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tracing: probeevent: Introduce new argument fetching code 

Replace {k,u}probe event argument fetching framework with switch-case based.
Currently that is implemented with structures, macros and chain of
function-pointers, which is more complicated than necessary and may get a
performance penalty by retpoline.

This simplify that with an array of "fetch_insn" (opcode and oprands), and
make process_fetch_insn() just interprets it. No function pointers are used.

Link: http://lkml.kernel.org/r/152465868340.26224.2551120475197839464.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
hifive-unleashed-5.1
Masami Hiramatsu 2018-04-25 21:18:03 +09:00 committed by Steven Rostedt (VMware)
parent 7bfbc63eda
commit 533059281e
5 changed files with 489 additions and 676 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

291
kernel/trace/trace_kprobe.c
View File

@ -14,6 +14,7 @@
#include "trace_kprobe_selftest.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"
#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096
@ -120,160 +121,6 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);
/* Memory fetching by symbol */
struct symbol_cache {
char *symbol;
long offset;
unsigned long addr;
};
unsigned long update_symbol_cache(struct symbol_cache *sc)
{
sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
if (sc->addr)
sc->addr += sc->offset;
return sc->addr;
}
void free_symbol_cache(struct symbol_cache *sc)
{
kfree(sc->symbol);
kfree(sc);
}
struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
{
struct symbol_cache *sc;
if (!sym || strlen(sym) == 0)
return NULL;
sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
if (!sc)
return NULL;
sc->symbol = kstrdup(sym, GFP_KERNEL);
if (!sc->symbol) {
kfree(sc);
return NULL;
}
sc->offset = offset;
update_symbol_cache(sc);
return sc;
}
/*
* Kprobes-specific fetch functions
*/
#define DEFINE_FETCH_stack(type) \
static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs, \
void *offset, void *dest) \
{ \
*(type *)dest = (type)regs_get_kernel_stack_nth(regs, \
(unsigned int)((unsigned long)offset)); \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
DEFINE_BASIC_FETCH_FUNCS(stack)
/* No string on the stack entry */
#define fetch_stack_string NULL
#define fetch_stack_string_size NULL
#define DEFINE_FETCH_memory(type) \
static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs, \
void *addr, void *dest) \
{ \
type retval; \
if (probe_kernel_address(addr, retval)) \
*(type *)dest = 0; \
else \
*(type *)dest = retval; \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
DEFINE_BASIC_FETCH_FUNCS(memory)
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
* length and relative data location.
*/
static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
void *addr, void *dest)
{
int maxlen = get_rloc_len(*(u32 *)dest);
u8 *dst = get_rloc_data(dest);
long ret;
if (!maxlen)
return;
/*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_unsafe(dst, addr, maxlen);
if (ret < 0) { /* Failed to fetch string */
dst[0] = '\0';
*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
} else {
*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
}
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
/* Return the length of string -- including null terminal byte */
static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
void *addr, void *dest)
{
mm_segment_t old_fs;
int ret, len = 0;
u8 c;
old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
do {
ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
pagefault_enable();
set_fs(old_fs);
if (ret < 0) /* Failed to check the length */
*(u32 *)dest = 0;
else
*(u32 *)dest = len;
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
#define DEFINE_FETCH_symbol(type) \
void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
{ \
struct symbol_cache *sc = data; \
if (sc->addr) \
fetch_memory_##type(regs, (void *)sc->addr, dest); \
else \
*(type *)dest = 0; \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
DEFINE_BASIC_FETCH_FUNCS(symbol)
DEFINE_FETCH_symbol(string)
DEFINE_FETCH_symbol(string_size)
/* kprobes don't support file_offset fetch methods */
#define fetch_file_offset_u8 NULL
#define fetch_file_offset_u16 NULL
#define fetch_file_offset_u32 NULL
#define fetch_file_offset_u64 NULL
#define fetch_file_offset_string NULL
#define fetch_file_offset_string_size NULL
/* Fetch type information table */
static const struct fetch_type kprobes_fetch_type_table[] = {
/* Special types */
@ -529,7 +376,7 @@ static bool within_notrace_func(struct trace_kprobe *tk)
/* Internal register function - just handle k*probes and flags */
static int __register_trace_kprobe(struct trace_kprobe *tk)
{
int i, ret;
int ret;
if (trace_probe_is_registered(&tk->tp))
return -EINVAL;
@ -540,9 +387,6 @@ static int __register_trace_kprobe(struct trace_kprobe *tk)
return -EINVAL;
}
for (i = 0; i < tk->tp.nr_args; i++)
traceprobe_update_arg(&tk->tp.args[i]);
/* Set/clear disabled flag according to tp->flag */
if (trace_probe_is_enabled(&tk->tp))
tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
@ -876,8 +720,8 @@ static int create_trace_kprobe(int argc, char **argv)
/* Parse fetch argument */
ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
is_return, true,
kprobes_fetch_type_table);
is_return, true,
kprobes_fetch_type_table);
if (ret) {
pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
goto error;
@ -1031,6 +875,133 @@ static const struct file_operations kprobe_profile_ops = {
.release = seq_release,
};
/* Kprobe specific fetch functions */
/* Return the length of string -- including null terminal byte */
static nokprobe_inline void
fetch_store_strlen(unsigned long addr, void *dest)
{
mm_segment_t old_fs;
int ret, len = 0;
u8 c;
old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
do {
ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
pagefault_enable();
set_fs(old_fs);
if (ret < 0) /* Failed to check the length */
*(u32 *)dest = 0;
else
*(u32 *)dest = len;
}
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* length and relative data location.
*/
static nokprobe_inline void
fetch_store_string(unsigned long addr, void *dest)
{
int maxlen = get_rloc_len(*(u32 *)dest);
u8 *dst = get_rloc_data(dest);
long ret;
if (!maxlen)
return;
/*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_unsafe(dst, (void *)addr, maxlen);
if (ret < 0) { /* Failed to fetch string */
dst[0] = '\0';
*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
} else {
*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
}
}
/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
bool pre)
{
unsigned long val;
int ret;
/* 1st stage: get value from context */
switch (code->op) {
case FETCH_OP_REG:
val = regs_get_register(regs, code->param);
break;
case FETCH_OP_STACK:
val = regs_get_kernel_stack_nth(regs, code->param);
break;
case FETCH_OP_STACKP:
val = kernel_stack_pointer(regs);
break;
case FETCH_OP_RETVAL:
val = regs_return_value(regs);
break;
case FETCH_OP_IMM:
val = code->immediate;
break;
case FETCH_OP_COMM:
val = (unsigned long)current->comm;
break;
default:
return -EILSEQ;
}
code++;
/* 2nd stage: dereference memory if needed */
while (code->op == FETCH_OP_DEREF) {
ret = probe_kernel_read(&val, (void *)val + code->offset,
sizeof(val));
if (ret)
return ret;
code++;
}
/* 3rd stage: store value to buffer */
switch (code->op) {
case FETCH_OP_ST_RAW:
fetch_store_raw(val, code, dest);
break;
case FETCH_OP_ST_MEM:
probe_kernel_read(dest, (void *)val + code->offset, code->size);
break;
case FETCH_OP_ST_STRING:
if (pre)
fetch_store_strlen(val + code->offset, dest);
else
fetch_store_string(val + code->offset, dest);
break;
default:
return -EILSEQ;
}
code++;
/* 4th stage: modify stored value if needed */
if (code->op == FETCH_OP_MOD_BF) {
fetch_apply_bitfield(code, dest);
code++;
}
return code->op == FETCH_OP_END ? 0 : -EILSEQ;
}
NOKPROBE_SYMBOL(process_fetch_insn)
/* Kprobe handler */
static nokprobe_inline void
__kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,

399
kernel/trace/trace_probe.c
View File

@ -61,174 +61,6 @@ int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
#define CHECK_FETCH_FUNCS(method, fn) \
(((FETCH_FUNC_NAME(method, u8) == fn) || \
(FETCH_FUNC_NAME(method, u16) == fn) || \
(FETCH_FUNC_NAME(method, u32) == fn) || \
(FETCH_FUNC_NAME(method, u64) == fn) || \
(FETCH_FUNC_NAME(method, string) == fn) || \
(FETCH_FUNC_NAME(method, string_size) == fn)) \
&& (fn != NULL))
/* Data fetch function templates */
#define DEFINE_FETCH_reg(type) \
void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, void *offset, void *dest) \
{ \
*(type *)dest = (type)regs_get_register(regs, \
(unsigned int)((unsigned long)offset)); \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(reg, type));
DEFINE_BASIC_FETCH_FUNCS(reg)
/* No string on the register */
#define fetch_reg_string NULL
#define fetch_reg_string_size NULL
#define DEFINE_FETCH_retval(type) \
void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs, \
void *dummy, void *dest) \
{ \
*(type *)dest = (type)regs_return_value(regs); \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(retval, type));
DEFINE_BASIC_FETCH_FUNCS(retval)
/* No string on the retval */
#define fetch_retval_string NULL
#define fetch_retval_string_size NULL
/* Dereference memory access function */
struct deref_fetch_param {
struct fetch_param orig;
long offset;
fetch_func_t fetch;
fetch_func_t fetch_size;
};
#define DEFINE_FETCH_deref(type) \
void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \
void *data, void *dest) \
{ \
struct deref_fetch_param *dprm = data; \
unsigned long addr; \
call_fetch(&dprm->orig, regs, &addr); \
if (addr) { \
addr += dprm->offset; \
dprm->fetch(regs, (void *)addr, dest); \
} else \
*(type *)dest = 0; \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, type));
DEFINE_BASIC_FETCH_FUNCS(deref)
DEFINE_FETCH_deref(string)
void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
void *data, void *dest)
{
struct deref_fetch_param *dprm = data;
unsigned long addr;
call_fetch(&dprm->orig, regs, &addr);
if (addr && dprm->fetch_size) {
addr += dprm->offset;
dprm->fetch_size(regs, (void *)addr, dest);
} else
*(string_size *)dest = 0;
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(deref, string_size));
static void update_deref_fetch_param(struct deref_fetch_param *data)
{
if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
update_deref_fetch_param(data->orig.data);
else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
update_symbol_cache(data->orig.data);
}
NOKPROBE_SYMBOL(update_deref_fetch_param);
static void free_deref_fetch_param(struct deref_fetch_param *data)
{
if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
free_deref_fetch_param(data->orig.data);
else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
free_symbol_cache(data->orig.data);
kfree(data);
}
NOKPROBE_SYMBOL(free_deref_fetch_param);
/* Bitfield fetch function */
struct bitfield_fetch_param {
struct fetch_param orig;
unsigned char hi_shift;
unsigned char low_shift;
};
#define DEFINE_FETCH_bitfield(type) \
void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs, \
void *data, void *dest) \
{ \
struct bitfield_fetch_param *bprm = data; \
type buf = 0; \
call_fetch(&bprm->orig, regs, &buf); \
if (buf) { \
buf <<= bprm->hi_shift; \
buf >>= bprm->low_shift; \
} \
*(type *)dest = buf; \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(bitfield, type));
DEFINE_BASIC_FETCH_FUNCS(bitfield)
#define fetch_bitfield_string NULL
#define fetch_bitfield_string_size NULL
static void
update_bitfield_fetch_param(struct bitfield_fetch_param *data)
{
/*
* Don't check the bitfield itself, because this must be the
* last fetch function.
*/
if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
update_deref_fetch_param(data->orig.data);
else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
update_symbol_cache(data->orig.data);
}
static void
free_bitfield_fetch_param(struct bitfield_fetch_param *data)
{
/*
* Don't check the bitfield itself, because this must be the
* last fetch function.
*/
if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
free_deref_fetch_param(data->orig.data);
else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
free_symbol_cache(data->orig.data);
kfree(data);
}
void FETCH_FUNC_NAME(comm, string)(struct pt_regs *regs,
void *data, void *dest)
{
int maxlen = get_rloc_len(*(u32 *)dest);
u8 *dst = get_rloc_data(dest);
long ret;
if (!maxlen)
return;
ret = strlcpy(dst, current->comm, maxlen);
*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string));
void FETCH_FUNC_NAME(comm, string_size)(struct pt_regs *regs,
void *data, void *dest)
{
*(u32 *)dest = strlen(current->comm) + 1;
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(comm, string_size));
static const struct fetch_type *find_fetch_type(const char *type,
const struct fetch_type *ftbl)
{
@ -272,37 +104,6 @@ fail:
return NULL;
}
/* Special function : only accept unsigned long */
static void fetch_kernel_stack_address(struct pt_regs *regs, void *dummy, void *dest)
{
*(unsigned long *)dest = kernel_stack_pointer(regs);
}
NOKPROBE_SYMBOL(fetch_kernel_stack_address);
static void fetch_user_stack_address(struct pt_regs *regs, void *dummy, void *dest)
{
*(unsigned long *)dest = user_stack_pointer(regs);
}
NOKPROBE_SYMBOL(fetch_user_stack_address);
static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
fetch_func_t orig_fn,
const struct fetch_type *ftbl)
{
int i;
if (type != &ftbl[FETCH_TYPE_STRING])
return NULL; /* Only string type needs size function */
for (i = 0; i < FETCH_MTD_END; i++)
if (type->fetch[i] == orig_fn)
return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
WARN_ON(1); /* This should not happen */
return NULL;
}
/* Split symbol and offset. */
int traceprobe_split_symbol_offset(char *symbol, long *offset)
{
@ -327,7 +128,7 @@ int traceprobe_split_symbol_offset(char *symbol, long *offset)
#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
static int parse_probe_vars(char *arg, const struct fetch_type *t,
struct fetch_param *f, bool is_return,
struct fetch_insn *code, bool is_return,
bool is_kprobe)
{
int ret = 0;
@ -335,33 +136,24 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
if (strcmp(arg, "retval") == 0) {
if (is_return)
f->fn = t->fetch[FETCH_MTD_retval];
code->op = FETCH_OP_RETVAL;
else
ret = -EINVAL;
} else if (strncmp(arg, "stack", 5) == 0) {
if (arg[5] == '\0') {
if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
return -EINVAL;
if (is_kprobe)
f->fn = fetch_kernel_stack_address;
else
f->fn = fetch_user_stack_address;
code->op = FETCH_OP_STACKP;
} else if (isdigit(arg[5])) {
ret = kstrtoul(arg + 5, 10, &param);
if (ret || (is_kprobe && param > PARAM_MAX_STACK))
ret = -EINVAL;
else {
f->fn = t->fetch[FETCH_MTD_stack];
f->data = (void *)param;
code->op = FETCH_OP_STACK;
code->param = (unsigned int)param;
}
} else
ret = -EINVAL;
} else if (strcmp(arg, "comm") == 0) {
if (strcmp(t->name, "string") != 0 &&
strcmp(t->name, "string_size") != 0)
return -EINVAL;
f->fn = t->fetch[FETCH_MTD_comm];
code->op = FETCH_OP_COMM;
} else
ret = -EINVAL;
@ -369,10 +161,13 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
}
/* Recursive argument parser */
static int parse_probe_arg(char *arg, const struct fetch_type *t,
struct fetch_param *f, bool is_return, bool is_kprobe,
const struct fetch_type *ftbl)
static int
parse_probe_arg(char *arg, const struct fetch_type *type,
struct fetch_insn **pcode, struct fetch_insn *end,
bool is_return, bool is_kprobe,
const struct fetch_type *ftbl)
{
struct fetch_insn *code = *pcode;
unsigned long param;
long offset;
char *tmp;
@ -380,14 +175,15 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
switch (arg[0]) {
case '$':
ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
ret = parse_probe_vars(arg + 1, type, code,
is_return, is_kprobe);
break;
case '%': /* named register */
ret = regs_query_register_offset(arg + 1);
if (ret >= 0) {
f->fn = t->fetch[FETCH_MTD_reg];
f->data = (void *)(unsigned long)ret;
code->op = FETCH_OP_REG;
code->param = (unsigned int)ret;
ret = 0;
}
break;
@ -397,9 +193,9 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
ret = kstrtoul(arg + 1, 0, &param);
if (ret)
break;
f->fn = t->fetch[FETCH_MTD_memory];
f->data = (void *)param;
/* load address */
code->op = FETCH_OP_IMM;
code->immediate = param;
} else if (arg[1] == '+') {
/* kprobes don't support file offsets */
if (is_kprobe)
@ -409,8 +205,8 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
if (ret)
break;
f->fn = t->fetch[FETCH_MTD_file_offset];
f->data = (void *)offset;
code->op = FETCH_OP_FOFFS;
code->immediate = (unsigned long)offset; // imm64?
} else {
/* uprobes don't support symbols */
if (!is_kprobe)
@ -420,10 +216,19 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
if (ret)
break;
f->data = alloc_symbol_cache(arg + 1, offset);
if (f->data)
f->fn = t->fetch[FETCH_MTD_symbol];
code->op = FETCH_OP_IMM;
code->immediate =
(unsigned long)kallsyms_lookup_name(arg + 1);
if (!code->immediate)
return -ENOENT;
code->immediate += offset;
}
/* These are fetching from memory */
if (++code == end)
return -E2BIG;
*pcode = code;
code->op = FETCH_OP_DEREF;
code->offset = offset;
break;
case '+': /* deref memory */
@ -431,11 +236,10 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
case '-':
tmp = strchr(arg, '(');
if (!tmp)
break;
return -EINVAL;
*tmp = '\0';
ret = kstrtol(arg, 0, &offset);
if (ret)
break;
@ -443,36 +247,29 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
tmp = strrchr(arg, ')');
if (tmp) {
struct deref_fetch_param *dprm;
const struct fetch_type *t2;
const struct fetch_type *t2;
t2 = find_fetch_type(NULL, ftbl);
*tmp = '\0';
dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
if (!dprm)
return -ENOMEM;
dprm->offset = offset;
dprm->fetch = t->fetch[FETCH_MTD_memory];
dprm->fetch_size = get_fetch_size_function(t,
dprm->fetch, ftbl);
ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
is_kprobe, ftbl);
ret = parse_probe_arg(arg, t2, &code, end, is_return,
is_kprobe, ftbl);
if (ret)
kfree(dprm);
else {
f->fn = t->fetch[FETCH_MTD_deref];
f->data = (void *)dprm;
}
break;
if (code->op == FETCH_OP_COMM)
return -EINVAL;
if (++code == end)
return -E2BIG;
*pcode = code;
code->op = FETCH_OP_DEREF;
code->offset = offset;
}
break;
}
if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
pr_info("%s type has no corresponding fetch method.\n", t->name);
if (!ret && code->op == FETCH_OP_NOP) {
/* Parsed, but do not find fetch method */
ret = -EINVAL;
}
return ret;
}
@ -481,22 +278,15 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
/* Bitfield type needs to be parsed into a fetch function */
static int __parse_bitfield_probe_arg(const char *bf,
const struct fetch_type *t,
struct fetch_param *f)
struct fetch_insn **pcode)
{
struct bitfield_fetch_param *bprm;
struct fetch_insn *code = *pcode;
unsigned long bw, bo;
char *tail;
if (*bf != 'b')
return 0;
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
if (!bprm)
return -ENOMEM;
bprm->orig = *f;
f->fn = t->fetch[FETCH_MTD_bitfield];
f->data = (void *)bprm;
bw = simple_strtoul(bf + 1, &tail, 0); /* Use simple one */
if (bw == 0 || *tail != '@')
@ -507,9 +297,15 @@ static int __parse_bitfield_probe_arg(const char *bf,
if (tail == bf || *tail != '/')
return -EINVAL;
code++;
if (code->op != FETCH_OP_NOP)
return -E2BIG;
*pcode = code;
bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
bprm->low_shift = bprm->hi_shift + bo;
code->op = FETCH_OP_MOD_BF;
code->lshift = BYTES_TO_BITS(t->size) - (bw + bo);
code->rshift = BYTES_TO_BITS(t->size) - bw;
code->basesize = t->size;
return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
}
@ -519,6 +315,7 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
struct probe_arg *parg, bool is_return, bool is_kprobe,
const struct fetch_type *ftbl)
{
struct fetch_insn *code, *tmp = NULL;
const char *t;
int ret;
@ -549,18 +346,60 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
}
parg->offset = *size;
*size += parg->type->size;
ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
is_kprobe, ftbl);
if (ret >= 0 && t != NULL)
ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
if (!code)
return -ENOMEM;
code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;
if (ret >= 0) {
parg->fetch_size.fn = get_fetch_size_function(parg->type,
parg->fetch.fn,
ftbl);
parg->fetch_size.data = parg->fetch.data;
ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
is_return, is_kprobe, ftbl);
if (ret)
goto fail;
/* Store operation */
if (!strcmp(parg->type->name, "string")) {
if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_IMM &&
code->op != FETCH_OP_COMM) {
pr_info("string only accepts memory or address.\n");
ret = -EINVAL;
goto fail;
}
/* Since IMM or COMM must be the 1st insn, this is safe */
if (code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM)
code++;
code->op = FETCH_OP_ST_STRING; /* In DEREF case, replace it */
parg->dynamic = true;
} else if (code->op == FETCH_OP_DEREF) {
code->op = FETCH_OP_ST_MEM;
code->size = parg->type->size;
} else {
code++;
if (code->op != FETCH_OP_NOP) {
ret = -E2BIG;
goto fail;
}
code->op = FETCH_OP_ST_RAW;
code->size = parg->type->size;
}
/* Modify operation */
if (t != NULL) {
ret = __parse_bitfield_probe_arg(t, parg->type, &code);
if (ret)
goto fail;
}
code++;
code->op = FETCH_OP_END;
/* Shrink down the code buffer */
parg->code = kzalloc(sizeof(*code) * (code - tmp + 1), GFP_KERNEL);
if (!parg->code)
ret = -ENOMEM;
else
memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));
fail:
kfree(tmp);
return ret;
}
@ -582,25 +421,9 @@ int traceprobe_conflict_field_name(const char *name,
return 0;
}
void traceprobe_update_arg(struct probe_arg *arg)
{
if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
update_bitfield_fetch_param(arg->fetch.data);
else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
update_deref_fetch_param(arg->fetch.data);
else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
update_symbol_cache(arg->fetch.data);
}
void traceprobe_free_probe_arg(struct probe_arg *arg)
{
if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
free_bitfield_fetch_param(arg->fetch.data);
else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
free_deref_fetch_param(arg->fetch.data);
else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
free_symbol_cache(arg->fetch.data);
kfree(arg->code);
kfree(arg->name);
kfree(arg->comm);
}

230
kernel/trace/trace_probe.h
View File

@ -79,25 +79,50 @@ static nokprobe_inline void *get_loc_data(u32 *dl, void *ent)
return (u8 *)ent + get_rloc_offs(*dl);
}
/* Data fetch function type */
typedef void (*fetch_func_t)(struct pt_regs *, void *, void *);
/* Printing function type */
typedef int (*print_type_func_t)(struct trace_seq *, void *, void *);
/* Fetch types */
enum {
FETCH_MTD_reg = 0,
FETCH_MTD_stack,
FETCH_MTD_retval,
FETCH_MTD_comm,
FETCH_MTD_memory,
FETCH_MTD_symbol,
FETCH_MTD_deref,
FETCH_MTD_bitfield,
FETCH_MTD_file_offset,
FETCH_MTD_END,
enum fetch_op {
FETCH_OP_NOP = 0,
// Stage 1 (load) ops
FETCH_OP_REG, /* Register : .param = offset */
FETCH_OP_STACK, /* Stack : .param = index */
FETCH_OP_STACKP, /* Stack pointer */
FETCH_OP_RETVAL, /* Return value */
FETCH_OP_IMM, /* Immediate : .immediate */
FETCH_OP_COMM, /* Current comm */
FETCH_OP_FOFFS, /* File offset: .immediate */
// Stage 2 (dereference) op
FETCH_OP_DEREF, /* Dereference: .offset */
// Stage 3 (store) ops
FETCH_OP_ST_RAW, /* Raw: .size */
FETCH_OP_ST_MEM, /* Mem: .offset, .size */
FETCH_OP_ST_STRING, /* String: .offset, .size */
// Stage 4 (modify) op
FETCH_OP_MOD_BF, /* Bitfield: .basesize, .lshift, .rshift */
FETCH_OP_END,
};
struct fetch_insn {
enum fetch_op op;
union {
unsigned int param;
struct {
unsigned int size;
int offset;
};
struct {
unsigned char basesize;
unsigned char lshift;
unsigned char rshift;
};
unsigned long immediate;
};
};
/* fetch + deref*N + store + mod + end <= 16, this allows N=12, enough */
#define FETCH_INSN_MAX 16
/* Fetch type information table */
struct fetch_type {
const char *name; /* Name of type */
@ -106,13 +131,6 @@ struct fetch_type {
print_type_func_t print; /* Print functions */
const char *fmt; /* Fromat string */
const char *fmttype; /* Name in format file */
/* Fetch functions */
fetch_func_t fetch[FETCH_MTD_END];
};
struct fetch_param {
fetch_func_t fn;
void *data;
};
/* For defining macros, define string/string_size types */
@ -142,66 +160,12 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(x64);
DECLARE_BASIC_PRINT_TYPE_FUNC(string);
#define FETCH_FUNC_NAME(method, type) fetch_##method##_##type
/* Declare macro for basic types */
#define DECLARE_FETCH_FUNC(method, type) \
extern void FETCH_FUNC_NAME(method, type)(struct pt_regs *regs, \
void *data, void *dest)
#define DECLARE_BASIC_FETCH_FUNCS(method) \
DECLARE_FETCH_FUNC(method, u8); \
DECLARE_FETCH_FUNC(method, u16); \
DECLARE_FETCH_FUNC(method, u32); \
DECLARE_FETCH_FUNC(method, u64)
DECLARE_BASIC_FETCH_FUNCS(reg);
#define fetch_reg_string NULL
#define fetch_reg_string_size NULL
DECLARE_BASIC_FETCH_FUNCS(retval);
#define fetch_retval_string NULL
#define fetch_retval_string_size NULL
DECLARE_BASIC_FETCH_FUNCS(symbol);
DECLARE_FETCH_FUNC(symbol, string);
DECLARE_FETCH_FUNC(symbol, string_size);
DECLARE_BASIC_FETCH_FUNCS(deref);
DECLARE_FETCH_FUNC(deref, string);
DECLARE_FETCH_FUNC(deref, string_size);
DECLARE_BASIC_FETCH_FUNCS(bitfield);
#define fetch_bitfield_string NULL
#define fetch_bitfield_string_size NULL
/* comm only makes sense as a string */
#define fetch_comm_u8 NULL
#define fetch_comm_u16 NULL
#define fetch_comm_u32 NULL
#define fetch_comm_u64 NULL
DECLARE_FETCH_FUNC(comm, string);
DECLARE_FETCH_FUNC(comm, string_size);
/*
* Define macro for basic types - we don't need to define s* types, because
* we have to care only about bitwidth at recording time.
*/
#define DEFINE_BASIC_FETCH_FUNCS(method) \
DEFINE_FETCH_##method(u8) \
DEFINE_FETCH_##method(u16) \
DEFINE_FETCH_##method(u32) \
DEFINE_FETCH_##method(u64)
/* Default (unsigned long) fetch type */
#define __DEFAULT_FETCH_TYPE(t) x##t
#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
#define ASSIGN_FETCH_FUNC(method, type) \
[FETCH_MTD_##method] = FETCH_FUNC_NAME(method, type)
#define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype) \
{.name = _name, \
.size = _size, \
@ -209,17 +173,6 @@ DEFINE_FETCH_##method(u64)
.print = PRINT_TYPE_FUNC_NAME(ptype), \
.fmt = PRINT_TYPE_FMT_NAME(ptype), \
.fmttype = _fmttype, \
.fetch = { \
ASSIGN_FETCH_FUNC(reg, ftype), \
ASSIGN_FETCH_FUNC(stack, ftype), \
ASSIGN_FETCH_FUNC(retval, ftype), \
ASSIGN_FETCH_FUNC(comm, ftype), \
ASSIGN_FETCH_FUNC(memory, ftype), \
ASSIGN_FETCH_FUNC(symbol, ftype), \
ASSIGN_FETCH_FUNC(deref, ftype), \
ASSIGN_FETCH_FUNC(bitfield, ftype), \
ASSIGN_FETCH_FUNC(file_offset, ftype), \
} \
}
#define ASSIGN_FETCH_TYPE(ptype, ftype, sign) \
@ -231,42 +184,13 @@ ASSIGN_FETCH_FUNC(file_offset, ftype), \
#define ASSIGN_FETCH_TYPE_END {}
#define FETCH_TYPE_STRING 0
#define FETCH_TYPE_STRSIZE 1
#define FETCH_TYPE_STRING 0
#define FETCH_TYPE_STRSIZE 1
#ifdef CONFIG_KPROBE_EVENTS
struct symbol_cache;
unsigned long update_symbol_cache(struct symbol_cache *sc);
void free_symbol_cache(struct symbol_cache *sc);
struct symbol_cache *alloc_symbol_cache(const char *sym, long offset);
bool trace_kprobe_on_func_entry(struct trace_event_call *call);
bool trace_kprobe_error_injectable(struct trace_event_call *call);
#else
/* uprobes do not support symbol fetch methods */
#define fetch_symbol_u8 NULL
#define fetch_symbol_u16 NULL
#define fetch_symbol_u32 NULL
#define fetch_symbol_u64 NULL
#define fetch_symbol_string NULL
#define fetch_symbol_string_size NULL
struct symbol_cache {
};
static inline unsigned long __used update_symbol_cache(struct symbol_cache *sc)
{
return 0;
}
static inline void __used free_symbol_cache(struct symbol_cache *sc)
{
}
static inline struct symbol_cache * __used
alloc_symbol_cache(const char *sym, long offset)
{
return NULL;
}
static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
return false;
@ -279,8 +203,8 @@ static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
#endif /* CONFIG_KPROBE_EVENTS */
struct probe_arg {
struct fetch_param fetch;
struct fetch_param fetch_size;
struct fetch_insn *code;
bool dynamic;/* Dynamic array (string) is used */
unsigned int offset; /* Offset from argument entry */
const char *name; /* Name of this argument */
const char *comm; /* Command of this argument */
@ -312,12 +236,6 @@ static inline bool trace_probe_is_registered(struct trace_probe *tp)
return !!(tp->flags & TP_FLAG_REGISTERED);
}
static nokprobe_inline void call_fetch(struct fetch_param *fprm,
struct pt_regs *regs, void *dest)
{
return fprm->fn(regs, fprm->data, dest);
}
/* Check the name is good for event/group/fields */
static inline bool is_good_name(const char *name)
{
@ -354,68 +272,6 @@ extern void traceprobe_free_probe_arg(struct probe_arg *arg);
extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
/* Sum up total data length for dynamic arraies (strings) */
static nokprobe_inline int
__get_data_size(struct trace_probe *tp, struct pt_regs *regs)
{
int i, ret = 0;
u32 len;
for (i = 0; i < tp->nr_args; i++)
if (unlikely(tp->args[i].fetch_size.fn)) {
call_fetch(&tp->args[i].fetch_size, regs, &len);
ret += len;
}
return ret;
}
/* Store the value of each argument */
static nokprobe_inline void
store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
u8 *data, int maxlen)
{
int i;
u32 end = tp->size;
u32 *dl; /* Data (relative) location */
for (i = 0; i < tp->nr_args; i++) {
if (unlikely(tp->args[i].fetch_size.fn)) {
/*
* First, we set the relative location and
* maximum data length to *dl
*/
dl = (u32 *)(data + tp->args[i].offset);
*dl = make_data_rloc(maxlen, end - tp->args[i].offset);
/* Then try to fetch string or dynamic array data */
call_fetch(&tp->args[i].fetch, regs, dl);
/* Reduce maximum length */
end += get_rloc_len(*dl);
maxlen -= get_rloc_len(*dl);
/* Trick here, convert data_rloc to data_loc */
*dl = convert_rloc_to_loc(*dl,
ent_size + tp->args[i].offset);
} else
/* Just fetching data normally */
call_fetch(&tp->args[i].fetch, regs,
data + tp->args[i].offset);
}
}
static inline int
print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
u8 *data, void *field)
{
int i;
for (i = 0; i < nr_args; i++) {
trace_seq_printf(s, " %s=", args[i].name);
if (!args[i].type->print(s, data + args[i].offset, field))
return -ENOMEM;
}
return 0;
}
extern int set_print_fmt(struct trace_probe *tp, bool is_return);
#ifdef CONFIG_PERF_EVENTS

120
kernel/trace/trace_probe_tmpl.h 100644
View File

@ -0,0 +1,120 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Traceprobe fetch helper inlines
*/
static nokprobe_inline void
fetch_store_raw(unsigned long val, struct fetch_insn *code, void *buf)
{
switch (code->size) {
case 1:
*(u8 *)buf = (u8)val;
break;
case 2:
*(u16 *)buf = (u16)val;
break;
case 4:
*(u32 *)buf = (u32)val;
break;
case 8:
//TBD: 32bit signed
*(u64 *)buf = (u64)val;
break;
default:
*(unsigned long *)buf = val;
}
}
static nokprobe_inline void
fetch_apply_bitfield(struct fetch_insn *code, void *buf)
{
switch (code->basesize) {
case 1:
*(u8 *)buf <<= code->lshift;
*(u8 *)buf >>= code->rshift;
break;
case 2:
*(u16 *)buf <<= code->lshift;
*(u16 *)buf >>= code->rshift;
break;
case 4:
*(u32 *)buf <<= code->lshift;
*(u32 *)buf >>= code->rshift;
break;
case 8:
*(u64 *)buf <<= code->lshift;
*(u64 *)buf >>= code->rshift;
break;
}
}
/* Define this for each callsite */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs,
void *dest, bool pre);
/* Sum up total data length for dynamic arraies (strings) */
static nokprobe_inline int
__get_data_size(struct trace_probe *tp, struct pt_regs *regs)
{
struct probe_arg *arg;
int i, ret = 0;
u32 len;
for (i = 0; i < tp->nr_args; i++) {
arg = tp->args + i;
if (unlikely(arg->dynamic)) {
process_fetch_insn(arg->code, regs, &len, true);
ret += len;
}
}
return ret;
}
/* Store the value of each argument */
static nokprobe_inline void
store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
u8 *data, int maxlen)
{
struct probe_arg *arg;
u32 end = tp->size;
u32 *dl; /* Data (relative) location */
int i;
for (i = 0; i < tp->nr_args; i++) {
arg = tp->args + i;
if (unlikely(arg->dynamic)) {
/*
* First, we set the relative location and
* maximum data length to *dl
*/
dl = (u32 *)(data + arg->offset);
*dl = make_data_rloc(maxlen, end - arg->offset);
/* Then try to fetch string or dynamic array data */
process_fetch_insn(arg->code, regs, dl, false);
/* Reduce maximum length */
end += get_rloc_len(*dl);
maxlen -= get_rloc_len(*dl);
/* Trick here, convert data_rloc to data_loc */
*dl = convert_rloc_to_loc(*dl, ent_size + arg->offset);
} else
/* Just fetching data normally */
process_fetch_insn(arg->code, regs, data + arg->offset,
false);
}
}
static inline int
print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
u8 *data, void *field)
{
int i;
for (i = 0; i < nr_args; i++) {
trace_seq_printf(s, " %s=", args[i].name);
if (!args[i].type->print(s, data + args[i].offset, field))
return -ENOMEM;
}
return 0;
}

125
kernel/trace/trace_uprobe.c
View File

@ -15,6 +15,7 @@
#include <linux/rculist.h>
#include "trace_probe.h"
#include "trace_probe_tmpl.h"
#define UPROBE_EVENT_SYSTEM "uprobes"
@ -99,37 +100,19 @@ static unsigned long get_user_stack_nth(struct pt_regs *regs, unsigned int n)
/*
* Uprobes-specific fetch functions
*/
#define DEFINE_FETCH_stack(type) \
static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs, \
void *offset, void *dest) \
{ \
*(type *)dest = (type)get_user_stack_nth(regs, \
((unsigned long)offset)); \
}
DEFINE_BASIC_FETCH_FUNCS(stack)
/* No string on the stack entry */
#define fetch_stack_string NULL
#define fetch_stack_string_size NULL
static nokprobe_inline int
probe_user_read(void *dest, void *src, size_t size)
{
void __user *vaddr = (void __force __user *)src;
#define DEFINE_FETCH_memory(type) \
static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs, \
void *addr, void *dest) \
{ \
type retval; \
void __user *vaddr = (void __force __user *) addr; \
\
if (copy_from_user(&retval, vaddr, sizeof(type))) \
*(type *)dest = 0; \
else \
*(type *) dest = retval; \
return copy_from_user(dest, vaddr, size);
}
DEFINE_BASIC_FETCH_FUNCS(memory)
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
* length and relative data location.
*/
static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
void *addr, void *dest)
static nokprobe_inline void
fetch_store_string(unsigned long addr, void *dest)
{
long ret;
u32 rloc = *(u32 *)dest;
@ -152,8 +135,9 @@ static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
}
}
static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
void *addr, void *dest)
/* Return the length of string -- including null terminal byte */
static nokprobe_inline void
fetch_store_strlen(unsigned long addr, void *dest)
{
int len;
void __user *vaddr = (void __force __user *) addr;
@ -166,7 +150,7 @@ static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
*(u32 *)dest = len;
}
static unsigned long translate_user_vaddr(void *file_offset)
static unsigned long translate_user_vaddr(unsigned long file_offset)
{
unsigned long base_addr;
struct uprobe_dispatch_data *udd;
@ -174,21 +158,9 @@ static unsigned long translate_user_vaddr(void *file_offset)
udd = (void *) current->utask->vaddr;
base_addr = udd->bp_addr - udd->tu->offset;
return base_addr + (unsigned long)file_offset;
return base_addr + file_offset;
}
#define DEFINE_FETCH_file_offset(type) \
static void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs, \
void *offset, void *dest)\
{ \
void *vaddr = (void *)translate_user_vaddr(offset); \
\
FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest); \
}
DEFINE_BASIC_FETCH_FUNCS(file_offset)
DEFINE_FETCH_file_offset(string)
DEFINE_FETCH_file_offset(string_size)
/* Fetch type information table */
static const struct fetch_type uprobes_fetch_type_table[] = {
/* Special types */
@ -213,6 +185,77 @@ static const struct fetch_type uprobes_fetch_type_table[] = {
ASSIGN_FETCH_TYPE_END
};
/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
bool pre)
{
unsigned long val;
int ret;
/* 1st stage: get value from context */
switch (code->op) {
case FETCH_OP_REG:
val = regs_get_register(regs, code->param);
break;
case FETCH_OP_STACK:
val = get_user_stack_nth(regs, code->param);
break;
case FETCH_OP_STACKP:
val = user_stack_pointer(regs);
break;
case FETCH_OP_RETVAL:
val = regs_return_value(regs);
break;
case FETCH_OP_IMM:
val = code->immediate;
break;
case FETCH_OP_FOFFS:
val = translate_user_vaddr(code->immediate);
break;
default:
return -EILSEQ;
}
code++;
/* 2nd stage: dereference memory if needed */
while (code->op == FETCH_OP_DEREF) {
ret = probe_user_read(&val, (void *)val + code->offset,
sizeof(val));
if (ret)
return ret;
code++;
}
/* 3rd stage: store value to buffer */
switch (code->op) {
case FETCH_OP_ST_RAW:
fetch_store_raw(val, code, dest);
break;
case FETCH_OP_ST_MEM:
probe_user_read(dest, (void *)val + code->offset, code->size);
break;
case FETCH_OP_ST_STRING:
if (pre)
fetch_store_strlen(val + code->offset, dest);
else
fetch_store_string(val + code->offset, dest);
break;
default:
return -EILSEQ;
}
code++;
/* 4th stage: modify stored value if needed */
if (code->op == FETCH_OP_MOD_BF) {
fetch_apply_bitfield(code, dest);
code++;
}
return code->op == FETCH_OP_END ? 0 : -EILSEQ;
}
NOKPROBE_SYMBOL(process_fetch_insn)
static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
{
rwlock_init(&filter->rwlock);