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.

1 files changed, 57 insertions, 0 deletions

diff --git a/gdb/arch/arm-linux.c b/gdb/arch/arm-linux.c
new file mode 100644
index 0000000..5d871e2
--- /dev/null
+++ b/gdb/arch/arm-linux.c
@@ -0,0 +1,57 @@
+/* Common target dependent code for GNU/Linux on ARM systems.
+
+   Copyright (C) 1999-2015 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 "common-defs.h"
+#include "arch/arm.h"
+#include "arm-linux.h"
+
+/* Calculate the offset from stack pointer of the pc register on the stack
+   in the case of a sigreturn or sigreturn_rt syscall.  */
+int
+arm_linux_sigreturn_next_pc_offset (unsigned long sp,
+				    unsigned long sp_data,
+				    unsigned long svc_number,
+				    int is_sigreturn)
+{
+  /* Offset of R0 register.  */
+  int r0_offset = 0;
+  /* Offset of PC register.  */
+  int pc_offset = 0;
+
+  if (is_sigreturn)
+    {
+      if (sp_data == ARM_NEW_SIGFRAME_MAGIC)
+	r0_offset = ARM_UCONTEXT_SIGCONTEXT + ARM_SIGCONTEXT_R0;
+      else
+	r0_offset = ARM_SIGCONTEXT_R0;
+    }
+  else
+    {
+      if (sp_data == sp + ARM_OLD_RT_SIGFRAME_SIGINFO)
+	r0_offset = ARM_OLD_RT_SIGFRAME_UCONTEXT;
+      else
+	r0_offset = ARM_NEW_RT_SIGFRAME_UCONTEXT;
+
+      r0_offset += ARM_UCONTEXT_SIGCONTEXT + ARM_SIGCONTEXT_R0;
+    }
+
+  pc_offset = r0_offset + INT_REGISTER_SIZE * ARM_PC_REGNUM;
+
+  return pc_offset;
+}