1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef __TRACE_PROBE_KERNEL_H_
  3#define __TRACE_PROBE_KERNEL_H_
  4
  5#define FAULT_STRING "(fault)"
  6
  7/*
  8 * This depends on trace_probe.h, but can not include it due to
  9 * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
 10 * Which means that any other user must include trace_probe.h before including
 11 * this file.
 12 */
 13/* Return the length of string -- including null terminal byte */
 14static nokprobe_inline int
 15kern_fetch_store_strlen_user(unsigned long addr)
 16{
 17	const void __user *uaddr =  (__force const void __user *)addr;
 18	int ret;
 19
 20	ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
 21	/*
 22	 * strnlen_user_nofault returns zero on fault, insert the
 23	 * FAULT_STRING when that occurs.
 24	 */
 25	if (ret <= 0)
 26		return strlen(FAULT_STRING) + 1;
 27	return ret;
 28}
 29
 30/* Return the length of string -- including null terminal byte */
 31static nokprobe_inline int
 32kern_fetch_store_strlen(unsigned long addr)
 33{
 34	int ret, len = 0;
 35	u8 c;
 36
 37#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 38	if (addr < TASK_SIZE)
 39		return kern_fetch_store_strlen_user(addr);
 40#endif
 41
 42	do {
 43		ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
 44		len++;
 45	} while (c && ret == 0 && len < MAX_STRING_SIZE);
 46
 47	/* For faults, return enough to hold the FAULT_STRING */
 48	return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
 49}
 50
 51static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
 52{
 53	if (ret >= 0) {
 54		*(u32 *)dest = make_data_loc(ret, __dest - base);
 55	} else {
 56		strscpy(__dest, FAULT_STRING, len);
 57		ret = strlen(__dest) + 1;
 58	}
 59}
 60
 61/*
 62 * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
 63 * with max length and relative data location.
 64 */
 65static nokprobe_inline int
 66kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
 67{
 68	const void __user *uaddr =  (__force const void __user *)addr;
 69	int maxlen = get_loc_len(*(u32 *)dest);
 70	void *__dest;
 71	long ret;
 72
 73	if (unlikely(!maxlen))
 74		return -ENOMEM;
 75
 76	__dest = get_loc_data(dest, base);
 77
 78	ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
 79	set_data_loc(ret, dest, __dest, base, maxlen);
 80
 81	return ret;
 82}
 83
 84/*
 85 * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
 86 * length and relative data location.
 87 */
 88static nokprobe_inline int
 89kern_fetch_store_string(unsigned long addr, void *dest, void *base)
 90{
 91	int maxlen = get_loc_len(*(u32 *)dest);
 92	void *__dest;
 93	long ret;
 94
 95#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 96	if ((unsigned long)addr < TASK_SIZE)
 97		return kern_fetch_store_string_user(addr, dest, base);
 98#endif
 99
100	if (unlikely(!maxlen))
101		return -ENOMEM;
102
103	__dest = get_loc_data(dest, base);
104
105	/*
106	 * Try to get string again, since the string can be changed while
107	 * probing.
108	 */
109	ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
110	set_data_loc(ret, dest, __dest, base, maxlen);
111
112	return ret;
113}
114
115#endif /* __TRACE_PROBE_KERNEL_H_ */