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    Subject[PATCH 4/6] jump label: Introduce static_branch() interface
    From: Jason Baron <jbaron@redhat.com>

    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>
    ---
    arch/mips/include/asm/jump_label.h | 22 +-
    arch/sparc/include/asm/jump_label.h | 25 +-
    arch/x86/include/asm/alternative.h | 3 +-
    arch/x86/include/asm/jump_label.h | 26 +-
    arch/x86/kernel/alternative.c | 2 +-
    arch/x86/kernel/module.c | 1 +
    include/asm-generic/vmlinux.lds.h | 14 +-
    include/linux/dynamic_debug.h | 2 -
    include/linux/jump_label.h | 89 ++++---
    include/linux/jump_label_ref.h | 44 ---
    include/linux/perf_event.h | 26 +-
    include/linux/tracepoint.h | 22 +-
    kernel/jump_label.c | 539 ++++++++++++++---------------------
    kernel/perf_event.c | 4 +-
    kernel/tracepoint.c | 23 +-
    15 files changed, 356 insertions(+), 486 deletions(-)
    delete mode 100644 include/linux/jump_label_ref.h

    diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
    index 7622ccf..1881b31 100644
    --- a/arch/mips/include/asm/jump_label.h
    +++ b/arch/mips/include/asm/jump_label.h
    @@ -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__ */

    diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
    index 427d468..fc73a82 100644
    --- a/arch/sparc/include/asm/jump_label.h
    +++ b/arch/sparc/include/asm/jump_label.h
    @@ -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__ */

    diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
    index 13009d1..8cdd1e2 100644
    --- a/arch/x86/include/asm/alternative.h
    +++ b/arch/x86/include/asm/alternative.h
    @@ -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);
    diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
    index 574dbc2..f217cee 100644
    --- a/arch/x86/include/asm/jump_label.h
    +++ b/arch/x86/include/asm/jump_label.h
    @@ -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(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)
    +#define JUMP_LABEL_INITIAL_NOP ".byte 0xe9 \n\t .long 0\n\t"
    +
    +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__ */

    diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
    index 4a23467..651454b 100644
    --- a/arch/x86/kernel/alternative.c
    +++ b/arch/x86/kernel/alternative.c
    @@ -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 };
    diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
    index ab23f1a..52f256f 100644
    --- a/arch/x86/kernel/module.c
    +++ b/arch/x86/kernel/module.c
    @@ -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>
    diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
    index 32c45e5..7952216 100644
    --- a/include/asm-generic/vmlinux.lds.h
    +++ b/include/asm-generic/vmlinux.lds.h
    @@ -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); \
    diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
    index 0c9653f..e747ecd 100644
    --- a/include/linux/dynamic_debug.h
    +++ b/include/linux/dynamic_debug.h
    @@ -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.
    diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
    index 7880f18..83e745f 100644
    --- a/include/linux/jump_label.h
    +++ b/include/linux/jump_label.h
    @@ -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);
    +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);

    -#define jump_label_enable(key) \
    - jump_label_update((unsigned long)key, JUMP_LABEL_ENABLE);
    +#else

    -#define jump_label_disable(key) \
    - jump_label_update((unsigned long)key, JUMP_LABEL_DISABLE);
    +#include <asm/atomic.h>

    -#else
    +#define JUMP_LABEL_INIT {ATOMIC_INIT(0)}

    -#define JUMP_LABEL(key, label) \
    -do { \
    - if (unlikely(*key)) \
    - goto label; \
    -} while (0)
    +struct jump_label_key {
    + atomic_t enabled;
    +};

    -#define jump_label_enable(cond_var) \
    -do { \
    - *(cond_var) = 1; \
    -} while (0)
    +static __always_inline bool static_branch(struct jump_label_key *key)
    +{
    + if (unlikely(atomic_read(&key->enabled)))
    + return true;
    + return false;
    +}

    -#define jump_label_disable(cond_var) \
    -do { \
    - *(cond_var) = 0; \
    -} while (0)
    +static inline void jump_label_inc(struct jump_label_key *key)
    +{
    + atomic_inc(&key->enabled);
    +}

    -static inline int jump_label_apply_nops(struct module *mod)
    +static inline void jump_label_dec(struct jump_label_key *key)
    {
    - return 0;
    + 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
    diff --git a/include/linux/jump_label_ref.h b/include/linux/jump_label_ref.h
    deleted file mode 100644
    index e5d012a..0000000
    --- a/include/linux/jump_label_ref.h
    +++ /dev/null
    @@ -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 */
    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 311b4dc..730b782 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -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);
    diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
    index 97c84a5..d530a44 100644
    --- a/include/linux/tracepoint.h
    +++ b/include/linux/tracepoint.h
    @@ -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) \
    diff --git a/kernel/jump_label.c b/kernel/jump_label.c
    index 3b79bd9..74d1c09 100644
    --- a/kernel/jump_label.c
    +++ b/kernel/jump_label.c
    @@ -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)
    -{
    - 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 void jump_label_update(struct jump_label_key *key, int enable);

    -static struct jump_label_entry *
    -add_jump_label_entry(jump_label_t key, int nr_entries, struct jump_entry *table)
    +void jump_label_inc(struct jump_label_key *key)
    {
    - 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;
    -}
    + if (atomic_inc_not_zero(&key->enabled))
    + return;

    -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_lock();
    + if (atomic_add_return(1, &key->enabled) == 1)
    + jump_label_update(key, JUMP_LABEL_ENABLE);
    + jump_label_unlock();
    }

    -/***
    - * 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)
    +void jump_label_dec(struct jump_label_key *key)
    {
    - 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_dec_and_mutex_lock(&key->enabled, &jump_label_mutex))
    + 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++;
    - }
    - }
    - }
    + jump_label_update(key, JUMP_LABEL_DISABLE);
    jump_label_unlock();
    }

    @@ -197,77 +89,33 @@ 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++;
    - }
    - }
    - }
    - }
    -out:
    - return conflict;
    -}
    -
    -#endif
    -
    -/***
    - * jump_label_text_reserved - check if addr range is reserved
    - * @start: start text addr
    - * @end: end text addr
    - *
    - * checks if the text addr located between @start and @end
    - * overlaps with any of the jump label patch addresses. Code
    - * that wants to modify kernel text should first verify that
    - * it does not overlap with any of the jump label addresses.
    - * Caller must hold jump_label_mutex.
    - *
    - * returns 1 if there is an overlap, 0 otherwise
    - */
    -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;

    iter = iter_start;
    while (iter < iter_stop) {
    - if (addr_conflict(iter, start, end)) {
    - conflict = 1;
    - goto out;
    - }
    + if (addr_conflict(iter, start, end))
    + return 1;
    iter++;
    }

    - /* now check modules */
    -#ifdef CONFIG_MODULES
    - conflict = module_conflict(start, end);
    -#endif
    -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);
    + }
    }

    /*
    @@ -277,142 +125,173 @@ void __weak arch_jump_label_text_poke_early(jump_label_t addr)
    {
    }

    -static __init int init_jump_label(void)
    +static __init int jump_label_init(void)
    {
    - int ret;
    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();
    - ret = build_jump_label_hashtable(__start___jump_table,
    - __stop___jump_table);
    - iter = iter_start;
    - while (iter < iter_stop) {
    + jump_label_sort_entries(iter_start, iter_stop);
    +
    + for (iter = iter_start; iter < iter_stop; iter++) {
    arch_jump_label_text_poke_early(iter->code);
    - iter++;
    + 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 ret;
    +
    + return 0;
    }
    -early_initcall(init_jump_label);
    +early_initcall(jump_label_init);

    #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_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_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;
    + 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 add_jump_label_module(struct module *mod)
    +static int jump_label_add_module(struct module *mod)
    {
    - struct jump_entry *iter, *iter_begin;
    - struct jump_label_entry *entry;
    - struct jump_label_module_entry *module_entry;
    - int count;
    + 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 (!mod->num_jump_entries)
    + if (iter_start == iter_stop)
    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);
    + 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;
    }
    - module_entry = add_jump_label_module_entry(entry, iter_begin,
    - count, mod);
    - if (IS_ERR(module_entry))
    - return PTR_ERR(module_entry);
    +
    + 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 remove_jump_label_module(struct module *mod)
    +static void jump_label_del_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;
    + 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;

    - /* if the module doesn't have jump label entries, just return */
    - if (!mod->num_jump_entries)
    - return;
    + 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;

    - 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);
    - }
    + while (jlm && jlm->mod != mod) {
    + prev = &jlm->next;
    + jlm = jlm->next;
    + }
    +
    + if (jlm) {
    + *prev = jlm->next;
    + kfree(jlm);
    }
    }
    }

    -static void remove_jump_label_module_init(struct module *mod)
    +static void jump_label_invalidate_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_start = mod->jump_entries;
    + struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
    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++;
    - }
    - }
    - }
    + for (iter = iter_start; iter < iter_stop; iter++) {
    + if (within_module_init(iter->code, mod))
    + iter->code = 0;
    }
    }

    @@ -426,59 +305,77 @@ jump_label_module_notify(struct notifier_block *self, unsigned long val,
    switch (val) {
    case MODULE_STATE_COMING:
    jump_label_lock();
    - ret = add_jump_label_module(mod);
    + ret = jump_label_add_module(mod);
    if (ret)
    - remove_jump_label_module(mod);
    + jump_label_del_module(mod);
    jump_label_unlock();
    break;
    case MODULE_STATE_GOING:
    jump_label_lock();
    - remove_jump_label_module(mod);
    + jump_label_del_module(mod);
    jump_label_unlock();
    break;
    case MODULE_STATE_LIVE:
    jump_label_lock();
    - remove_jump_label_module_init(mod);
    + jump_label_invalidate_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)
    -{
    - struct jump_entry *iter;
    -
    - /* if the module doesn't have jump label entries, just return */
    - if (!mod->num_jump_entries)
    - return;
    -
    - iter = mod->jump_entries;
    - while (iter < mod->jump_entries + mod->num_jump_entries) {
    - arch_jump_label_text_poke_early(iter->code);
    - iter++;
    - }
    + return notifier_from_errno(ret);
    }

    struct notifier_block jump_label_module_nb = {
    .notifier_call = jump_label_module_notify,
    - .priority = 0,
    + .priority = 1, /* higher than tracepoints */
    };

    -static __init int init_jump_label_module(void)
    +static __init int jump_label_init_module(void)
    {
    return register_module_notifier(&jump_label_module_nb);
    }
    -early_initcall(init_jump_label_module);
    +early_initcall(jump_label_init_module);

    #endif /* CONFIG_MODULES */

    +/***
    + * jump_label_text_reserved - check if addr range is reserved
    + * @start: start text addr
    + * @end: end text addr
    + *
    + * checks if the text addr located between @start and @end
    + * overlaps with any of the jump label patch addresses. Code
    + * that wants to modify kernel text should first verify that
    + * it does not overlap with any of the jump label addresses.
    + * Caller must hold jump_label_mutex.
    + *
    + * returns 1 if there is an overlap, 0 otherwise
    + */
    +int jump_label_text_reserved(void *start, void *end)
    +{
    + int ret = __jump_label_text_reserved(__start___jump_table,
    + __stop___jump_table, start, end);
    +
    + if (ret)
    + return ret;
    +
    +#ifdef CONFIG_MODULES
    + ret = __jump_label_mod_text_reserved(start, end);
    +#endif
    + return ret;
    +}
    +
    +static void jump_label_update(struct jump_label_key *key, int enable)
    +{
    + struct jump_entry *entry = key->entries;
    +
    + /* if there are no users, entry can be NULL */
    + if (entry)
    + __jump_label_update(key, entry, enable);
    +
    +#ifdef CONFIG_MODULES
    + __jump_label_mod_update(key, enable);
    +#endif
    +}
    +
    #endif
    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index c75925c..d665e92 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -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 @@ fail:
    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)
    {
    diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
    index 68187af..b219f14 100644
    --- a/kernel/tracepoint.c
    +++ b/kernel/tracepoint.c
    @@ -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);
    }

    --
    1.7.2.3



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      Last update: 2011-04-04 21:21    [W:0.092 / U:3.596 seconds]
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