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d360dcc001
Initially, IBT and SHSTK are marked as active when CPU supports them and CET are enabled in glibc. They can be disabled early by tunables before relocation. Since after relocation, GLRO(dl_x86_cpu_features) becomes read-only, we can't update GLRO(dl_x86_cpu_features) to mark IBT and SHSTK as inactive. Instead, check the feature_1 field in TCB to decide if IBT and SHST are active.
82 lines
2.6 KiB
C
82 lines
2.6 KiB
C
/* Data structure for x86 CPU features.
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This file is part of the GNU C Library.
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Copyright (C) 2008-2023 Free Software Foundation, Inc.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _SYS_PLATFORM_X86_H
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#define _SYS_PLATFORM_X86_H
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#include <features.h>
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#include <stdbool.h>
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#include <bits/platform/x86.h>
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__BEGIN_DECLS
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/* Get a pointer to the CPU feature structure. */
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extern const struct cpuid_feature *__x86_get_cpuid_feature_leaf (unsigned int)
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__attribute__ ((pure));
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static __inline__ _Bool
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x86_cpu_present (unsigned int __index)
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{
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const struct cpuid_feature *__ptr = __x86_get_cpuid_feature_leaf
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(__index / (8 * sizeof (unsigned int) * 4));
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unsigned int __reg
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= __index & (8 * sizeof (unsigned int) * 4 - 1);
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unsigned int __bit = __reg & (8 * sizeof (unsigned int) - 1);
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__reg /= 8 * sizeof (unsigned int);
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return __ptr->cpuid_array[__reg] & (1 << __bit);
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}
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static __inline__ _Bool
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x86_cpu_active (unsigned int __index)
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{
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if (__index == x86_cpu_IBT || __index == x86_cpu_SHSTK)
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{
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#ifdef __x86_64__
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unsigned int __feature_1;
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# ifdef __LP64__
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__asm__ ("mov %%fs:72, %0" : "=r" (__feature_1));
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# else
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__asm__ ("mov %%fs:40, %0" : "=r" (__feature_1));
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# endif
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if (__index == x86_cpu_IBT)
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return __feature_1 & x86_feature_1_ibt;
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else
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return __feature_1 & x86_feature_1_shstk;
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#else
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return false;
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#endif
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}
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const struct cpuid_feature *__ptr = __x86_get_cpuid_feature_leaf
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(__index / (8 * sizeof (unsigned int) * 4));
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unsigned int __reg
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= __index & (8 * sizeof (unsigned int) * 4 - 1);
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unsigned int __bit = __reg & (8 * sizeof (unsigned int) - 1);
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__reg /= 8 * sizeof (unsigned int);
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return __ptr->active_array[__reg] & (1 << __bit);
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}
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/* CPU_FEATURE_PRESENT evaluates to true if CPU supports the feature. */
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#define CPU_FEATURE_PRESENT(name) x86_cpu_present (x86_cpu_##name)
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/* CPU_FEATURE_ACTIVE evaluates to true if the feature is active. */
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#define CPU_FEATURE_ACTIVE(name) x86_cpu_active (x86_cpu_##name)
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__END_DECLS
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#endif /* _SYS_PLATFORM_X86_H */
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