gdbserver-amd64: add HAVE_STRUCT_USER_REGS_STRUCT_(GS|FS)_BASE for gdbserver.

The macros mentioned in the title were set only for GDB. In gdbserver they
were not set until now.  To align the code in GDB and gdbserver these macros
are also added into gdbserver, enabling read and write of gs_base and fs_base
registers from the system in new and old kernels.

2017-01-27  Walfred Tedeschi  <walfred.tedeschi@intel.com>

gdb/gdbserver/ChangeLog:

    	* configure.ac: Check if the fs_base and gs_base members of
    	`struct user_regs_struct' exist.
    	* config.in: Regenerated.
    	* configure: Likewise.

4 files changed, 46 insertions, 0 deletions

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index d3fba9b..79fe2f9 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,10 @@
+2017-01-27  Walfred Tedeschi  <walfred.tedeschi@intel.com>
+
+	* configure.ac: Check if the fs_base and gs_base members of
+	`struct user_regs_struct' exist.
+	* config.in: Regenerated.
+	* configure: Likewise.
+
 2017-01-09  Antoine Tremblay  <antoine.tremblay@ericsson.com>
 
 	* linux-aarch32-low.c (arm_breakpoint_kind_from_pc): Use
diff --git a/gdb/gdbserver/config.in b/gdb/gdbserver/config.in
index b721ea8..34a7443 100644
--- a/gdb/gdbserver/config.in
+++ b/gdb/gdbserver/config.in
@@ -238,6 +238,12 @@
 /* Define to 1 if `struct stat' is a member of `st_blocks'. */
 #undef HAVE_STRUCT_STAT_ST_BLOCKS
 
+/* Define to 1 if `struct user_regs_struct' is a member of `fs_base'. */
+#undef HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE
+
+/* Define to 1 if `struct user_regs_struct' is a member of `gs_base'. */
+#undef HAVE_STRUCT_USER_REGS_STRUCT_GS_BASE
+
 /* Define to 1 if the target supports __sync_*_compare_and_swap */
 #undef HAVE_SYNC_BUILTINS
 
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index 53c26f3..6ae4865 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -7498,6 +7498,32 @@ _ACEOF
 fi
 
 
+# See if <sys/user.h> supports the %fs_base and %gs_base amd64 segment
+# registers.  Older amd64 Linux's don't have the fs_base and gs_base
+# members of `struct user_regs_struct'.
+ac_fn_c_check_member "$LINENO" "struct user_regs_struct" "fs_base" "ac_cv_member_struct_user_regs_struct_fs_base" "#include <sys/user.h>
+"
+if test "x$ac_cv_member_struct_user_regs_struct_fs_base" = x""yes; then :
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE 1
+_ACEOF
+
+
+fi
+ac_fn_c_check_member "$LINENO" "struct user_regs_struct" "gs_base" "ac_cv_member_struct_user_regs_struct_gs_base" "#include <sys/user.h>
+"
+if test "x$ac_cv_member_struct_user_regs_struct_gs_base" = x""yes; then :
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_STRUCT_USER_REGS_STRUCT_GS_BASE 1
+_ACEOF
+
+
+fi
+
+
+
 ac_fn_c_check_type "$LINENO" "socklen_t" "ac_cv_type_socklen_t" "#include <sys/types.h>
 #include <sys/socket.h>
 
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index d013c21..4ea7913 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -163,6 +163,13 @@ AC_CHECK_DECLS([strerror, perror, vasprintf, vsnprintf])
 
 AC_CHECK_MEMBERS([struct stat.st_blocks, struct stat.st_blksize])
 
+# See if <sys/user.h> supports the %fs_base and %gs_bas amd64 segment registers.
+# Older amd64 Linux's don't have the fs_base and gs_base members of
+# `struct user_regs_struct'.
+AC_CHECK_MEMBERS([struct user_regs_struct.fs_base, struct user_regs_struct.gs_base],
+		 [], [], [#include <sys/user.h>])
+
+
 AC_CHECK_TYPES(socklen_t, [], [],
 [#include <sys/types.h>
 #include <sys/socket.h>