Declare.
	(nto_x86_arch_setup): Set `nto_tdesc'.

gdb/
2013-06-07  Pedro Alves  <palves@redhat.com>

	* regformats/regdat.sh: Output #include tdesc.h.  Make globals
	static.  Output a global target description pointer.
	(init_registers_${name}): Adjust to initialize a
	target description structure.

1 files changed, 137 insertions, 56 deletions

diff --git a/gdb/gdbserver/linux-mips-low.c b/gdb/gdbserver/linux-mips-low.c
index 0cf83be212d..1010528524b 100644
--- a/gdb/gdbserver/linux-mips-low.c
+++ b/gdb/gdbserver/linux-mips-low.c
@@ -26,16 +26,23 @@
 
 /* Defined in auto-generated file mips-linux.c.  */
 void init_registers_mips_linux (void);
+extern const struct target_desc *tdesc_mips_linux;
+
 /* Defined in auto-generated file mips-dsp-linux.c.  */
 void init_registers_mips_dsp_linux (void);
+extern const struct target_desc *tdesc_mips_dsp_linux;
+
 /* Defined in auto-generated file mips64-linux.c.  */
 void init_registers_mips64_linux (void);
+extern const struct target_desc *tdesc_mips64_linux;
+
 /* Defined in auto-generated file mips64-dsp-linux.c.  */
 void init_registers_mips64_dsp_linux (void);
+extern const struct target_desc *tdesc_mips64_dsp_linux;
 
 #ifdef __mips64
-#define init_registers_mips_linux init_registers_mips64_linux
-#define init_registers_mips_dsp_linux init_registers_mips64_dsp_linux
+#define tdesc_mips_linux tdesc_mips64_linux
+#define tdesc_mips_dsp_linux tdesc_mips64_dsp_linux
 #endif
 
 #ifndef PTRACE_GET_THREAD_AREA
@@ -108,17 +115,15 @@ static unsigned char mips_dsp_regset_bitmap[(mips_dsp_num_regs + 7) / 8] = {
   0xfe, 0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xff, 0xff, 0x80
 };
 
+static int have_dsp = -1;
+
 /* Try peeking at an arbitrarily chosen DSP register and pick the available
    user register set accordingly.  */
 
-static void
-mips_arch_setup (void)
+static const struct target_desc *
+mips_read_description (void)
 {
-  static void (*init_registers) (void);
-
-  gdb_assert (current_inferior);
-
-  if (init_registers == NULL)
+  if (have_dsp < 0)
     {
       int pid = lwpid_of (get_thread_lwp (current_inferior));
 
@@ -126,23 +131,32 @@ mips_arch_setup (void)
       switch (errno)
 	{
 	case 0:
-	  the_low_target.num_regs = mips_dsp_num_regs;
-	  the_low_target.regmap = mips_dsp_regmap;
-	  the_low_target.regset_bitmap = mips_dsp_regset_bitmap;
-	  init_registers = init_registers_mips_dsp_linux;
+	  have_dsp = 1;
 	  break;
 	case EIO:
-	  the_low_target.num_regs = mips_num_regs;
-	  the_low_target.regmap = mips_regmap;
-	  the_low_target.regset_bitmap = NULL;
-	  init_registers = init_registers_mips_linux;
+	  have_dsp = 0;
 	  break;
 	default:
 	  perror_with_name ("ptrace");
 	  break;
 	}
     }
-  init_registers ();
+
+  return have_dsp ? tdesc_mips_dsp_linux : tdesc_mips_linux;
+}
+
+static void
+mips_arch_setup (void)
+{
+  current_process ()->tdesc = mips_read_description ();
+}
+
+static struct usrregs_info *
+get_usrregs_info (void)
+{
+  const struct regs_info *regs_info = the_low_target.regs_info ();
+
+  return regs_info->usrregs;
 }
 
 /* From mips-linux-nat.c.  */
@@ -155,10 +169,14 @@ mips_arch_setup (void)
 static int
 mips_cannot_fetch_register (int regno)
 {
-  if (the_low_target.regmap[regno] == -1)
+  const struct target_desc *tdesc;
+
+  if (get_usrregs_info ()->regmap[regno] == -1)
     return 1;
 
-  if (find_regno ("r0") == regno)
+  tdesc = current_process ()->tdesc;
+
+  if (find_regno (tdesc, "r0") == regno)
     return 1;
 
   return 0;
@@ -167,19 +185,23 @@ mips_cannot_fetch_register (int regno)
 static int
 mips_cannot_store_register (int regno)
 {
-  if (the_low_target.regmap[regno] == -1)
+  const struct target_desc *tdesc;
+
+  if (get_usrregs_info ()->regmap[regno] == -1)
     return 1;
 
-  if (find_regno ("r0") == regno)
+  tdesc = current_process ()->tdesc;
+
+  if (find_regno (tdesc, "r0") == regno)
     return 1;
 
-  if (find_regno ("cause") == regno)
+  if (find_regno (tdesc, "cause") == regno)
     return 1;
 
-  if (find_regno ("badvaddr") == regno)
+  if (find_regno (tdesc, "badvaddr") == regno)
     return 1;
 
-  if (find_regno ("fir") == regno)
+  if (find_regno (tdesc, "fir") == regno)
     return 1;
 
   return 0;
@@ -190,14 +212,14 @@ mips_get_pc (struct regcache *regcache)
 {
   union mips_register pc;
   collect_register_by_name (regcache, "pc", pc.buf);
-  return register_size (0) == 4 ? pc.reg32 : pc.reg64;
+  return register_size (regcache->tdesc, 0) == 4 ? pc.reg32 : pc.reg64;
 }
 
 static void
 mips_set_pc (struct regcache *regcache, CORE_ADDR pc)
 {
   union mips_register newpc;
-  if (register_size (0) == 4)
+  if (register_size (regcache->tdesc, 0) == 4)
     newpc.reg32 = pc;
   else
     newpc.reg64 = pc;
@@ -218,7 +240,7 @@ mips_reinsert_addr (void)
   struct regcache *regcache = get_thread_regcache (current_inferior, 1);
   union mips_register ra;
   collect_register_by_name (regcache, "r31", ra.buf);
-  return register_size (0) == 4 ? ra.reg32 : ra.reg64;
+  return register_size (regcache->tdesc, 0) == 4 ? ra.reg32 : ra.reg64;
 }
 
 static int
@@ -315,27 +337,28 @@ mips_fill_gregset (struct regcache *regcache, void *buf)
 {
   union mips_register *regset = buf;
   int i, use_64bit;
+  const struct target_desc *tdesc = regcache->tdesc;
 
-  use_64bit = (register_size (0) == 8);
+  use_64bit = (register_size (tdesc, 0) == 8);
 
   for (i = 1; i < 32; i++)
     mips_collect_register (regcache, use_64bit, i, regset + i);
 
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("lo"), regset + 32);
+			 find_regno (tdesc, "lo"), regset + 32);
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("hi"), regset + 33);
+			 find_regno (tdesc, "hi"), regset + 33);
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("pc"), regset + 34);
+			 find_regno (tdesc, "pc"), regset + 34);
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("badvaddr"), regset + 35);
+			 find_regno (tdesc, "badvaddr"), regset + 35);
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("status"), regset + 36);
+			 find_regno (tdesc, "status"), regset + 36);
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("cause"), regset + 37);
+			 find_regno (tdesc, "cause"), regset + 37);
 
   mips_collect_register (regcache, use_64bit,
-			 find_regno ("restart"), regset + 0);
+			 find_regno (tdesc, "restart"), regset + 0);
 }
 
 static void
@@ -344,23 +367,26 @@ mips_store_gregset (struct regcache *regcache, const void *buf)
   const union mips_register *regset = buf;
   int i, use_64bit;
 
-  use_64bit = (register_size (0) == 8);
+  use_64bit = (register_size (regcache->tdesc, 0) == 8);
 
   for (i = 0; i < 32; i++)
     mips_supply_register (regcache, use_64bit, i, regset + i);
 
-  mips_supply_register (regcache, use_64bit, find_regno ("lo"), regset + 32);
-  mips_supply_register (regcache, use_64bit, find_regno ("hi"), regset + 33);
-  mips_supply_register (regcache, use_64bit, find_regno ("pc"), regset + 34);
   mips_supply_register (regcache, use_64bit,
-			find_regno ("badvaddr"), regset + 35);
+			find_regno (regcache->tdesc, "lo"), regset + 32);
+  mips_supply_register (regcache, use_64bit,
+			find_regno (regcache->tdesc, "hi"), regset + 33);
   mips_supply_register (regcache, use_64bit,
-			find_regno ("status"), regset + 36);
+			find_regno (regcache->tdesc, "pc"), regset + 34);
   mips_supply_register (regcache, use_64bit,
-			find_regno ("cause"), regset + 37);
+			find_regno (regcache->tdesc, "badvaddr"), regset + 35);
+  mips_supply_register (regcache, use_64bit,
+			find_regno (regcache->tdesc, "status"), regset + 36);
+  mips_supply_register (regcache, use_64bit,
+			find_regno (regcache->tdesc, "cause"), regset + 37);
 
   mips_supply_register (regcache, use_64bit,
-			find_regno ("restart"), regset + 0);
+			find_regno (regcache->tdesc, "restart"), regset + 0);
 }
 
 static void
@@ -369,8 +395,8 @@ mips_fill_fpregset (struct regcache *regcache, void *buf)
   union mips_register *regset = buf;
   int i, use_64bit, first_fp, big_endian;
 
-  use_64bit = (register_size (0) == 8);
-  first_fp = find_regno ("f0");
+  use_64bit = (register_size (regcache->tdesc, 0) == 8);
+  first_fp = find_regno (regcache->tdesc, "f0");
   big_endian = (__BYTE_ORDER == __BIG_ENDIAN);
 
   /* See GDB for a discussion of this peculiar layout.  */
@@ -382,8 +408,9 @@ mips_fill_fpregset (struct regcache *regcache, void *buf)
 			regset[i & ~1].buf + 4 * (big_endian != (i & 1)));
 
   mips_collect_register_32bit (regcache, use_64bit,
-			       find_regno ("fcsr"), regset[32].buf);
-  mips_collect_register_32bit (regcache, use_64bit, find_regno ("fir"),
+			       find_regno (regcache->tdesc, "fcsr"), regset[32].buf);
+  mips_collect_register_32bit (regcache, use_64bit,
+			       find_regno (regcache->tdesc, "fir"),
 			       regset[32].buf + 4);
 }
 
@@ -393,8 +420,8 @@ mips_store_fpregset (struct regcache *regcache, const void *buf)
   const union mips_register *regset = buf;
   int i, use_64bit, first_fp, big_endian;
 
-  use_64bit = (register_size (0) == 8);
-  first_fp = find_regno ("f0");
+  use_64bit = (register_size (regcache->tdesc, 0) == 8);
+  first_fp = find_regno (regcache->tdesc, "f0");
   big_endian = (__BYTE_ORDER == __BIG_ENDIAN);
 
   /* See GDB for a discussion of this peculiar layout.  */
@@ -406,13 +433,15 @@ mips_store_fpregset (struct regcache *regcache, const void *buf)
 		       regset[i & ~1].buf + 4 * (big_endian != (i & 1)));
 
   mips_supply_register_32bit (regcache, use_64bit,
-			      find_regno ("fcsr"), regset[32].buf);
-  mips_supply_register_32bit (regcache, use_64bit, find_regno ("fir"),
+			      find_regno (regcache->tdesc, "fcsr"),
+			      regset[32].buf);
+  mips_supply_register_32bit (regcache, use_64bit,
+			      find_regno (regcache->tdesc, "fir"),
 			      regset[32].buf + 4);
 }
 #endif /* HAVE_PTRACE_GETREGS */
 
-struct regset_info target_regsets[] = {
+static struct regset_info mips_regsets[] = {
 #ifdef HAVE_PTRACE_GETREGS
   { PTRACE_GETREGS, PTRACE_SETREGS, 0, 38 * 8, GENERAL_REGS,
     mips_fill_gregset, mips_store_gregset },
@@ -422,11 +451,51 @@ struct regset_info target_regsets[] = {
   { 0, 0, 0, -1, -1, NULL, NULL }
 };
 
+static struct regsets_info mips_regsets_info =
+  {
+    mips_regsets, /* regsets */
+    0, /* num_regsets */
+    NULL, /* disabled_regsets */
+  };
+
+static struct usrregs_info mips_dsp_usrregs_info =
+  {
+    mips_dsp_num_regs,
+    mips_dsp_regmap,
+  };
+
+static struct usrregs_info mips_usrregs_info =
+  {
+    mips_num_regs,
+    mips_regmap,
+  };
+
+static struct regs_info dsp_regs_info =
+  {
+    mips_dsp_regset_bitmap,
+    &mips_dsp_usrregs_info,
+    &mips_regsets_info
+  };
+
+static struct regs_info regs_info =
+  {
+    NULL, /* regset_bitmap */
+    &mips_usrregs_info,
+    &mips_regsets_info
+  };
+
+static const struct regs_info *
+mips_regs_info (void)
+{
+  if (have_dsp)
+    return &dsp_regs_info;
+  else
+    return &regs_info;
+}
+
 struct linux_target_ops the_low_target = {
   mips_arch_setup,
-  -1,
-  NULL,
-  NULL,
+  mips_regs_info,
   mips_cannot_fetch_register,
   mips_cannot_store_register,
   NULL, /* fetch_register */
@@ -438,3 +507,15 @@ struct linux_target_ops the_low_target = {
   0,
   mips_breakpoint_at,
 };
+
+void
+initialize_low_arch (void)
+{
+  /* Initialize the Linux target descriptions.  */
+  init_registers_mips_linux ();
+  init_registers_mips_dsp_linux ();
+  init_registers_mips64_linux ();
+  init_registers_mips64_dsp_linux ();
+
+  initialize_regsets_info (&mips_regsets_info);
+}