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75 lines
2.6 KiB
C
75 lines
2.6 KiB
C
/* X86 definitions for libc main startup.
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Copyright (C) 2018-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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 SHARED
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# define ARCH_SETUP_IREL() apply_irel ()
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# define ARCH_APPLY_IREL()
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# ifdef __CET__
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/* Get CET features enabled in the static executable. */
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static inline unsigned int
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get_cet_feature (void)
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{
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/* Check if CET is supported and not disabled by tunables. */
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const struct cpu_features *cpu_features = __get_cpu_features ();
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unsigned int cet_feature = 0;
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if (CPU_FEATURE_USABLE_P (cpu_features, IBT))
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cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
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if (CPU_FEATURE_USABLE_P (cpu_features, SHSTK))
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cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
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if (!cet_feature)
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return cet_feature;
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struct link_map *main_map = _dl_get_dl_main_map ();
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/* Scan program headers backward to check PT_GNU_PROPERTY early for
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x86 feature bits on static executable. */
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const ElfW(Phdr) *phdr = GL(dl_phdr);
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const ElfW(Phdr) *ph;
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for (ph = phdr + GL(dl_phnum); ph != phdr; ph--)
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if (ph[-1].p_type == PT_GNU_PROPERTY)
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{
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_dl_process_pt_gnu_property (main_map, -1, &ph[-1]);
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/* Enable IBT and SHSTK only if they are enabled on static
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executable. */
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cet_feature &= (main_map->l_x86_feature_1_and
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& (GNU_PROPERTY_X86_FEATURE_1_IBT
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| GNU_PROPERTY_X86_FEATURE_1_SHSTK));
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/* Set GL(dl_x86_feature_1) to the enabled CET features. */
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GL(dl_x86_feature_1) = cet_feature;
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break;
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}
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return cet_feature;
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}
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/* The function using this macro to enable shadow stack must not return
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to avoid shadow stack underflow. */
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# define ARCH_SETUP_TLS() \
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{ \
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__libc_setup_tls (); \
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\
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unsigned int cet_feature = get_cet_feature (); \
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ENABLE_X86_CET (cet_feature); \
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_dl_cet_setup_features (cet_feature); \
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}
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# else
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# define ARCH_SETUP_TLS() __libc_setup_tls ()
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# endif
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#endif /* !SHARED */
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