14ca8cc8dSAlexander Potapenko /* SPDX-License-Identifier: GPL-2.0 */ 24ca8cc8dSAlexander Potapenko /* 34ca8cc8dSAlexander Potapenko * x86 KMSAN support. 44ca8cc8dSAlexander Potapenko * 54ca8cc8dSAlexander Potapenko * Copyright (C) 2022, Google LLC 64ca8cc8dSAlexander Potapenko * Author: Alexander Potapenko <glider@google.com> 74ca8cc8dSAlexander Potapenko */ 84ca8cc8dSAlexander Potapenko 94ca8cc8dSAlexander Potapenko #ifndef _ASM_X86_KMSAN_H 104ca8cc8dSAlexander Potapenko #define _ASM_X86_KMSAN_H 114ca8cc8dSAlexander Potapenko 124ca8cc8dSAlexander Potapenko #ifndef MODULE 134ca8cc8dSAlexander Potapenko 14*ce732a75SAlexander Potapenko #include <asm/cpu_entry_area.h> 154ca8cc8dSAlexander Potapenko #include <asm/processor.h> 164ca8cc8dSAlexander Potapenko #include <linux/mmzone.h> 174ca8cc8dSAlexander Potapenko 18*ce732a75SAlexander Potapenko DECLARE_PER_CPU(char[CPU_ENTRY_AREA_SIZE], cpu_entry_area_shadow); 19*ce732a75SAlexander Potapenko DECLARE_PER_CPU(char[CPU_ENTRY_AREA_SIZE], cpu_entry_area_origin); 20*ce732a75SAlexander Potapenko 21*ce732a75SAlexander Potapenko /* 22*ce732a75SAlexander Potapenko * Functions below are declared in the header to make sure they are inlined. 23*ce732a75SAlexander Potapenko * They all are called from kmsan_get_metadata() for every memory access in 24*ce732a75SAlexander Potapenko * the kernel, so speed is important here. 25*ce732a75SAlexander Potapenko */ 26*ce732a75SAlexander Potapenko 27*ce732a75SAlexander Potapenko /* 28*ce732a75SAlexander Potapenko * Compute metadata addresses for the CPU entry area on x86. 29*ce732a75SAlexander Potapenko */ 30*ce732a75SAlexander Potapenko static inline void *arch_kmsan_get_meta_or_null(void *addr, bool is_origin) 31*ce732a75SAlexander Potapenko { 32*ce732a75SAlexander Potapenko unsigned long addr64 = (unsigned long)addr; 33*ce732a75SAlexander Potapenko char *metadata_array; 34*ce732a75SAlexander Potapenko unsigned long off; 35*ce732a75SAlexander Potapenko int cpu; 36*ce732a75SAlexander Potapenko 37*ce732a75SAlexander Potapenko if ((addr64 < CPU_ENTRY_AREA_BASE) || 38*ce732a75SAlexander Potapenko (addr64 >= (CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_MAP_SIZE))) 39*ce732a75SAlexander Potapenko return NULL; 40*ce732a75SAlexander Potapenko cpu = (addr64 - CPU_ENTRY_AREA_BASE) / CPU_ENTRY_AREA_SIZE; 41*ce732a75SAlexander Potapenko off = addr64 - (unsigned long)get_cpu_entry_area(cpu); 42*ce732a75SAlexander Potapenko if ((off < 0) || (off >= CPU_ENTRY_AREA_SIZE)) 43*ce732a75SAlexander Potapenko return NULL; 44*ce732a75SAlexander Potapenko metadata_array = is_origin ? cpu_entry_area_origin : 45*ce732a75SAlexander Potapenko cpu_entry_area_shadow; 46*ce732a75SAlexander Potapenko return &per_cpu(metadata_array[off], cpu); 47*ce732a75SAlexander Potapenko } 48*ce732a75SAlexander Potapenko 494ca8cc8dSAlexander Potapenko /* 504ca8cc8dSAlexander Potapenko * Taken from arch/x86/mm/physaddr.h to avoid using an instrumented version. 514ca8cc8dSAlexander Potapenko */ 524ca8cc8dSAlexander Potapenko static inline bool kmsan_phys_addr_valid(unsigned long addr) 534ca8cc8dSAlexander Potapenko { 544ca8cc8dSAlexander Potapenko if (IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT)) 554ca8cc8dSAlexander Potapenko return !(addr >> boot_cpu_data.x86_phys_bits); 564ca8cc8dSAlexander Potapenko else 574ca8cc8dSAlexander Potapenko return true; 584ca8cc8dSAlexander Potapenko } 594ca8cc8dSAlexander Potapenko 604ca8cc8dSAlexander Potapenko /* 614ca8cc8dSAlexander Potapenko * Taken from arch/x86/mm/physaddr.c to avoid using an instrumented version. 624ca8cc8dSAlexander Potapenko */ 634ca8cc8dSAlexander Potapenko static inline bool kmsan_virt_addr_valid(void *addr) 644ca8cc8dSAlexander Potapenko { 654ca8cc8dSAlexander Potapenko unsigned long x = (unsigned long)addr; 664ca8cc8dSAlexander Potapenko unsigned long y = x - __START_KERNEL_map; 674ca8cc8dSAlexander Potapenko 684ca8cc8dSAlexander Potapenko /* use the carry flag to determine if x was < __START_KERNEL_map */ 694ca8cc8dSAlexander Potapenko if (unlikely(x > y)) { 704ca8cc8dSAlexander Potapenko x = y + phys_base; 714ca8cc8dSAlexander Potapenko 724ca8cc8dSAlexander Potapenko if (y >= KERNEL_IMAGE_SIZE) 734ca8cc8dSAlexander Potapenko return false; 744ca8cc8dSAlexander Potapenko } else { 754ca8cc8dSAlexander Potapenko x = y + (__START_KERNEL_map - PAGE_OFFSET); 764ca8cc8dSAlexander Potapenko 774ca8cc8dSAlexander Potapenko /* carry flag will be set if starting x was >= PAGE_OFFSET */ 784ca8cc8dSAlexander Potapenko if ((x > y) || !kmsan_phys_addr_valid(x)) 794ca8cc8dSAlexander Potapenko return false; 804ca8cc8dSAlexander Potapenko } 814ca8cc8dSAlexander Potapenko 824ca8cc8dSAlexander Potapenko return pfn_valid(x >> PAGE_SHIFT); 834ca8cc8dSAlexander Potapenko } 844ca8cc8dSAlexander Potapenko 854ca8cc8dSAlexander Potapenko #endif /* !MODULE */ 864ca8cc8dSAlexander Potapenko 874ca8cc8dSAlexander Potapenko #endif /* _ASM_X86_KMSAN_H */ 88