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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>
52 lines
1.7 KiB
C
52 lines
1.7 KiB
C
/* Thread-local storage handling in the ELF dynamic linker. i386 version.
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Copyright (C) 2002-2025 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_TLS_H
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#define _DL_TLS_H
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/* Type used for the representation of TLS information in the GOT. */
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typedef struct dl_tls_index
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{
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unsigned long int ti_module;
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unsigned long int ti_offset;
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} tls_index;
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/* Dynamic thread vector pointers point to the start of each
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TLS block. */
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#define TLS_DTV_OFFSET 0
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/* Static TLS offsets are relative to the unadjusted thread pointer. */
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#define TLS_TP_OFFSET 0
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#ifdef SHARED
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/* This is the prototype for the GNU version. */
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extern void *___tls_get_addr (tls_index *ti)
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__attribute__ ((__regparm__ (1)));
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# if IS_IN (rtld)
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/* Prepare using the definition of __tls_get_addr in the generic
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version of this file. */
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# define __tls_get_addr \
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__attribute__ ((__regparm__ (1))) ___tls_get_addr_internal
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# else
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/* Users should get the better interface. */
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# define __tls_get_addr ___tls_get_addr
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# endif
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#endif
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#endif /* _DL_TLS_H */
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