public inbox for glibc-cvs@sourceware.org help / color / mirror / Atom feed
From: H.J. Lu <hjl@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] x86: Set FSGSBASE to active if enabled by kernel Date: Mon, 3 Apr 2023 18:51:38 +0000 (GMT) [thread overview] Message-ID: <20230403185138.E41343858D39@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=743113d42e6cad77477769a3de5542d33443ae76 commit 743113d42e6cad77477769a3de5542d33443ae76 Author: H.J. Lu <hjl.tools@gmail.com> Date: Wed Mar 15 17:42:54 2023 -0700 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 <fweimer@redhat.com> Diff: --- sysdeps/unix/sysv/linux/x86/dl-hwcap2.h | 27 +++++++++++++++++++++++++++ sysdeps/x86/cpu-features.c | 3 +++ sysdeps/x86/dl-hwcap2.h | 21 +++++++++++++++++++++ sysdeps/x86/tst-cpu-features-cpuinfo.c | 7 +++++++ 4 files changed, 58 insertions(+) diff --git a/sysdeps/unix/sysv/linux/x86/dl-hwcap2.h b/sysdeps/unix/sysv/linux/x86/dl-hwcap2.h new file mode 100644 index 0000000000..28f38ea510 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/dl-hwcap2.h @@ -0,0 +1,27 @@ +/* Handle AT_HWCAP2. Linux/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 + <https://www.gnu.org/licenses/>. */ + +/* The following must match the kernel's <asm/hwcap2.h>. */ +#define HWCAP2_RING3MWAIT (1 << 0) +#define HWCAP2_FSGSBASE (1 << 1) + +static inline void +dl_check_hwcap2 (struct cpu_features *cpu_features) +{ + if ((GLRO(dl_hwcap2) & HWCAP2_FSGSBASE) != 0) + CPU_FEATURE_SET_ACTIVE (cpu_features, FSGSBASE); +} diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index 978eb29f72..95ad48b501 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -22,6 +22,7 @@ #include <cacheinfo.h> #include <dl-cacheinfo.h> #include <dl-minsigstacksize.h> +#include <dl-hwcap2.h> extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *) attribute_hidden; @@ -299,6 +300,8 @@ update_active (struct cpu_features *cpu_features) CPU_FEATURE_SET_ACTIVE (cpu_features, WIDE_KL); } + dl_check_hwcap2 (cpu_features); + cpu_features->isa_1 = get_isa_level (cpu_features); } 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 + <https://www.gnu.org/licenses/>. */ + +static inline void +dl_check_hwcap2 (struct cpu_features *cpu_features) +{ +} diff --git a/sysdeps/x86/tst-cpu-features-cpuinfo.c b/sysdeps/x86/tst-cpu-features-cpuinfo.c index e963592c4b..18d64375ca 100644 --- a/sysdeps/x86/tst-cpu-features-cpuinfo.c +++ b/sysdeps/x86/tst-cpu-features-cpuinfo.c @@ -96,6 +96,11 @@ check_proc (const char *proc_name, const char *search_name, int flag, CPU_FEATURE_USABLE (name), \ "HAS_CPU_FEATURE (" #name ")") +#define CHECK_PROC_ACTIVE(str, name) \ + check_proc (#str, " "#str" ", CPU_FEATURE_USABLE (name), \ + CPU_FEATURE_USABLE (name), \ + "CPU_FEATURE_USABLE (" #name ")") + static int do_test (int argc, char **argv) { @@ -298,6 +303,8 @@ do_test (int argc, char **argv) fails += CHECK_PROC (xsaves, XSAVES); fails += CHECK_PROC (xtpr, XTPRUPDCTRL); + fails += CHECK_PROC_ACTIVE (fsgsbase, FSGSBASE); + printf ("%d differences between /proc/cpuinfo and glibc code.\n", fails); return (fails != 0);
reply other threads:[~2023-04-03 18:51 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20230403185138.E41343858D39@sourceware.org \ --to=hjl@sourceware.org \ --cc=glibc-cvs@sourceware.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).