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 --- sysdeps/i386/dl-machine.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'sysdeps/i386/dl-machine.h') diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h index fc1ef96587..50d74fe6e9 100644 --- a/sysdeps/i386/dl-machine.h +++ b/sysdeps/i386/dl-machine.h @@ -347,7 +347,7 @@ and creates an unsatisfiable circular dependency.\n", { td->arg = _dl_make_tlsdesc_dynamic (sym_map, sym->st_value + (ElfW(Word))td->arg); - td->entry = _dl_tlsdesc_dynamic; + td->entry = GLRO(dl_x86_tlsdesc_dynamic); } else # endif -- cgit 1.4.1