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a364304718
Compiler generates the following instruction sequence for GNU2 dynamic
TLS access:
leaq tls_var@TLSDESC(%rip), %rax
call *tls_var@TLSCALL(%rax)
or
leal tls_var@TLSDESC(%ebx), %eax
call *tls_var@TLSCALL(%eax)
CALL instruction is transparent to compiler which assumes all registers,
except for EFLAGS and RAX/EAX, are unchanged after CALL. When
_dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
path. __tls_get_addr is a normal function which doesn't preserve any
caller-saved registers. _dl_tlsdesc_dynamic saved and restored integer
caller-saved registers, but didn't preserve any other caller-saved
registers. Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
XSAVE and XSAVEC to save and restore all caller-saved registers. This
fixes BZ #31372.
Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
to optimize elf_machine_runtime_setup.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
(cherry picked from commit 0aac205a81)
35 lines
1.4 KiB
C
35 lines
1.4 KiB
C
/* x86-64 PLT trampoline register save macros.
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Copyright (C) 2024 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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<https://www.gnu.org/licenses/>. */
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#ifndef DL_STACK_ALIGNMENT
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/* Due to GCC bug:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58066
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__tls_get_addr may be called with 8-byte stack alignment. Although
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this bug has been fixed in GCC 4.9.4, 5.3 and 6, we can't assume
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that stack will be always aligned at 16 bytes. */
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# define DL_STACK_ALIGNMENT 8
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#endif
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/* True if _dl_runtime_resolve should align stack for STATE_SAVE or align
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stack to 16 bytes before calling _dl_fixup. */
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#define DL_RUNTIME_RESOLVE_REALIGN_STACK \
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(STATE_SAVE_ALIGNMENT > DL_STACK_ALIGNMENT \
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|| 16 > DL_STACK_ALIGNMENT)
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