From 0aac205a814a8511e98d02b91a8dc908f1c53cde Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Mon, 26 Feb 2024 06:37:03 -0800 Subject: x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers Compiler generates the following instruction sequence for GNU2 dynamic TLS access: leaq tls_var@TLSDESC(%rip), %rax call *tls_var@TLSCALL(%rax) or leal tls_var@TLSDESC(%ebx), %eax call *tls_var@TLSCALL(%eax) CALL instruction is transparent to compiler which assumes all registers, except for EFLAGS and RAX/EAX, are unchanged after CALL. When _dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow path. __tls_get_addr is a normal function which doesn't preserve any caller-saved registers. _dl_tlsdesc_dynamic saved and restored integer caller-saved registers, but didn't preserve any other caller-saved registers. Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE, XSAVE and XSAVEC to save and restore all caller-saved registers. This fixes BZ #31372. Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic) to optimize elf_machine_runtime_setup. Reviewed-by: Noah Goldstein --- elf/tst-gnu2-tls2.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 elf/tst-gnu2-tls2.h (limited to 'elf/tst-gnu2-tls2.h') diff --git a/elf/tst-gnu2-tls2.h b/elf/tst-gnu2-tls2.h new file mode 100644 index 0000000000..77964a57a3 --- /dev/null +++ b/elf/tst-gnu2-tls2.h @@ -0,0 +1,36 @@ +/* Test TLSDESC relocation. + Copyright (C) 2024 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 + . */ + +#include + +struct tls +{ + int64_t a, b, c, d; +}; + +extern struct tls *apply_tls (struct tls *); + +/* An architecture can define them to verify that clobber caller-saved + registers aren't changed by the implicit TLSDESC call. */ +#ifndef BEFORE_TLSDESC_CALL +# define BEFORE_TLSDESC_CALL() +#endif + +#ifndef AFTER_TLSDESC_CALL +# define AFTER_TLSDESC_CALL() +#endif -- cgit 1.4.1