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>

1 files changed, 128 insertions, 0 deletions

diff --git a/sysdeps/arm/tst-gnu2-tls2.h b/sysdeps/arm/tst-gnu2-tls2.h
new file mode 100644
index 0000000000..e413ac21fb
--- /dev/null
+++ b/sysdeps/arm/tst-gnu2-tls2.h
@@ -0,0 +1,128 @@
+/* Test TLSDESC relocation.  ARM version.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include <sys/auxv.h>
+#include <string.h>
+#include <stdlib.h>
+#include <endian.h>
+
+#ifndef __SOFTFP__
+
+# ifdef HAVE_ARM_PCS_VFP_D32
+#  define SAVE_VFP_D32					\
+      asm volatile ("vldr d16,=17" : : : "d16");	\
+      asm volatile ("vldr d17,=18" : : : "d17");	\
+      asm volatile ("vldr d18,=19" : : : "d18");	\
+      asm volatile ("vldr d19,=20" : : : "d19");	\
+      asm volatile ("vldr d20,=21" : : : "d20");	\
+      asm volatile ("vldr d21,=22" : : : "d21");	\
+      asm volatile ("vldr d22,=23" : : : "d22");	\
+      asm volatile ("vldr d23,=24" : : : "d23");	\
+      asm volatile ("vldr d24,=25" : : : "d24");	\
+      asm volatile ("vldr d25,=26" : : : "d25");	\
+      asm volatile ("vldr d26,=27" : : : "d26");	\
+      asm volatile ("vldr d27,=28" : : : "d27");	\
+      asm volatile ("vldr d28,=29" : : : "d28");	\
+      asm volatile ("vldr d29,=30" : : : "d29");	\
+      asm volatile ("vldr d30,=31" : : : "d30");	\
+      asm volatile ("vldr d31,=32" : : : "d31");
+# else
+#  define SAVE_VFP_D32
+# endif
+
+# define INIT_TLSDESC_CALL()				\
+  unsigned long hwcap = getauxval (AT_HWCAP)
+
+/* Set each vector register to a value from 1 to 32 before the TLS access,
+   dump to memory after TLS access, and compare with the expected values.  */
+
+# define BEFORE_TLSDESC_CALL()				\
+  if (hwcap & HWCAP_ARM_VFP)				\
+    {							\
+      asm volatile ("vldr  d0,=1" : : : "d0");		\
+      asm volatile ("vldr  d1,=2" : : : "d1");		\
+      asm volatile ("vldr  d2,=3" : : : "d1");		\
+      asm volatile ("vldr  d3,=4" : : : "d3");		\
+      asm volatile ("vldr  d4,=5" : : : "d4");		\
+      asm volatile ("vldr  d5,=6" : : : "d5");		\
+      asm volatile ("vldr  d6,=7" : : : "d6");		\
+      asm volatile ("vldr  d7,=8" : : : "d7");		\
+      asm volatile ("vldr  d8,=9" : : : "d8");		\
+      asm volatile ("vldr  d9,=10" : : : "d9");		\
+      asm volatile ("vldr d10,=11" : : : "d10");	\
+      asm volatile ("vldr d11,=12" : : : "d11");	\
+      asm volatile ("vldr d12,=13" : : : "d12");	\
+      asm volatile ("vldr d13,=14" : : : "d13");	\
+      asm volatile ("vldr d14,=15" : : : "d14");	\
+      asm volatile ("vldr d15,=16" : : : "d15");	\
+    }							\
+  if (hwcap & HWCAP_ARM_VFPD32)				\
+    {							\
+      SAVE_VFP_D32					\
+    }
+
+# define VFP_STACK_REQ (16*8)
+# if __BYTE_ORDER == __BIG_ENDIAN
+#  define DISP 7
+# else
+#  define DISP 0
+# endif
+
+# ifdef HAVE_ARM_PCS_VFP_D32
+#  define CHECK_VFP_D32							\
+      char vfp[VFP_STACK_REQ];						\
+      asm volatile ("vstmia %0, {d16-d31}\n"				\
+		    :							\
+		    : "r" (vfp)						\
+		    : "memory");					\
+									\
+      char expected[VFP_STACK_REQ] = { 0 };				\
+      for (int i = 0; i < 16; ++i)					\
+	expected[i * 8 + DISP] = i + 17;				\
+									\
+      if (memcmp (vfp, expected, VFP_STACK_REQ) != 0)			\
+        abort ();
+# else
+#  define CHECK_VFP_D32
+# endif
+
+# define AFTER_TLSDESC_CALL()						\
+  if (hwcap & HWCAP_ARM_VFP)						\
+    {									\
+      char vfp[VFP_STACK_REQ];						\
+      asm volatile ("vstmia %0, {d0-d15}\n"				\
+		    :							\
+		    : "r" (vfp)						\
+		    : "memory");					\
+									\
+      char expected[VFP_STACK_REQ] = { 0 };				\
+      for (int i = 0; i < 16; ++i)					\
+	expected[i * 8 + DISP] = i + 1;					\
+									\
+      if (memcmp (vfp, expected, VFP_STACK_REQ) != 0)			\
+        abort ();							\
+    }									\
+  if (hwcap & HWCAP_ARM_VFPD32)						\
+    {									\
+      CHECK_VFP_D32							\
+    }
+
+#endif /* __SOFTFP__ */
+
+#include_next <tst-gnu2-tls2.h>