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137 lines
4.0 KiB
ArmAsm
137 lines
4.0 KiB
ArmAsm
/* Thread-local storage handling in the ELF dynamic linker. i386 version.
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Copyright (C) 2004-2024 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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#include <sysdep.h>
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#include <tls.h>
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#include "tlsdesc.h"
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.text
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/* This function is used to compute the TP offset for symbols in
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Static TLS, i.e., whose TP offset is the same for all
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threads.
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The incoming %eax points to the TLS descriptor, such that
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0(%eax) points to _dl_tlsdesc_return itself, and 4(%eax) holds
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the TP offset of the symbol corresponding to the object
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denoted by the argument. */
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.hidden _dl_tlsdesc_return
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.global _dl_tlsdesc_return
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.type _dl_tlsdesc_return,@function
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cfi_startproc
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.align 16
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_dl_tlsdesc_return:
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_CET_ENDBR
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movl 4(%eax), %eax
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ret
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cfi_endproc
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.size _dl_tlsdesc_return, .-_dl_tlsdesc_return
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/* This function is used for undefined weak TLS symbols, for
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which the base address (i.e., disregarding any addend) should
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resolve to NULL.
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%eax points to the TLS descriptor, such that 0(%eax) points to
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_dl_tlsdesc_undefweak itself, and 4(%eax) holds the addend.
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We return the addend minus the TP, such that, when the caller
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adds TP, it gets the addend back. If that's zero, as usual,
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that's most likely a NULL pointer. */
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.hidden _dl_tlsdesc_undefweak
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.global _dl_tlsdesc_undefweak
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.type _dl_tlsdesc_undefweak,@function
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cfi_startproc
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.align 16
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_dl_tlsdesc_undefweak:
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_CET_ENDBR
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movl 4(%eax), %eax
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subl %gs:0, %eax
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ret
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cfi_endproc
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.size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
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#ifdef SHARED
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.hidden _dl_tlsdesc_dynamic
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.global _dl_tlsdesc_dynamic
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.type _dl_tlsdesc_dynamic,@function
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/* This function is used for symbols that need dynamic TLS.
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%eax points to the TLS descriptor, such that 0(%eax) points to
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_dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
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tlsdesc_dynamic_arg object. It must return in %eax the offset
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between the thread pointer and the object denoted by the
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argument, without clobbering any registers.
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The assembly code that follows is a rendition of the following
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C code, hand-optimized a little bit.
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ptrdiff_t
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__attribute__ ((__regparm__ (1)))
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_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
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{
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struct tlsdesc_dynamic_arg *td = tdp->arg;
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dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
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if (__builtin_expect (td->gen_count <= dtv[0].counter
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&& (dtv[td->tlsinfo.ti_module].pointer.val
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!= TLS_DTV_UNALLOCATED),
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1))
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return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
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- __thread_pointer;
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return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
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}
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*/
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cfi_startproc
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.align 16
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_dl_tlsdesc_dynamic:
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_CET_ENDBR
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/* Like all TLS resolvers, preserve call-clobbered registers.
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We need two scratch regs anyway. */
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subl $28, %esp
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cfi_adjust_cfa_offset (28)
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movl %ecx, 20(%esp)
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movl %edx, 24(%esp)
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movl TLSDESC_ARG(%eax), %eax
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movl %gs:DTV_OFFSET, %edx
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movl TLSDESC_GEN_COUNT(%eax), %ecx
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cmpl (%edx), %ecx
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ja .Lslow
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movl TLSDESC_MODID(%eax), %ecx
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movl (%edx,%ecx,8), %edx
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cmpl $-1, %edx
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je .Lslow
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movl TLSDESC_MODOFF(%eax), %eax
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addl %edx, %eax
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.Lret:
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movl 20(%esp), %ecx
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subl %gs:0, %eax
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movl 24(%esp), %edx
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addl $28, %esp
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cfi_adjust_cfa_offset (-28)
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ret
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.p2align 4,,7
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.Lslow:
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cfi_adjust_cfa_offset (28)
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call HIDDEN_JUMPTARGET (___tls_get_addr)
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jmp .Lret
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cfi_endproc
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.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
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#endif /* SHARED */
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