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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __TRACE_PROBE_KERNEL_H_
#define __TRACE_PROBE_KERNEL_H_
#define FAULT_STRING "(fault)"
/*
* This depends on trace_probe.h, but can not include it due to
* the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
* Which means that any other user must include trace_probe.h before including
* this file.
*/
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
kern_fetch_store_strlen_user(unsigned long addr)
{
const void __user *uaddr = (__force const void __user *)addr;
int ret;
ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
/*
* strnlen_user_nofault returns zero on fault, insert the
* FAULT_STRING when that occurs.
*/
if (ret <= 0)
return strlen(FAULT_STRING) + 1;
return ret;
}
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
kern_fetch_store_strlen(unsigned long addr)
{
int ret, len = 0;
u8 c;
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if (addr < TASK_SIZE)
return kern_fetch_store_strlen_user(addr);
#endif
do {
ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
/* For faults, return enough to hold the FAULT_STRING */
return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
}
static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
{
if (ret >= 0) {
*(u32 *)dest = make_data_loc(ret, __dest - base);
} else {
strscpy(__dest, FAULT_STRING, len);
ret = strlen(__dest) + 1;
}
}
/*
* Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
* with max length and relative data location.
*/
static nokprobe_inline int
kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
{
const void __user *uaddr = (__force const void __user *)addr;
int maxlen = get_loc_len(*(u32 *)dest);
void *__dest;
long ret;
if (unlikely(!maxlen))
return -ENOMEM;
__dest = get_loc_data(dest, base);
ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
set_data_loc(ret, dest, __dest, base, maxlen);
return ret;
}
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* length and relative data location.
*/
static nokprobe_inline int
kern_fetch_store_string(unsigned long addr, void *dest, void *base)
{
int maxlen = get_loc_len(*(u32 *)dest);
void *__dest;
long ret;
#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
if ((unsigned long)addr < TASK_SIZE)
return kern_fetch_store_string_user(addr, dest, base);
#endif
if (unlikely(!maxlen))
return -ENOMEM;
__dest = get_loc_data(dest, base);
/*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
set_data_loc(ret, dest, __dest, base, maxlen);
return ret;
}
#endif /* __TRACE_PROBE_KERNEL_H_ */
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