aarch64 multi-arch (part 3): get thread area

With the kernle fix <http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/356511.html>,
aarch64 GDB is able to read the base of thread area of 32-bit arm
program through NT_ARM_TLS.

This patch is to teach both GDB and GDBserver to read the base of
thread area correctly in the multi-arch case.  A new function
aarch64_ps_get_thread_area is added, and is shared between GDB and
GDBserver.

With this patch applied, the following fails in multi-arch testing
(GDB is aarch64 but the test cases are arm) are fixed,

 -FAIL: gdb.threads/tls-nodebug.exp: thread local storage
 -FAIL: gdb.threads/tls-shared.exp: print thread local storage variable
 -FAIL: gdb.threads/tls-so_extern.exp: print thread local storage variable
 -FAIL: gdb.threads/tls-var.exp: print tls_var
 -FAIL: gdb.threads/tls.exp: first thread local storage
 -FAIL: gdb.threads/tls.exp: first another thread local storage
 -FAIL: gdb.threads/tls.exp: p a_thread_local
 -FAIL: gdb.threads/tls.exp: p file2_thread_local
 -FAIL: gdb.threads/tls.exp: p a_thread_local second time

gdb:

2015-09-18  Yao Qi  <yao.qi@linaro.org>

	* nat/aarch64-linux.c: Include elf/common.h,
	nat/gdb_ptrace.h, asm/ptrace.h and sys/uio.h.
	(aarch64_ps_get_thread_area): New function.
	* nat/aarch64-linux.h: Include gdb_proc_service.h.
	(aarch64_ps_get_thread_area): Declare.
	* aarch64-linux-nat.c (ps_get_thread_area): Call
	aarch64_ps_get_thread_area.

gdb/gdbserver:

2015-09-18  Yao Qi  <yao.qi@linaro.org>

	* linux-aarch64-low.c: Don't include sys/uio.h.
	(ps_get_thread_area): Call aarch64_ps_get_thread_area.

1 files changed, 3 insertions, 14 deletions

diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index d7ac19eb5a..c9f439f75e 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -460,21 +460,10 @@ ps_err_e
 ps_get_thread_area (const struct ps_prochandle *ph,
 		    lwpid_t lwpid, int idx, void **base)
 {
-  struct iovec iovec;
-  uint64_t reg;
-
-  iovec.iov_base = ®
-  iovec.iov_len = sizeof (reg);
-
-  if (ptrace (PTRACE_GETREGSET, lwpid, NT_ARM_TLS, &iovec) != 0)
-    return PS_ERR;
-
-  /* IDX is the bias from the thread pointer to the beginning of the
-     thread descriptor.  It has to be subtracted due to implementation
-     quirks in libthread_db.  */
-  *base = (void *) (reg - idx);
+  int is_64bit_p
+    = (gdbarch_bfd_arch_info (target_gdbarch ())->bits_per_word == 64);
 
-  return PS_OK;
+  return aarch64_ps_get_thread_area (ph, lwpid, idx, base, is_64bit_p);
 }