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
  17 /* lttng_counter_handle_create - for UST. */
  18 extern
  19 struct lttng_counter_shm_handle *lttng_counter_handle_create(void *data,
  20                                 uint64_t memory_map_size, int wakeup_fd);
  21 /* lttng_counter_handle_add_cpu - for UST. */
  22 extern
  23 int lttng_counter_handle_add_cpu(struct lttng_counter_shm_handle *handle,
  24                 int shm_fd, uint32_t cpu_nr,
  25                 uint64_t memory_map_size);
  26
  27 unsigned int lttng_counter_handle_get_nr_cpus(struct lttng_counter_shm_handle *handle)
  28         __attribute__((visibility("hidden")));
  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 struct lttng_counter_shm_object_table *lttng_counter_shm_object_table_create(size_t max_nb_obj)
  77         __attribute__((visibility("hidden")));
  78
  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         __attribute__((visibility("hidden")));
  85
  86 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_shm(struct lttng_counter_shm_object_table *table,
  87                         int shm_fd, size_t memory_map_size)
  88         __attribute__((visibility("hidden")));
  89
  90 /* mem ownership is passed to lttng_counter_shm_object_table_append_mem(). */
  91 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_mem(struct lttng_counter_shm_object_table *table,
  92                         void *mem, size_t memory_map_size)
  93         __attribute__((visibility("hidden")));
  94
  95 void lttng_counter_shm_object_table_destroy(struct lttng_counter_shm_object_table *table, int consumer)
  96         __attribute__((visibility("hidden")));
  97
  98 /*
  99  * lttng_counter_zalloc_shm - allocate memory within a shm object.
 100  *
 101  * Shared memory is already zeroed by shmget.
 102  * *NOT* multithread-safe (should be protected by mutex).
 103  * Returns a -1, -1 tuple on error.
 104  */
 105 struct lttng_counter_shm_ref lttng_counter_zalloc_shm(struct lttng_counter_shm_object *obj, size_t len)
 106         __attribute__((visibility("hidden")));
 107
 108 void lttng_counter_align_shm(struct lttng_counter_shm_object *obj, size_t align)
 109         __attribute__((visibility("hidden")));
 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 */