libcounter/shm.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _LIBCOUNTER_SHM_H
   8 #define _LIBCOUNTER_SHM_H
   9
  10 #include <stddef.h>
  11 #include <stdint.h>
  12 #include <unistd.h>
  13 #include <usterr-signal-safe.h>
  14 #include <urcu/compiler.h>
  15 #include "shm_types.h"
  16 #include "helper.h"
  17
  18 /* lttng_counter_handle_create - for UST. */
  19 extern
  20 struct lttng_counter_shm_handle *lttng_counter_handle_create(void *data,
  21                                 uint64_t memory_map_size, int wakeup_fd);
  22 /* lttng_counter_handle_add_cpu - for UST. */
  23 extern
  24 int lttng_counter_handle_add_cpu(struct lttng_counter_shm_handle *handle,
  25                 int shm_fd, uint32_t cpu_nr,
  26                 uint64_t memory_map_size);
  27 LTTNG_HIDDEN
  28 unsigned int lttng_counter_handle_get_nr_cpus(struct lttng_counter_shm_handle *handle);
  29
  30 /*
  31  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  32  * both the index and offset with known boundaries.
  33  *
  34  * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
  35  * target type, even in the occurrence of shm_ref modification by an
  36  * untrusted process having write access to the shm_ref. We return a
  37  * NULL pointer if the ranges are invalid.
  38  */
  39 static inline
  40 char *_lttng_counter_shmp_offset(struct lttng_counter_shm_object_table *table,
  41                 struct lttng_counter_shm_ref *ref,
  42                 size_t idx, size_t elem_size)
  43 {
  44         struct lttng_counter_shm_object *obj;
  45         size_t objindex, ref_offset;
  46
  47         objindex = (size_t) ref->index;
  48         if (caa_unlikely(objindex >= table->allocated_len))
  49                 return NULL;
  50         obj = &table->objects[objindex];
  51         ref_offset = (size_t) ref->offset;
  52         ref_offset += idx * elem_size;
  53         /* Check if part of the element returned would exceed the limits. */
  54         if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
  55                 return NULL;
  56         return &obj->memory_map[ref_offset];
  57 }
  58
  59 #define lttng_counter_shmp_index(handle, ref, index)                    \
  60         ({                                                              \
  61                 __typeof__((ref)._type) ____ptr_ret;                    \
  62                 ____ptr_ret = (__typeof__(____ptr_ret)) _lttng_counter_shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));  \
  63                 ____ptr_ret;                                            \
  64         })
  65
  66 #define lttng_counter_shmp(handle, ref) lttng_counter_shmp_index(handle, ref, 0)
  67
  68 static inline
  69 void _lttng_counter_set_shmp(struct lttng_counter_shm_ref *ref, struct lttng_counter_shm_ref src)
  70 {
  71         *ref = src;
  72 }
  73
  74 #define lttng_counter_set_shmp(ref, src)        _lttng_counter_set_shmp(&(ref)._ref, src)
  75
  76 LTTNG_HIDDEN
  77 struct lttng_counter_shm_object_table *lttng_counter_shm_object_table_create(size_t max_nb_obj);
  78 LTTNG_HIDDEN
  79 struct lttng_counter_shm_object *lttng_counter_shm_object_table_alloc(struct lttng_counter_shm_object_table *table,
  80                         size_t memory_map_size,
  81                         enum lttng_counter_shm_object_type type,
  82                         const int cpu_fd,
  83                         int cpu);
  84 LTTNG_HIDDEN
  85 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_shm(struct lttng_counter_shm_object_table *table,
  86                         int shm_fd, size_t memory_map_size);
  87 /* mem ownership is passed to lttng_counter_shm_object_table_append_mem(). */
  88 LTTNG_HIDDEN
  89 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_mem(struct lttng_counter_shm_object_table *table,
  90                         void *mem, size_t memory_map_size);
  91 LTTNG_HIDDEN
  92 void lttng_counter_shm_object_table_destroy(struct lttng_counter_shm_object_table *table, int consumer);
  93
  94 /*
  95  * lttng_counter_zalloc_shm - allocate memory within a shm object.
  96  *
  97  * Shared memory is already zeroed by shmget.
  98  * *NOT* multithread-safe (should be protected by mutex).
  99  * Returns a -1, -1 tuple on error.
 100  */
 101 LTTNG_HIDDEN
 102 struct lttng_counter_shm_ref lttng_counter_zalloc_shm(struct lttng_counter_shm_object *obj, size_t len);
 103 LTTNG_HIDDEN
 104 void lttng_counter_align_shm(struct lttng_counter_shm_object *obj, size_t align);
 105
 106 static inline
 107 int lttng_counter_shm_get_shm_fd(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref)
 108 {
 109         struct lttng_counter_shm_object_table *table = handle->table;
 110         struct lttng_counter_shm_object *obj;
 111         size_t index;
 112
 113         index = (size_t) ref->index;
 114         if (caa_unlikely(index >= table->allocated_len))
 115                 return -EPERM;
 116         obj = &table->objects[index];
 117         return obj->shm_fd;
 118 }
 119
 120
 121 static inline
 122 int lttng_counter_shm_get_shm_size(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref,
 123                 uint64_t *size)
 124 {
 125         struct lttng_counter_shm_object_table *table = handle->table;
 126         struct lttng_counter_shm_object *obj;
 127         size_t index;
 128
 129         index = (size_t) ref->index;
 130         if (caa_unlikely(index >= table->allocated_len))
 131                 return -EPERM;
 132         obj = &table->objects[index];
 133         *size = obj->memory_map_size;
 134         return 0;
 135 }
 136
 137 #endif /* _LIBCOUNTER_SHM_H */