arm: Update _dl_tlsdesc_dynamic to preserve caller-saved registers (BZ 31372)

ARM _dl_tlsdesc_dynamic slow path has two issues:

  * The ip/r12 is defined by AAPCS as a scratch register, and gcc is
    used to save the stack pointer before on some function calls.  So it
    should also be saved/restored as well.  It fixes the tst-gnu2-tls2.

  * None of the possible VFP registers are saved/restored.  ARM has the
    additional complexity to have different VFP bank sizes (depending of
    VFP support by the chip).

The tst-gnu2-tls2 test is extended to check for VFP registers, although
only for hardfp builds.  Different than setcontext, _dl_tlsdesc_dynamic
does not have  HWCAP_ARM_IWMMXT (I don't have a way to properly test
it and it is almost a decade since newer hardware was released).

With this patch there is no need to mark tst-gnu2-tls2 as XFAIL.

Checked on arm-linux-gnueabihf.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

(cherry picked from commit 64c7e344289ed085517c2227d8e3b06388242c13)

1 files changed, 2 insertions, 1 deletions

diff --git a/elf/tst-gnu2-tls2mod1.c b/elf/tst-gnu2-tls2mod1.c
index e10b9dbc0a..e210538468 100644
--- a/elf/tst-gnu2-tls2mod1.c
+++ b/elf/tst-gnu2-tls2mod1.c
@@ -16,13 +16,14 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include "tst-gnu2-tls2.h"
+#include <tst-gnu2-tls2.h>
 
 __thread struct tls tls_var1[100] __attribute__ ((visibility ("hidden")));
 
 struct tls *
 apply_tls (struct tls *p)
 {
+  INIT_TLSDESC_CALL ();
   BEFORE_TLSDESC_CALL ();
   tls_var1[1] = *p;
   struct tls *ret = &tls_var1[1];