src/common/counter/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 <stdbool.h>
  14 #include "common/logging.h"
  15 #include <urcu/compiler.h>
  16 #include "shm_types.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
  28 unsigned int lttng_counter_handle_get_nr_cpus(struct lttng_counter_shm_handle *handle)
  29         __attribute__((visibility("hidden")));
  30
  31 /*
  32  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  33  * both the index and offset with known boundaries.
  34  *
  35  * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
  36  * target type, even in the occurrence of shm_ref modification by an
  37  * untrusted process having write access to the shm_ref. We return a
  38  * NULL pointer if the ranges are invalid.
  39  */
  40 static inline
  41 char *_lttng_counter_shmp_offset(struct lttng_counter_shm_object_table *table,
  42                 struct lttng_counter_shm_ref *ref,
  43                 size_t idx, size_t elem_size)
  44 {
  45         struct lttng_counter_shm_object *obj;
  46         size_t objindex, ref_offset;
  47
  48         objindex = (size_t) ref->index;
  49         if (caa_unlikely(objindex >= table->allocated_len))
  50                 return NULL;
  51         obj = &table->objects[objindex];
  52         ref_offset = (size_t) ref->offset;
  53         ref_offset += idx * elem_size;
  54         /* Check if part of the element returned would exceed the limits. */
  55         if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
  56                 return NULL;
  57         return &obj->memory_map[ref_offset];
  58 }
  59
  60 #define lttng_counter_shmp_index(handle, ref, index)                    \
  61         ({                                                              \
  62                 __typeof__((ref)._type) ____ptr_ret;                    \
  63                 ____ptr_ret = (__typeof__(____ptr_ret)) _lttng_counter_shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));  \
  64                 ____ptr_ret;                                            \
  65         })
  66
  67 #define lttng_counter_shmp(handle, ref) lttng_counter_shmp_index(handle, ref, 0)
  68
  69 static inline
  70 void _lttng_counter_set_shmp(struct lttng_counter_shm_ref *ref, struct lttng_counter_shm_ref src)
  71 {
  72         *ref = src;
  73 }
  74
  75 #define lttng_counter_set_shmp(ref, src)        _lttng_counter_set_shmp(&(ref)._ref, src)
  76
  77 struct lttng_counter_shm_object_table *lttng_counter_shm_object_table_create(size_t max_nb_obj, bool populate)
  78         __attribute__((visibility("hidden")));
  79
  80 struct lttng_counter_shm_object *lttng_counter_shm_object_table_alloc(struct lttng_counter_shm_object_table *table,
  81                         size_t memory_map_size,
  82                         enum lttng_counter_shm_object_type type,
  83                         const int cpu_fd,
  84                         int cpu, bool populate)
  85         __attribute__((visibility("hidden")));
  86
  87 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_shm(struct lttng_counter_shm_object_table *table,
  88                         int shm_fd, size_t memory_map_size, bool populate)
  89         __attribute__((visibility("hidden")));
  90
  91 /* mem ownership is passed to lttng_counter_shm_object_table_append_mem(). */
  92 struct lttng_counter_shm_object *lttng_counter_shm_object_table_append_mem(struct lttng_counter_shm_object_table *table,
  93                         void *mem, size_t memory_map_size)
  94         __attribute__((visibility("hidden")));
  95
  96 void lttng_counter_shm_object_table_destroy(struct lttng_counter_shm_object_table *table, int consumer)
  97         __attribute__((visibility("hidden")));
  98
  99 /*
 100  * lttng_counter_zalloc_shm - allocate memory within a shm object.
 101  *
 102  * Shared memory is already zeroed by shmget.
 103  * *NOT* multithread-safe (should be protected by mutex).
 104  * Returns a -1, -1 tuple on error.
 105  */
 106 struct lttng_counter_shm_ref lttng_counter_zalloc_shm(struct lttng_counter_shm_object *obj, size_t len)
 107         __attribute__((visibility("hidden")));
 108
 109 void lttng_counter_align_shm(struct lttng_counter_shm_object *obj, size_t align)
 110         __attribute__((visibility("hidden")));
 111
 112 static inline
 113 int lttng_counter_shm_get_shm_fd(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref)
 114 {
 115         struct lttng_counter_shm_object_table *table = handle->table;
 116         struct lttng_counter_shm_object *obj;
 117         size_t index;
 118
 119         index = (size_t) ref->index;
 120         if (caa_unlikely(index >= table->allocated_len))
 121                 return -EPERM;
 122         obj = &table->objects[index];
 123         return obj->shm_fd;
 124 }
 125
 126
 127 static inline
 128 int lttng_counter_shm_get_shm_size(struct lttng_counter_shm_handle *handle, struct lttng_counter_shm_ref *ref,
 129                 uint64_t *size)
 130 {
 131         struct lttng_counter_shm_object_table *table = handle->table;
 132         struct lttng_counter_shm_object *obj;
 133         size_t index;
 134
 135         index = (size_t) ref->index;
 136         if (caa_unlikely(index >= table->allocated_len))
 137                 return -EPERM;
 138         obj = &table->objects[index];
 139         *size = obj->memory_map_size;
 140         return 0;
 141 }
 142
 143 #endif /* _LIBCOUNTER_SHM_H */