http://sourceware.org/ml/gdb-patches/2015-02/msg00727.html

Subject: [PATCH 6/8] gdbserver: Support the "swbreak"/"hwbreak" stop reasons

This patch teaches the core of gdbserver about the new "swbreak" and

"hwbreak" stop reasons, and adds the necessary hooks a backend needs

to implement to support the feature.

gdb/gdbserver/ChangeLog:

2015-02-25  Pedro Alves  <palves@redhat.com>

	* remote-utils.c (prepare_resume_reply): Report swbreak/hbreak.

	* server.c (swbreak_feature, hwbreak_feature): New globals.

	(handle_query) <qSupported>: Handle "swbreak+" and "hwbreak+".

	(captured_main): Clear swbreak_feature and hwbreak_feature.

	* server.h (swbreak_feature, hwbreak_feature): Declare.

	* target.h (struct target_ops) 

	supports_stopped_by_sw_breakpoint, stopped_by_hw_breakpoint,

	supports_stopped_by_hw_breakpoint>: New fields.

	(target_supports_stopped_by_sw_breakpoint)

	(target_stopped_by_sw_breakpoint)

	(target_supports_stopped_by_hw_breakpoint)

	(target_stopped_by_hw_breakpoint): Declare.

---

 gdb/gdbserver/remote-utils.c | 10 ++++++++++

 gdb/gdbserver/server.c       | 25 +++++++++++++++++++++++++

 gdb/gdbserver/server.h       | 11 +++++++++++

 gdb/gdbserver/target.h       | 31 +++++++++++++++++++++++++++++++

 4 files changed, 77 insertions(+)

Index: gdb-7.6.1/gdb/gdbserver/remote-utils.c

===================================================================

--- gdb-7.6.1.orig/gdb/gdbserver/remote-utils.c	2016-03-13 19:45:54.182550173 +0100

+++ gdb-7.6.1/gdb/gdbserver/remote-utils.c	2016-03-13 19:45:59.518589318 +0100

@@ -1355,6 +1355,11 @@

 	      *buf++ = tohex ((addr >> (i - 1) * 4) & 0xf);

 	    *buf++ = ';';

 	  }

+	else if (hwbreak_feature && target_stopped_by_hw_breakpoint ())

+	  {

+	    sprintf (buf, "hwbreak:;");

+	    buf += strlen (buf);

+	  }

 	while (*regp)

 	  {

Index: gdb-7.6.1/gdb/gdbserver/server.c

===================================================================

--- gdb-7.6.1.orig/gdb/gdbserver/server.c	2016-03-13 19:45:54.184550187 +0100

+++ gdb-7.6.1/gdb/gdbserver/server.c	2016-03-13 19:46:24.182770265 +0100

@@ -56,6 +56,7 @@

 int multi_process;

 int non_stop;

+int hwbreak_feature;

 /* Whether we should attempt to disable the operating system's address

    space randomization feature before starting an inferior.  */

@@ -1728,6 +1729,13 @@

 		  /* GDB supports relocate instruction requests.  */

 		  gdb_supports_qRelocInsn = 1;

 		}

+	      else if (strcmp (p, "hwbreak+") == 0)

+		{

+		  /* GDB wants us to report whether a trap is caused

+		     by a hardware breakpoint.  */

+		  if (target_supports_stopped_by_hw_breakpoint ())

+		    hwbreak_feature = 1;

+		}

 	      else

 		target_process_qsupported (p);

@@ -1817,6 +1825,9 @@

 	  strcat (own_buf, ";qXfer:btrace:read+");

 	}

+      if (target_supports_stopped_by_hw_breakpoint ())

+	strcat (own_buf, ";hwbreak+");

+

       return;

     }

@@ -2933,6 +2944,7 @@

       multi_process = 0;

       /* Be sure we're out of tfind mode.  */

       current_traceframe = -1;

+      hwbreak_feature = 0;

       remote_open (port);

Index: gdb-7.6.1/gdb/gdbserver/server.h

===================================================================

--- gdb-7.6.1.orig/gdb/gdbserver/server.h	2016-03-13 19:45:54.184550187 +0100

+++ gdb-7.6.1/gdb/gdbserver/server.h	2016-03-13 19:45:59.520589333 +0100

@@ -237,6 +237,11 @@

 extern int multi_process;

 extern int non_stop;

+/* True if the "hwbreak+" feature is active.  In that case, GDB wants

+   us to report whether a trap is explained by a hardware breakpoint.

+   Only enabled if the target supports it.  */

+extern int hwbreak_feature;

+

 extern int disable_randomization;

 #if USE_WIN32API

Index: gdb-7.6.1/gdb/gdbserver/target.h

===================================================================

--- gdb-7.6.1.orig/gdb/gdbserver/target.h	2016-03-13 19:45:54.185550195 +0100

+++ gdb-7.6.1/gdb/gdbserver/target.h	2016-03-13 19:45:59.520589333 +0100

@@ -250,6 +250,13 @@

   int (*insert_point) (char type, CORE_ADDR addr, int len);

   int (*remove_point) (char type, CORE_ADDR addr, int len);

+  /* Returns 1 if the target stopped for a hardware breakpoint.  */

+  int (*stopped_by_hw_breakpoint) (void);

+

+  /* Returns true if the target knows whether a trap was caused by a

+     HW breakpoint triggering.  */

+  int (*supports_stopped_by_hw_breakpoint) (void);

+

   /* Returns 1 if target was stopped due to a watchpoint hit, 0 otherwise.  */

   int (*stopped_by_watchpoint) (void);

@@ -549,6 +556,14 @@

 #define target_read_btrace(tinfo, buffer, type)	\

   (*the_target->read_btrace) (tinfo, buffer, type)

+#define target_supports_stopped_by_hw_breakpoint() \

+  (the_target->supports_stopped_by_hw_breakpoint ? \

+   (*the_target->supports_stopped_by_hw_breakpoint) () : 0)

+

+#define target_stopped_by_hw_breakpoint() \

+  (the_target->stopped_by_hw_breakpoint ? \

+   (*the_target->stopped_by_hw_breakpoint) () : 0)

+

 /* Start non-stop mode, returns 0 on success, -1 on failure.   */

 int start_non_stop (int nonstop);