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
  31 /* lttng_counter_handle_create - for UST. */
  32 extern
  33 struct lttng_counter_shm_handle *lttng_counter_handle_create(void *data,
  34                                 uint64_t memory_map_size, int wakeup_fd);
  35 /* lttng_counter_handle_add_cpu - for UST. */
  36 extern
  37 int lttng_counter_handle_add_cpu(struct lttng_counter_shm_handle *handle,
  38                 int shm_fd, uint32_t cpu_nr,
  39                 uint64_t memory_map_size);
  40 unsigned int lttng_counter_handle_get_nr_cpus(struct lttng_counter_shm_handle *handle);
  41
  42 /*
  43  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  44  * both the index and offset with known boundaries.
  45  *
  46  * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
  47  * target type, even in the occurrence of shm_ref modification by an
  48  * untrusted process having write access to the shm_ref. We return a
  49  * NULL pointer if the ranges are invalid.
  50  */
  51 static inline
  52 char *_lttng_counter_shmp_offset(struct lttng_counter_shm_object_table *table,
  53                 struct lttng_counter_shm_ref *ref,
  54                 size_t idx, size_t elem_size)
  55 {
  56         struct lttng_counter_shm_object *obj;
  57         size_t objindex, ref_offset;
  58
  59         objindex = (size_t) ref->index;
  60         if (caa_unlikely(objindex >= table->allocated_len))
  61                 return NULL;
  62         obj = &table->objects[objindex];
  63         ref_offset = (size_t) ref->offset;
  64         ref_offset += idx * elem_size;
  65         /* Check if part of the element returned would exceed the limits. */
  66         if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
  67                 return NULL;
  68         return &obj->memory_map[ref_offset];
  69 }
  70
  71 #define lttng_counter_shmp_index(handle, ref, index)                    \
  72         ({                                                              \
  73                 __typeof__((ref)._type) ____ptr_ret;                    \
  74                 ____ptr_ret = (__typeof__(____ptr_ret)) _lttng_counter_shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));  \
  75                 ____ptr_ret;                                            \
  76         })
  77
  78 #define lttng_counter_shmp(handle, ref) lttng_counter_shmp_index(handle, ref, 0)
  79
  80 static inline
  81 void _lttng_counter_set_shmp(struct lttng_counter_shm_ref *ref, struct lttng_counter_shm_ref src)
  82 {
  83         *ref = src;
  84 }
  85
  86 #define lttng_counter_set_shmp(ref, src)        _lttng_counter_set_shmp(&(ref)._ref, src)
  87
  88 struct lttng_counter_shm_object_table *lttng_counter_shm_object_table_create(size_t max_nb_obj);
  89 struct lttng_counter_shm_object *lttng_counter_shm_object_table_alloc(struct lttng_counter_shm_object_table *table,
  90                         size_t memory_map_size,
  91                         enum lttng_counter_shm_object_type type,
  92                         const int cpu_fd,
  93                         int cpu);
  94 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_shm(struct lttng_counter_shm_object_table *table,
  95                         int shm_fd, size_t memory_map_size);
  96 /* mem ownership is passed to lttng_counter_shm_object_table_append_mem(). */
  97 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_mem(struct lttng_counter_shm_object_table *table,
  98                         void *mem, size_t memory_map_size);
  99 void lttng_counter_shm_object_table_destroy(struct lttng_counter_shm_object_table *table, int consumer);
 100
 101 /*
 102  * lttng_counter_zalloc_shm - allocate memory within a shm object.
 103  *
 104  * Shared memory is already zeroed by shmget.
 105  * *NOT* multithread-safe (should be protected by mutex).
 106  * Returns a -1, -1 tuple on error.
 107  */
 108 struct lttng_counter_shm_ref lttng_counter_zalloc_shm(struct lttng_counter_shm_object *obj, size_t len);
 109 void lttng_counter_align_shm(struct lttng_counter_shm_object *obj, size_t align);
 110
 111 static inline
 112 int lttng_counter_shm_get_shm_fd(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref)
 113 {
 114         struct lttng_counter_shm_object_table *table = handle->table;
 115         struct lttng_counter_shm_object *obj;
 116         size_t index;
 117
 118         index = (size_t) ref->index;
 119         if (caa_unlikely(index >= table->allocated_len))
 120                 return -EPERM;
 121         obj = &table->objects[index];
 122         return obj->shm_fd;
 123 }
 124
 125
 126 static inline
 127 int lttng_counter_shm_get_shm_size(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref,
 128                 uint64_t *size)
 129 {
 130         struct lttng_counter_shm_object_table *table = handle->table;
 131         struct lttng_counter_shm_object *obj;
 132         size_t index;
 133
 134         index = (size_t) ref->index;
 135         if (caa_unlikely(index >= table->allocated_len))
 136                 return -EPERM;
 137         obj = &table->objects[index];
 138         *size = obj->memory_map_size;
 139         return 0;
 140 }
 141
 142 #endif /* _LIBCOUNTER_SHM_H */