libcounter/shm.h

   1 #ifndef _LIBCOUNTER_SHM_H
   2 #define _LIBCOUNTER_SHM_H
   3
   4 /*
   5  * libcounter/shm.h
   6  *
   7  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; only
  12  * version 2.1 of the License.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <stddef.h>
  25 #include <stdint.h>
  26 #include <unistd.h>
  27 #include <usterr-signal-safe.h>
  28 #include <urcu/compiler.h>
  29 #include "shm_types.h"
  30 #include "helper.h"
  31
  32 /* lttng_counter_handle_create - for UST. */
  33 extern
  34 struct lttng_counter_shm_handle *lttng_counter_handle_create(void *data,
  35                                 uint64_t memory_map_size, int wakeup_fd);
  36 /* lttng_counter_handle_add_cpu - for UST. */
  37 extern
  38 int lttng_counter_handle_add_cpu(struct lttng_counter_shm_handle *handle,
  39                 int shm_fd, uint32_t cpu_nr,
  40                 uint64_t memory_map_size);
  41 LTTNG_HIDDEN
  42 unsigned int lttng_counter_handle_get_nr_cpus(struct lttng_counter_shm_handle *handle);
  43
  44 /*
  45  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  46  * both the index and offset with known boundaries.
  47  *
  48  * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
  49  * target type, even in the occurrence of shm_ref modification by an
  50  * untrusted process having write access to the shm_ref. We return a
  51  * NULL pointer if the ranges are invalid.
  52  */
  53 static inline
  54 char *_lttng_counter_shmp_offset(struct lttng_counter_shm_object_table *table,
  55                 struct lttng_counter_shm_ref *ref,
  56                 size_t idx, size_t elem_size)
  57 {
  58         struct lttng_counter_shm_object *obj;
  59         size_t objindex, ref_offset;
  60
  61         objindex = (size_t) ref->index;
  62         if (caa_unlikely(objindex >= table->allocated_len))
  63                 return NULL;
  64         obj = &table->objects[objindex];
  65         ref_offset = (size_t) ref->offset;
  66         ref_offset += idx * elem_size;
  67         /* Check if part of the element returned would exceed the limits. */
  68         if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
  69                 return NULL;
  70         return &obj->memory_map[ref_offset];
  71 }
  72
  73 #define lttng_counter_shmp_index(handle, ref, index)                    \
  74         ({                                                              \
  75                 __typeof__((ref)._type) ____ptr_ret;                    \
  76                 ____ptr_ret = (__typeof__(____ptr_ret)) _lttng_counter_shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));  \
  77                 ____ptr_ret;                                            \
  78         })
  79
  80 #define lttng_counter_shmp(handle, ref) lttng_counter_shmp_index(handle, ref, 0)
  81
  82 static inline
  83 void _lttng_counter_set_shmp(struct lttng_counter_shm_ref *ref, struct lttng_counter_shm_ref src)
  84 {
  85         *ref = src;
  86 }
  87
  88 #define lttng_counter_set_shmp(ref, src)        _lttng_counter_set_shmp(&(ref)._ref, src)
  89
  90 LTTNG_HIDDEN
  91 struct lttng_counter_shm_object_table *lttng_counter_shm_object_table_create(size_t max_nb_obj);
  92 LTTNG_HIDDEN
  93 struct lttng_counter_shm_object *lttng_counter_shm_object_table_alloc(struct lttng_counter_shm_object_table *table,
  94                         size_t memory_map_size,
  95                         enum lttng_counter_shm_object_type type,
  96                         const int cpu_fd,
  97                         int cpu);
  98 LTTNG_HIDDEN
  99 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_shm(struct lttng_counter_shm_object_table *table,
 100                         int shm_fd, size_t memory_map_size);
 101 /* mem ownership is passed to lttng_counter_shm_object_table_append_mem(). */
 102 LTTNG_HIDDEN
 103 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_mem(struct lttng_counter_shm_object_table *table,
 104                         void *mem, size_t memory_map_size);
 105 LTTNG_HIDDEN
 106 void lttng_counter_shm_object_table_destroy(struct lttng_counter_shm_object_table *table, int consumer);
 107
 108 /*
 109  * lttng_counter_zalloc_shm - allocate memory within a shm object.
 110  *
 111  * Shared memory is already zeroed by shmget.
 112  * *NOT* multithread-safe (should be protected by mutex).
 113  * Returns a -1, -1 tuple on error.
 114  */
 115 LTTNG_HIDDEN
 116 struct lttng_counter_shm_ref lttng_counter_zalloc_shm(struct lttng_counter_shm_object *obj, size_t len);
 117 LTTNG_HIDDEN
 118 void lttng_counter_align_shm(struct lttng_counter_shm_object *obj, size_t align);
 119
 120 static inline
 121 int lttng_counter_shm_get_shm_fd(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref)
 122 {
 123         struct lttng_counter_shm_object_table *table = handle->table;
 124         struct lttng_counter_shm_object *obj;
 125         size_t index;
 126
 127         index = (size_t) ref->index;
 128         if (caa_unlikely(index >= table->allocated_len))
 129                 return -EPERM;
 130         obj = &table->objects[index];
 131         return obj->shm_fd;
 132 }
 133
 134
 135 static inline
 136 int lttng_counter_shm_get_shm_size(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref,
 137                 uint64_t *size)
 138 {
 139         struct lttng_counter_shm_object_table *table = handle->table;
 140         struct lttng_counter_shm_object *obj;
 141         size_t index;
 142
 143         index = (size_t) ref->index;
 144         if (caa_unlikely(index >= table->allocated_len))
 145                 return -EPERM;
 146         obj = &table->objects[index];
 147         *size = obj->memory_map_size;
 148         return 0;
 149 }
 150
 151 #endif /* _LIBCOUNTER_SHM_H */