| 1 | /* |
| 2 | * lttng-syscalls.c |
| 3 | * |
| 4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * LTTng sched probes. |
| 7 | * |
| 8 | * Dual LGPL v2.1/GPL v2 license. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <asm/ptrace.h> |
| 14 | #include <asm/syscall.h> |
| 15 | |
| 16 | #include "ltt-events.h" |
| 17 | |
| 18 | static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id); |
| 19 | |
| 20 | /* |
| 21 | * Create LTTng tracepoint probes. |
| 22 | */ |
| 23 | #define LTTNG_PACKAGE_BUILD |
| 24 | #define CREATE_TRACE_POINTS |
| 25 | |
| 26 | /* Hijack probe callback for system calls */ |
| 27 | #define TP_PROBE_CB(_template) &syscall_entry_probe |
| 28 | #define TP_MODULE_OVERRIDE |
| 29 | |
| 30 | #define TRACE_INCLUDE_PATH ../instrumentation/syscalls/headers |
| 31 | |
| 32 | #include "instrumentation/syscalls/headers/syscalls.h" |
| 33 | |
| 34 | #undef TP_MODULE_OVERRIDE |
| 35 | #undef TP_PROBE_CB |
| 36 | #undef LTTNG_PACKAGE_BUILD |
| 37 | #undef CREATE_TRACE_POINTS |
| 38 | |
| 39 | struct trace_syscall_entry { |
| 40 | void *func; |
| 41 | const struct lttng_event_desc *desc; /* Set dynamically */ |
| 42 | const struct lttng_event_field *fields; |
| 43 | unsigned int nrargs; |
| 44 | }; |
| 45 | |
| 46 | static int sc_table_desc_filled; |
| 47 | |
| 48 | #define CREATE_SYSCALL_TABLE |
| 49 | |
| 50 | #undef TRACE_SYSCALL_TABLE |
| 51 | #define TRACE_SYSCALL_TABLE(_name, _nr, _nrargs) \ |
| 52 | [ _nr ] = { \ |
| 53 | .func = __event_probe__##_name, \ |
| 54 | .nrargs = (_nrargs), \ |
| 55 | .fields = __event_fields___##_name, \ |
| 56 | }, |
| 57 | |
| 58 | static struct trace_syscall_entry sc_table[] = { |
| 59 | #include "instrumentation/syscalls/headers/syscalls.h" |
| 60 | }; |
| 61 | |
| 62 | #undef CREATE_SYSCALL_TABLE |
| 63 | |
| 64 | static void syscall_entry_probe(void *__data, struct pt_regs *regs, long id) |
| 65 | { |
| 66 | struct trace_syscall_entry *entry; |
| 67 | struct ltt_channel *chan = __data; |
| 68 | struct ltt_event *event; |
| 69 | |
| 70 | if (unlikely(id >= ARRAY_SIZE(sc_table))) |
| 71 | return; |
| 72 | entry = &sc_table[id]; |
| 73 | if (unlikely(!entry->func)) |
| 74 | return; |
| 75 | event = chan->sc_table[id]; |
| 76 | WARN_ON_ONCE(!event); |
| 77 | |
| 78 | switch (entry->nrargs) { |
| 79 | case 0: |
| 80 | { |
| 81 | void (*fptr)(void *__data) = entry->func; |
| 82 | |
| 83 | fptr(event); |
| 84 | break; |
| 85 | } |
| 86 | case 1: |
| 87 | { |
| 88 | void (*fptr)(void *__data, unsigned long arg0) = entry->func; |
| 89 | unsigned long args[1]; |
| 90 | |
| 91 | syscall_get_arguments(current, regs, 0, entry->nrargs, args); |
| 92 | fptr(event, args[0]); |
| 93 | break; |
| 94 | } |
| 95 | case 2: |
| 96 | { |
| 97 | void (*fptr)(void *__data, |
| 98 | unsigned long arg0, |
| 99 | unsigned long arg1) = entry->func; |
| 100 | unsigned long args[2]; |
| 101 | |
| 102 | syscall_get_arguments(current, regs, 0, entry->nrargs, args); |
| 103 | fptr(event, args[0], args[1]); |
| 104 | break; |
| 105 | } |
| 106 | case 3: |
| 107 | { |
| 108 | void (*fptr)(void *__data, |
| 109 | unsigned long arg0, |
| 110 | unsigned long arg1, |
| 111 | unsigned long arg2) = entry->func; |
| 112 | unsigned long args[3]; |
| 113 | |
| 114 | syscall_get_arguments(current, regs, 0, entry->nrargs, args); |
| 115 | fptr(event, args[0], args[1], args[2]); |
| 116 | break; |
| 117 | } |
| 118 | case 4: |
| 119 | { |
| 120 | void (*fptr)(void *__data, |
| 121 | unsigned long arg0, |
| 122 | unsigned long arg1, |
| 123 | unsigned long arg2, |
| 124 | unsigned long arg3) = entry->func; |
| 125 | unsigned long args[4]; |
| 126 | |
| 127 | syscall_get_arguments(current, regs, 0, entry->nrargs, args); |
| 128 | fptr(event, args[0], args[1], args[2], args[3]); |
| 129 | break; |
| 130 | } |
| 131 | case 5: |
| 132 | { |
| 133 | void (*fptr)(void *__data, |
| 134 | unsigned long arg0, |
| 135 | unsigned long arg1, |
| 136 | unsigned long arg2, |
| 137 | unsigned long arg3, |
| 138 | unsigned long arg4) = entry->func; |
| 139 | unsigned long args[5]; |
| 140 | |
| 141 | syscall_get_arguments(current, regs, 0, entry->nrargs, args); |
| 142 | fptr(event, args[0], args[1], args[2], args[3], args[4]); |
| 143 | break; |
| 144 | } |
| 145 | case 6: |
| 146 | { |
| 147 | void (*fptr)(void *__data, |
| 148 | unsigned long arg0, |
| 149 | unsigned long arg1, |
| 150 | unsigned long arg2, |
| 151 | unsigned long arg3, |
| 152 | unsigned long arg4, |
| 153 | unsigned long arg5) = entry->func; |
| 154 | unsigned long args[6]; |
| 155 | |
| 156 | syscall_get_arguments(current, regs, 0, entry->nrargs, args); |
| 157 | fptr(event, args[0], args[1], args[2], |
| 158 | args[3], args[4], args[5]); |
| 159 | break; |
| 160 | } |
| 161 | default: |
| 162 | break; |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | static const struct lttng_event_desc *find_syscall_desc(unsigned int id) |
| 167 | { |
| 168 | unsigned int i; |
| 169 | |
| 170 | for (i = 0; i < __probe_desc___syscalls.nr_events; i++) { |
| 171 | if (__probe_desc___syscalls.event_desc[i].fields |
| 172 | == sc_table[id].fields) |
| 173 | return &__probe_desc___syscalls.event_desc[i]; |
| 174 | } |
| 175 | WARN_ON_ONCE(1); |
| 176 | return NULL; |
| 177 | } |
| 178 | |
| 179 | static void fill_sc_table_desc(void) |
| 180 | { |
| 181 | unsigned int i; |
| 182 | |
| 183 | if (sc_table_desc_filled) |
| 184 | return; |
| 185 | /* |
| 186 | * This is O(n^2), but rare. Eventually get the TRACE_EVENT code |
| 187 | * to emit per-event symbols to skip this. |
| 188 | */ |
| 189 | for (i = 0; i < ARRAY_SIZE(sc_table); i++) { |
| 190 | const struct lttng_event_desc **desc = &sc_table[i].desc; |
| 191 | |
| 192 | if (!sc_table[i].func) |
| 193 | continue; |
| 194 | (*desc) = find_syscall_desc(i); |
| 195 | } |
| 196 | sc_table_desc_filled = 1; |
| 197 | } |
| 198 | |
| 199 | |
| 200 | int lttng_syscalls_register(struct ltt_channel *chan, void *filter) |
| 201 | { |
| 202 | unsigned int i; |
| 203 | int ret; |
| 204 | |
| 205 | wrapper_vmalloc_sync_all(); |
| 206 | fill_sc_table_desc(); |
| 207 | |
| 208 | if (!chan->sc_table) { |
| 209 | /* create syscall table mapping syscall to events */ |
| 210 | chan->sc_table = kzalloc(sizeof(struct ltt_event *) |
| 211 | * ARRAY_SIZE(sc_table), GFP_KERNEL); |
| 212 | if (!chan->sc_table) |
| 213 | return -ENOMEM; |
| 214 | } |
| 215 | |
| 216 | /* Allocate events for each syscall, insert into table */ |
| 217 | for (i = 0; i < ARRAY_SIZE(sc_table); i++) { |
| 218 | struct lttng_kernel_event ev; |
| 219 | const struct lttng_event_desc *desc = sc_table[i].desc; |
| 220 | |
| 221 | if (!desc) |
| 222 | continue; |
| 223 | /* |
| 224 | * Skip those already populated by previous failed |
| 225 | * register for this channel. |
| 226 | */ |
| 227 | if (chan->sc_table[i]) |
| 228 | continue; |
| 229 | memset(&ev, 0, sizeof(ev)); |
| 230 | strncpy(ev.name, desc->name, LTTNG_SYM_NAME_LEN); |
| 231 | ev.name[LTTNG_SYM_NAME_LEN - 1] = '\0'; |
| 232 | ev.instrumentation = LTTNG_KERNEL_NOOP; |
| 233 | chan->sc_table[i] = ltt_event_create(chan, &ev, filter, |
| 234 | desc); |
| 235 | if (!chan->sc_table[i]) { |
| 236 | /* |
| 237 | * If something goes wrong in event registration |
| 238 | * after the first one, we have no choice but to |
| 239 | * leave the previous events in there, until |
| 240 | * deleted by session teardown. |
| 241 | */ |
| 242 | return -EINVAL; |
| 243 | } |
| 244 | } |
| 245 | ret = tracepoint_probe_register("sys_enter", |
| 246 | (void *) syscall_entry_probe, chan); |
| 247 | return ret; |
| 248 | } |
| 249 | |
| 250 | /* |
| 251 | * Only called at session destruction. |
| 252 | */ |
| 253 | int lttng_syscalls_unregister(struct ltt_channel *chan) |
| 254 | { |
| 255 | int ret; |
| 256 | |
| 257 | if (!chan->sc_table) |
| 258 | return 0; |
| 259 | ret = tracepoint_probe_unregister("sys_enter", |
| 260 | (void *) syscall_entry_probe, chan); |
| 261 | if (ret) |
| 262 | return ret; |
| 263 | /* ltt_event destroy will be performed by ltt_session_destroy() */ |
| 264 | kfree(chan->sc_table); |
| 265 | return 0; |
| 266 | } |