vasilito
dc68054305
- Restore 29 recipe symlinks (libdrm, qtbase, dbus, sddm, pipewire, etc.) - Restore 33 patches (KDE, libdrm, mesa, pipewire, sddm, wireplumber) - Restore 20+ local/scripts (audit, lint, test, build helpers) - Restore src/cook/scheduler.rs, status.rs, gnu-config/ - Restore scripts/patch-inclusion-gate.sh, run_mini1.sh, validate-collision-log.sh - Recover TLC source from HEAD (was overwritten by 0.2.3 checkout) - Recover 11 local/docs plans from HEAD (were overwritten) - Recover qt6-wayland-smoke symlink from HEAD - Fix MOTD: remove garbled ASCII art, use clean text - Update version: 0.2.0 -> 0.2.4 in os-release, motd, config - Reduce filesystem_size: 1536 -> 512 MiB - Add ABSOLUTE RULE to AGENTS.md: never delete/ignore packages - Reduce pcid scheme log verbosity: info -> debug
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Supervisor Mode Access Prevention support
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*
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* Copyright (C) 2012 Intel Corporation
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* Author: H. Peter Anvin <hpa@linux.intel.com>
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*/
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#ifndef _ASM_X86_SMAP_H
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#define _ASM_X86_SMAP_H
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#include <asm/nops.h>
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#include <asm/cpufeatures.h>
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#include <asm/alternative.h>
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#ifdef __ASSEMBLER__
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#define ASM_CLAC \
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ALTERNATIVE "", "clac", X86_FEATURE_SMAP
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#define ASM_STAC \
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ALTERNATIVE "", "stac", X86_FEATURE_SMAP
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#else /* __ASSEMBLER__ */
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/*
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* The CLAC/STAC instructions toggle the enforcement of
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* X86_FEATURE_SMAP along with X86_FEATURE_LASS.
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*
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* SMAP enforcement is based on the _PAGE_BIT_USER bit in the page
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* tables. The kernel is not allowed to touch pages with that bit set
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* unless the AC bit is set.
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*
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* Use stac()/clac() when accessing userspace (_PAGE_USER) mappings,
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* regardless of location.
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*
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* Note: a barrier is implicit in alternative().
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*/
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static __always_inline void clac(void)
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{
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alternative("", "clac", X86_FEATURE_SMAP);
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}
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static __always_inline void stac(void)
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{
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alternative("", "stac", X86_FEATURE_SMAP);
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}
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/*
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* LASS enforcement is based on bit 63 of the virtual address. The
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* kernel is not allowed to touch memory in the lower half of the
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* virtual address space.
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*
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* Use lass_stac()/lass_clac() to toggle the AC bit for kernel data
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* accesses (!_PAGE_USER) that are blocked by LASS, but not by SMAP.
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*
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* Even with the AC bit set, LASS will continue to block instruction
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* fetches from the user half of the address space. To allow those,
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* clear CR4.LASS to disable the LASS mechanism entirely.
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*
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* Note: a barrier is implicit in alternative().
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*/
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static __always_inline void lass_clac(void)
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{
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alternative("", "clac", X86_FEATURE_LASS);
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}
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static __always_inline void lass_stac(void)
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{
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alternative("", "stac", X86_FEATURE_LASS);
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}
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static __always_inline unsigned long smap_save(void)
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{
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unsigned long flags;
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asm volatile ("# smap_save\n\t"
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ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE "\n\t"
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"", "pushf; pop %0; clac",
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X86_FEATURE_SMAP)
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: "=rm" (flags) : : "memory", "cc");
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return flags;
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}
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static __always_inline void smap_restore(unsigned long flags)
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{
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asm volatile ("# smap_restore\n\t"
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ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE "\n\t"
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"", "push %0; popf",
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X86_FEATURE_SMAP)
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: : "g" (flags) : "memory", "cc");
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}
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/* These macros can be used in asm() statements */
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#define ASM_CLAC \
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ALTERNATIVE("", "clac", X86_FEATURE_SMAP)
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#define ASM_STAC \
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ALTERNATIVE("", "stac", X86_FEATURE_SMAP)
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#define ASM_CLAC_UNSAFE \
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ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "\n\t" "clac", X86_FEATURE_SMAP)
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#define ASM_STAC_UNSAFE \
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ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "\n\t" "stac", X86_FEATURE_SMAP)
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#endif /* __ASSEMBLER__ */
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#endif /* _ASM_X86_SMAP_H */
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