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author | H.J. Lu <hjl.tools@gmail.com> | 2023-03-15 17:42:54 -0700 |
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committer | H.J. Lu <hjl.tools@gmail.com> | 2023-04-03 11:36:48 -0700 |
commit | 743113d42e6cad77477769a3de5542d33443ae76 (patch) | |
tree | 02f5ac20ff2715acfd54dd50fb670eb49ee43c94 /sysdeps | |
parent | 5d1ccdda7b0c625751661d50977f3dfbc73f8eae (diff) | |
download | glibc-743113d42e6cad77477769a3de5542d33443ae76.zip glibc-743113d42e6cad77477769a3de5542d33443ae76.tar.gz glibc-743113d42e6cad77477769a3de5542d33443ae76.tar.bz2 |
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>
Diffstat (limited to 'sysdeps')
-rw-r--r-- | sysdeps/unix/sysv/linux/x86/dl-hwcap2.h | 27 | ||||
-rw-r--r-- | sysdeps/x86/cpu-features.c | 3 | ||||
-rw-r--r-- | sysdeps/x86/dl-hwcap2.h | 21 | ||||
-rw-r--r-- | sysdeps/x86/tst-cpu-features-cpuinfo.c | 7 |
4 files changed, 58 insertions, 0 deletions
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 0000000..28f38ea --- /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 978eb29..95ad48b 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 0000000..73cd6cc --- /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 e963592..18d6437 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); |