+/* Read an integer symbol value from the current target. */
+
+static LONGEST
+fbsd_read_integer_by_name (struct gdbarch *gdbarch, const char *name)
+{
+ bound_minimal_symbol ms = lookup_minimal_symbol (name, NULL, NULL);
+ if (ms.minsym == NULL)
+ error (_("Unable to resolve symbol '%s'"), name);
+
+ gdb_byte buf[4];
+ if (target_read_memory (BMSYMBOL_VALUE_ADDRESS (ms), buf, sizeof buf) != 0)
+ error (_("Unable to read value of '%s'"), name);
+
+ return extract_signed_integer (buf, sizeof buf, gdbarch_byte_order (gdbarch));
+}
+
+/* Lookup offsets of fields in the runtime linker's 'Obj_Entry'
+ structure needed to determine the TLS index of an object file. */
+
+static void
+fbsd_fetch_rtld_offsets (struct gdbarch *gdbarch, struct fbsd_pspace_data *data)
+{
+ TRY
+ {
+ /* Fetch offsets from debug symbols in rtld. */
+ struct symbol *obj_entry_sym
+ = lookup_symbol_in_language ("Struct_Obj_Entry", NULL, STRUCT_DOMAIN,
+ language_c, NULL).symbol;
+ if (obj_entry_sym == NULL)
+ error (_("Unable to find Struct_Obj_Entry symbol"));
+ data->off_linkmap = lookup_struct_elt (SYMBOL_TYPE(obj_entry_sym),
+ "linkmap", 0).offset / 8;
+ data->off_tlsindex = lookup_struct_elt (SYMBOL_TYPE(obj_entry_sym),
+ "tlsindex", 0).offset / 8;
+ data->rtld_offsets_valid = true;
+ return;
+ }
+ CATCH (e, RETURN_MASK_ERROR)
+ {
+ data->off_linkmap = -1;
+ }
+ END_CATCH
+
+ TRY
+ {
+ /* Fetch offsets from global variables in libthr. Note that
+ this does not work for single-threaded processes that are not
+ linked against libthr. */
+ data->off_linkmap = fbsd_read_integer_by_name (gdbarch,
+ "_thread_off_linkmap");
+ data->off_tlsindex = fbsd_read_integer_by_name (gdbarch,
+ "_thread_off_tlsindex");
+ data->rtld_offsets_valid = true;
+ return;
+ }
+ CATCH (e, RETURN_MASK_ERROR)
+ {
+ data->off_linkmap = -1;
+ }
+ END_CATCH
+}
+
+/* Helper function to read the TLS index of an object file associated
+ with a link map entry at LM_ADDR. */
+
+static LONGEST
+fbsd_get_tls_index (struct gdbarch *gdbarch, CORE_ADDR lm_addr)
+{
+ struct fbsd_pspace_data *data = get_fbsd_pspace_data (current_program_space);
+
+ if (!data->rtld_offsets_valid)
+ fbsd_fetch_rtld_offsets (gdbarch, data);
+
+ if (data->off_linkmap == -1)
+ throw_error (TLS_GENERIC_ERROR,
+ _("Cannot fetch runtime linker structure offsets"));
+
+ /* Simulate container_of to convert from LM_ADDR to the Obj_Entry
+ pointer and then compute the offset of the tlsindex member. */
+ CORE_ADDR tlsindex_addr = lm_addr - data->off_linkmap + data->off_tlsindex;
+
+ gdb_byte buf[4];
+ if (target_read_memory (tlsindex_addr, buf, sizeof buf) != 0)
+ throw_error (TLS_GENERIC_ERROR,
+ _("Cannot find thread-local variables on this target"));
+
+ return extract_signed_integer (buf, sizeof buf, gdbarch_byte_order (gdbarch));
+}
+
+/* See fbsd-tdep.h. */
+
+CORE_ADDR
+fbsd_get_thread_local_address (struct gdbarch *gdbarch, CORE_ADDR dtv_addr,
+ CORE_ADDR lm_addr, CORE_ADDR offset)
+{
+ LONGEST tls_index = fbsd_get_tls_index (gdbarch, lm_addr);
+
+ gdb_byte buf[gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT];
+ if (target_read_memory (dtv_addr, buf, sizeof buf) != 0)
+ throw_error (TLS_GENERIC_ERROR,
+ _("Cannot find thread-local variables on this target"));
+
+ const struct builtin_type *builtin = builtin_type (gdbarch);
+ CORE_ADDR addr = gdbarch_pointer_to_address (gdbarch,
+ builtin->builtin_data_ptr, buf);
+
+ addr += (tls_index + 1) * TYPE_LENGTH (builtin->builtin_data_ptr);
+ if (target_read_memory (addr, buf, sizeof buf) != 0)
+ throw_error (TLS_GENERIC_ERROR,
+ _("Cannot find thread-local variables on this target"));
+
+ addr = gdbarch_pointer_to_address (gdbarch, builtin->builtin_data_ptr, buf);
+ return addr + offset;
+}
+