88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* x86 KMSAN support.
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*
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* Copyright (C) 2022, Google LLC
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* Author: Alexander Potapenko <glider@google.com>
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*/
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#ifndef _ASM_X86_KMSAN_H
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#define _ASM_X86_KMSAN_H
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#ifndef MODULE
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#include <asm/cpu_entry_area.h>
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#include <asm/processor.h>
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#include <linux/mmzone.h>
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DECLARE_PER_CPU(char[CPU_ENTRY_AREA_SIZE], cpu_entry_area_shadow);
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DECLARE_PER_CPU(char[CPU_ENTRY_AREA_SIZE], cpu_entry_area_origin);
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/*
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* Functions below are declared in the header to make sure they are inlined.
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* They all are called from kmsan_get_metadata() for every memory access in
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* the kernel, so speed is important here.
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*/
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/*
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* Compute metadata addresses for the CPU entry area on x86.
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*/
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static inline void *arch_kmsan_get_meta_or_null(void *addr, bool is_origin)
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{
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unsigned long addr64 = (unsigned long)addr;
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char *metadata_array;
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unsigned long off;
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int cpu;
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if ((addr64 < CPU_ENTRY_AREA_BASE) ||
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(addr64 >= (CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_MAP_SIZE)))
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return NULL;
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cpu = (addr64 - CPU_ENTRY_AREA_BASE) / CPU_ENTRY_AREA_SIZE;
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off = addr64 - (unsigned long)get_cpu_entry_area(cpu);
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if ((off < 0) || (off >= CPU_ENTRY_AREA_SIZE))
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return NULL;
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metadata_array = is_origin ? cpu_entry_area_origin :
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cpu_entry_area_shadow;
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return &per_cpu(metadata_array[off], cpu);
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}
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/*
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* Taken from arch/x86/mm/physaddr.h to avoid using an instrumented version.
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*/
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static inline bool kmsan_phys_addr_valid(unsigned long addr)
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{
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if (IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT))
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return !(addr >> boot_cpu_data.x86_phys_bits);
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else
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return true;
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}
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/*
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* Taken from arch/x86/mm/physaddr.c to avoid using an instrumented version.
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*/
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static inline bool kmsan_virt_addr_valid(void *addr)
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{
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unsigned long x = (unsigned long)addr;
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unsigned long y = x - __START_KERNEL_map;
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/* use the carry flag to determine if x was < __START_KERNEL_map */
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if (unlikely(x > y)) {
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x = y + phys_base;
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if (y >= KERNEL_IMAGE_SIZE)
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return false;
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} else {
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x = y + (__START_KERNEL_map - PAGE_OFFSET);
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/* carry flag will be set if starting x was >= PAGE_OFFSET */
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if ((x > y) || !kmsan_phys_addr_valid(x))
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return false;
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}
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return pfn_valid(x >> PAGE_SHIFT);
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}
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#endif /* !MODULE */
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#endif /* _ASM_X86_KMSAN_H */
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