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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103/* SPDX-License-Identifier: GPL-2.0 *//* * KCSAN watchpoint encoding. * * Copyright (C) 2019, Google LLC. */
#ifndef _KERNEL_KCSAN_ENCODING_H#define _KERNEL_KCSAN_ENCODING_H
#include <linux/bits.h>#include <linux/log2.h>#include <linux/mm.h>
#include "kcsan.h"
#define SLOT_RANGE PAGE_SIZE
#define INVALID_WATCHPOINT 0#define CONSUMED_WATCHPOINT 1
/* * The maximum useful size of accesses for which we set up watchpoints is the * max range of slots we check on an access. */#define MAX_ENCODABLE_SIZE (SLOT_RANGE * (1 + KCSAN_CHECK_ADJACENT))
/* * Number of bits we use to store size info. */#define WATCHPOINT_SIZE_BITS bits_per(MAX_ENCODABLE_SIZE)/* * This encoding for addresses discards the upper (1 for is-write + SIZE_BITS); * however, most 64-bit architectures do not use the full 64-bit address space. * Also, in order for a false positive to be observable 2 things need to happen: * * 1. different addresses but with the same encoded address race; * 2. and both map onto the same watchpoint slots; * * Both these are assumed to be very unlikely. However, in case it still * happens, the report logic will filter out the false positive (see report.c). */#define WATCHPOINT_ADDR_BITS (BITS_PER_LONG-1 - WATCHPOINT_SIZE_BITS)
/* Bitmasks for the encoded watchpoint access information. */#define WATCHPOINT_WRITE_MASK BIT(BITS_PER_LONG-1)#define WATCHPOINT_SIZE_MASK GENMASK(BITS_PER_LONG-2, WATCHPOINT_ADDR_BITS)#define WATCHPOINT_ADDR_MASK GENMASK(WATCHPOINT_ADDR_BITS-1, 0)static_assert(WATCHPOINT_ADDR_MASK == (1UL << WATCHPOINT_ADDR_BITS) - 1);static_assert((WATCHPOINT_WRITE_MASK ^ WATCHPOINT_SIZE_MASK ^ WATCHPOINT_ADDR_MASK) == ~0UL);
static inline bool check_encodable(unsigned long addr, size_t size){ /* * While we can encode addrs<PAGE_SIZE, avoid crashing with a NULL * pointer deref inside KCSAN. */ return addr >= PAGE_SIZE && size <= MAX_ENCODABLE_SIZE;}
static inline longencode_watchpoint(unsigned long addr, size_t size, bool is_write){ return (long)((is_write ? WATCHPOINT_WRITE_MASK : 0) | (size << WATCHPOINT_ADDR_BITS) | (addr & WATCHPOINT_ADDR_MASK));}
static __always_inline bool decode_watchpoint(long watchpoint, unsigned long *addr_masked, size_t *size, bool *is_write){ if (watchpoint == INVALID_WATCHPOINT || watchpoint == CONSUMED_WATCHPOINT) return false;
*addr_masked = (unsigned long)watchpoint & WATCHPOINT_ADDR_MASK; *size = ((unsigned long)watchpoint & WATCHPOINT_SIZE_MASK) >> WATCHPOINT_ADDR_BITS; *is_write = !!((unsigned long)watchpoint & WATCHPOINT_WRITE_MASK);
return true;}
/* * Return watchpoint slot for an address. */static __always_inline int watchpoint_slot(unsigned long addr){ return (addr / PAGE_SIZE) % CONFIG_KCSAN_NUM_WATCHPOINTS;}
static __always_inline bool matching_access(unsigned long addr1, size_t size1, unsigned long addr2, size_t size2){ unsigned long end_range1 = addr1 + size1 - 1; unsigned long end_range2 = addr2 + size2 - 1;
return addr1 <= end_range2 && addr2 <= end_range1;}
#endif /* _KERNEL_KCSAN_ENCODING_H */