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Backport of this upstream patch:
commit 031e519c95c069abe4e4c7c59e2b4b67efccdee5
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Thu Jul 6 04:43:06 2017 -0700
x86-64: Align the stack in __tls_get_addr [BZ #21609]
This change forces realignment of the stack pointer in __tls_get_addr, so
that binaries compiled by GCCs older than GCC 4.9:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
continue to work even if vector instructions are used in glibc which
require the ABI stack realignment.
__tls_get_addr_slow is added to handle the slow paths in the default
implementation of__tls_get_addr in elf/dl-tls.c. The new __tls_get_addr
calls __tls_get_addr_slow after realigning the stack. Internal calls
within ld.so go directly to the default implementation of __tls_get_addr
because they do not need stack realignment.
[BZ #21609]
* sysdeps/x86_64/Makefile (sysdep-dl-routines): Add tls_get_addr.
(gen-as-const-headers): Add rtld-offsets.sym.
* sysdeps/x86_64/dl-tls.c: New file.
* sysdeps/x86_64/rtld-offsets.sym: Likwise.
* sysdeps/x86_64/tls_get_addr.S: Likewise.
* sysdeps/x86_64/dl-tls.h: Add multiple inclusion guards.
* sysdeps/x86_64/tlsdesc.sym (TI_MODULE_OFFSET): New.
(TI_OFFSET_OFFSET): Likwise.
Adjusted for drift in sysdeps/x86_64/Makefile and lack of
TLS_DTV_UNALLOCATED consolidation (upstream commit
aca1daef298b43bd7b1987b31f5aabcf6c2f6021).
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
index 6c03a89fb3ea3063..c6766bb2b443a28a 100644
--- a/sysdeps/x86_64/Makefile
+++ b/sysdeps/x86_64/Makefile
@@ -19,7 +19,7 @@ gen-as-const-headers += locale-defines.sym
endif
ifeq ($(subdir),elf)
-sysdep-dl-routines += tlsdesc dl-tlsdesc
+sysdep-dl-routines += tlsdesc dl-tlsdesc tls_get_addr
tests += ifuncmain8
modules-names += ifuncmod8
@@ -69,5 +69,5 @@ endif
endif
ifeq ($(subdir),csu)
-gen-as-const-headers += tlsdesc.sym
+gen-as-const-headers += tlsdesc.sym rtld-offsets.sym
endif
diff --git a/sysdeps/x86_64/dl-tls.c b/sysdeps/x86_64/dl-tls.c
new file mode 100644
index 0000000000000000..3584805c8ecca59a
--- /dev/null
+++ b/sysdeps/x86_64/dl-tls.c
@@ -0,0 +1,53 @@
+/* Thread-local storage handling in the ELF dynamic linker. x86-64 version.
+ Copyright (C) 2017 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
+ <http://www.gnu.org/licenses/>. */
+
+#ifdef SHARED
+/* Work around GCC PR58066, due to which __tls_get_addr may be called
+ with an unaligned stack. The compat implementation is in
+ tls_get_addr-compat.S. */
+
+# include <dl-tls.h>
+
+/* Define __tls_get_addr within elf/dl-tls.c under a different
+ name. */
+extern __typeof__ (__tls_get_addr) ___tls_get_addr;
+
+# define __tls_get_addr ___tls_get_addr
+# include <elf/dl-tls.c>
+# undef __tls_get_addr
+
+hidden_ver (___tls_get_addr, __tls_get_addr)
+
+/* Only handle slow paths for __tls_get_addr. */
+attribute_hidden
+void *
+__tls_get_addr_slow (GET_ADDR_ARGS)
+{
+ dtv_t *dtv = THREAD_DTV ();
+
+ if (__glibc_unlikely (dtv[0].counter != GL(dl_tls_generation)))
+ return update_get_addr (GET_ADDR_PARAM);
+
+ return tls_get_addr_tail (GET_ADDR_PARAM, dtv, NULL);
+}
+#else
+
+/* No compatibility symbol needed. */
+# include <elf/dl-tls.c>
+
+#endif
diff --git a/sysdeps/x86_64/dl-tls.h b/sysdeps/x86_64/dl-tls.h
index 56162ee64a4aae7d..0b4a6b3b634a83f4 100644
--- a/sysdeps/x86_64/dl-tls.h
+++ b/sysdeps/x86_64/dl-tls.h
@@ -16,6 +16,10 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#ifndef _X86_64_DL_TLS_H
+#define _X86_64_DL_TLS_H
+
+#include <stdint.h>
/* Type used for the representation of TLS information in the GOT. */
typedef struct dl_tls_index
@@ -29,3 +33,5 @@ extern void *__tls_get_addr (tls_index *ti);
/* Value used for dtv entries for which the allocation is delayed. */
#define TLS_DTV_UNALLOCATED ((void *) -1l)
+
+#endif /* _X86_64_DL_TLS_H */
diff --git a/sysdeps/x86_64/rtld-offsets.sym b/sysdeps/x86_64/rtld-offsets.sym
new file mode 100644
index 0000000000000000..fd41b51521ac80bd
--- /dev/null
+++ b/sysdeps/x86_64/rtld-offsets.sym
@@ -0,0 +1,6 @@
+#define SHARED
+#include <ldsodefs.h>
+
+--
+
+GL_TLS_GENERATION_OFFSET offsetof (struct rtld_global, _dl_tls_generation)
diff --git a/sysdeps/x86_64/tls_get_addr.S b/sysdeps/x86_64/tls_get_addr.S
new file mode 100644
index 0000000000000000..9d38fb3be54fbcb5
--- /dev/null
+++ b/sysdeps/x86_64/tls_get_addr.S
@@ -0,0 +1,61 @@
+/* Stack-aligning implementation of __tls_get_addr. x86-64 version.
+ Copyright (C) 2017 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
+ <http://www.gnu.org/licenses/>. */
+
+#ifdef SHARED
+
+# include <sysdep.h>
+# include "tlsdesc.h"
+# include "rtld-offsets.h"
+
+/* See __tls_get_addr and __tls_get_addr_slow in dl-tls.c. This function
+ call __tls_get_addr_slow on both slow paths. It realigns the stack
+ before the call to work around GCC PR58066. */
+
+ENTRY (__tls_get_addr)
+ mov %fs:DTV_OFFSET, %RDX_LP
+ mov GL_TLS_GENERATION_OFFSET+_rtld_local(%rip), %RAX_LP
+ /* GL(dl_tls_generation) == dtv[0].counter */
+ cmp %RAX_LP, (%rdx)
+ jne 1f
+ mov TI_MODULE_OFFSET(%rdi), %RAX_LP
+ /* dtv[ti->ti_module] */
+# ifdef __LP64__
+ salq $4, %rax
+ movq (%rdx,%rax), %rax
+# else
+ movl (%rdx,%rax, 8), %eax
+# endif
+ cmp $-1, %RAX_LP
+ je 1f
+ add TI_OFFSET_OFFSET(%rdi), %RAX_LP
+ ret
+1:
+ /* On the slow path, align the stack. */
+ pushq %rbp
+ cfi_def_cfa_offset (16)
+ cfi_offset (%rbp, -16)
+ mov %RSP_LP, %RBP_LP
+ cfi_def_cfa_register (%rbp)
+ and $-16, %RSP_LP
+ call __tls_get_addr_slow
+ mov %RBP_LP, %RSP_LP
+ popq %rbp
+ cfi_def_cfa (%rsp, 8)
+ ret
+END (__tls_get_addr)
+#endif /* SHARED */
diff --git a/sysdeps/x86_64/tlsdesc.sym b/sysdeps/x86_64/tlsdesc.sym
index 33854975d04184b2..fc897ab4b522b1a9 100644
--- a/sysdeps/x86_64/tlsdesc.sym
+++ b/sysdeps/x86_64/tlsdesc.sym
@@ -15,3 +15,6 @@ TLSDESC_ARG offsetof(struct tlsdesc, arg)
TLSDESC_GEN_COUNT offsetof(struct tlsdesc_dynamic_arg, gen_count)
TLSDESC_MODID offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_module)
TLSDESC_MODOFF offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_offset)
+
+TI_MODULE_OFFSET offsetof(tls_index, ti_module)
+TI_OFFSET_OFFSET offsetof(tls_index, ti_offset)