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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.
This commit is contained in:
H.J. Lu
parent
0cae0b1a28
commit
031e519c95
13
ChangeLog
13
ChangeLog
@ -1,3 +1,16 @@
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2017-07-06 Florian Weimer <fweimer@redhat.com>
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H.J. Lu <hongjiu.lu@intel.com>
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[BZ #21609]
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* sysdeps/x86_64/Makefile (sysdep-dl-routines): Add tls_get_addr.
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(gen-as-const-headers): Add rtld-offsets.sym.
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* sysdeps/x86_64/dl-tls.c: New file.
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* sysdeps/x86_64/rtld-offsets.sym: Likwise.
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* sysdeps/x86_64/tls_get_addr.S: Likewise.
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* sysdeps/x86_64/dl-tls.h: Add multiple inclusion guards.
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* sysdeps/x86_64/tlsdesc.sym (TI_MODULE_OFFSET): New.
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(TI_OFFSET_OFFSET): Likwise.
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2017-07-05 Adhemerval Zanella <adhemerval.zanella@linaro.org>
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[BZ# 21697]
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@ -27,7 +27,7 @@ ifeq ($(subdir),elf)
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CFLAGS-.os += $(if $(filter $(@F),$(patsubst %,%.os,$(all-rtld-routines))),\
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-mno-mmx)
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sysdep-dl-routines += tlsdesc dl-tlsdesc
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sysdep-dl-routines += tlsdesc dl-tlsdesc tls_get_addr
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tests += ifuncmain8
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modules-names += ifuncmod8
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@ -120,5 +120,5 @@ endif
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endif
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ifeq ($(subdir),csu)
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gen-as-const-headers += tlsdesc.sym
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gen-as-const-headers += tlsdesc.sym rtld-offsets.sym
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endif
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53
sysdeps/x86_64/dl-tls.c
Normal file
53
sysdeps/x86_64/dl-tls.c
Normal file
@ -0,0 +1,53 @@
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/* Thread-local storage handling in the ELF dynamic linker. x86-64 version.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifdef SHARED
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/* Work around GCC PR58066, due to which __tls_get_addr may be called
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with an unaligned stack. The compat implementation is in
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tls_get_addr-compat.S. */
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# include <dl-tls.h>
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/* Define __tls_get_addr within elf/dl-tls.c under a different
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name. */
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extern __typeof__ (__tls_get_addr) ___tls_get_addr;
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# define __tls_get_addr ___tls_get_addr
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# include <elf/dl-tls.c>
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# undef __tls_get_addr
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hidden_ver (___tls_get_addr, __tls_get_addr)
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/* Only handle slow paths for __tls_get_addr. */
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attribute_hidden
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void *
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__tls_get_addr_slow (GET_ADDR_ARGS)
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{
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dtv_t *dtv = THREAD_DTV ();
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if (__glibc_unlikely (dtv[0].counter != GL(dl_tls_generation)))
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return update_get_addr (GET_ADDR_PARAM);
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return tls_get_addr_tail (GET_ADDR_PARAM, dtv, NULL);
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}
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#else
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/* No compatibility symbol needed. */
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# include <elf/dl-tls.c>
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#endif
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@ -16,6 +16,9 @@
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _X86_64_DL_TLS_H
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#define _X86_64_DL_TLS_H
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#include <stdint.h>
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/* Type used for the representation of TLS information in the GOT. */
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@ -27,3 +30,5 @@ typedef struct dl_tls_index
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extern void *__tls_get_addr (tls_index *ti);
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#endif /* _X86_64_DL_TLS_H */
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6
sysdeps/x86_64/rtld-offsets.sym
Normal file
6
sysdeps/x86_64/rtld-offsets.sym
Normal file
@ -0,0 +1,6 @@
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#define SHARED
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#include <ldsodefs.h>
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--
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GL_TLS_GENERATION_OFFSET offsetof (struct rtld_global, _dl_tls_generation)
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61
sysdeps/x86_64/tls_get_addr.S
Normal file
61
sysdeps/x86_64/tls_get_addr.S
Normal file
@ -0,0 +1,61 @@
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/* Stack-aligning implementation of __tls_get_addr. x86-64 version.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifdef SHARED
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# include <sysdep.h>
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# include "tlsdesc.h"
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# include "rtld-offsets.h"
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/* See __tls_get_addr and __tls_get_addr_slow in dl-tls.c. This function
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call __tls_get_addr_slow on both slow paths. It realigns the stack
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before the call to work around GCC PR58066. */
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ENTRY (__tls_get_addr)
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mov %fs:DTV_OFFSET, %RDX_LP
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mov GL_TLS_GENERATION_OFFSET+_rtld_local(%rip), %RAX_LP
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/* GL(dl_tls_generation) == dtv[0].counter */
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cmp %RAX_LP, (%rdx)
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jne 1f
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mov TI_MODULE_OFFSET(%rdi), %RAX_LP
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/* dtv[ti->ti_module] */
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# ifdef __LP64__
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salq $4, %rax
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movq (%rdx,%rax), %rax
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# else
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movl (%rdx,%rax, 8), %eax
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# endif
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cmp $-1, %RAX_LP
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je 1f
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add TI_OFFSET_OFFSET(%rdi), %RAX_LP
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ret
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1:
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/* On the slow path, align the stack. */
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pushq %rbp
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cfi_def_cfa_offset (16)
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cfi_offset (%rbp, -16)
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mov %RSP_LP, %RBP_LP
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cfi_def_cfa_register (%rbp)
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and $-16, %RSP_LP
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call __tls_get_addr_slow
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mov %RBP_LP, %RSP_LP
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popq %rbp
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cfi_def_cfa (%rsp, 8)
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ret
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END (__tls_get_addr)
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#endif /* SHARED */
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@ -15,3 +15,6 @@ TLSDESC_ARG offsetof(struct tlsdesc, arg)
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TLSDESC_GEN_COUNT offsetof(struct tlsdesc_dynamic_arg, gen_count)
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TLSDESC_MODID offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_module)
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TLSDESC_MODOFF offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_offset)
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TI_MODULE_OFFSET offsetof(tls_index, ti_module)
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TI_OFFSET_OFFSET offsetof(tls_index, ti_offset)
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