glibc/sysdeps/x86_64/tls_get_addr.S

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/* Stack-aligning implementation of __tls_get_addr. x86-64 version.
Copyright (C) 2017-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifdef SHARED
# include <sysdep.h>
# include "tlsdesc.h"
# include "rtld-offsets.h"
/* See __tls_get_addr and __tls_get_addr_slow in dl-tls.c. This function
call __tls_get_addr_slow on both slow paths. It realigns the stack
before the call to work around GCC PR58066. */
ENTRY (__tls_get_addr)
mov %fs:DTV_OFFSET, %RDX_LP
mov GL_TLS_GENERATION_OFFSET+_rtld_local(%rip), %RAX_LP
/* GL(dl_tls_generation) == dtv[0].counter */
cmp %RAX_LP, (%rdx)
jne 1f
mov TI_MODULE_OFFSET(%rdi), %RAX_LP
/* dtv[ti->ti_module] */
# ifdef __LP64__
salq $4, %rax
movq (%rdx,%rax), %rax
# else
movl (%rdx,%rax, 8), %eax
# endif
cmp $-1, %RAX_LP
je 1f
add TI_OFFSET_OFFSET(%rdi), %RAX_LP
ret
1:
/* On the slow path, align the stack. */
pushq %rbp
cfi_def_cfa_offset (16)
cfi_offset (%rbp, -16)
mov %RSP_LP, %RBP_LP
cfi_def_cfa_register (%rbp)
and $-16, %RSP_LP
call __tls_get_addr_slow
mov %RBP_LP, %RSP_LP
popq %rbp
cfi_def_cfa (%rsp, 8)
ret
END (__tls_get_addr)
#endif /* SHARED */