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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.
40 lines
1.3 KiB
C
40 lines
1.3 KiB
C
/* Get CPUID feature leaf.
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Copyright (C) 2021-2023 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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#include <assert.h>
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#include <tcb-offsets.h>
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#include <ldsodefs.h>
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#ifdef __x86_64__
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# ifdef __LP64__
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_Static_assert (FEATURE_1_OFFSET == 72, "FEATURE_1_OFFSET != 72");
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# else
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_Static_assert (FEATURE_1_OFFSET == 40, "FEATURE_1_OFFSET != 40");
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# endif
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#endif
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const struct cpuid_feature *
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__x86_get_cpuid_feature_leaf (unsigned int leaf)
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{
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static const struct cpuid_feature feature = {};
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if (leaf < CPUID_INDEX_MAX)
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return ((const struct cpuid_feature *)
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&GLRO(dl_x86_cpu_features).features[leaf]);
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else
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return &feature;
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}
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