src/plugins/lttng-utils/debug-info/dwarf.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright 2015 Antoine Busque <abusque@efficios.com>
   5  *
   6  * Babeltrace - DWARF Information Reader
   7  */
   8
   9 #ifndef _BABELTRACE_DWARF_H
  10 #define _BABELTRACE_DWARF_H
  11
  12 #include <stdbool.h>
  13 #include <stdint.h>
  14 #include <stdlib.h>
  15 #include <dwarf.h>
  16 #include <elfutils/libdw.h>
  17 #include "common/macros.h"
  18
  19 /*
  20  * bt_dwarf is a wrapper over libdw providing a nicer, higher-level
  21  * interface, to access basic debug information.
  22  */
  23
  24 /*
  25  * This structure corresponds to a single compilation unit (CU) for a
  26  * given set of debug information (Dwarf type).
  27  */
  28 struct bt_dwarf_cu {
  29         Dwarf *dwarf_info;
  30         /* Offset in bytes in the DWARF file to current CU header. */
  31         Dwarf_Off offset;
  32         /* Offset in bytes in the DWARF file to next CU header. */
  33         Dwarf_Off next_offset;
  34         /* Size in bytes of CU header */
  35         size_t header_size;
  36 };
  37
  38 /*
  39  * This structure represents a single debug information entry (DIE),
  40  * within a compilation unit (CU).
  41  */
  42 struct bt_dwarf_die {
  43         struct bt_dwarf_cu *cu;
  44         Dwarf_Die *dwarf_die;
  45         /*
  46          * A depth of 0 represents a root DIE, located in the DWARF
  47          * layout on the same level as its corresponding CU entry. Its
  48          * children DIEs will have a depth of 1, and so forth.
  49          */
  50         unsigned int depth;
  51 };
  52
  53 /**
  54  * Instantiate a structure to access compile units (CU) from a given
  55  * `dwarf_info`.
  56  *
  57  * @param dwarf_info    Dwarf instance
  58  * @returns             Pointer to the new bt_dwarf_cu on success,
  59  *                      NULL on failure.
  60  */
  61 struct bt_dwarf_cu *bt_dwarf_cu_create(Dwarf *dwarf_info);
  62
  63 /**
  64  * Destroy the given bt_dwarf_cu instance.
  65  *
  66  * @param cu    bt_dwarf_cu instance
  67  */
  68 void bt_dwarf_cu_destroy(struct bt_dwarf_cu *cu);
  69
  70 /**
  71  * Advance the compile unit `cu` to the next one.
  72  *
  73  * On success, `cu`'s offset is set to that of the current compile
  74  * unit in the executable. On failure, `cu` remains unchanged.
  75  *
  76  * @param cu    bt_dwarf_cu instance
  77  * @returns     0 on success, 1 if no next CU is available,
  78  *              -1 on failure
  79  */
  80 int bt_dwarf_cu_next(struct bt_dwarf_cu *cu);
  81
  82 /**
  83  * Instantiate a structure to access debug information entries (DIE)
  84  * for the given compile unit `cu`.
  85  *
  86  * @param cu    bt_dwarf_cu instance
  87  * @returns     Pointer to the new bt_dwarf_die on success,
  88  *              NULL on failure.
  89  */
  90 struct bt_dwarf_die *bt_dwarf_die_create(struct bt_dwarf_cu *cu);
  91
  92 /**
  93  * Destroy the given bt_dwarf_die instance.
  94  *
  95  * @param die   bt_dwarf_die instance
  96  */
  97 void bt_dwarf_die_destroy(struct bt_dwarf_die *die);
  98
  99 /**
 100  * Indicates if the debug information entry `die` has children DIEs.
 101  *
 102  * @param die   bt_dwarf_die instance
 103  * @returns     0 if the die no child, 1 otherwise
 104  */
 105 int bt_dwarf_die_has_children(struct bt_dwarf_die *die);
 106
 107 /**
 108  * Advance the debug information entry `die` to its first child, if
 109  * any.
 110  *
 111  * @param die   bt_dwarf_die instance
 112  * @returns     0 on success, 1 if no child DIE is available,
 113  *              -1 on failure
 114  */
 115 int bt_dwarf_die_child(struct bt_dwarf_die *die);
 116
 117 /**
 118  * Advance the debug information entry `die` to the next one.
 119  *
 120  * The next DIE is considered to be its sibling on the same level. The
 121  * only exception is when the depth of the given DIE is 0, i.e. a
 122  * newly created bt_dwarf_die, in which case next returns the first
 123  * DIE at depth 1.
 124  *
 125  * The reason for staying at a depth of 1 is that this is where all
 126  * the function DIEs (those with a tag value of DW_TAG_subprogram) are
 127  * located, from which more specific child DIEs can then be accessed
 128  * if needed via bt_dwarf_die_child.
 129  *
 130  * @param die   bt_dwarf_die instance
 131  * @returns     0 on success, 1 if no other siblings are available, -1 on
 132  *              failure
 133  */
 134 int bt_dwarf_die_next(struct bt_dwarf_die *die);
 135
 136 /**
 137  * Get a DIE's tag.
 138  *
 139  * On success, the `tag` out parameter is set to the `die`'s tag's
 140  * value. It remains unchanged on failure.
 141  *
 142  * @param die   bt_dwarf_die instance
 143  * @param tag   Out parameter, the DIE's tag value
 144  * @returns     0 on success, -1 on failure.
 145  */
 146 int bt_dwarf_die_get_tag(struct bt_dwarf_die *die, int *tag);
 147
 148 /**
 149  * Get a DIE's name.
 150  *
 151  * On success, the `name` out parameter is set to the DIE's name. It
 152  * remains unchanged on failure.
 153  *
 154  * @param die   bt_dwarf_die instance
 155  * @param name  Out parameter, the DIE's name
 156  * @returns     0 on success, -1 on failure
 157  */
 158 int bt_dwarf_die_get_name(struct bt_dwarf_die *die, char **name);
 159
 160 /**
 161  * Get the full path to the DIE's callsite file.
 162  *
 163  * Only applies to DW_TAG_inlined_subroutine entries. The out
 164  * parameter `filename` is set on success, unchanged on failure.
 165  *
 166  * @param die           bt_dwarf_die instance
 167  * @param filename      Out parameter, the filename for the subroutine's
 168  *                      callsite
 169  * @returns             0 on success, -1 on failure
 170  */
 171 int bt_dwarf_die_get_call_file(struct bt_dwarf_die *die, char **filename);
 172
 173 /**
 174  * Get line number for the DIE's callsite.
 175  *
 176  * Only applies to DW_TAG_inlined_subroutine entries. The out
 177  * parameter `line_no` is set on success, unchanged on failure.
 178  *
 179  * @param die           bt_dwarf_die instance
 180  * @param line_no       Out parameter, the line number for the
 181  *                      subroutine's callsite
 182  * @returns             0 on success, -1 on failure
 183  */
 184 int bt_dwarf_die_get_call_line(struct bt_dwarf_die *die,
 185                 uint64_t *line_no);
 186
 187 /**
 188  * Verifies whether a given DIE contains the virtual memory address
 189  * `addr`.
 190  *
 191  * On success, the out parameter `contains` is set with the boolean
 192  * value indicating whether the DIE's range covers `addr`. On failure,
 193  * it remains unchanged.
 194  *
 195  * @param die           bt_dwarf_die instance
 196  * @param addr          The memory address to verify
 197  * @param contains      Out parameter, true if addr is contained,
 198  *                      false if not
 199  * @returns             0 on success, -1 on failure
 200  */
 201 int bt_dwarf_die_contains_addr(struct bt_dwarf_die *die, uint64_t addr,
 202                 bool *contains);
 203
 204 #endif  /* _BABELTRACE_DWARF_H */