mirror of
https://github.com/torvalds/linux.git
synced 2024-11-14 16:12:02 +00:00
bd0ccc4afc
Adds missing license and/or copyright headers for KCSAN source files. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
/* 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 long
|
|
encode_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 */
|