Support software single step on ARM in GDBServer

Support software single step on ARM in GDBServer

This patch teaches GDBServer how to software single step on ARM
linux by sharing code with GDB.

The arm_get_next_pcs function in GDB is now shared with GDBServer.  So
that GDBServer can use the function to return the possible addresses of
the next PC.

A proper shared context was also needed so that we could share the code,
this context is described in the arm_get_next_pcs structure.

Testing :

No regressions, tested on ubuntu 14.04 ARMv7 and x86.
With gdbserver-{native,extended} / { -marm -mthumb }

gdb/ChangeLog:

	* Makefile.in (ALL_TARGET_OBS): Append arm-get-next-pcs.o,
	arm-linux.o.
	(ALLDEPFILES): Append arm-get-next-pcs.c, arm-linux.c
	(arm-linux.o): New rule.
	(arm-get-next-pcs.o): New rule.
	* arch/arm-get-next-pcs.c: New file.
	* arch/arm-get-next-pcs.h: New file.
	* arch/arm-linux.h: New file.
	* arch/arm-linux.c: New file.
	* arm.c: Include common-regcache.c.
	(thumb_advance_itstate): Moved from arm-tdep.c.
	(arm_instruction_changes_pc): Likewise.
	(thumb_instruction_changes_pc): Likewise.
	(thumb2_instruction_changes_pc): Likewise.
	(shifted_reg_val): Likewise.
	* arm.h (submask): Move macro from arm-tdep.h
	(bit): Likewise.
	(bits): Likewise.
	(sbits): Likewise.
	(BranchDest): Likewise.
	(thumb_advance_itstate): Moved declaration from arm-tdep.h
	(arm_instruction_changes_pc): Likewise.
	(thumb_instruction_changes_pc): Likewise.
	(thumb2_instruction_changes_pc): Likewise.
	(shifted_reg_val): Likewise.
	* arm-linux-tdep.c: Include arch/arm.h, arch/arm-get-next-pcs.h
	arch/arm-linux.h.
	(arm_linux_get_next_pcs_ops): New struct.
	(ARM_SIGCONTEXT_R0, ARM_UCONTEXT_SIGCONTEXT,
	ARM_OLD_RT_SIGFRAME_SIGINFO, ARM_OLD_RT_SIGFRAME_UCONTEXT,
	ARM_NEW_RT_SIGFRAME_UCONTEXT, ARM_NEW_SIGFRAME_MAGIC): Move stack
	layout defines to arch/arm-linux.h.
	(arm_linux_sigreturn_next_pc_offset): Move to arch/arm-linux.c.
	(arm_linux_software_single_step): Adjust for arm_get_next_pcs
	implementation.
	* arm-tdep.c: Include arch/arm-get-next-pcs.h.
	(arm_get_next_pcs_ops): New struct.
	(submask): Move macro to arm.h.
	(bit): Likewise.
	(bits): Likewise.
	(sbits): Likewise.
	(BranchDest): Likewise.
	(thumb_instruction_changes_pc): Move to arm.c
	(thumb2_instruction_changes_pc): Likewise.
	(arm_instruction_changes_pc): Likewise.
	(shifted_reg_val): Likewise.
	(thumb_advance_itstate): Likewise.
	(thumb_get_next_pc_raw): Move to arm-get-next-pcs.c.
	(arm_get_next_pc_raw): Likewise.
	(arm_get_next_pc): Likewise.
	(thumb_deal_with_atomic_sequence_raw): Likewise.
	(arm_deal_with_atomic_sequence_raw): Likewise.
	(arm_deal_with_atomic_sequence): Likewise.
	(arm_get_next_pcs_read_memory_unsigned_integer): New function.
	(arm_get_next_pcs_addr_bits_remove): Likewise.
	(arm_get_next_pcs_syscall_next_pc): Likewise.
	(arm_get_next_pcs_is_thumb): Likewise.
	(arm_software_single_step): Adjust for arm_get_next_pcs
	implementation.
	* arm-tdep.h: (arm_get_next_pc): Remove declaration.
	(arm_get_next_pcs_read_memory_unsigned_integer):
	New declaration.
	(arm_get_next_pcs_addr_bits_remove): Likewise.
	(arm_get_next_pcs_syscall_next_pc): Likewise.
	(arm_get_next_pcs_is_thumb): Likewise.
	(arm_deal_with_atomic_sequence: Remove declaration.
	* common/gdb_vecs.h: Add CORE_ADDR vector definition.
	* configure.tgt (aarch64*-*-linux): Add arm-get-next-pcs.o,
	arm-linux.o.
	(arm*-wince-pe): Add arm-get-next-pcs.o.
	(arm*-*-linux*): Add arm-get-next-pcs.o, arm-linux.o,
	arm-get-next-pcs.o
	(arm*-*-netbsd*,arm*-*-knetbsd*-gnu): Add arm-get-next-pcs.o.
	(arm*-*-openbsd*): Likewise.
	(arm*-*-symbianelf*): Likewise.
	(arm*-*-*): Likewise.
	* symtab.h: Move CORE_ADDR vector definition to gdb_vecs.h.

gdb/gdbserver/ChangeLog:

	* Makefile.in (SFILES): Append arch/arm-linux.c,
	arch/arm-get-next-pcs.c.
	(arm-linux.o): New rule.
	(arm-get-next-pcs.o): New rule.
	* configure.srv (arm*-*-linux*): Add arm-get-next-pcs.o,
	arm-linux.o.
	* linux-aarch32-low.c (arm_abi_breakpoint): Remove macro.  Moved
	to linux-aarch32-low.c.
	(arm_eabi_breakpoint, arm_breakpoint): Likewise.
	(arm_breakpoint_len, thumb_breakpoint): Likewise.
	(thumb_breakpoint_len, thumb2_breakpoint): Likewise.
	(thumb2_breakpoint_len): Likewise.
	(arm_is_thumb_mode): Make non-static.
	* linux-aarch32-low.h (arm_abi_breakpoint): New macro.  Moved
	from linux-aarch32-low.c.
	(arm_eabi_breakpoint, arm_breakpoint): Likewise.
	(arm_breakpoint_len, thumb_breakpoint): Likewise.
	(thumb_breakpoint_len, thumb2_breakpoint): Likewise.
	(thumb2_breakpoint_len): Likewise.
	(arm_is_thumb_mode): New declaration.
	* linux-arm-low.c: Include arch/arm-linux.h
	aarch/arm-get-next-pcs.h, sys/syscall.h.
	(get_next_pcs_ops): New struct.
	(get_next_pcs_addr_bits_remove): New function.
	(get_next_pcs_is_thumb): New function.
	(get_next_pcs_read_memory_unsigned_integer): Likewise.
	(arm_sigreturn_next_pc): Likewise.
	(get_next_pcs_syscall_next_pc): Likewise.
	(arm_gdbserver_get_next_pcs): Likewise.
	(struct linux_target_ops) <arm_gdbserver_get_next_pcs>:
	Initialize.
	* linux-low.h: Move CORE_ADDR vector definition to gdb_vecs.h.
	* server.h: Include gdb_vecs.h.