_dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic access the thread pointer
via the tcb field in TCB:
_dl_tlsdesc_undefweak:
_CET_ENDBR
movq 8(%rax), %rax
subq %fs:0, %rax
ret
_dl_tlsdesc_dynamic:
...
subq %fs:0, %rax
movq -8(%rsp), %rdi
ret
Since the tcb field in TCB is a pointer, %fs:0 is a 32-bit location,
not 64-bit. It should use "sub %fs:0, %RAX_LP" instead. Since
_dl_tlsdesc_undefweak returns ptrdiff_t and _dl_make_tlsdesc_dynamic
returns void *, RAX_LP is appropriate here for x32 and x86-64. This
fixes BZ #31185.
_dl_tlsdesc_undefweak:
_CET_ENDBR
movq 8(%rax), %rax
- subq %fs:0, %rax
+ sub %fs:0, %RAX_LP
ret
cfi_endproc
.size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
addq TLSDESC_MODOFF(%rdi), %rax
.Lret:
movq -16(%rsp), %rsi
- subq %fs:0, %rax
+ sub %fs:0, %RAX_LP
movq -8(%rsp), %rdi
ret
.Lslow: