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147 lines
4.3 KiB
ArmAsm
147 lines
4.3 KiB
ArmAsm
/* Thread-local storage handling in the ELF dynamic linker. x86_64 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 %rax points to the TLS descriptor, such that
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0(%rax) points to _dl_tlsdesc_return itself, and 8(%rax) 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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movq 8(%rax), %rax
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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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%rax points to the TLS descriptor, such that 0(%rax) points to
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_dl_tlsdesc_undefweak itself, and 8(%rax) 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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movq 8(%rax), %rax
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sub %fs:0, %RAX_LP
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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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/* %rax points to the TLS descriptor, such that 0(%rax) points to
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_dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
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tlsdesc_dynamic_arg object. It must return in %rax 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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_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
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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_internal (&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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/* Preserve call-clobbered registers that we modify.
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We need two scratch regs anyway. */
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movq %rsi, -16(%rsp)
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mov %fs:DTV_OFFSET, %RSI_LP
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movq %rdi, -8(%rsp)
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movq TLSDESC_ARG(%rax), %rdi
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movq (%rsi), %rax
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cmpq %rax, TLSDESC_GEN_COUNT(%rdi)
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ja .Lslow
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movq TLSDESC_MODID(%rdi), %rax
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salq $4, %rax
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movq (%rax,%rsi), %rax
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cmpq $-1, %rax
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je .Lslow
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addq TLSDESC_MODOFF(%rdi), %rax
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.Lret:
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movq -16(%rsp), %rsi
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sub %fs:0, %RAX_LP
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movq -8(%rsp), %rdi
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ret
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.Lslow:
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/* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9,
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r10 and r11. Also, align the stack, that's off by 8 bytes. */
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subq $72, %rsp
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cfi_adjust_cfa_offset (72)
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movq %rdx, 8(%rsp)
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movq %rcx, 16(%rsp)
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movq %r8, 24(%rsp)
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movq %r9, 32(%rsp)
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movq %r10, 40(%rsp)
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movq %r11, 48(%rsp)
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/* %rdi already points to the tlsinfo data structure. */
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call HIDDEN_JUMPTARGET (__tls_get_addr)
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movq 8(%rsp), %rdx
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movq 16(%rsp), %rcx
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movq 24(%rsp), %r8
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movq 32(%rsp), %r9
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movq 40(%rsp), %r10
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movq 48(%rsp), %r11
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addq $72, %rsp
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cfi_adjust_cfa_offset (-72)
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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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