Skip test 'watch -location nullptr->p->x' if null pointer can be dereferenced

gdb.base/watchpoint.exp has a test below which expects to see "Cannot
access memory at address 0x0" when a null pointer is dereferenced.

    gdb_test "watch -location nullptr->p->x" \
	"Cannot access memory at address 0x0"

This assumption is not true when the target is no-mmu, so we get

watch -location nullptr->p->x
Hardware watchpoint 28: -location nullptr->p->x
(gdb) FAIL: gdb.base/watchpoint.exp: watch -location nullptr->p->x

This patch is to check whether null pointer can be dereferenced first
and then do the test.

gdb/testsuite:

2014-06-01  Yao Qi  <yao@codesourcery.com>

	* gdb.base/watchpoint.exp (test_watch_location): Check null
	pointer can be dereferenced.  If not, do the test, otherwise
	skip it.
[Patch, microblaze]: Add wdc.ext.clear and wdc.ext.flush insns

Added two new instructions, wdc.ext.clear and wdc.ext.flush,
to enable MicroBlaze to flush an external cache, which is
used with the new coherency support for multiprocessing.

Signed-off-by:nagaraju <nmekala@xilix.com>
Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[Patch, microblaze]: Add mlittle-endian and mbig-endian flags

Added support in gas for mlittle-endian and mbig-endian flags
as options.

Updated show usage for MicroBlaze specific assembler options
to include new entries.

Signed-off-by:nagaraju <nmekala@xilix.com>
Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[Patch, microblaze]: Initial port of microblaze core reading support

Added support for reading notes in linux core dumps
Support for reading of PRSTATUS and PSINFO information for rebuilding
".reg" sections of core dumps at run time.

Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
[Patch, microblaze]: Communicate in larger blocks with the target

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
[Patch, microblaze]: Add mb singlestepping.

Fix prologue analysis for little-endian.
Always provide a frame base.

Signed-off-by: Edgar E. Iglesias <edgar@axis.com>
[Patch, microblaze]: Add initial port of linux gdbserver

add gdb_proc_service_h to gdbserver microblaze-linux

gdbserver needs to initialise the microblaze registers

other archs use this step to run a *_arch_setup() to carry out all
architecture specific setup - may need to add in future

 * add linux-ptrace.o to gdbserver configure
 * gdb/configure.tgt: Set build_gdbserver=yes
 * Update breakpoint opcode
 * fix segfault on connecting gdbserver
 * add microblaze_linux_memory_remove_breakpoint
 * add set_solib_svr4_fetch_link_map_offsets
 * add set_gdbarch_fetch_tls_load_module_address
 * Force reading of r0 as 0, prevent stores

Signed-off-by: David Holsgrove <david.holsgrove@petalogix.com>
Signed-off-by: Nathan Rossi <nathan.rossi@petalogix.com>
[Patch, microblaze]: Add slr and shr regs and little-endian breakpoint

Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[Patch, microblaze]: Added Backtrace support to GDB

Added backtrace support without debugging information.

Earlier backtrace used to work only when debug information is available.
Previous pc & sp values are calculated incorrectly due to which backtrace
was failing.

In this patch, previous frame sp & pc values are calculated correctly
in microblaze_frame_cache function and supplied them to
microblaze_frame_prev_register function

Signed-off-by:nagaraju <nmekala@xilix.com>
[Patch, microblaze]: Initial support for native gdb

microblaze: Follow PPC method of getting setting registers
using PTRACE PEEK/POKE

Signed-off-by: David Holsgrove <david.holsgrove@petalogix.com>
[Patch, gdb]: Robustify inline function support

Signed-off-by: Edgar E. Iglesias <edgar@axis.com>
[Patch, gdb]: Fix debug message when register is unavailable

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[LOCAL]: Disable the warning message for eh_frame_hdr

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
[LOCAL]: Fix relaxation of assembler resolved references
[LOCAL]: Fixup debug_loc sections after linker relaxation

Adds a new reloctype R_MICROBLAZE_32_NONE, used for passing
reloc info from the assembler to the linker when the linker
manages to fully resolve a local symbol reference.

This is a workaround for design flaws in the assembler to
linker interface with regards to linker relaxation.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[LOCAL]: upstream change to garbage collection sweep causes mb regression

Upstream change for PR13177 now clears the def_regular during gc_sweep of a
section. (All other archs in binutils/bfd/elf32-*.c received an update
to a warning about unresolvable relocations - this warning is not present
in binutils/bfd/elf32-microblaze.c, but this warning check would not
prevent the error being seen)

The visible issue with this change is when running a c++ application
in Petalinux which links libstdc++.so for exception handling it segfaults
on execution.

This does not occur if static linking libstdc++.a, so its during the
relocations for a shared lib with garbage collection this occurs

Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>
[LOCAL]: Add Support for cfi asm insn

Signed-off-by: David Holsgrove <david.holsgrove@xilinx.com>