return val;
}
+\f
+#ifdef OBJ_ELF
+enum mstate
+{
+ MAP_DATA,
+ MAP_ARM,
+ MAP_THUMB
+};
+
+/* This code is to handle mapping symbols as defined in the ARM ELF spec.
+ (This text is taken from version B-02 of the spec):
+
+ 4.4.7 Mapping and tagging symbols
+
+ A section of an ARM ELF file can contain a mixture of ARM code,
+ Thumb code, and data. There are inline transitions between code
+ and data at literal pool boundaries. There can also be inline
+ transitions between ARM code and Thumb code, for example in
+ ARM-Thumb inter-working veneers. Linkers, machine-level
+ debuggers, profiling tools, and disassembly tools need to map
+ images accurately. For example, setting an ARM breakpoint on a
+ Thumb location, or in a literal pool, can crash the program
+ being debugged, ruining the debugging session.
+
+ ARM ELF entities are mapped (see section 4.4.7.1 below) and
+ tagged (see section 4.4.7.2 below) using local symbols (with
+ binding STB_LOCAL). To assist consumers, mapping and tagging
+ symbols should be collated first in the symbol table, before
+ other symbols with binding STB_LOCAL.
+
+ To allow properly collated mapping and tagging symbols to be
+ skipped by consumers that have no interest in them, the first
+ such symbol should have the name $m and its st_value field equal
+ to the total number of mapping and tagging symbols (including
+ the $m) in the symbol table.
+
+ 4.4.7.1 Mapping symbols
+
+ $a Labels the first byte of a sequence of ARM instructions.
+ Its type is STT_FUNC.
+
+ $d Labels the first byte of a sequence of data items.
+ Its type is STT_OBJECT.
+
+ $t Labels the first byte of a sequence of Thumb instructions.
+ Its type is STT_FUNC.
+
+ This list of mapping symbols may be extended in the future.
+
+ Section-relative mapping symbols
+
+ Mapping symbols defined in a section define a sequence of
+ half-open address intervals that cover the address range of the
+ section. Each interval starts at the address defined by a
+ mapping symbol, and continues up to, but not including, the
+ address defined by the next (in address order) mapping symbol or
+ the end of the section. A corollary is that there must be a
+ mapping symbol defined at the beginning of each section.
+ Consumers can ignore the size of a section-relative mapping
+ symbol. Producers can set it to 0.
+
+ Absolute mapping symbols
+
+ Because of the need to crystallize a Thumb address with the
+ Thumb-bit set, absolute symbol of type STT_FUNC (symbols of type
+ STT_FUNC defined in section SHN_ABS) need to be mapped with $a
+ or $t.
+
+ The extent of a mapping symbol defined in SHN_ABS is [st_value,
+ st_value + st_size), or [st_value, st_value + 1) if st_size = 0,
+ where [x, y) denotes the half-open address range from x,
+ inclusive, to y, exclusive.
+
+ In the absence of a mapping symbol, a consumer can interpret a
+ function symbol with an odd value as the Thumb code address
+ obtained by clearing the least significant bit of the
+ value. This interpretation is deprecated, and it may not work in
+ the future.
+
+ Note - the Tagging symbols ($b, $f, $p $m) have been dropped from
+ the EABI (which is still under development), so they are not
+ implemented here. */
+
+static void
+mapping_state (enum mstate state)
+{
+ static enum mstate mapstate = MAP_DATA;
+ symbolS * symbolP;
+ const char * symname;
+ int type;
+
+ if (mapstate == state)
+ /* The mapping symbol has already been emitted.
+ There is nothing else to do. */
+ return;
+
+ mapstate = state;
+
+ switch (state)
+ {
+ case MAP_DATA:
+ symname = "$d";
+ type = BSF_OBJECT;
+ break;
+ case MAP_ARM:
+ symname = "$a";
+ type = BSF_FUNCTION;
+ break;
+ case MAP_THUMB:
+ symname = "$t";
+ type = BSF_FUNCTION;
+ break;
+ default:
+ abort ();
+ }
+
+ symbolP = symbol_new (symname, now_seg, (valueT) frag_now_fix (), frag_now);
+ symbol_table_insert (symbolP);
+ symbol_get_bfdsym (symbolP)->flags |= type | BSF_LOCAL;
+
+ switch (state)
+ {
+ case MAP_ARM:
+ THUMB_SET_FUNC (symbolP, 0);
+ ARM_SET_THUMB (symbolP, 0);
+ ARM_SET_INTERWORK (symbolP, support_interwork);
+ break;
+
+ case MAP_THUMB:
+ THUMB_SET_FUNC (symbolP, 1);
+ ARM_SET_THUMB (symbolP, 1);
+ ARM_SET_INTERWORK (symbolP, support_interwork);
+ break;
+
+ case MAP_DATA:
+ default:
+ return;
+ }
+}
+
+/* When we change sections we need to issue a new mapping symbol. */
+
+static void
+arm_elf_change_section (void)
+{
+ flagword flags;
+
+ if (!SEG_NORMAL (now_seg))
+ return;
+
+ flags = bfd_get_section_flags (stdoutput, now_seg);
+
+ /* We can ignore sections that only contain debug info. */
+ if ((flags & SEC_ALLOC) == 0)
+ return;
+
+ if (flags & SEC_CODE)
+ {
+ if (thumb_mode)
+ mapping_state (MAP_THUMB);
+ else
+ mapping_state (MAP_ARM);
+ }
+ else
+ /* This section does not contain code. Therefore it must contain data. */
+ mapping_state (MAP_DATA);
+}
+#else
+#define mapping_state(a)
+#endif /* OBJ_ELF */
+\f
+
static void
s_req (a)
int a ATTRIBUTE_UNUSED;
marking in_bss, then looking at s_skip for clues. */
subseg_set (bss_section, 0);
demand_empty_rest_of_line ();
+ mapping_state (MAP_DATA);
}
static void
coming from ARM mode, which is word-aligned. */
record_alignment (now_seg, 1);
}
+ mapping_state (MAP_THUMB);
break;
case 32:
record_alignment (now_seg, 1);
}
+ mapping_state (MAP_ARM);
break;
default:
return;
}
+ mapping_state (MAP_THUMB);
inst.instruction = opcode->value;
inst.size = opcode->size;
(*opcode->parms) (p);
return;
}
+ mapping_state (MAP_ARM);
inst.instruction = opcode->value;
inst.size = INSN_SIZE;
(*opcode->parms) (p);
md_cons_align (nbytes);
#endif
+ mapping_state (MAP_DATA);
do
{
bfd_reloc_code_real_type reloc;
projects / binutils-gdb.git / commitdiff