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jump label: Introduce static_branch() interface

Browse source 
Introduce:

static __always_inline bool static_branch(struct jump_label_key *key);

instead of the old JUMP_LABEL(key, label) macro.

In this way, jump labels become really easy to use:

Define:

        struct jump_label_key jump_key;

Can be used as:

        if (static_branch(&jump_key))
                do unlikely code

enable/disale via:

        jump_label_inc(&jump_key);
        jump_label_dec(&jump_key);

that's it!

For the jump labels disabled case, the static_branch() becomes an
atomic_read(), and jump_label_inc()/dec() are simply atomic_inc(),
atomic_dec() operations. We show testing results for this change below.

Thanks to H. Peter Anvin for suggesting the 'static_branch()' construct.

Since we now require a 'struct jump_label_key *key', we can store a pointer into
the jump table addresses. In this way, we can enable/disable jump labels, in
basically constant time. This change allows us to completely remove the previous
hashtable scheme. Thanks to Peter Zijlstra for this re-write.

Testing:

I ran a series of 'tbench 20' runs 5 times (with reboots) for 3
configurations, where tracepoints were disabled.

jump label configured in
avg: 815.6

jump label *not* configured in (using atomic reads)
avg: 800.1

jump label *not* configured in (regular reads)
avg: 803.4

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110316212947.GA8792@redhat.com>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Suggested-by: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: David Daney <ddaney@caviumnetworks.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jason Baron 2011-03-16 17:29:47 -04:00 committed by Steven Rostedt
parent ee5e51f51b
commit d430d3d7e6
15 changed files with 416 additions and 546 deletions
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22
arch/mips/include/asm/jump_label.h
View file

@ -20,16 +20,18 @@
#define WORD_INSN ".word"
#endif
#define JUMP_LABEL(key, label) \
do { \
asm goto("1:\tnop\n\t" \
"nop\n\t" \
".pushsection __jump_table, \"a\"\n\t" \
WORD_INSN " 1b, %l[" #label "], %0\n\t" \
".popsection\n\t" \
: : "i" (key) : : label); \
} while (0)
static __always_inline bool arch_static_branch(struct jump_label_key *key)
{
asm goto("1:\tnop\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
: : "i" (key) : : l_yes);
return false;
l_yes:
return true;
}
#endif /* __KERNEL__ */

25
arch/sparc/include/asm/jump_label.h
View file

@ -7,17 +7,20 @@
#define JUMP_LABEL_NOP_SIZE 4
#define JUMP_LABEL(key, label) \
do { \
asm goto("1:\n\t" \
"nop\n\t" \
"nop\n\t" \
".pushsection __jump_table, \"a\"\n\t"\
".align 4\n\t" \
".word 1b, %l[" #label "], %c0\n\t" \
".popsection \n\t" \
: : "i" (key) : : label);\
} while (0)
static __always_inline bool arch_static_branch(struct jump_label_key *key)
{
asm goto("1:\n\t"
"nop\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".align 4\n\t"
".word 1b, %l[l_yes], %c0\n\t"
".popsection \n\t"
: : "i" (key) : : l_yes);
return false;
l_yes:
return true;
}
#endif /* __KERNEL__ */

3
arch/x86/include/asm/alternative.h
View file

@ -4,7 +4,6 @@
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/stringify.h>
#include <linux/jump_label.h>
#include <asm/asm.h>
/*
@ -191,7 +190,7 @@ extern void *text_poke(void *addr, const void *opcode, size_t len);
extern void *text_poke_smp(void *addr, const void *opcode, size_t len);
extern void text_poke_smp_batch(struct text_poke_param *params, int n);
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(CONFIG_JUMP_LABEL)
#define IDEAL_NOP_SIZE_5 5
extern unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
extern void arch_init_ideal_nop5(void);

24
arch/x86/include/asm/jump_label.h
View file

@ -5,20 +5,24 @@
#include <linux/types.h>
#include <asm/nops.h>
#include <asm/asm.h>
#define JUMP_LABEL_NOP_SIZE 5
# define JUMP_LABEL_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t"
#define JUMP_LABEL_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t"
# define JUMP_LABEL(key, label) \
do { \
asm goto("1:" \
JUMP_LABEL_INITIAL_NOP \
".pushsection __jump_table, \"aw\" \n\t"\
_ASM_PTR "1b, %l[" #label "], %c0 \n\t" \
".popsection \n\t" \
: : "i" (key) : : label); \
} while (0)
static __always_inline bool arch_static_branch(struct jump_label_key *key)
{
asm goto("1:"
JUMP_LABEL_INITIAL_NOP
".pushsection __jump_table, \"aw\" \n\t"
_ASM_PTR "1b, %l[l_yes], %c0 \n\t"
".popsection \n\t"
: : "i" (key) : : l_yes);
return false;
l_yes:
return true;
}
#endif /* __KERNEL__ */

2
arch/x86/kernel/alternative.c
View file

@ -679,7 +679,7 @@ void __kprobes text_poke_smp_batch(struct text_poke_param *params, int n)
__stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
}
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(CONFIG_JUMP_LABEL)
#ifdef CONFIG_X86_64
unsigned char ideal_nop5[5] = { 0x66, 0x66, 0x66, 0x66, 0x90 };

1
arch/x86/kernel/module.c
View file

@ -24,6 +24,7 @@
#include <linux/bug.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/jump_label.h>
#include <asm/system.h>
#include <asm/page.h>

14
include/asm-generic/vmlinux.lds.h
View file

@ -170,6 +170,10 @@
STRUCT_ALIGN(); \
*(__tracepoints) \
/* implement dynamic printk debug */ \
. = ALIGN(8); \
VMLINUX_SYMBOL(__start___jump_table) = .; \
*(__jump_table) \
VMLINUX_SYMBOL(__stop___jump_table) = .; \
. = ALIGN(8); \
VMLINUX_SYMBOL(__start___verbose) = .; \
*(__verbose) \
@ -228,8 +232,6 @@
\
BUG_TABLE \
\
JUMP_TABLE \
\
/* PCI quirks */ \
.pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start_pci_fixups_early) = .; \
@ -589,14 +591,6 @@
#define BUG_TABLE
#endif
#define JUMP_TABLE \
. = ALIGN(8); \
__jump_table : AT(ADDR(__jump_table) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___jump_table) = .; \
*(__jump_table) \
VMLINUX_SYMBOL(__stop___jump_table) = .; \
}
#ifdef CONFIG_PM_TRACE
#define TRACEDATA \
. = ALIGN(4); \

2
include/linux/dynamic_debug.h
View file

@ -1,8 +1,6 @@
#ifndef _DYNAMIC_DEBUG_H
#define _DYNAMIC_DEBUG_H
#include <linux/jump_label.h>
/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
* bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
* use independent hash functions, to reduce the chance of false positives.

91
include/linux/jump_label.h
View file

@ -1,20 +1,43 @@
#ifndef _LINUX_JUMP_LABEL_H
#define _LINUX_JUMP_LABEL_H
#include <linux/types.h>
#include <linux/compiler.h>
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
struct jump_label_key {
atomic_t enabled;
struct jump_entry *entries;
#ifdef CONFIG_MODULES
struct jump_label_mod *next;
#endif
};
# include <asm/jump_label.h>
# define HAVE_JUMP_LABEL
#endif
enum jump_label_type {
JUMP_LABEL_DISABLE = 0,
JUMP_LABEL_ENABLE,
JUMP_LABEL_DISABLE
};
struct module;
#ifdef HAVE_JUMP_LABEL
#ifdef CONFIG_MODULES
#define JUMP_LABEL_INIT {{ 0 }, NULL, NULL}
#else
#define JUMP_LABEL_INIT {{ 0 }, NULL}
#endif
static __always_inline bool static_branch(struct jump_label_key *key)
{
return arch_static_branch(key);
}
extern struct jump_entry __start___jump_table[];
extern struct jump_entry __stop___jump_table[];
@ -23,37 +46,37 @@ extern void jump_label_unlock(void);
extern void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type);
extern void arch_jump_label_text_poke_early(jump_label_t addr);
extern void jump_label_update(unsigned long key, enum jump_label_type type);
extern void jump_label_apply_nops(struct module *mod);
extern int jump_label_text_reserved(void *start, void *end);
#define jump_label_enable(key) \
jump_label_update((unsigned long)key, JUMP_LABEL_ENABLE);
#define jump_label_disable(key) \
jump_label_update((unsigned long)key, JUMP_LABEL_DISABLE);
extern void jump_label_inc(struct jump_label_key *key);
extern void jump_label_dec(struct jump_label_key *key);
extern bool jump_label_enabled(struct jump_label_key *key);
extern void jump_label_apply_nops(struct module *mod);
#else
#define JUMP_LABEL(key, label) \
do { \
if (unlikely(*key)) \
goto label; \
} while (0)
#include <asm/atomic.h>
#define jump_label_enable(cond_var) \
do { \
*(cond_var) = 1; \
} while (0)
#define JUMP_LABEL_INIT {ATOMIC_INIT(0)}
#define jump_label_disable(cond_var) \
do { \
*(cond_var) = 0; \
} while (0)
struct jump_label_key {
atomic_t enabled;
};
static inline int jump_label_apply_nops(struct module *mod)
static __always_inline bool static_branch(struct jump_label_key *key)
{
return 0;
if (unlikely(atomic_read(&key->enabled)))
return true;
return false;
}
static inline void jump_label_inc(struct jump_label_key *key)
{
atomic_inc(&key->enabled);
}
static inline void jump_label_dec(struct jump_label_key *key)
{
atomic_dec(&key->enabled);
}
static inline int jump_label_text_reserved(void *start, void *end)
@ -64,16 +87,16 @@ static inline int jump_label_text_reserved(void *start, void *end)
static inline void jump_label_lock(void) {}
static inline void jump_label_unlock(void) {}
#endif
static inline bool jump_label_enabled(struct jump_label_key *key)
{
return !!atomic_read(&key->enabled);
}
#define COND_STMT(key, stmt) \
do { \
__label__ jl_enabled; \
JUMP_LABEL(key, jl_enabled); \
if (0) { \
jl_enabled: \
stmt; \
} \
} while (0)
static inline int jump_label_apply_nops(struct module *mod)
{
return 0;
}
#endif
#endif

44
include/linux/jump_label_ref.h
View file

@ -1,44 +0,0 @@
#ifndef _LINUX_JUMP_LABEL_REF_H
#define _LINUX_JUMP_LABEL_REF_H
#include <linux/jump_label.h>
#include <asm/atomic.h>
#ifdef HAVE_JUMP_LABEL
static inline void jump_label_inc(atomic_t *key)
{
if (atomic_add_return(1, key) == 1)
jump_label_enable(key);
}
static inline void jump_label_dec(atomic_t *key)
{
if (atomic_dec_and_test(key))
jump_label_disable(key);
}
#else /* !HAVE_JUMP_LABEL */
static inline void jump_label_inc(atomic_t *key)
{
atomic_inc(key);
}
static inline void jump_label_dec(atomic_t *key)
{
atomic_dec(key);
}
#undef JUMP_LABEL
#define JUMP_LABEL(key, label) \
do { \
if (unlikely(__builtin_choose_expr( \
__builtin_types_compatible_p(typeof(key), atomic_t *), \
atomic_read((atomic_t *)(key)), *(key)))) \
goto label; \
} while (0)
#endif /* HAVE_JUMP_LABEL */
#endif /* _LINUX_JUMP_LABEL_REF_H */

26
include/linux/perf_event.h
View file

@ -505,7 +505,7 @@ struct perf_guest_info_callbacks {
#include <linux/ftrace.h>
#include <linux/cpu.h>
#include <linux/irq_work.h>
#include <linux/jump_label_ref.h>
#include <linux/jump_label.h>
#include <asm/atomic.h>
#include <asm/local.h>
@ -1034,7 +1034,7 @@ static inline int is_software_event(struct perf_event *event)
return event->pmu->task_ctx_nr == perf_sw_context;
}
extern atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
extern struct jump_label_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
extern void __perf_sw_event(u32, u64, int, struct pt_regs *, u64);
@ -1063,22 +1063,21 @@ perf_sw_event(u32 event_id, u64 nr, int nmi, struct pt_regs *regs, u64 addr)
{
struct pt_regs hot_regs;
JUMP_LABEL(&perf_swevent_enabled[event_id], have_event);
return;
have_event:
if (!regs) {
perf_fetch_caller_regs(&hot_regs);
regs = &hot_regs;
if (static_branch(&perf_swevent_enabled[event_id])) {
if (!regs) {
perf_fetch_caller_regs(&hot_regs);
regs = &hot_regs;
}
__perf_sw_event(event_id, nr, nmi, regs, addr);
}
__perf_sw_event(event_id, nr, nmi, regs, addr);
}
extern atomic_t perf_sched_events;
extern struct jump_label_key perf_sched_events;
static inline void perf_event_task_sched_in(struct task_struct *task)
{
COND_STMT(&perf_sched_events, __perf_event_task_sched_in(task));
if (static_branch(&perf_sched_events))
__perf_event_task_sched_in(task);
}
static inline
@ -1086,7 +1085,8 @@ void perf_event_task_sched_out(struct task_struct *task, struct task_struct *nex
{
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
COND_STMT(&perf_sched_events, __perf_event_task_sched_out(task, next));
if (static_branch(&perf_sched_events))
__perf_event_task_sched_out(task, next);
}
extern void perf_event_mmap(struct vm_area_struct *vma);

22
include/linux/tracepoint.h
View file

@ -29,7 +29,7 @@ struct tracepoint_func {
struct tracepoint {
const char *name; /* Tracepoint name */
int state; /* State. */
struct jump_label_key key;
void (*regfunc)(void);
void (*unregfunc)(void);
struct tracepoint_func __rcu *funcs;
@ -146,9 +146,7 @@ void tracepoint_update_probe_range(struct tracepoint * const *begin,
extern struct tracepoint __tracepoint_##name; \
static inline void trace_##name(proto) \
{ \
JUMP_LABEL(&__tracepoint_##name.state, do_trace); \
return; \
do_trace: \
if (static_branch(&__tracepoint_##name.key)) \
__DO_TRACE(&__tracepoint_##name, \
TP_PROTO(data_proto), \
TP_ARGS(data_args), \
@ -176,14 +174,14 @@ do_trace: \
* structures, so we create an array of pointers that will be used for iteration
* on the tracepoints.
*/
#define DEFINE_TRACE_FN(name, reg, unreg) \
static const char __tpstrtab_##name[] \
__attribute__((section("__tracepoints_strings"))) = #name; \
struct tracepoint __tracepoint_##name \
__attribute__((section("__tracepoints"))) = \
{ __tpstrtab_##name, 0, reg, unreg, NULL }; \
static struct tracepoint * const __tracepoint_ptr_##name __used \
__attribute__((section("__tracepoints_ptrs"))) = \
#define DEFINE_TRACE_FN(name, reg, unreg) \
static const char __tpstrtab_##name[] \
__attribute__((section("__tracepoints_strings"))) = #name; \
struct tracepoint __tracepoint_##name \
__attribute__((section("__tracepoints"))) = \
{ __tpstrtab_##name, JUMP_LABEL_INIT, reg, unreg, NULL };\
static struct tracepoint * const __tracepoint_ptr_##name __used \
__attribute__((section("__tracepoints_ptrs"))) = \
&__tracepoint_##name;
#define DEFINE_TRACE(name) \

659
kernel/jump_label.c
View file

@ -2,43 +2,23 @@
* jump label support
*
* Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
* Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
*
*/
#include <linux/jump_label.h>
#include <linux/memory.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/jhash.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/err.h>
#include <linux/jump_label.h>
#ifdef HAVE_JUMP_LABEL
#define JUMP_LABEL_HASH_BITS 6
#define JUMP_LABEL_TABLE_SIZE (1 << JUMP_LABEL_HASH_BITS)
static struct hlist_head jump_label_table[JUMP_LABEL_TABLE_SIZE];
/* mutex to protect coming/going of the the jump_label table */
static DEFINE_MUTEX(jump_label_mutex);
struct jump_label_entry {
struct hlist_node hlist;
struct jump_entry *table;
int nr_entries;
/* hang modules off here */
struct hlist_head modules;
unsigned long key;
};
struct jump_label_module_entry {
struct hlist_node hlist;
struct jump_entry *table;
int nr_entries;
struct module *mod;
};
void jump_label_lock(void)
{
mutex_lock(&jump_label_mutex);
@ -49,6 +29,11 @@ void jump_label_unlock(void)
mutex_unlock(&jump_label_mutex);
}
bool jump_label_enabled(struct jump_label_key *key)
{
return !!atomic_read(&key->enabled);
}
static int jump_label_cmp(const void *a, const void *b)
{
const struct jump_entry *jea = a;
@ -64,7 +49,7 @@ static int jump_label_cmp(const void *a, const void *b)
}
static void
sort_jump_label_entries(struct jump_entry *start, struct jump_entry *stop)
jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
{
unsigned long size;
@ -73,118 +58,25 @@ sort_jump_label_entries(struct jump_entry *start, struct jump_entry *stop)
sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
}
static struct jump_label_entry *get_jump_label_entry(jump_label_t key)
static void jump_label_update(struct jump_label_key *key, int enable);
void jump_label_inc(struct jump_label_key *key)
{
struct hlist_head *head;
struct hlist_node *node;
struct jump_label_entry *e;
u32 hash = jhash((void *)&key, sizeof(jump_label_t), 0);
head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
hlist_for_each_entry(e, node, head, hlist) {
if (key == e->key)
return e;
}
return NULL;
}
static struct jump_label_entry *
add_jump_label_entry(jump_label_t key, int nr_entries, struct jump_entry *table)
{
struct hlist_head *head;
struct jump_label_entry *e;
u32 hash;
e = get_jump_label_entry(key);
if (e)
return ERR_PTR(-EEXIST);
e = kmalloc(sizeof(struct jump_label_entry), GFP_KERNEL);
if (!e)
return ERR_PTR(-ENOMEM);
hash = jhash((void *)&key, sizeof(jump_label_t), 0);
head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
e->key = key;
e->table = table;
e->nr_entries = nr_entries;
INIT_HLIST_HEAD(&(e->modules));
hlist_add_head(&e->hlist, head);
return e;
}
static int
build_jump_label_hashtable(struct jump_entry *start, struct jump_entry *stop)
{
struct jump_entry *iter, *iter_begin;
struct jump_label_entry *entry;
int count;
sort_jump_label_entries(start, stop);
iter = start;
while (iter < stop) {
entry = get_jump_label_entry(iter->key);
if (!entry) {
iter_begin = iter;
count = 0;
while ((iter < stop) &&
(iter->key == iter_begin->key)) {
iter++;
count++;
}
entry = add_jump_label_entry(iter_begin->key,
count, iter_begin);
if (IS_ERR(entry))
return PTR_ERR(entry);
} else {
WARN_ONCE(1, KERN_ERR "build_jump_hashtable: unexpected entry!\n");
return -1;
}
}
return 0;
}
/***
* jump_label_update - update jump label text
* @key - key value associated with a a jump label
* @type - enum set to JUMP_LABEL_ENABLE or JUMP_LABEL_DISABLE
*
* Will enable/disable the jump for jump label @key, depending on the
* value of @type.
*
*/
void jump_label_update(unsigned long key, enum jump_label_type type)
{
struct jump_entry *iter;
struct jump_label_entry *entry;
struct hlist_node *module_node;
struct jump_label_module_entry *e_module;
int count;
if (atomic_inc_not_zero(&key->enabled))
return;
jump_label_lock();
entry = get_jump_label_entry((jump_label_t)key);
if (entry) {
count = entry->nr_entries;
iter = entry->table;
while (count--) {
if (kernel_text_address(iter->code))
arch_jump_label_transform(iter, type);
iter++;
}
/* eanble/disable jump labels in modules */
hlist_for_each_entry(e_module, module_node, &(entry->modules),
hlist) {
count = e_module->nr_entries;
iter = e_module->table;
while (count--) {
if (iter->key &&
kernel_text_address(iter->code))
arch_jump_label_transform(iter, type);
iter++;
}
}
}
if (atomic_add_return(1, &key->enabled) == 1)
jump_label_update(key, JUMP_LABEL_ENABLE);
jump_label_unlock();
}
void jump_label_dec(struct jump_label_key *key)
{
if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex))
return;
jump_label_update(key, JUMP_LABEL_DISABLE);
jump_label_unlock();
}
@ -197,41 +89,254 @@ static int addr_conflict(struct jump_entry *entry, void *start, void *end)
return 0;
}
#ifdef CONFIG_MODULES
static int module_conflict(void *start, void *end)
static int __jump_label_text_reserved(struct jump_entry *iter_start,
struct jump_entry *iter_stop, void *start, void *end)
{
struct hlist_head *head;
struct hlist_node *node, *node_next, *module_node, *module_node_next;
struct jump_label_entry *e;
struct jump_label_module_entry *e_module;
struct jump_entry *iter;
int i, count;
int conflict = 0;
for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
head = &jump_label_table[i];
hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
hlist_for_each_entry_safe(e_module, module_node,
module_node_next,
&(e->modules), hlist) {
count = e_module->nr_entries;
iter = e_module->table;
while (count--) {
if (addr_conflict(iter, start, end)) {
conflict = 1;
goto out;
}
iter++;
}
}
}
iter = iter_start;
while (iter < iter_stop) {
if (addr_conflict(iter, start, end))
return 1;
iter++;
}
out:
return conflict;
return 0;
}
static void __jump_label_update(struct jump_label_key *key,
struct jump_entry *entry, int enable)
{
for (; entry->key == (jump_label_t)(unsigned long)key; entry++) {
/*
* entry->code set to 0 invalidates module init text sections
* kernel_text_address() verifies we are not in core kernel
* init code, see jump_label_invalidate_module_init().
*/
if (entry->code && kernel_text_address(entry->code))
arch_jump_label_transform(entry, enable);
}
}
/*
* Not all archs need this.
*/
void __weak arch_jump_label_text_poke_early(jump_label_t addr)
{
}
static __init int jump_label_init(void)
{
struct jump_entry *iter_start = __start___jump_table;
struct jump_entry *iter_stop = __stop___jump_table;
struct jump_label_key *key = NULL;
struct jump_entry *iter;
jump_label_lock();
jump_label_sort_entries(iter_start, iter_stop);
for (iter = iter_start; iter < iter_stop; iter++) {
arch_jump_label_text_poke_early(iter->code);
if (iter->key == (jump_label_t)(unsigned long)key)
continue;
key = (struct jump_label_key *)(unsigned long)iter->key;
atomic_set(&key->enabled, 0);
key->entries = iter;
#ifdef CONFIG_MODULES
key->next = NULL;
#endif
}
jump_label_unlock();
return 0;
}
early_initcall(jump_label_init);
#ifdef CONFIG_MODULES
struct jump_label_mod {
struct jump_label_mod *next;
struct jump_entry *entries;
struct module *mod;
};
static int __jump_label_mod_text_reserved(void *start, void *end)
{
struct module *mod;
mod = __module_text_address((unsigned long)start);
if (!mod)
return 0;
WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
return __jump_label_text_reserved(mod->jump_entries,
mod->jump_entries + mod->num_jump_entries,
start, end);
}
static void __jump_label_mod_update(struct jump_label_key *key, int enable)
{
struct jump_label_mod *mod = key->next;
while (mod) {
__jump_label_update(key, mod->entries, enable);
mod = mod->next;
}
}
/***
* apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
* @mod: module to patch
*
* Allow for run-time selection of the optimal nops. Before the module
* loads patch these with arch_get_jump_label_nop(), which is specified by
* the arch specific jump label code.
*/
void jump_label_apply_nops(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
struct jump_entry *iter;
/* if the module doesn't have jump label entries, just return */
if (iter_start == iter_stop)
return;
for (iter = iter_start; iter < iter_stop; iter++)
arch_jump_label_text_poke_early(iter->code);
}
static int jump_label_add_module(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
struct jump_entry *iter;
struct jump_label_key *key = NULL;
struct jump_label_mod *jlm;
/* if the module doesn't have jump label entries, just return */
if (iter_start == iter_stop)
return 0;
jump_label_sort_entries(iter_start, iter_stop);
for (iter = iter_start; iter < iter_stop; iter++) {
if (iter->key == (jump_label_t)(unsigned long)key)
continue;
key = (struct jump_label_key *)(unsigned long)iter->key;
if (__module_address(iter->key) == mod) {
atomic_set(&key->enabled, 0);
key->entries = iter;
key->next = NULL;
continue;
}
jlm = kzalloc(sizeof(struct jump_label_mod), GFP_KERNEL);
if (!jlm)
return -ENOMEM;
jlm->mod = mod;
jlm->entries = iter;
jlm->next = key->next;
key->next = jlm;
if (jump_label_enabled(key))
__jump_label_update(key, iter, JUMP_LABEL_ENABLE);
}
return 0;
}
static void jump_label_del_module(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
struct jump_entry *iter;
struct jump_label_key *key = NULL;
struct jump_label_mod *jlm, **prev;
for (iter = iter_start; iter < iter_stop; iter++) {
if (iter->key == (jump_label_t)(unsigned long)key)
continue;
key = (struct jump_label_key *)(unsigned long)iter->key;
if (__module_address(iter->key) == mod)
continue;
prev = &key->next;
jlm = key->next;
while (jlm && jlm->mod != mod) {
prev = &jlm->next;
jlm = jlm->next;
}
if (jlm) {
*prev = jlm->next;
kfree(jlm);
}
}
}
static void jump_label_invalidate_module_init(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
struct jump_entry *iter;
for (iter = iter_start; iter < iter_stop; iter++) {
if (within_module_init(iter->code, mod))
iter->code = 0;
}
}
static int
jump_label_module_notify(struct notifier_block *self, unsigned long val,
void *data)
{
struct module *mod = data;
int ret = 0;
switch (val) {
case MODULE_STATE_COMING:
jump_label_lock();
ret = jump_label_add_module(mod);
if (ret)
jump_label_del_module(mod);
jump_label_unlock();
break;
case MODULE_STATE_GOING:
jump_label_lock();
jump_label_del_module(mod);
jump_label_unlock();
break;
case MODULE_STATE_LIVE:
jump_label_lock();
jump_label_invalidate_module_init(mod);
jump_label_unlock();
break;
}
return notifier_from_errno(ret);
}
struct notifier_block jump_label_module_nb = {
.notifier_call = jump_label_module_notify,
.priority = 1, /* higher than tracepoints */
};
static __init int jump_label_init_module(void)
{
return register_module_notifier(&jump_label_module_nb);
}
early_initcall(jump_label_init_module);
#endif /* CONFIG_MODULES */
/***
* jump_label_text_reserved - check if addr range is reserved
@ -248,237 +353,29 @@ static int module_conflict(void *start, void *end)
*/
int jump_label_text_reserved(void *start, void *end)
{
struct jump_entry *iter;
struct jump_entry *iter_start = __start___jump_table;
struct jump_entry *iter_stop = __start___jump_table;
int conflict = 0;
int ret = __jump_label_text_reserved(__start___jump_table,
__stop___jump_table, start, end);
iter = iter_start;
while (iter < iter_stop) {
if (addr_conflict(iter, start, end)) {
conflict = 1;
goto out;
}
iter++;
}
if (ret)
return ret;
/* now check modules */
#ifdef CONFIG_MODULES
conflict = module_conflict(start, end);
ret = __jump_label_mod_text_reserved(start, end);
#endif
out:
return conflict;
}
/*
* Not all archs need this.
*/
void __weak arch_jump_label_text_poke_early(jump_label_t addr)
{
}
static __init int init_jump_label(void)
{
int ret;
struct jump_entry *iter_start = __start___jump_table;
struct jump_entry *iter_stop = __stop___jump_table;
struct jump_entry *iter;
jump_label_lock();
ret = build_jump_label_hashtable(__start___jump_table,
__stop___jump_table);
iter = iter_start;
while (iter < iter_stop) {
arch_jump_label_text_poke_early(iter->code);
iter++;
}
jump_label_unlock();
return ret;
}
early_initcall(init_jump_label);
#ifdef CONFIG_MODULES
static struct jump_label_module_entry *
add_jump_label_module_entry(struct jump_label_entry *entry,
struct jump_entry *iter_begin,
int count, struct module *mod)
{
struct jump_label_module_entry *e;
e = kmalloc(sizeof(struct jump_label_module_entry), GFP_KERNEL);
if (!e)
return ERR_PTR(-ENOMEM);
e->mod = mod;
e->nr_entries = count;
e->table = iter_begin;
hlist_add_head(&e->hlist, &entry->modules);
return e;
}
static int add_jump_label_module(struct module *mod)
{
struct jump_entry *iter, *iter_begin;
struct jump_label_entry *entry;
struct jump_label_module_entry *module_entry;
int count;
/* if the module doesn't have jump label entries, just return */
if (!mod->num_jump_entries)
return 0;
sort_jump_label_entries(mod->jump_entries,
mod->jump_entries + mod->num_jump_entries);
iter = mod->jump_entries;
while (iter < mod->jump_entries + mod->num_jump_entries) {
entry = get_jump_label_entry(iter->key);
iter_begin = iter;
count = 0;
while ((iter < mod->jump_entries + mod->num_jump_entries) &&
(iter->key == iter_begin->key)) {
iter++;
count++;
}
if (!entry) {
entry = add_jump_label_entry(iter_begin->key, 0, NULL);
if (IS_ERR(entry))
return PTR_ERR(entry);
}
module_entry = add_jump_label_module_entry(entry, iter_begin,
count, mod);
if (IS_ERR(module_entry))
return PTR_ERR(module_entry);
}
return 0;
}
static void remove_jump_label_module(struct module *mod)
{
struct hlist_head *head;
struct hlist_node *node, *node_next, *module_node, *module_node_next;
struct jump_label_entry *e;
struct jump_label_module_entry *e_module;
int i;
/* if the module doesn't have jump label entries, just return */
if (!mod->num_jump_entries)
return;
for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
head = &jump_label_table[i];
hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
hlist_for_each_entry_safe(e_module, module_node,
module_node_next,
&(e->modules), hlist) {
if (e_module->mod == mod) {
hlist_del(&e_module->hlist);
kfree(e_module);
}
}
if (hlist_empty(&e->modules) && (e->nr_entries == 0)) {
hlist_del(&e->hlist);
kfree(e);
}
}
}
}
static void remove_jump_label_module_init(struct module *mod)
{
struct hlist_head *head;
struct hlist_node *node, *node_next, *module_node, *module_node_next;
struct jump_label_entry *e;
struct jump_label_module_entry *e_module;
struct jump_entry *iter;
int i, count;
/* if the module doesn't have jump label entries, just return */
if (!mod->num_jump_entries)
return;
for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
head = &jump_label_table[i];
hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
hlist_for_each_entry_safe(e_module, module_node,
module_node_next,
&(e->modules), hlist) {
if (e_module->mod != mod)
continue;
count = e_module->nr_entries;
iter = e_module->table;
while (count--) {
if (within_module_init(iter->code, mod))
iter->key = 0;
iter++;
}
}
}
}
}
static int
jump_label_module_notify(struct notifier_block *self, unsigned long val,
void *data)
{
struct module *mod = data;
int ret = 0;
switch (val) {
case MODULE_STATE_COMING:
jump_label_lock();
ret = add_jump_label_module(mod);
if (ret)
remove_jump_label_module(mod);
jump_label_unlock();
break;
case MODULE_STATE_GOING:
jump_label_lock();
remove_jump_label_module(mod);
jump_label_unlock();
break;
case MODULE_STATE_LIVE:
jump_label_lock();
remove_jump_label_module_init(mod);
jump_label_unlock();
break;
}
return ret;
}
/***
* apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
* @mod: module to patch
*
* Allow for run-time selection of the optimal nops. Before the module
* loads patch these with arch_get_jump_label_nop(), which is specified by
* the arch specific jump label code.
*/
void jump_label_apply_nops(struct module *mod)
static void jump_label_update(struct jump_label_key *key, int enable)
{
struct jump_entry *iter;
struct jump_entry *entry = key->entries;
/* if the module doesn't have jump label entries, just return */
if (!mod->num_jump_entries)
return;
/* if there are no users, entry can be NULL */
if (entry)
__jump_label_update(key, entry, enable);
iter = mod->jump_entries;
while (iter < mod->jump_entries + mod->num_jump_entries) {
arch_jump_label_text_poke_early(iter->code);
iter++;
}
#ifdef CONFIG_MODULES
__jump_label_mod_update(key, enable);
#endif
}
struct notifier_block jump_label_module_nb = {
.notifier_call = jump_label_module_notify,
.priority = 0,
};
static __init int init_jump_label_module(void)
{
return register_module_notifier(&jump_label_module_nb);
}
early_initcall(init_jump_label_module);
#endif /* CONFIG_MODULES */
#endif

4
kernel/perf_event.c
View file

@ -125,7 +125,7 @@ enum event_type_t {
* perf_sched_events : >0 events exist
* perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
*/
atomic_t perf_sched_events __read_mostly;
struct jump_label_key perf_sched_events __read_mostly;
static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
static atomic_t nr_mmap_events __read_mostly;
@ -5417,7 +5417,7 @@ static int swevent_hlist_get(struct perf_event *event)
return err;
}
atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
struct jump_label_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
static void sw_perf_event_destroy(struct perf_event *event)
{

23
kernel/tracepoint.c
View file

@ -251,9 +251,9 @@ static void set_tracepoint(struct tracepoint_entry **entry,
{
WARN_ON(strcmp((*entry)->name, elem->name) != 0);
if (elem->regfunc && !elem->state && active)
if (elem->regfunc && !jump_label_enabled(&elem->key) && active)
elem->regfunc();
else if (elem->unregfunc && elem->state && !active)
else if (elem->unregfunc && jump_label_enabled(&elem->key) && !active)
elem->unregfunc();
/*
@ -264,13 +264,10 @@ static void set_tracepoint(struct tracepoint_entry **entry,
* is used.
*/
rcu_assign_pointer(elem->funcs, (*entry)->funcs);
if (!elem->state && active) {
jump_label_enable(&elem->state);
elem->state = active;
} else if (elem->state && !active) {
jump_label_disable(&elem->state);
elem->state = active;
}
if (active && !jump_label_enabled(&elem->key))
jump_label_inc(&elem->key);
else if (!active && jump_label_enabled(&elem->key))
jump_label_dec(&elem->key);
}
/*
@ -281,13 +278,11 @@ static void set_tracepoint(struct tracepoint_entry **entry,
*/
static void disable_tracepoint(struct tracepoint *elem)
{
if (elem->unregfunc && elem->state)
if (elem->unregfunc && jump_label_enabled(&elem->key))
elem->unregfunc();
if (elem->state) {
jump_label_disable(&elem->state);
elem->state = 0;
}
if (jump_label_enabled(&elem->key))
jump_label_dec(&elem->key);
rcu_assign_pointer(elem->funcs, NULL);
}