i386: Update ___tls_get_addr to preserve vector registers

Compiler generates the following instruction sequence for dynamic TLS
access:

	leal	tls_var@tlsgd(,%ebx,1), %eax
	call	___tls_get_addr@PLT

CALL instruction is transparent to compiler which assumes all registers,
except for EFLAGS, AX, CX, and DX, are unchanged after CALL.  But
___tls_get_addr is a normal function which doesn't preserve any vector
registers.

1. Rename the generic __tls_get_addr function to ___tls_get_addr_internal.
2. Change ___tls_get_addr to a wrapper function with implementations for
FNSAVE, FXSAVE, XSAVE and XSAVEC to save and restore all vector registers.
3. dl-tlsdesc-dynamic.h has:

_dl_tlsdesc_dynamic:
	/* Like all TLS resolvers, preserve call-clobbered registers.
	   We need two scratch regs anyway.  */
	subl	$32, %esp
	cfi_adjust_cfa_offset (32)

It is wrong to use

	movl	%ebx, -28(%esp)
	movl	%esp, %ebx
	cfi_def_cfa_register(%ebx)
	...
	mov	%ebx, %esp
	cfi_def_cfa_register(%esp)
	movl	-28(%esp), %ebx

to preserve EBX on stack.  Fix it with:

	movl	%ebx, 28(%esp)
	movl	%esp, %ebx
	cfi_def_cfa_register(%ebx)
	...
	mov	%ebx, %esp
	cfi_def_cfa_register(%esp)
	movl	28(%esp), %ebx

4. Update _dl_tlsdesc_dynamic to call ___tls_get_addr_internal directly.
5. Add have-test-mtls-traditional to compile tst-tls23-mod.c with
traditional TLS variant to verify the fix.
6. Define DL_RUNTIME_RESOLVE_REALIGN_STACK in sysdeps/x86/sysdep.h.

This fixes BZ #32996.

Co-Authored-By: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

4 files changed, 95 insertions, 1 deletions

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index 01b0192ddf..f64cee3cd9 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -4,7 +4,13 @@ endif
 
 ifeq ($(subdir),elf)
 sysdep_routines += get-cpuid-feature-leaf
-sysdep-dl-routines += dl-get-cpu-features
+sysdep-dl-routines += \
+  dl-get-cpu-features \
+  dl-tlsdesc \
+  tls_get_addr \
+  tlsdesc \
+# sysdep-dl-routines
+
 sysdep_headers += \
   bits/platform/features.h \
   bits/platform/x86.h \
@@ -113,6 +119,14 @@ $(objpfx)tst-gnu2-tls2-x86-noxsavexsavec.out: \
   $(objpfx)tst-gnu2-tls2mod0.so \
   $(objpfx)tst-gnu2-tls2mod1.so \
   $(objpfx)tst-gnu2-tls2mod2.so
+
+CFLAGS-tst-tls23.c += -msse2
+CFLAGS-tst-tls23-mod.c += -msse2 -mtune=haswell
+
+LDFLAGS-tst-tls23 += -rdynamic
+tst-tls23-mod.so-no-z-defs = yes
+
+$(objpfx)tst-tls23-mod.so: $(libsupport)
 endif
 
 ifeq ($(subdir),math)
diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
index c3c73e75dd..b8e963b654 100644
--- a/sysdeps/x86/sysdep.h
+++ b/sysdeps/x86/sysdep.h
@@ -183,6 +183,29 @@
 
 #define atom_text_section .section ".text.atom", "ax"
 
+#ifndef DL_STACK_ALIGNMENT
+/* Due to GCC bug:
+
+   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
+
+   __tls_get_addr may be called with 8-byte/4-byte stack alignment.
+   Although this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't
+   assume that stack will be always aligned at 16 bytes.  */
+# ifdef __x86_64__
+#  define DL_STACK_ALIGNMENT 8
+#  define MINIMUM_ALIGNMENT 16
+# else
+#  define DL_STACK_ALIGNMENT 4
+# endif
+#endif
+
+/* True if _dl_runtime_resolve/_dl_tlsdesc_dynamic should align stack for
+   STATE_SAVE or align stack to MINIMUM_ALIGNMENT bytes before calling
+   _dl_fixup/__tls_get_addr.  */
+#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
+  (STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
+   || MINIMUM_ALIGNMENT > DL_STACK_ALIGNMENT)
+
 #endif	/* __ASSEMBLER__ */
 
 #endif	/* _X86_SYSDEP_H */
diff --git a/sysdeps/x86/tst-tls23.c b/sysdeps/x86/tst-tls23.c
new file mode 100644
index 0000000000..6130d91cf8
--- /dev/null
+++ b/sysdeps/x86/tst-tls23.c
@@ -0,0 +1,22 @@
+#ifndef __x86_64__
+#include <sys/platform/x86.h>
+
+#define IS_SUPPORTED() CPU_FEATURE_ACTIVE (SSE2)
+#endif
+
+/* Set XMM0...XMM7 to all 1s.  */
+#define PREPARE_MALLOC()					\
+{								\
+  asm volatile ("pcmpeqd %%xmm0, %%xmm0" : : : "xmm0" );	\
+  asm volatile ("pcmpeqd %%xmm1, %%xmm1" : : : "xmm1" );	\
+  asm volatile ("pcmpeqd %%xmm2, %%xmm2" : : : "xmm2" );	\
+  asm volatile ("pcmpeqd %%xmm3, %%xmm3" : : : "xmm3" );	\
+  asm volatile ("pcmpeqd %%xmm4, %%xmm4" : : : "xmm4" );	\
+  asm volatile ("pcmpeqd %%xmm5, %%xmm5" : : : "xmm5" );	\
+  asm volatile ("pcmpeqd %%xmm6, %%xmm6" : : : "xmm6" );	\
+  asm volatile ("pcmpeqd %%xmm7, %%xmm7" : : : "xmm7" );	\
+}
+
+#include <elf/tst-tls23.c>
+
+v2di v1, v2, v3;
diff --git a/sysdeps/x86/tst-tls23.h b/sysdeps/x86/tst-tls23.h
new file mode 100644
index 0000000000..21cee4ca07
--- /dev/null
+++ b/sysdeps/x86/tst-tls23.h
@@ -0,0 +1,35 @@
+/* Test that __tls_get_addr preserves XMM registers.
+   Copyright (C) 2025 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 <support/check.h>
+
+typedef long long v2di __attribute__((vector_size(16)));
+extern v2di v1, v2, v3;
+
+#define BEFORE_TLS_CALL()					\
+  v1 = __extension__(v2di){0, 0};				\
+  v2 = __extension__(v2di){0, 0};
+
+#define AFTER_TLS_CALL()					\
+  v3 = __extension__(v2di){0, 0};				\
+  asm volatile ("" : "+x" (v3));				\
+  union { v2di x; long long a[2]; } u;				\
+  u.x = v3;							\
+  TEST_VERIFY_EXIT (u.a[0] == 0 && u.a[1] == 0);
+
+#include <elf/tst-tls23.h>