Implement event notifiers for syscalls
[lttng-modules.git] / src / lttng-syscalls.c
index 0528404063f8e2b123ca6b632f5b100fa1a2cf4f..c18a1418468f3ca81de3e019a99a0b932c26cf6d 100644 (file)
@@ -29,6 +29,7 @@
 #include <wrapper/rcu.h>
 #include <wrapper/syscall.h>
 #include <lttng/events.h>
+#include <lttng/utils.h>
 
 #ifndef CONFIG_COMPAT
 # ifndef is_compat_task
@@ -59,9 +60,13 @@ enum sc_type {
 #define COMPAT_SYSCALL_EXIT_STR                __stringify(COMPAT_SYSCALL_EXIT_TOK)
 
 static
-void syscall_entry_probe(void *__data, struct pt_regs *regs, long id);
+void syscall_entry_event_probe(void *__data, struct pt_regs *regs, long id);
 static
-void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret);
+void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret);
+
+static
+void syscall_entry_event_notifier_probe(void *__data, struct pt_regs *regs,
+               long id);
 
 /*
  * Forward declarations for old kernels.
@@ -122,7 +127,7 @@ typedef __kernel_old_time_t time_t;
 
 /* Hijack probe callback for system call enter */
 #undef TP_PROBE_CB
-#define TP_PROBE_CB(_template)         &syscall_entry_probe
+#define TP_PROBE_CB(_template)         &syscall_entry_event_probe
 #define SC_LTTNG_TRACEPOINT_EVENT(_name, _proto, _args, _fields) \
        LTTNG_TRACEPOINT_EVENT(syscall_entry_##_name, PARAMS(_proto), PARAMS(_args), \
                PARAMS(_fields))
@@ -158,7 +163,7 @@ typedef __kernel_old_time_t time_t;
 #undef _TRACE_SYSCALLS_POINTERS_H
 
 /* Hijack probe callback for compat system call enter */
-#define TP_PROBE_CB(_template)         &syscall_entry_probe
+#define TP_PROBE_CB(_template)         &syscall_entry_event_probe
 #define LTTNG_SC_COMPAT
 #define SC_LTTNG_TRACEPOINT_EVENT(_name, _proto, _args, _fields) \
        LTTNG_TRACEPOINT_EVENT(compat_syscall_entry_##_name, PARAMS(_proto), PARAMS(_args), \
@@ -207,7 +212,7 @@ typedef __kernel_old_time_t time_t;
 #define sc_inout(...)          __VA_ARGS__
 
 /* Hijack probe callback for system call exit */
-#define TP_PROBE_CB(_template)         &syscall_exit_probe
+#define TP_PROBE_CB(_template)         &syscall_exit_event_probe
 #define SC_LTTNG_TRACEPOINT_EVENT(_name, _proto, _args, _fields) \
        LTTNG_TRACEPOINT_EVENT(syscall_exit_##_name, PARAMS(_proto), PARAMS(_args), \
                PARAMS(_fields))
@@ -242,7 +247,7 @@ typedef __kernel_old_time_t time_t;
 
 
 /* Hijack probe callback for compat system call exit */
-#define TP_PROBE_CB(_template)         &syscall_exit_probe
+#define TP_PROBE_CB(_template)         &syscall_exit_event_probe
 #define LTTNG_SC_COMPAT
 #define SC_LTTNG_TRACEPOINT_EVENT(_name, _proto, _args, _fields) \
        LTTNG_TRACEPOINT_EVENT(compat_syscall_exit_##_name, PARAMS(_proto), PARAMS(_args), \
@@ -284,7 +289,8 @@ typedef __kernel_old_time_t time_t;
 #undef CREATE_TRACE_POINTS
 
 struct trace_syscall_entry {
-       void *func;
+       void *event_func;
+       void *event_notifier_func;
        const struct lttng_event_desc *desc;
        const struct lttng_event_field *fields;
        unsigned int nrargs;
@@ -300,13 +306,14 @@ struct trace_syscall_entry {
 #undef TRACE_SYSCALL_TABLE
 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)    \
        [ _nr ] = {                                             \
-               .func = __event_probe__syscall_entry_##_template, \
+               .event_func = __event_probe__syscall_entry_##_template, \
+               .event_notifier_func = __event_notifier_probe__syscall_entry_##_template, \
                .nrargs = (_nrargs),                            \
                .fields = __event_fields___syscall_entry_##_template, \
                .desc = &__event_desc___syscall_entry_##_name,  \
        },
 
-/* Syscall enter tracing table */
+/* Event syscall enter tracing table */
 static const struct trace_syscall_entry sc_table[] = {
 #include <instrumentation/syscalls/headers/syscalls_integers.h>
 #include <instrumentation/syscalls/headers/syscalls_pointers.h>
@@ -315,13 +322,14 @@ static const struct trace_syscall_entry sc_table[] = {
 #undef TRACE_SYSCALL_TABLE
 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)    \
        [ _nr ] = {                                             \
-               .func = __event_probe__compat_syscall_entry_##_template, \
+               .event_func = __event_probe__compat_syscall_entry_##_template, \
+               .event_notifier_func = __event_notifier_probe__compat_syscall_entry_##_template, \
                .nrargs = (_nrargs),                            \
                .fields = __event_fields___compat_syscall_entry_##_template, \
                .desc = &__event_desc___compat_syscall_entry_##_name, \
        },
 
-/* Compat syscall enter table */
+/* Event compat syscall enter table */
 const struct trace_syscall_entry compat_sc_table[] = {
 #include <instrumentation/syscalls/headers/compat_syscalls_integers.h>
 #include <instrumentation/syscalls/headers/compat_syscalls_pointers.h>
@@ -337,13 +345,14 @@ const struct trace_syscall_entry compat_sc_table[] = {
 #undef TRACE_SYSCALL_TABLE
 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)    \
        [ _nr ] = {                                             \
-               .func = __event_probe__syscall_exit_##_template, \
+               .event_func = __event_probe__syscall_exit_##_template, \
+               .event_notifier_func = __event_notifier_probe__syscall_exit_##_template, \
                .nrargs = (_nrargs),                            \
                .fields = __event_fields___syscall_exit_##_template, \
                .desc = &__event_desc___syscall_exit_##_name, \
        },
 
-/* Syscall exit table */
+/* Event syscall exit table */
 static const struct trace_syscall_entry sc_exit_table[] = {
 #include <instrumentation/syscalls/headers/syscalls_integers.h>
 #include <instrumentation/syscalls/headers/syscalls_pointers.h>
@@ -352,13 +361,14 @@ static const struct trace_syscall_entry sc_exit_table[] = {
 #undef TRACE_SYSCALL_TABLE
 #define TRACE_SYSCALL_TABLE(_template, _name, _nr, _nrargs)    \
        [ _nr ] = {                                             \
-               .func = __event_probe__compat_syscall_exit_##_template, \
+               .event_func = __event_probe__compat_syscall_exit_##_template, \
+               .event_notifier_func = __event_notifier_probe__compat_syscall_exit_##_template, \
                .nrargs = (_nrargs),                            \
                .fields = __event_fields___compat_syscall_exit_##_template, \
                .desc = &__event_desc___compat_syscall_exit_##_name, \
        },
 
-/* Compat syscall exit table */
+/* Event compat syscall exit table */
 const struct trace_syscall_entry compat_sc_exit_table[] = {
 #include <instrumentation/syscalls/headers/compat_syscalls_integers.h>
 #include <instrumentation/syscalls/headers/compat_syscalls_pointers.h>
@@ -375,7 +385,7 @@ struct lttng_syscall_filter {
        DECLARE_BITMAP(sc_compat_exit, NR_compat_syscalls);
 };
 
-static void syscall_entry_unknown(struct lttng_event *event,
+static void syscall_entry_event_unknown(struct lttng_event *event,
        struct pt_regs *regs, unsigned int id)
 {
        unsigned long args[LTTNG_SYSCALL_NR_ARGS];
@@ -387,77 +397,50 @@ static void syscall_entry_unknown(struct lttng_event *event,
                __event_probe__syscall_entry_unknown(event, id, args);
 }
 
-void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
+static void syscall_entry_event_notifier_unknown(
+               struct lttng_event_notifier_group *notifier_group,
+               struct pt_regs *regs, unsigned int id)
 {
-       struct lttng_channel *chan = __data;
-       struct lttng_event *event, *unknown_event;
-       const struct trace_syscall_entry *table, *entry;
-       size_t table_len;
-
-       if (unlikely(in_compat_syscall())) {
-               struct lttng_syscall_filter *filter = chan->sc_filter;
-
-               if (id < 0 || id >= NR_compat_syscalls
-                       || (!READ_ONCE(chan->syscall_all) && !test_bit(id, filter->sc_compat_entry))) {
-                       /* System call filtered out. */
-                       return;
-               }
-               table = compat_sc_table;
-               table_len = ARRAY_SIZE(compat_sc_table);
-               unknown_event = chan->sc_compat_unknown;
-       } else {
-               struct lttng_syscall_filter *filter = chan->sc_filter;
+       unsigned long args[LTTNG_SYSCALL_NR_ARGS];
+       struct lttng_event *event;
 
-               if (id < 0 || id >= NR_syscalls
-                       || (!READ_ONCE(chan->syscall_all) && !test_bit(id, filter->sc_entry))) {
-                       /* System call filtered out. */
-                       return;
-               }
-               table = sc_table;
-               table_len = ARRAY_SIZE(sc_table);
-               unknown_event = chan->sc_unknown;
-       }
-       if (unlikely(id < 0 || id >= table_len)) {
-               syscall_entry_unknown(unknown_event, regs, id);
-               return;
-       }
+       lttng_syscall_get_arguments(current, regs, args);
        if (unlikely(in_compat_syscall()))
-               event = chan->compat_sc_table[id];
+               __event_probe__compat_syscall_notifier_entry_unknown(event, id, args);
        else
-               event = chan->sc_table[id];
-       if (unlikely(!event)) {
-               syscall_entry_unknown(unknown_event, regs, id);
-               return;
-       }
-       entry = &table[id];
-       WARN_ON_ONCE(!entry);
+               __event_probe__syscall_notifier_entry_unknown(event, id, args);
+}
 
-       switch (entry->nrargs) {
+static __always_inline
+void syscall_entry_call_func(void *func, unsigned int nrargs, void *data,
+               struct pt_regs *regs)
+{
+       switch (nrargs) {
        case 0:
        {
-               void (*fptr)(void *__data) = entry->func;
+               void (*fptr)(void *__data) = func;
 
-               fptr(event);
+               fptr(data);
                break;
        }
        case 1:
        {
-               void (*fptr)(void *__data, unsigned long arg0) = entry->func;
+               void (*fptr)(void *__data, unsigned long arg0) = func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
-               fptr(event, args[0]);
+               fptr(data, args[0]);
                break;
        }
        case 2:
        {
                void (*fptr)(void *__data,
                        unsigned long arg0,
-                       unsigned long arg1) = entry->func;
+                       unsigned long arg1) = func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
-               fptr(event, args[0], args[1]);
+               fptr(data, args[0], args[1]);
                break;
        }
        case 3:
@@ -465,11 +448,11 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                void (*fptr)(void *__data,
                        unsigned long arg0,
                        unsigned long arg1,
-                       unsigned long arg2) = entry->func;
+                       unsigned long arg2) = func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
-               fptr(event, args[0], args[1], args[2]);
+               fptr(data, args[0], args[1], args[2]);
                break;
        }
        case 4:
@@ -478,11 +461,11 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg0,
                        unsigned long arg1,
                        unsigned long arg2,
-                       unsigned long arg3) = entry->func;
+                       unsigned long arg3) = func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
-               fptr(event, args[0], args[1], args[2], args[3]);
+               fptr(data, args[0], args[1], args[2], args[3]);
                break;
        }
        case 5:
@@ -492,11 +475,11 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg1,
                        unsigned long arg2,
                        unsigned long arg3,
-                       unsigned long arg4) = entry->func;
+                       unsigned long arg4) = func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
-               fptr(event, args[0], args[1], args[2], args[3], args[4]);
+               fptr(data, args[0], args[1], args[2], args[3], args[4]);
                break;
        }
        case 6:
@@ -507,11 +490,11 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
                        unsigned long arg2,
                        unsigned long arg3,
                        unsigned long arg4,
-                       unsigned long arg5) = entry->func;
+                       unsigned long arg5) = func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
-               fptr(event, args[0], args[1], args[2],
+               fptr(data, args[0], args[1], args[2],
                        args[3], args[4], args[5]);
                break;
        }
@@ -520,7 +503,92 @@ void syscall_entry_probe(void *__data, struct pt_regs *regs, long id)
        }
 }
 
-static void syscall_exit_unknown(struct lttng_event *event,
+void syscall_entry_event_probe(void *__data, struct pt_regs *regs, long id)
+{
+       struct lttng_channel *chan = __data;
+       struct lttng_event *event, *unknown_event;
+       const struct trace_syscall_entry *table, *entry;
+       size_t table_len;
+
+       if (unlikely(in_compat_syscall())) {
+               struct lttng_syscall_filter *filter = chan->sc_filter;
+
+               if (id < 0 || id >= NR_compat_syscalls
+                       || (!READ_ONCE(chan->syscall_all) && !test_bit(id, filter->sc_compat_entry))) {
+                       /* System call filtered out. */
+                       return;
+               }
+               table = compat_sc_table;
+               table_len = ARRAY_SIZE(compat_sc_table);
+               unknown_event = chan->sc_compat_unknown;
+       } else {
+               struct lttng_syscall_filter *filter = chan->sc_filter;
+
+               if (id < 0 || id >= NR_syscalls
+                       || (!READ_ONCE(chan->syscall_all) && !test_bit(id, filter->sc_entry))) {
+                       /* System call filtered out. */
+                       return;
+               }
+               table = sc_table;
+               table_len = ARRAY_SIZE(sc_table);
+               unknown_event = chan->sc_unknown;
+       }
+       if (unlikely(id < 0 || id >= table_len)) {
+               syscall_entry_event_unknown(unknown_event, regs, id);
+               return;
+       }
+       if (unlikely(in_compat_syscall()))
+               event = chan->compat_sc_table[id];
+       else
+               event = chan->sc_table[id];
+       if (unlikely(!event)) {
+               syscall_entry_event_unknown(unknown_event, regs, id);
+               return;
+       }
+       entry = &table[id];
+       WARN_ON_ONCE(!entry);
+       syscall_entry_call_func(entry->event_func, entry->nrargs, event, regs);
+}
+
+void syscall_entry_event_notifier_probe(void *__data, struct pt_regs *regs, long id)
+{
+       struct lttng_event_notifier_group *event_notifier_group = __data;
+       const struct trace_syscall_entry *entry;
+       struct list_head *dispatch_list;
+       struct lttng_event_notifier *iter;
+       size_t table_len;
+
+       if (unlikely(in_compat_syscall())) {
+               table_len = ARRAY_SIZE(compat_sc_table);
+               if (unlikely(id < 0 || id >= table_len)) {
+                       return;
+               }
+               entry = &compat_sc_table[id];
+               dispatch_list = &event_notifier_group->event_notifier_compat_syscall_dispatch[id];
+       } else {
+               table_len = ARRAY_SIZE(sc_table);
+               if (unlikely(id < 0 || id >= table_len)) {
+                       return;
+               }
+               entry = &sc_table[id];
+               dispatch_list = &event_notifier_group->event_notifier_syscall_dispatch[id];
+       }
+
+       if (unlikely(id < 0 || id >= table_len)) {
+               syscall_entry_event_notifier_unknown(event_notifier_group, regs, id);
+               return;
+       }
+
+       /* TODO handle unknown syscall */
+
+       list_for_each_entry_rcu(iter, dispatch_list, u.syscall.node) {
+               BUG_ON(iter->u.syscall.syscall_id != id);
+               syscall_entry_call_func(entry->event_notifier_func,
+                               entry->nrargs, iter, regs);
+       }
+}
+
+static void syscall_exit_event_unknown(struct lttng_event *event,
        struct pt_regs *regs, int id, long ret)
 {
        unsigned long args[LTTNG_SYSCALL_NR_ARGS];
@@ -533,7 +601,7 @@ static void syscall_exit_unknown(struct lttng_event *event,
                __event_probe__syscall_exit_unknown(event, id, ret, args);
 }
 
-void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
+void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret)
 {
        struct lttng_channel *chan = __data;
        struct lttng_event *event, *unknown_event;
@@ -566,7 +634,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                unknown_event = chan->sc_exit_unknown;
        }
        if (unlikely(id < 0 || id >= table_len)) {
-               syscall_exit_unknown(unknown_event, regs, id, ret);
+               syscall_exit_event_unknown(unknown_event, regs, id, ret);
                return;
        }
        if (unlikely(in_compat_syscall()))
@@ -574,7 +642,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
        else
                event = chan->sc_exit_table[id];
        if (unlikely(!event)) {
-               syscall_exit_unknown(unknown_event, regs, id, ret);
+               syscall_exit_event_unknown(unknown_event, regs, id, ret);
                return;
        }
        entry = &table[id];
@@ -583,7 +651,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
        switch (entry->nrargs) {
        case 0:
        {
-               void (*fptr)(void *__data, long ret) = entry->func;
+               void (*fptr)(void *__data, long ret) = entry->event_func;
 
                fptr(event, ret);
                break;
@@ -592,7 +660,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
        {
                void (*fptr)(void *__data,
                        long ret,
-                       unsigned long arg0) = entry->func;
+                       unsigned long arg0) = entry->event_func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
@@ -604,7 +672,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                void (*fptr)(void *__data,
                        long ret,
                        unsigned long arg0,
-                       unsigned long arg1) = entry->func;
+                       unsigned long arg1) = entry->event_func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
@@ -617,7 +685,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        long ret,
                        unsigned long arg0,
                        unsigned long arg1,
-                       unsigned long arg2) = entry->func;
+                       unsigned long arg2) = entry->event_func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
@@ -631,7 +699,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg0,
                        unsigned long arg1,
                        unsigned long arg2,
-                       unsigned long arg3) = entry->func;
+                       unsigned long arg3) = entry->event_func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
@@ -646,7 +714,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg1,
                        unsigned long arg2,
                        unsigned long arg3,
-                       unsigned long arg4) = entry->func;
+                       unsigned long arg4) = entry->event_func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
@@ -662,7 +730,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
                        unsigned long arg2,
                        unsigned long arg3,
                        unsigned long arg4,
-                       unsigned long arg5) = entry->func;
+                       unsigned long arg5) = entry->event_func;
                unsigned long args[LTTNG_SYSCALL_NR_ARGS];
 
                lttng_syscall_get_arguments(current, regs, args);
@@ -680,7 +748,7 @@ void syscall_exit_probe(void *__data, struct pt_regs *regs, long ret)
  * Should be called with sessions lock held.
  */
 static
-int fill_table(const struct trace_syscall_entry *table, size_t table_len,
+int fill_event_table(const struct trace_syscall_entry *table, size_t table_len,
        struct lttng_event **chan_table, struct lttng_channel *chan,
        void *filter, enum sc_type type)
 {
@@ -743,7 +811,7 @@ int fill_table(const struct trace_syscall_entry *table, size_t table_len,
 /*
  * Should be called with sessions lock held.
  */
-int lttng_syscalls_register(struct lttng_channel *chan, void *filter)
+int lttng_syscalls_register_event(struct lttng_channel *chan, void *filter)
 {
        struct lttng_kernel_event ev;
        int ret;
@@ -858,22 +926,22 @@ int lttng_syscalls_register(struct lttng_channel *chan, void *filter)
                }
        }
 
-       ret = fill_table(sc_table, ARRAY_SIZE(sc_table),
+       ret = fill_event_table(sc_table, ARRAY_SIZE(sc_table),
                        chan->sc_table, chan, filter, SC_TYPE_ENTRY);
        if (ret)
                return ret;
-       ret = fill_table(sc_exit_table, ARRAY_SIZE(sc_exit_table),
+       ret = fill_event_table(sc_exit_table, ARRAY_SIZE(sc_exit_table),
                        chan->sc_exit_table, chan, filter, SC_TYPE_EXIT);
        if (ret)
                return ret;
 
 #ifdef CONFIG_COMPAT
-       ret = fill_table(compat_sc_table, ARRAY_SIZE(compat_sc_table),
+       ret = fill_event_table(compat_sc_table, ARRAY_SIZE(compat_sc_table),
                        chan->compat_sc_table, chan, filter,
                        SC_TYPE_COMPAT_ENTRY);
        if (ret)
                return ret;
-       ret = fill_table(compat_sc_exit_table, ARRAY_SIZE(compat_sc_exit_table),
+       ret = fill_event_table(compat_sc_exit_table, ARRAY_SIZE(compat_sc_exit_table),
                        chan->compat_sc_exit_table, chan, filter,
                        SC_TYPE_COMPAT_EXIT);
        if (ret)
@@ -889,7 +957,7 @@ int lttng_syscalls_register(struct lttng_channel *chan, void *filter)
 
        if (!chan->sys_enter_registered) {
                ret = lttng_wrapper_tracepoint_probe_register("sys_enter",
-                               (void *) syscall_entry_probe, chan);
+                               (void *) syscall_entry_event_probe, chan);
                if (ret)
                        return ret;
                chan->sys_enter_registered = 1;
@@ -900,10 +968,10 @@ int lttng_syscalls_register(struct lttng_channel *chan, void *filter)
         */
        if (!chan->sys_exit_registered) {
                ret = lttng_wrapper_tracepoint_probe_register("sys_exit",
-                               (void *) syscall_exit_probe, chan);
+                               (void *) syscall_exit_event_probe, chan);
                if (ret) {
                        WARN_ON_ONCE(lttng_wrapper_tracepoint_probe_unregister("sys_enter",
-                               (void *) syscall_entry_probe, chan));
+                               (void *) syscall_entry_event_probe, chan));
                        return ret;
                }
                chan->sys_exit_registered = 1;
@@ -912,9 +980,158 @@ int lttng_syscalls_register(struct lttng_channel *chan, void *filter)
 }
 
 /*
- * Only called at session destruction.
+ * Should be called with sessions lock held.
  */
-int lttng_syscalls_unregister(struct lttng_channel *chan)
+int lttng_syscalls_register_event_notifier(struct lttng_event_notifier_enabler *event_notifier_enabler, void *filter)
+{
+       struct lttng_event_notifier_group *group = event_notifier_enabler->group;
+       unsigned int i;
+       int ret = 0;
+
+       wrapper_vmalloc_sync_mappings();
+
+       if (!group->event_notifier_syscall_dispatch) {
+               group->event_notifier_syscall_dispatch = kzalloc(sizeof(struct list_head)
+                                       * ARRAY_SIZE(sc_table), GFP_KERNEL);
+               if (!group->event_notifier_syscall_dispatch)
+                       return -ENOMEM;
+
+               /* Initialize all list_head */
+               for (i = 0; i < ARRAY_SIZE(sc_table); i++)
+                       INIT_LIST_HEAD(&group->event_notifier_syscall_dispatch[i]);
+       }
+
+#ifdef CONFIG_COMPAT
+       if (!group->event_notifier_compat_syscall_dispatch) {
+               group->event_notifier_compat_syscall_dispatch = kzalloc(sizeof(struct list_head)
+                                       * ARRAY_SIZE(compat_sc_table), GFP_KERNEL);
+               if (!group->event_notifier_syscall_dispatch)
+                       return -ENOMEM;
+
+               /* Initialize all list_head */
+               for (i = 0; i < ARRAY_SIZE(compat_sc_table); i++)
+                       INIT_LIST_HEAD(&group->event_notifier_compat_syscall_dispatch[i]);
+       }
+#endif
+
+       if (!group->sys_enter_registered) {
+               ret = lttng_wrapper_tracepoint_probe_register("sys_enter",
+                               (void *) syscall_entry_event_notifier_probe, group);
+               if (ret)
+                       return ret;
+               group->sys_enter_registered = 1;
+       }
+
+       return ret;
+}
+
+static int create_matching_event_notifiers(struct lttng_event_notifier_enabler *event_notifier_enabler,
+               void *filter, const struct trace_syscall_entry *table,
+               size_t table_len, bool is_compat)
+{
+       struct lttng_event_notifier_group *group = event_notifier_enabler->group;
+       const struct lttng_event_desc *desc;
+       uint64_t user_token = event_notifier_enabler->base.user_token;
+       unsigned int i;
+       int ret = 0;
+
+       /* iterate over all syscall and create event_notifier that match */
+       for (i = 0; i < table_len; i++) {
+               struct lttng_event_notifier *event_notifier;
+               struct lttng_kernel_event_notifier event_notifier_param;
+               struct hlist_head *head;
+               int found = 0;
+
+               desc = table[i].desc;
+               if (!desc) {
+                       /* Unknown syscall */
+                       continue;
+               }
+
+               if (!lttng_desc_match_enabler(desc,
+                               lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
+                       continue;
+
+               /*
+                * Check if already created.
+                */
+               head = utils_borrow_hash_table_bucket(group->event_notifiers_ht.table,
+                       LTTNG_EVENT_NOTIFIER_HT_SIZE, desc->name);
+               lttng_hlist_for_each_entry(event_notifier, head, hlist) {
+                       if (event_notifier->desc == desc
+                               && event_notifier->user_token == event_notifier_enabler->base.user_token)
+                               found = 1;
+               }
+               if (found)
+                       continue;
+
+               memset(&event_notifier_param, 0, sizeof(event_notifier_param));
+               strncat(event_notifier_param.event.name, desc->name,
+                       LTTNG_KERNEL_SYM_NAME_LEN - strlen(event_notifier_param.event.name) - 1);
+               event_notifier_param.event.name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
+               event_notifier_param.event.instrumentation = LTTNG_KERNEL_SYSCALL;
+
+               event_notifier = _lttng_event_notifier_create(desc, user_token, group,
+                       &event_notifier_param, filter,
+                       event_notifier_param.event.instrumentation);
+               if (IS_ERR(event_notifier)) {
+                       printk(KERN_INFO "Unable to create event_notifier %s\n",
+                               desc->name);
+                       ret = -ENOMEM;
+                       goto end;
+               }
+
+               event_notifier->u.syscall.syscall_id = i;
+               event_notifier->u.syscall.is_compat = is_compat;
+       }
+end:
+       return ret;
+
+}
+
+int lttng_syscals_create_matching_event_notifiers(struct lttng_event_notifier_enabler *event_notifier_enabler, void *filter)
+{
+       int ret;
+
+       ret = create_matching_event_notifiers(event_notifier_enabler, filter, sc_table,
+               ARRAY_SIZE(sc_table), false);
+       if (ret)
+               goto end;
+
+       ret = create_matching_event_notifiers(event_notifier_enabler, filter, compat_sc_table,
+               ARRAY_SIZE(compat_sc_table), true);
+end:
+       return ret;
+}
+
+/*
+ * Unregister the syscall event_notifier probes from the callsites.
+ */
+int lttng_syscalls_unregister_event_notifier(struct lttng_event_notifier_group *event_notifier_group)
+{
+       int ret;
+
+       /*
+        * Only register the event_notifier probe on the `sys_enter` callsite for now.
+        * At the moment, we don't think it's desirable to have one fired
+        * event_notifier for the entry and one for the exit of a syscall.
+        */
+       if (event_notifier_group->sys_enter_registered) {
+               ret = lttng_wrapper_tracepoint_probe_unregister("sys_enter",
+                               (void *) syscall_entry_event_notifier_probe, event_notifier_group);
+               if (ret)
+                       return ret;
+               event_notifier_group->sys_enter_registered = 0;
+       }
+
+       kfree(event_notifier_group->event_notifier_syscall_dispatch);
+#ifdef CONFIG_COMPAT
+       kfree(event_notifier_group->event_notifier_compat_syscall_dispatch);
+#endif
+       return 0;
+}
+
+int lttng_syscalls_unregister_event(struct lttng_channel *chan)
 {
        int ret;
 
@@ -922,14 +1139,14 @@ int lttng_syscalls_unregister(struct lttng_channel *chan)
                return 0;
        if (chan->sys_enter_registered) {
                ret = lttng_wrapper_tracepoint_probe_unregister("sys_enter",
-                               (void *) syscall_entry_probe, chan);
+                               (void *) syscall_entry_event_probe, chan);
                if (ret)
                        return ret;
                chan->sys_enter_registered = 0;
        }
        if (chan->sys_exit_registered) {
                ret = lttng_wrapper_tracepoint_probe_unregister("sys_exit",
-                               (void *) syscall_exit_probe, chan);
+                               (void *) syscall_exit_event_probe, chan);
                if (ret)
                        return ret;
                chan->sys_exit_registered = 0;
@@ -937,7 +1154,7 @@ int lttng_syscalls_unregister(struct lttng_channel *chan)
        return 0;
 }
 
-int lttng_syscalls_destroy(struct lttng_channel *chan)
+int lttng_syscalls_destroy_event(struct lttng_channel *chan)
 {
        kfree(chan->sc_table);
        kfree(chan->sc_exit_table);
@@ -1034,7 +1251,7 @@ const char *get_syscall_name(struct lttng_event *event)
        return event->desc->name + prefix_len;
 }
 
-int lttng_syscall_filter_enable(struct lttng_channel *chan,
+int lttng_syscall_filter_enable_event(struct lttng_channel *chan,
                struct lttng_event *event)
 {
        struct lttng_syscall_filter *filter = chan->sc_filter;
@@ -1093,7 +1310,24 @@ int lttng_syscall_filter_enable(struct lttng_channel *chan,
        return 0;
 }
 
-int lttng_syscall_filter_disable(struct lttng_channel *chan,
+int lttng_syscall_filter_enable_event_notifier(
+               struct lttng_event_notifier *event_notifier)
+{
+       struct lttng_event_notifier_group *group = event_notifier->group;
+       unsigned int syscall_id = event_notifier->u.syscall.syscall_id;
+       struct list_head *dispatch_list;
+
+       if (event_notifier->u.syscall.is_compat)
+               dispatch_list = &group->event_notifier_compat_syscall_dispatch[syscall_id];
+       else
+               dispatch_list = &group->event_notifier_syscall_dispatch[syscall_id];
+
+       list_add_rcu(&event_notifier->u.syscall.node, dispatch_list);
+
+       return 0;
+}
+
+int lttng_syscall_filter_disable_event(struct lttng_channel *chan,
                struct lttng_event *event)
 {
        struct lttng_syscall_filter *filter = chan->sc_filter;
@@ -1153,6 +1387,13 @@ int lttng_syscall_filter_disable(struct lttng_channel *chan,
        return 0;
 }
 
+int lttng_syscall_filter_disable_event_notifier(
+               struct lttng_event_notifier *event_notifier)
+{
+       list_del_rcu(&event_notifier->u.syscall.node);
+       return 0;
+}
+
 static
 const struct trace_syscall_entry *syscall_list_get_entry(loff_t *pos)
 {
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