Nios II R2 support for GDB.

2015-08-03  Sandra Loosemore  <sandra@codesourcery.com>

	gdb/
	* nios2-tdep.h: Include opcode/nios2.h here.
	(NIOS2_CDX_OPCODE_SIZE): New.
	(struct gdbarch_tdep): Add OP parameter to syscall_next_pc.
	* nios2-tdep.c: Don't include opcode/nios2.h here.
	(nios2_fetch_insn): For R2, try reading 2-byte instruction if
	4-byte read fails.
	(nios2_match_add, nios2_match_sub): Add cases for R2 encodings.
	(nios2_match_addi, nios2_match_orhi): Likewise.
	(nios2_match_stw, nios2_match_ldw): Likewise.
	(nios2_match_rdctl): Likewise.
	(nios2_match_stwm, nios2_match_ldwm): New.
	(nios2_match_branch): Add cases for R2 encodings.
	(nios2_match_jmpi, nios2_match_calli): Likewise.
	(nios2_match_jmpr, nios2_match_callr): Likewise.
	(nios2_match_break, nios2_match_trap): Likewise.
	(nios2_in_epilogue_p): Add R2 support.
	(nios2_analyze_prologue): Update comments.  Recognize R2 CDX
	prologues.
	(nios2_breakpoint_from_pc): Handle R2 instructions.
	(nios2_get_next_pc): Likewise.  Adjust call to
	tdep->syscall_next_pc.
	* nios2-linux-tdep.c (nios2_r1_linux_rt_sigreturn_tramp_frame):
	Renamed from nios2_linux_rt_sigreturn_tramp_frame.  Use
	instruction field macros instead of literal hex values.
	(nios2_r2_linux_rt_sigreturn_tramp_frame): New.
	(nios2_linux_syscall_next_pc): Adjust signature to pass OP.
	Use size field from OP instead of assuming all instructions
	are the same size.
	(nios2_linux_init_abi): Register appropriate unwinder for mach.

	gdb/gdbserver/
	* linux-nios2-low.c (NIOS2_BREAKPOINT): Conditionalize for
	arch variant.
	(CDX_BREAKPOINT): Define for R2.
	(nios2_breakpoint_at): Check for CDX_BREAKPOINT when R2.
	(the_low_target): Add comments.

1 files changed, 29 insertions, 7 deletions

diff --git a/gdb/nios2-linux-tdep.c b/gdb/nios2-linux-tdep.c
index 68c949a09fb..6b483e82f42 100644
--- a/gdb/nios2-linux-tdep.c
+++ b/gdb/nios2-linux-tdep.c
@@ -156,13 +156,30 @@ nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
   trad_frame_set_id (this_cache, frame_id_build (base, func));
 }
 
-static struct tramp_frame nios2_linux_rt_sigreturn_tramp_frame =
+/* Trampoline for sigreturn.  This has the form
+     movi r2, __NR_rt_sigreturn
+     trap 0
+   appropriately encoded for R1 or R2.  */
+
+static struct tramp_frame nios2_r1_linux_rt_sigreturn_tramp_frame =
+{
+  SIGTRAMP_FRAME,
+  4,
+  {
+    { MATCH_R1_MOVI | SET_IW_I_B (2) | SET_IW_I_IMM16 (139), -1 },
+    { MATCH_R1_TRAP | SET_IW_R_IMM5 (0), -1},
+    { TRAMP_SENTINEL_INSN }
+  },
+  nios2_linux_rt_sigreturn_init
+};
+
+static struct tramp_frame nios2_r2_linux_rt_sigreturn_tramp_frame =
 {
   SIGTRAMP_FRAME,
   4,
   {
-    { 0x00800004 | (139 << 6), -1 },  /* movi r2,__NR_rt_sigreturn */
-    { 0x003b683a, -1 },               /* trap */
+    { MATCH_R2_MOVI | SET_IW_F2I16_B (2) | SET_IW_F2I16_IMM16 (139), -1 },
+    { MATCH_R2_TRAP | SET_IW_X2L5_IMM5 (0), -1},
     { TRAMP_SENTINEL_INSN }
   },
   nios2_linux_rt_sigreturn_init
@@ -172,7 +189,8 @@ static struct tramp_frame nios2_linux_rt_sigreturn_tramp_frame =
    instruction to be executed.  */
 
 static CORE_ADDR
-nios2_linux_syscall_next_pc (struct frame_info *frame)
+nios2_linux_syscall_next_pc (struct frame_info *frame,
+			     const struct nios2_opcode *op)
 {
   CORE_ADDR pc = get_frame_pc (frame);
   ULONGEST syscall_nr = get_frame_register_unsigned (frame, NIOS2_R2_REGNUM);
@@ -182,7 +200,7 @@ nios2_linux_syscall_next_pc (struct frame_info *frame)
   if (syscall_nr == 139 /* rt_sigreturn */)
     return frame_unwind_caller_pc (frame);
 
-  return pc + NIOS2_OPCODE_SIZE;
+  return pc + op->size;
 }
 
 /* Hook function for gdbarch_register_osabi.  */
@@ -207,8 +225,12 @@ nios2_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_iterate_over_regset_sections
     (gdbarch, nios2_iterate_over_regset_sections);
   /* Linux signal frame unwinders.  */
-  tramp_frame_prepend_unwinder (gdbarch,
-                                &nios2_linux_rt_sigreturn_tramp_frame);
+  if (gdbarch_bfd_arch_info (gdbarch)->mach == bfd_mach_nios2r2)
+    tramp_frame_prepend_unwinder (gdbarch,
+				  &nios2_r2_linux_rt_sigreturn_tramp_frame);
+  else
+    tramp_frame_prepend_unwinder (gdbarch,
+				  &nios2_r1_linux_rt_sigreturn_tramp_frame);
 
   tdep->syscall_next_pc = nios2_linux_syscall_next_pc;