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// SPDX-License-Identifier: GPL-2.0
/*
* fprobe - Simple ftrace probe wrapper for function entry.
*/
#define pr_fmt(fmt) "fprobe: " fmt
#include <linux/err.h>
#include <linux/fprobe.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/slab.h>
#include <linux/sort.h>
static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
struct fprobe *fp;
int bit;
fp = container_of(ops, struct fprobe, ops);
if (fprobe_disabled(fp))
return;
bit = ftrace_test_recursion_trylock(ip, parent_ip);
if (bit < 0) {
fp->nmissed++;
return;
}
if (fp->entry_handler)
fp->entry_handler(fp, ip, ftrace_get_regs(fregs));
ftrace_test_recursion_unlock(bit);
}
NOKPROBE_SYMBOL(fprobe_handler);
/* Convert ftrace location address from symbols */
static unsigned long *get_ftrace_locations(const char **syms, int num)
{
unsigned long addr, size;
unsigned long *addrs;
int i;
/* Convert symbols to symbol address */
addrs = kcalloc(num, sizeof(*addrs), GFP_KERNEL);
if (!addrs)
return ERR_PTR(-ENOMEM);
for (i = 0; i < num; i++) {
addr = kallsyms_lookup_name(syms[i]);
if (!addr) /* Maybe wrong symbol */
goto error;
/* Convert symbol address to ftrace location. */
if (!kallsyms_lookup_size_offset(addr, &size, NULL) || !size)
goto error;
addr = ftrace_location_range(addr, addr + size - 1);
if (!addr) /* No dynamic ftrace there. */
goto error;
addrs[i] = addr;
}
return addrs;
error:
kfree(addrs);
return ERR_PTR(-ENOENT);
}
static void fprobe_init(struct fprobe *fp)
{
fp->nmissed = 0;
fp->ops.func = fprobe_handler;
fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
}
/**
* register_fprobe() - Register fprobe to ftrace by pattern.
* @fp: A fprobe data structure to be registered.
* @filter: A wildcard pattern of probed symbols.
* @notfilter: A wildcard pattern of NOT probed symbols.
*
* Register @fp to ftrace for enabling the probe on the symbols matched to @filter.
* If @notfilter is not NULL, the symbols matched the @notfilter are not probed.
*
* Return 0 if @fp is registered successfully, -errno if not.
*/
int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
{
unsigned char *str;
int ret, len;
if (!fp || !filter)
return -EINVAL;
fprobe_init(fp);
len = strlen(filter);
str = kstrdup(filter, GFP_KERNEL);
ret = ftrace_set_filter(&fp->ops, str, len, 0);
kfree(str);
if (ret)
return ret;
if (notfilter) {
len = strlen(notfilter);
str = kstrdup(notfilter, GFP_KERNEL);
ret = ftrace_set_notrace(&fp->ops, str, len, 0);
kfree(str);
if (ret)
goto out;
}
ret = register_ftrace_function(&fp->ops);
out:
if (ret)
ftrace_free_filter(&fp->ops);
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe);
/**
* register_fprobe_ips() - Register fprobe to ftrace by address.
* @fp: A fprobe data structure to be registered.
* @addrs: An array of target ftrace location addresses.
* @num: The number of entries of @addrs.
*
* Register @fp to ftrace for enabling the probe on the address given by @addrs.
* The @addrs must be the addresses of ftrace location address, which may be
* the symbol address + arch-dependent offset.
* If you unsure what this mean, please use other registration functions.
*
* Return 0 if @fp is registered successfully, -errno if not.
*/
int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
{
int ret;
if (!fp || !addrs || num <= 0)
return -EINVAL;
fprobe_init(fp);
ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0);
if (!ret)
ret = register_ftrace_function(&fp->ops);
if (ret)
ftrace_free_filter(&fp->ops);
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe_ips);
/**
* register_fprobe_syms() - Register fprobe to ftrace by symbols.
* @fp: A fprobe data structure to be registered.
* @syms: An array of target symbols.
* @num: The number of entries of @syms.
*
* Register @fp to the symbols given by @syms array. This will be useful if
* you are sure the symbols exist in the kernel.
*
* Return 0 if @fp is registered successfully, -errno if not.
*/
int register_fprobe_syms(struct fprobe *fp, const char **syms, int num)
{
unsigned long *addrs;
int ret;
if (!fp || !syms || num <= 0)
return -EINVAL;
addrs = get_ftrace_locations(syms, num);
if (IS_ERR(addrs))
return PTR_ERR(addrs);
ret = register_fprobe_ips(fp, addrs, num);
kfree(addrs);
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe_syms);
/**
* unregister_fprobe() - Unregister fprobe from ftrace
* @fp: A fprobe data structure to be unregistered.
*
* Unregister fprobe (and remove ftrace hooks from the function entries).
*
* Return 0 if @fp is unregistered successfully, -errno if not.
*/
int unregister_fprobe(struct fprobe *fp)
{
int ret;
if (!fp || fp->ops.func != fprobe_handler)
return -EINVAL;
ret = unregister_ftrace_function(&fp->ops);
if (!ret)
ftrace_free_filter(&fp->ops);
return ret;
}
EXPORT_SYMBOL_GPL(unregister_fprobe);
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