Support catch syscall on aarch64 linux

Hi,
This patch is to support catch syscall on aarch64 linux.  We
implement gdbarch method get_syscall_number for aarch64-linux,
and add aarch64-linux.xml file, which looks straightforward, however
the changes to test case doesn't.

First of all, we enable catch-syscall.exp on aarch64-linux target,
but skip the multi_arch testing on current stage.  I plan to touch
multi arch debugging on aarch64-linux later.

Then, when I run catch-syscall.exp on aarch64-linux, gcc errors that
SYS_pipe isn't defined.  We find that aarch64 kernel only has pipe2
syscall and libc already convert pipe to pipe2.  As a result, I change
catch-syscall.c to use SYS_pipe if it is defined, otherwise use
SYS_pipe2 instead.  The vector all_syscalls in catch-syscall.exp can't
be pre-determined, so I add a new proc setup_all_syscalls to fill it,
according to the availability of SYS_pipe.

Regression tested on {x86_64, aarch64}-linux x {native, gdbserver}.

gdb:

2015-03-18  Yao Qi  <yao.qi@linaro.org>

	PR tdep/18107
	* aarch64-linux-tdep.c: Include xml-syscall.h
	(aarch64_linux_get_syscall_number): New function.
	(aarch64_linux_init_abi): Call
	set_gdbarch_get_syscall_number.
	* syscalls/aarch64-linux.xml: New file.

gdb/testsuite:

2015-03-18  Yao Qi  <yao.qi@linaro.org>

	PR tdep/18107
	* gdb.base/catch-syscall.c [!SYS_pipe] (pipe2_syscall): New
	variable.
	* gdb.base/catch-syscall.exp: Don't skip it on
	aarch64*-*-linux* target.  Remove elements in all_syscalls.
	(test_catch_syscall_multi_arch): Skip it on aarch64*-linux*
	target.
	(setup_all_syscalls): New proc.

1 files changed, 27 insertions, 0 deletions

diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index 1e1ca36..0ee5ecb 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -39,6 +39,7 @@
 #include "stap-probe.h"
 #include "parser-defs.h"
 #include "user-regs.h"
+#include "xml-syscall.h"
 #include <ctype.h>
 
 /* Signal frame handling.
@@ -341,6 +342,28 @@ aarch64_stap_parse_special_token (struct gdbarch *gdbarch,
   return 1;
 }
 
+/* Implement the "get_syscall_number" gdbarch method.  */
+
+static LONGEST
+aarch64_linux_get_syscall_number (struct gdbarch *gdbarch,
+				  ptid_t ptid)
+{
+  struct regcache *regs = get_thread_regcache (ptid);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+
+  /* The content of register x8.  */
+  gdb_byte buf[X_REGISTER_SIZE];
+  /* The result.  */
+  LONGEST ret;
+
+  /* Getting the system call number from the register x8.  */
+  regcache_cooked_read (regs, AARCH64_DWARF_X0 + 8, buf);
+
+  ret = extract_signed_integer (buf, X_REGISTER_SIZE, byte_order);
+
+  return ret;
+}
+
 static void
 aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -385,6 +408,10 @@ aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_stap_is_single_operand (gdbarch, aarch64_stap_is_single_operand);
   set_gdbarch_stap_parse_special_token (gdbarch,
 					aarch64_stap_parse_special_token);
+
+  /* `catch syscall' */
+  set_xml_syscall_file_name (gdbarch, "syscalls/aarch64-linux.xml");
+  set_gdbarch_get_syscall_number (gdbarch, aarch64_linux_get_syscall_number);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */