Detect broken ptrace in gdb_skip_float_test

We recently found a ARM kernel ptrace bug
http://lists.infradead.org/pipermail/linux-arm-kernel/2016-May/431962.html
Details can be found in the comment in gdb_skip_float_test.  We can
skip floating point tests if the kernel bug is detected.

This patch adds more code in gdb_skip_float_test to detect the broken
ptrace on arm-linux.  Such detection should be done at the beginning
of the test, because it starts a fresh GDB, so change the test cases
to invoke gdb_skip_float_test at the beginning of test, and use its
return value afterwards.

Since gdb_skip_float_test becomes a gdb_caching_proc, so it can't
have an argument, this patch also removes argument "msg", which isn't
useful.

gdb/testsuite:

2016-09-02  Yao Qi  <yao.qi@linaro.org>

	* gdb.arch/arm-neon.exp: Skip it if gdb_skip_float_test returns
	true.
	* gdb.base/call-ar-st.exp: Invoke gdb_skip_float_test.
	* gdb.base/call-rt-st.exp: Likewise.
	* gdb.base/call-sc.exp: Invoke gdb_skip_float_test and use its
	return value instead of gdb,skip_float_test.
	* gdb.base/callfuncs.exp: Invoke gdb_skip_float_test.
	(do_function_calls): Use its return value instead of
	gdb,skip_float_test.
	* gdb.base/finish.exp: Likewise.
	* gdb.base/funcargs.exp: Likewise.
	* gdb.base/return.exp: Likewise.
	* gdb.base/return2.exp: Likewise.
	* gdb.base/varargs.exp: Likewise.
	* lib/gdb.exp (gdb_skip_float_test): Change it to
	gdb_caching_proc.  Detect the broken ptrace on arm-linux.

1 files changed, 3 insertions, 2 deletions

diff --git a/gdb/testsuite/gdb.base/finish.exp b/gdb/testsuite/gdb.base/finish.exp
index 47bf6f881d..c5387bb2d0 100644
--- a/gdb/testsuite/gdb.base/finish.exp
+++ b/gdb/testsuite/gdb.base/finish.exp
@@ -15,6 +15,7 @@
 
 # This file was written by Michael Snyder (msnyder@redhat.com)
 
+set skip_float_test [gdb_skip_float_test]
 
 # re-use the program from the "return2" test.
 if { [prepare_for_testing finish.exp finish return2.c] } {
@@ -86,7 +87,7 @@ proc finish_abbreviation { abbrev } {
 }
 
 proc finish_tests { } {
-    global gdb_prompt
+    global gdb_prompt skip_float_test
 
     if { ! [ runto_main ] } then {
 	untested finish.exp
@@ -99,7 +100,7 @@ proc finish_tests { } {
     finish_1 "int"
     finish_1 "long"
     finish_1 "long_long"
-    if ![target_info exists gdb,skip_float_tests] {
+    if {!$skip_float_test} {
 	finish_1 "float"
 	finish_1 "double"
     }