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fprobe: Rewrite fprobe on function-graph tracer

Rewrite fprobe implementation on function-graph tracer.
Major API changes are:
 -  'nr_maxactive' field is deprecated.
 -  This depends on CONFIG_DYNAMIC_FTRACE_WITH_ARGS or
    !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, and
    CONFIG_HAVE_FUNCTION_GRAPH_FREGS. So currently works only
    on x86_64.
 -  Currently the entry size is limited in 15 * sizeof(long).
 -  If there is too many fprobe exit handler set on the same
    function, it will fail to probe.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/173519003970.391279.14406792285453830996.stgit@devnote2
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu (Google) 2024-12-26 14:13:59 +09:00 committed by Steven Rostedt (Google)
parent 7495e179b4
commit 4346ba1604
10 changed files with 545 additions and 252 deletions

View file

@ -135,6 +135,12 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)
return arch_ftrace_regs(fregs)->fp;
}
static __always_inline unsigned long
ftrace_regs_get_return_address(const struct ftrace_regs *fregs)
{
return arch_ftrace_regs(fregs)->lr;
}
static __always_inline struct pt_regs *
ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
{

View file

@ -61,6 +61,12 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
#define ftrace_regs_get_frame_pointer(fregs) \
(arch_ftrace_regs(fregs)->regs.regs[22])
static __always_inline unsigned long
ftrace_regs_get_return_address(struct ftrace_regs *fregs)
{
return *(unsigned long *)(arch_ftrace_regs(fregs)->regs.regs[1]);
}
#define ftrace_graph_func ftrace_graph_func
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);

View file

@ -57,6 +57,12 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
regs_set_return_ip(&arch_ftrace_regs(fregs)->regs, ip);
}
static __always_inline unsigned long
ftrace_regs_get_return_address(struct ftrace_regs *fregs)
{
return arch_ftrace_regs(fregs)->regs.link;
}
struct ftrace_ops;
#define ftrace_graph_func ftrace_graph_func

View file

@ -186,6 +186,11 @@ static __always_inline unsigned long ftrace_regs_get_return_value(const struct f
return arch_ftrace_regs(fregs)->a0;
}
static __always_inline unsigned long ftrace_regs_get_return_address(const struct ftrace_regs *fregs)
{
return arch_ftrace_regs(fregs)->ra;
}
static __always_inline void ftrace_regs_set_return_value(struct ftrace_regs *fregs,
unsigned long ret)
{

View file

@ -77,6 +77,12 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
return ftrace_regs_get_stack_pointer(fregs);
}
static __always_inline unsigned long
ftrace_regs_get_return_address(const struct ftrace_regs *fregs)
{
return arch_ftrace_regs(fregs)->regs.gprs[14];
}
#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \
(_regs)->psw.mask = 0; \
(_regs)->psw.addr = arch_ftrace_regs(fregs)->regs.psw.addr; \

View file

@ -58,6 +58,12 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
do { arch_ftrace_regs(fregs)->regs.ip = (_ip); } while (0)
static __always_inline unsigned long
ftrace_regs_get_return_address(struct ftrace_regs *fregs)
{
return *(unsigned long *)ftrace_regs_get_stack_pointer(fregs);
}
struct ftrace_ops;
#define ftrace_graph_func ftrace_graph_func
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

View file

@ -5,10 +5,11 @@
#include <linux/compiler.h>
#include <linux/ftrace.h>
#include <linux/rethook.h>
#include <linux/rcupdate.h>
#include <linux/refcount.h>
#include <linux/slab.h>
struct fprobe;
typedef int (*fprobe_entry_cb)(struct fprobe *fp, unsigned long entry_ip,
unsigned long ret_ip, struct ftrace_regs *regs,
void *entry_data);
@ -17,35 +18,57 @@ typedef void (*fprobe_exit_cb)(struct fprobe *fp, unsigned long entry_ip,
unsigned long ret_ip, struct ftrace_regs *regs,
void *entry_data);
/**
* struct fprobe_hlist_node - address based hash list node for fprobe.
*
* @hlist: The hlist node for address search hash table.
* @addr: One of the probing address of @fp.
* @fp: The fprobe which owns this.
*/
struct fprobe_hlist_node {
struct hlist_node hlist;
unsigned long addr;
struct fprobe *fp;
};
/**
* struct fprobe_hlist - hash list nodes for fprobe.
*
* @hlist: The hlist node for existence checking hash table.
* @rcu: rcu_head for RCU deferred release.
* @fp: The fprobe which owns this fprobe_hlist.
* @size: The size of @array.
* @array: The fprobe_hlist_node for each address to probe.
*/
struct fprobe_hlist {
struct hlist_node hlist;
struct rcu_head rcu;
struct fprobe *fp;
int size;
struct fprobe_hlist_node array[] __counted_by(size);
};
/**
* struct fprobe - ftrace based probe.
* @ops: The ftrace_ops.
*
* @nmissed: The counter for missing events.
* @flags: The status flag.
* @rethook: The rethook data structure. (internal data)
* @entry_data_size: The private data storage size.
* @nr_maxactive: The max number of active functions.
* @nr_maxactive: The max number of active functions. (*deprecated)
* @entry_handler: The callback function for function entry.
* @exit_handler: The callback function for function exit.
* @hlist_array: The fprobe_hlist for fprobe search from IP hash table.
*/
struct fprobe {
#ifdef CONFIG_FUNCTION_TRACER
/*
* If CONFIG_FUNCTION_TRACER is not set, CONFIG_FPROBE is disabled too.
* But user of fprobe may keep embedding the struct fprobe on their own
* code. To avoid build error, this will keep the fprobe data structure
* defined here, but remove ftrace_ops data structure.
*/
struct ftrace_ops ops;
#endif
unsigned long nmissed;
unsigned int flags;
struct rethook *rethook;
size_t entry_data_size;
int nr_maxactive;
fprobe_entry_cb entry_handler;
fprobe_exit_cb exit_handler;
struct fprobe_hlist *hlist_array;
};
/* This fprobe is soft-disabled. */
@ -121,4 +144,9 @@ static inline void enable_fprobe(struct fprobe *fp)
fp->flags &= ~FPROBE_FL_DISABLED;
}
/* The entry data size is 4 bits (=16) * sizeof(long) in maximum */
#define FPROBE_DATA_SIZE_BITS 4
#define MAX_FPROBE_DATA_SIZE_WORD ((1L << FPROBE_DATA_SIZE_BITS) - 1)
#define MAX_FPROBE_DATA_SIZE (MAX_FPROBE_DATA_SIZE_WORD * sizeof(long))
#endif

View file

@ -307,11 +307,9 @@ config DYNAMIC_FTRACE_WITH_ARGS
config FPROBE
bool "Kernel Function Probe (fprobe)"
depends on FUNCTION_TRACER
depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
depends on HAVE_FTRACE_REGS_HAVING_PT_REGS || !HAVE_DYNAMIC_FTRACE_WITH_ARGS
depends on HAVE_RETHOOK
select RETHOOK
depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC
depends on DYNAMIC_FTRACE_WITH_ARGS
select FUNCTION_GRAPH_TRACER
default n
help
This option enables kernel function probe (fprobe) based on ftrace.

View file

@ -8,98 +8,195 @@
#include <linux/fprobe.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/rethook.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include "trace.h"
struct fprobe_rethook_node {
struct rethook_node node;
unsigned long entry_ip;
unsigned long entry_parent_ip;
char data[];
};
#define FPROBE_IP_HASH_BITS 8
#define FPROBE_IP_TABLE_SIZE (1 << FPROBE_IP_HASH_BITS)
static inline void __fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
struct fprobe_rethook_node *fpr;
struct rethook_node *rh = NULL;
struct fprobe *fp;
void *entry_data = NULL;
int ret = 0;
#define FPROBE_HASH_BITS 6
#define FPROBE_TABLE_SIZE (1 << FPROBE_HASH_BITS)
fp = container_of(ops, struct fprobe, ops);
#define SIZE_IN_LONG(x) ((x + sizeof(long) - 1) >> (sizeof(long) == 8 ? 3 : 2))
if (fp->exit_handler) {
rh = rethook_try_get(fp->rethook);
if (!rh) {
fp->nmissed++;
return;
}
fpr = container_of(rh, struct fprobe_rethook_node, node);
fpr->entry_ip = ip;
fpr->entry_parent_ip = parent_ip;
if (fp->entry_data_size)
entry_data = fpr->data;
}
if (fp->entry_handler)
ret = fp->entry_handler(fp, ip, parent_ip, fregs, entry_data);
/* If entry_handler returns !0, nmissed is not counted. */
if (rh) {
if (ret)
rethook_recycle(rh);
else
rethook_hook(rh, ftrace_get_regs(fregs), true);
}
}
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;
/* recursion detection has to go before any traceable function and
* all functions before this point should be marked as notrace
/*
* fprobe_table: hold 'fprobe_hlist::hlist' for checking the fprobe still
* exists. The key is the address of fprobe instance.
* fprobe_ip_table: hold 'fprobe_hlist::array[*]' for searching the fprobe
* instance related to the funciton address. The key is the ftrace IP
* address.
*
* When unregistering the fprobe, fprobe_hlist::fp and fprobe_hlist::array[*].fp
* are set NULL and delete those from both hash tables (by hlist_del_rcu).
* After an RCU grace period, the fprobe_hlist itself will be released.
*
* fprobe_table and fprobe_ip_table can be accessed from either
* - Normal hlist traversal and RCU add/del under 'fprobe_mutex' is held.
* - RCU hlist traversal under disabling preempt
*/
bit = ftrace_test_recursion_trylock(ip, parent_ip);
if (bit < 0) {
fp->nmissed++;
return;
}
__fprobe_handler(ip, parent_ip, ops, fregs);
ftrace_test_recursion_unlock(bit);
static struct hlist_head fprobe_table[FPROBE_TABLE_SIZE];
static struct hlist_head fprobe_ip_table[FPROBE_IP_TABLE_SIZE];
static DEFINE_MUTEX(fprobe_mutex);
}
NOKPROBE_SYMBOL(fprobe_handler);
static void fprobe_kprobe_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;
/* recursion detection has to go before any traceable function and
* all functions called before this point should be marked as notrace
/*
* Find first fprobe in the hlist. It will be iterated twice in the entry
* probe, once for correcting the total required size, the second time is
* calling back the user handlers.
* Thus the hlist in the fprobe_table must be sorted and new probe needs to
* be added *before* the first fprobe.
*/
bit = ftrace_test_recursion_trylock(ip, parent_ip);
if (bit < 0) {
fp->nmissed++;
static struct fprobe_hlist_node *find_first_fprobe_node(unsigned long ip)
{
struct fprobe_hlist_node *node;
struct hlist_head *head;
head = &fprobe_ip_table[hash_ptr((void *)ip, FPROBE_IP_HASH_BITS)];
hlist_for_each_entry_rcu(node, head, hlist,
lockdep_is_held(&fprobe_mutex)) {
if (node->addr == ip)
return node;
}
return NULL;
}
NOKPROBE_SYMBOL(find_first_fprobe_node);
/* Node insertion and deletion requires the fprobe_mutex */
static void insert_fprobe_node(struct fprobe_hlist_node *node)
{
unsigned long ip = node->addr;
struct fprobe_hlist_node *next;
struct hlist_head *head;
lockdep_assert_held(&fprobe_mutex);
next = find_first_fprobe_node(ip);
if (next) {
hlist_add_before_rcu(&node->hlist, &next->hlist);
return;
}
head = &fprobe_ip_table[hash_ptr((void *)ip, FPROBE_IP_HASH_BITS)];
hlist_add_head_rcu(&node->hlist, head);
}
/* Return true if there are synonims */
static bool delete_fprobe_node(struct fprobe_hlist_node *node)
{
lockdep_assert_held(&fprobe_mutex);
WRITE_ONCE(node->fp, NULL);
hlist_del_rcu(&node->hlist);
return !!find_first_fprobe_node(node->addr);
}
/* Check existence of the fprobe */
static bool is_fprobe_still_exist(struct fprobe *fp)
{
struct hlist_head *head;
struct fprobe_hlist *fph;
head = &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)];
hlist_for_each_entry_rcu(fph, head, hlist,
lockdep_is_held(&fprobe_mutex)) {
if (fph->fp == fp)
return true;
}
return false;
}
NOKPROBE_SYMBOL(is_fprobe_still_exist);
static int add_fprobe_hash(struct fprobe *fp)
{
struct fprobe_hlist *fph = fp->hlist_array;
struct hlist_head *head;
lockdep_assert_held(&fprobe_mutex);
if (WARN_ON_ONCE(!fph))
return -EINVAL;
if (is_fprobe_still_exist(fp))
return -EEXIST;
head = &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)];
hlist_add_head_rcu(&fp->hlist_array->hlist, head);
return 0;
}
static int del_fprobe_hash(struct fprobe *fp)
{
struct fprobe_hlist *fph = fp->hlist_array;
lockdep_assert_held(&fprobe_mutex);
if (WARN_ON_ONCE(!fph))
return -EINVAL;
if (!is_fprobe_still_exist(fp))
return -ENOENT;
fph->fp = NULL;
hlist_del_rcu(&fph->hlist);
return 0;
}
/* Generic fprobe_header */
struct __fprobe_header {
struct fprobe *fp;
unsigned long size_words;
} __packed;
#define FPROBE_HEADER_SIZE_IN_LONG SIZE_IN_LONG(sizeof(struct __fprobe_header))
static inline bool write_fprobe_header(unsigned long *stack,
struct fprobe *fp, unsigned int size_words)
{
struct __fprobe_header *fph = (struct __fprobe_header *)stack;
if (WARN_ON_ONCE(size_words > MAX_FPROBE_DATA_SIZE_WORD))
return false;
fph->fp = fp;
fph->size_words = size_words;
return true;
}
static inline void read_fprobe_header(unsigned long *stack,
struct fprobe **fp, unsigned int *size_words)
{
struct __fprobe_header *fph = (struct __fprobe_header *)stack;
*fp = fph->fp;
*size_words = fph->size_words;
}
/*
* fprobe shadow stack management:
* Since fprobe shares a single fgraph_ops, it needs to share the stack entry
* among the probes on the same function exit. Note that a new probe can be
* registered before a target function is returning, we can not use the hash
* table to find the corresponding probes. Thus the probe address is stored on
* the shadow stack with its entry data size.
*
*/
static inline int __fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct fprobe *fp, struct ftrace_regs *fregs,
void *data)
{
if (!fp->entry_handler)
return 0;
return fp->entry_handler(fp, ip, parent_ip, fregs, data);
}
static inline int __fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
struct fprobe *fp, struct ftrace_regs *fregs,
void *data)
{
int ret;
/*
* This user handler is shared with other kprobes and is not expected to be
* called recursively. So if any other kprobe handler is running, this will
@ -108,45 +205,183 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
*/
if (unlikely(kprobe_running())) {
fp->nmissed++;
goto recursion_unlock;
return 0;
}
kprobe_busy_begin();
__fprobe_handler(ip, parent_ip, ops, fregs);
ret = __fprobe_handler(ip, parent_ip, fp, fregs, data);
kprobe_busy_end();
recursion_unlock:
ftrace_test_recursion_unlock(bit);
return ret;
}
static void fprobe_exit_handler(struct rethook_node *rh, void *data,
unsigned long ret_ip, struct pt_regs *regs)
static int fprobe_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
struct ftrace_regs *fregs)
{
struct fprobe *fp = (struct fprobe *)data;
struct fprobe_rethook_node *fpr;
struct ftrace_regs *fregs = (struct ftrace_regs *)regs;
int bit;
struct fprobe_hlist_node *node, *first;
unsigned long *fgraph_data = NULL;
unsigned long func = trace->func;
unsigned long ret_ip;
int reserved_words;
struct fprobe *fp;
int used, ret;
if (!fp || fprobe_disabled(fp))
return;
if (WARN_ON_ONCE(!fregs))
return 0;
fpr = container_of(rh, struct fprobe_rethook_node, node);
first = node = find_first_fprobe_node(func);
if (unlikely(!first))
return 0;
reserved_words = 0;
hlist_for_each_entry_from_rcu(node, hlist) {
if (node->addr != func)
break;
fp = READ_ONCE(node->fp);
if (!fp || !fp->exit_handler)
continue;
/*
* Since fprobe can be enabled until the next loop, we ignore the
* fprobe's disabled flag in this loop.
*/
reserved_words +=
FPROBE_HEADER_SIZE_IN_LONG + SIZE_IN_LONG(fp->entry_data_size);
}
node = first;
if (reserved_words) {
fgraph_data = fgraph_reserve_data(gops->idx, reserved_words * sizeof(long));
if (unlikely(!fgraph_data)) {
hlist_for_each_entry_from_rcu(node, hlist) {
if (node->addr != func)
break;
fp = READ_ONCE(node->fp);
if (fp && !fprobe_disabled(fp))
fp->nmissed++;
}
return 0;
}
}
/*
* we need to assure no calls to traceable functions in-between the
* end of fprobe_handler and the beginning of fprobe_exit_handler.
* TODO: recursion detection has been done in the fgraph. Thus we need
* to add a callback to increment missed counter.
*/
bit = ftrace_test_recursion_trylock(fpr->entry_ip, fpr->entry_parent_ip);
if (bit < 0) {
fp->nmissed++;
ret_ip = ftrace_regs_get_return_address(fregs);
used = 0;
hlist_for_each_entry_from_rcu(node, hlist) {
int data_size;
void *data;
if (node->addr != func)
break;
fp = READ_ONCE(node->fp);
if (!fp || fprobe_disabled(fp))
continue;
data_size = fp->entry_data_size;
if (data_size && fp->exit_handler)
data = fgraph_data + used + FPROBE_HEADER_SIZE_IN_LONG;
else
data = NULL;
if (fprobe_shared_with_kprobes(fp))
ret = __fprobe_kprobe_handler(func, ret_ip, fp, fregs, data);
else
ret = __fprobe_handler(func, ret_ip, fp, fregs, data);
/* If entry_handler returns !0, nmissed is not counted but skips exit_handler. */
if (!ret && fp->exit_handler) {
int size_words = SIZE_IN_LONG(data_size);
if (write_fprobe_header(&fgraph_data[used], fp, size_words))
used += FPROBE_HEADER_SIZE_IN_LONG + size_words;
}
}
if (used < reserved_words)
memset(fgraph_data + used, 0, reserved_words - used);
/* If any exit_handler is set, data must be used. */
return used != 0;
}
NOKPROBE_SYMBOL(fprobe_entry);
static void fprobe_return(struct ftrace_graph_ret *trace,
struct fgraph_ops *gops,
struct ftrace_regs *fregs)
{
unsigned long *fgraph_data = NULL;
unsigned long ret_ip;
struct fprobe *fp;
int size, curr;
int size_words;
fgraph_data = (unsigned long *)fgraph_retrieve_data(gops->idx, &size);
if (WARN_ON_ONCE(!fgraph_data))
return;
size_words = SIZE_IN_LONG(size);
ret_ip = ftrace_regs_get_instruction_pointer(fregs);
preempt_disable();
curr = 0;
while (size_words > curr) {
read_fprobe_header(&fgraph_data[curr], &fp, &size);
if (!fp)
break;
curr += FPROBE_HEADER_SIZE_IN_LONG;
if (is_fprobe_still_exist(fp) && !fprobe_disabled(fp)) {
if (WARN_ON_ONCE(curr + size > size_words))
break;
fp->exit_handler(fp, trace->func, ret_ip, fregs,
size ? fgraph_data + curr : NULL);
}
curr += size;
}
preempt_enable();
}
NOKPROBE_SYMBOL(fprobe_return);
static struct fgraph_ops fprobe_graph_ops = {
.entryfunc = fprobe_entry,
.retfunc = fprobe_return,
};
static int fprobe_graph_active;
/* Add @addrs to the ftrace filter and register fgraph if needed. */
static int fprobe_graph_add_ips(unsigned long *addrs, int num)
{
int ret;
lockdep_assert_held(&fprobe_mutex);
ret = ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 0, 0);
if (ret)
return ret;
if (!fprobe_graph_active) {
ret = register_ftrace_graph(&fprobe_graph_ops);
if (WARN_ON_ONCE(ret)) {
ftrace_free_filter(&fprobe_graph_ops.ops);
return ret;
}
}
fprobe_graph_active++;
return 0;
}
/* Remove @addrs from the ftrace filter and unregister fgraph if possible. */
static void fprobe_graph_remove_ips(unsigned long *addrs, int num)
{
lockdep_assert_held(&fprobe_mutex);
fprobe_graph_active--;
if (!fprobe_graph_active) {
/* Q: should we unregister it ? */
unregister_ftrace_graph(&fprobe_graph_ops);
return;
}
fp->exit_handler(fp, fpr->entry_ip, ret_ip, fregs,
fp->entry_data_size ? (void *)fpr->data : NULL);
ftrace_test_recursion_unlock(bit);
ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0);
}
NOKPROBE_SYMBOL(fprobe_exit_handler);
static int symbols_cmp(const void *a, const void *b)
{
@ -176,53 +411,96 @@ static unsigned long *get_ftrace_locations(const char **syms, int num)
return ERR_PTR(-ENOENT);
}
static void fprobe_init(struct fprobe *fp)
{
fp->nmissed = 0;
if (fprobe_shared_with_kprobes(fp))
fp->ops.func = fprobe_kprobe_handler;
else
fp->ops.func = fprobe_handler;
struct filter_match_data {
const char *filter;
const char *notfilter;
size_t index;
size_t size;
unsigned long *addrs;
};
fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
static int filter_match_callback(void *data, const char *name, unsigned long addr)
{
struct filter_match_data *match = data;
if (!glob_match(match->filter, name) ||
(match->notfilter && glob_match(match->notfilter, name)))
return 0;
if (!ftrace_location(addr))
return 0;
if (match->addrs)
match->addrs[match->index] = addr;
match->index++;
return match->index == match->size;
}
static int fprobe_init_rethook(struct fprobe *fp, int num)
/*
* Make IP list from the filter/no-filter glob patterns.
* Return the number of matched symbols, or -ENOENT.
*/
static int ip_list_from_filter(const char *filter, const char *notfilter,
unsigned long *addrs, size_t size)
{
int size;
struct filter_match_data match = { .filter = filter, .notfilter = notfilter,
.index = 0, .size = size, .addrs = addrs};
int ret;
if (!fp->exit_handler) {
fp->rethook = NULL;
return 0;
}
ret = kallsyms_on_each_symbol(filter_match_callback, &match);
if (ret < 0)
return ret;
ret = module_kallsyms_on_each_symbol(NULL, filter_match_callback, &match);
if (ret < 0)
return ret;
/* Initialize rethook if needed */
if (fp->nr_maxactive)
num = fp->nr_maxactive;
else
num *= num_possible_cpus() * 2;
if (num <= 0)
return -EINVAL;
size = sizeof(struct fprobe_rethook_node) + fp->entry_data_size;
/* Initialize rethook */
fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler, size, num);
if (IS_ERR(fp->rethook))
return PTR_ERR(fp->rethook);
return 0;
return match.index ?: -ENOENT;
}
static void fprobe_fail_cleanup(struct fprobe *fp)
{
if (!IS_ERR_OR_NULL(fp->rethook)) {
/* Don't need to cleanup rethook->handler because this is not used. */
rethook_free(fp->rethook);
fp->rethook = NULL;
kfree(fp->hlist_array);
fp->hlist_array = NULL;
}
ftrace_free_filter(&fp->ops);
/* Initialize the fprobe data structure. */
static int fprobe_init(struct fprobe *fp, unsigned long *addrs, int num)
{
struct fprobe_hlist *hlist_array;
unsigned long addr;
int size, i;
if (!fp || !addrs || num <= 0)
return -EINVAL;
size = ALIGN(fp->entry_data_size, sizeof(long));
if (size > MAX_FPROBE_DATA_SIZE)
return -E2BIG;
fp->entry_data_size = size;
hlist_array = kzalloc(struct_size(hlist_array, array, num), GFP_KERNEL);
if (!hlist_array)
return -ENOMEM;
fp->nmissed = 0;
hlist_array->size = num;
fp->hlist_array = hlist_array;
hlist_array->fp = fp;
for (i = 0; i < num; i++) {
hlist_array->array[i].fp = fp;
addr = ftrace_location(addrs[i]);
if (!addr) {
fprobe_fail_cleanup(fp);
return -ENOENT;
}
hlist_array->array[i].addr = addr;
}
return 0;
}
#define FPROBE_IPS_MAX INT_MAX
/**
* register_fprobe() - Register fprobe to ftrace by pattern.
@ -237,46 +515,24 @@ static void fprobe_fail_cleanup(struct fprobe *fp)
*/
int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
{
struct ftrace_hash *hash;
unsigned char *str;
int ret, len;
unsigned long *addrs;
int ret;
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)
ret = ip_list_from_filter(filter, notfilter, NULL, FPROBE_IPS_MAX);
if (ret < 0)
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;
}
addrs = kcalloc(ret, sizeof(unsigned long), GFP_KERNEL);
if (!addrs)
return -ENOMEM;
ret = ip_list_from_filter(filter, notfilter, addrs, ret);
if (ret > 0)
ret = register_fprobe_ips(fp, addrs, ret);
/* TODO:
* correctly calculate the total number of filtered symbols
* from both filter and notfilter.
*/
hash = rcu_access_pointer(fp->ops.local_hash.filter_hash);
if (WARN_ON_ONCE(!hash))
goto out;
ret = fprobe_init_rethook(fp, (int)hash->count);
if (!ret)
ret = register_ftrace_function(&fp->ops);
out:
if (ret)
fprobe_fail_cleanup(fp);
kfree(addrs);
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe);
@ -284,7 +540,7 @@ 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.
* @addrs: An array of target function address.
* @num: The number of entries of @addrs.
*
* Register @fp to ftrace for enabling the probe on the address given by @addrs.
@ -296,23 +552,27 @@ EXPORT_SYMBOL_GPL(register_fprobe);
*/
int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
{
int ret;
struct fprobe_hlist *hlist_array;
int ret, i;
if (!fp || !addrs || num <= 0)
return -EINVAL;
fprobe_init(fp);
ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0);
ret = fprobe_init(fp, addrs, num);
if (ret)
return ret;
ret = fprobe_init_rethook(fp, num);
if (!ret)
ret = register_ftrace_function(&fp->ops);
mutex_lock(&fprobe_mutex);
hlist_array = fp->hlist_array;
ret = fprobe_graph_add_ips(addrs, num);
if (!ret) {
add_fprobe_hash(fp);
for (i = 0; i < hlist_array->size; i++)
insert_fprobe_node(&hlist_array->array[i]);
}
mutex_unlock(&fprobe_mutex);
if (ret)
fprobe_fail_cleanup(fp);
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe_ips);
@ -350,14 +610,13 @@ EXPORT_SYMBOL_GPL(register_fprobe_syms);
bool fprobe_is_registered(struct fprobe *fp)
{
if (!fp || (fp->ops.saved_func != fprobe_handler &&
fp->ops.saved_func != fprobe_kprobe_handler))
if (!fp || !fp->hlist_array)
return false;
return true;
}
/**
* unregister_fprobe() - Unregister fprobe from ftrace
* unregister_fprobe() - Unregister fprobe.
* @fp: A fprobe data structure to be unregistered.
*
* Unregister fprobe (and remove ftrace hooks from the function entries).
@ -366,23 +625,41 @@ bool fprobe_is_registered(struct fprobe *fp)
*/
int unregister_fprobe(struct fprobe *fp)
{
int ret;
struct fprobe_hlist *hlist_array;
unsigned long *addrs = NULL;
int ret = 0, i, count;
if (!fprobe_is_registered(fp))
return -EINVAL;
mutex_lock(&fprobe_mutex);
if (!fp || !is_fprobe_still_exist(fp)) {
ret = -EINVAL;
goto out;
}
if (!IS_ERR_OR_NULL(fp->rethook))
rethook_stop(fp->rethook);
hlist_array = fp->hlist_array;
addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL);
if (!addrs) {
ret = -ENOMEM; /* TODO: Fallback to one-by-one loop */
goto out;
}
ret = unregister_ftrace_function(&fp->ops);
if (ret < 0)
return ret;
/* Remove non-synonim ips from table and hash */
count = 0;
for (i = 0; i < hlist_array->size; i++) {
if (!delete_fprobe_node(&hlist_array->array[i]))
addrs[count++] = hlist_array->array[i].addr;
}
del_fprobe_hash(fp);
if (!IS_ERR_OR_NULL(fp->rethook))
rethook_free(fp->rethook);
if (count)
fprobe_graph_remove_ips(addrs, count);
ftrace_free_filter(&fp->ops);
kfree_rcu(hlist_array, rcu);
fp->hlist_array = NULL;
out:
mutex_unlock(&fprobe_mutex);
kfree(addrs);
return ret;
}
EXPORT_SYMBOL_GPL(unregister_fprobe);

View file

@ -17,10 +17,8 @@ static u32 rand1, entry_val, exit_val;
/* Use indirect calls to avoid inlining the target functions */
static u32 (*target)(u32 value);
static u32 (*target2)(u32 value);
static u32 (*target_nest)(u32 value, u32 (*nest)(u32));
static unsigned long target_ip;
static unsigned long target2_ip;
static unsigned long target_nest_ip;
static int entry_return_value;
static noinline u32 fprobe_selftest_target(u32 value)
@ -33,11 +31,6 @@ static noinline u32 fprobe_selftest_target2(u32 value)
return (value / div_factor) + 1;
}
static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
{
return nest(value + 2);
}
static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
struct ftrace_regs *fregs, void *data)
@ -79,22 +72,6 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
KUNIT_EXPECT_NULL(current_test, data);
}
static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
struct ftrace_regs *fregs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
return 0;
}
static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
struct ftrace_regs *fregs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
KUNIT_EXPECT_EQ(current_test, ip, target_nest_ip);
}
/* Test entry only (no rethook) */
static void test_fprobe_entry(struct kunit *test)
{
@ -191,25 +168,6 @@ static void test_fprobe_data(struct kunit *test)
KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
}
/* Test nr_maxactive */
static void test_fprobe_nest(struct kunit *test)
{
static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_nest_target"};
struct fprobe fp = {
.entry_handler = nest_entry_handler,
.exit_handler = nest_exit_handler,
.nr_maxactive = 1,
};
current_test = test;
KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2));
target_nest(rand1, target);
KUNIT_EXPECT_EQ(test, 1, fp.nmissed);
KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
}
static void test_fprobe_skip(struct kunit *test)
{
struct fprobe fp = {
@ -247,10 +205,8 @@ static int fprobe_test_init(struct kunit *test)
rand1 = get_random_u32_above(div_factor);
target = fprobe_selftest_target;
target2 = fprobe_selftest_target2;
target_nest = fprobe_selftest_nest_target;
target_ip = get_ftrace_location(target);
target2_ip = get_ftrace_location(target2);
target_nest_ip = get_ftrace_location(target_nest);
return 0;
}
@ -260,7 +216,6 @@ static struct kunit_case fprobe_testcases[] = {
KUNIT_CASE(test_fprobe),
KUNIT_CASE(test_fprobe_syms),
KUNIT_CASE(test_fprobe_data),
KUNIT_CASE(test_fprobe_nest),
KUNIT_CASE(test_fprobe_skip),
{}
};