[PATCH v2 7/7] Support software breakpoints for ARM linux in GDBServer.

[Antoine Tremblay <antoine dot tremblay at ericsson dot com>]

This patch implements the breakpoint_from_kind operation introduced
in a previous patch.

The proper breakpoint can then be returned to be inserted in memory.

It enables software breakpoints via GDB's Z0 packets on ARM.

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

gdb/ChangeLog:
	* NEWS: Add news for software breakpoints.

gdb/gdbserver/ChangeLog:
	* linux-arm-low.c (arm_breakpoint_from_kind): New function.
	(arm_supports_z_point_type): Add software breakpoint support.
	(struct linux_target_ops) <breakpoint_from_kind>: Initialize field.
---
 gdb/NEWS                      |  2 ++
 gdb/gdbserver/linux-arm-low.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/gdb/NEWS b/gdb/NEWS
index 2e38d9a..17f1c05 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,8 @@
 
 *** Changes since GDB 7.10
 
+* Support for software breakpoints on ARM linux was added in GDBServer.
+
 * Record btrace now supports non-stop mode.
 
 * Support for tracepoints on aarch64-linux was added in GDBserver.
diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
index d16ea60..bd499f8 100644
--- a/gdb/gdbserver/linux-arm-low.c
+++ b/gdb/gdbserver/linux-arm-low.c
@@ -336,6 +336,28 @@ arm_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
     }
 }
 
+/* Get the breakpoint from the remote kind
+   2 is thumb-16
+   3 is thumb2-32
+   4 is arm
+*/
+static const unsigned char *
+arm_breakpoint_from_kind (int *kind)
+{
+  switch (*kind) {
+  case 2:
+    return (unsigned char *) &thumb_breakpoint;
+  case 3:
+    *kind = 4;
+    return (unsigned char *) &thumb2_breakpoint;
+  case 4:
+    return (unsigned char *) &arm_breakpoint;
+  default:
+    return NULL;
+  }
+  return NULL;
+}
+
 /* We only place breakpoints in empty marker functions, and thread locking
    is outside of the function.  So rather than importing software single-step,
    we can just run until exit.  */
@@ -577,6 +599,7 @@ arm_supports_z_point_type (char z_type)
 {
   switch (z_type)
     {
+    case Z_PACKET_SW_BP:
     case Z_PACKET_HW_BP:
     case Z_PACKET_WRITE_WP:
     case Z_PACKET_READ_WP:
@@ -988,6 +1011,14 @@ struct linux_target_ops the_low_target = {
   arm_new_thread,
   arm_new_fork,
   arm_prepare_to_resume,
+  NULL, /* process_qsupported */
+  NULL, /* supports_tracepoints */
+  NULL, /* get_thread_area */
+  NULL, /* install_fast_tracepoint_jump_pad */
+  NULL, /* emit_ops */
+  NULL, /* get_min_fast_tracepoint_insn_len */
+  NULL, /* supports_range_stepping */
+  arm_breakpoint_from_kind,
 };
 
 void
-- 
1.9.1