Detect SW breakpoints in Cell/B.E. combined debugging

The Linux target and gdbserver now check the siginfo si_code
reported on a SIGTRAP to detect whether the trap indicates
a software breakpoint was hit.

Unfortunately, on Cell/B.E., the kernel uses an si_code value
of TRAP_BRKPT when a SW breakpoint was hit in PowerPC code,
but a si_code value of SI_KERNEL when a SW breakpoint was
hit in SPU code.

This patch updates Linux target and gdbserver to accept both
si_code values to indicate SW breakpoint on PowerPC.

ChangeLog:

	* nat/linux-ptrace.h (GDB_ARCH_TRAP_BRKPT): Replace by ...
	(GDB_ARCH_IS_TRAP_BRKPT): ... this.  Add __powerpc__ case.
	* linux-nat.c (check_stopped_by_breakpoint): Use
	GDB_ARCH_IS_TRAP_BRKPT instead of GDB_ARCH_TRAP_BRKPT.

gdbserver/ChangeLog:

	* linux-low.c (check_stopped_by_breakpoint): Use
	GDB_ARCH_IS_TRAP_BRKPT instead of GDB_ARCH_TRAP_BRKPT.

5 files changed, 25 insertions, 6 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8319083..61e9851 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2015-08-08  Ulrich Weigand  <uweigand@de.ibm.com>
 
+	* nat/linux-ptrace.h (GDB_ARCH_TRAP_BRKPT): Replace by ...
+	(GDB_ARCH_IS_TRAP_BRKPT): ... this.  Add __powerpc__ case.
+	* linux-nat.c (check_stopped_by_breakpoint): Use
+	GDB_ARCH_IS_TRAP_BRKPT instead of GDB_ARCH_TRAP_BRKPT.
+
+2015-08-08  Ulrich Weigand  <uweigand@de.ibm.com>
+
 	* linux-thread-db.c (thread_db_get_thread_local_address): If the
 	thread was not yet discovered, use thread_from_lwp instead of
 	calling thread_db_find_new_threads_1.
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 0be3030..cc733d8 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2015-08-27  Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
+
+	* linux-low.c (check_stopped_by_breakpoint): Use
+	GDB_ARCH_IS_TRAP_BRKPT instead of GDB_ARCH_TRAP_BRKPT.
+
 2015-08-27  Pedro Alves  <palves@redhat.com>
 
 	* proc-service.c (ps_pdwrite): Return PS_ERR/PS_OK explicily.
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index a8fa91c..f4c6029 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -651,7 +651,7 @@ check_stopped_by_breakpoint (struct lwp_info *lwp)
     {
       if (siginfo.si_signo == SIGTRAP)
 	{
-	  if (siginfo.si_code == GDB_ARCH_TRAP_BRKPT)
+	  if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
 	    {
 	      if (debug_threads)
 		{
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 4da361d..51541d5 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -2801,7 +2801,7 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
     {
       if (siginfo.si_signo == SIGTRAP)
 	{
-	  if (siginfo.si_code == GDB_ARCH_TRAP_BRKPT)
+	  if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
 	    {
 	      if (debug_linux_nat)
 		fprintf_unfiltered (gdb_stdlog,
diff --git a/gdb/nat/linux-ptrace.h b/gdb/nat/linux-ptrace.h
index 41f668c..8bff908 100644
--- a/gdb/nat/linux-ptrace.h
+++ b/gdb/nat/linux-ptrace.h
@@ -135,12 +135,19 @@ struct buffer;
    running to a breakpoint and checking what comes out of
    siginfo->si_code.
 
-   The generic Linux target code should use GDB_ARCH_TRAP_BRKPT
-   instead of TRAP_BRKPT to abstract out this x86 peculiarity.  */
+   The ppc kernel does use TRAP_BRKPT for software breakpoints
+   in PowerPC code, but it uses SI_KERNEL for software breakpoints
+   in SPU code on a Cell/B.E.  However, SI_KERNEL is never seen
+   on a SIGTRAP for any other reason.
+
+   The generic Linux target code should use GDB_ARCH_IS_TRAP_BRKPT
+   instead of TRAP_BRKPT to abstract out these peculiarities.  */
 #if defined __i386__ || defined __x86_64__
-# define GDB_ARCH_TRAP_BRKPT SI_KERNEL
+# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
+#elif defined __powerpc__
+# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
 #else
-# define GDB_ARCH_TRAP_BRKPT TRAP_BRKPT
+# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
 #endif
 
 #ifndef TRAP_HWBKPT