/* SPDX-License-Identifier: GPL-2.0 */ #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 */