From 743113d42e6cad77477769a3de5542d33443ae76 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Wed, 15 Mar 2023 17:42:54 -0700 Subject: x86: Set FSGSBASE to active if enabled by kernel Linux kernel uses AT_HWCAP2 to indicate if FSGSBASE instructions are enabled. If the HWCAP2_FSGSBASE bit in AT_HWCAP2 is set, FSGSBASE instructions can be used in user space. Define dl_check_hwcap2 to set the FSGSBASE feature to active on Linux when the HWCAP2_FSGSBASE bit is set. Add a test to verify that FSGSBASE is active on current kernels. NB: This test will fail if the kernel doesn't set the HWCAP2_FSGSBASE bit in AT_HWCAP2 while fsgsbase shows up in /proc/cpuinfo. Reviewed-by: Florian Weimer --- sysdeps/x86/dl-hwcap2.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 sysdeps/x86/dl-hwcap2.h (limited to 'sysdeps/x86/dl-hwcap2.h') diff --git a/sysdeps/x86/dl-hwcap2.h b/sysdeps/x86/dl-hwcap2.h new file mode 100644 index 0000000000..73cd6cc37d --- /dev/null +++ b/sysdeps/x86/dl-hwcap2.h @@ -0,0 +1,21 @@ +/* Handle AT_HWCAP2. Generic x86 version. + Copyright (C) 2023 Free Software Foundation, Inc. + + 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 + . */ + +static inline void +dl_check_hwcap2 (struct cpu_features *cpu_features) +{ +} -- cgit 1.4.1