/* This module handles expression trees.
- Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
- 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
- Free Software Foundation, Inc.
+ Copyright (C) 1991-2015 Free Software Foundation, Inc.
Written by Steve Chamberlain of Cygnus Support <sac@cygnus.com>.
This file is part of the GNU Binutils.
struct ldexp_control expld;
+/* This structure records symbols for which we need to keep track of
+ definedness for use in the DEFINED () test. */
+
+struct definedness_hash_entry
+{
+ struct bfd_hash_entry root;
+ unsigned int by_object : 1;
+ unsigned int by_script : 1;
+ unsigned int iteration : 1;
+};
+
+static struct bfd_hash_table definedness_table;
+
/* Print the string representation of the given token. Surround it
with spaces if INFIX_P is TRUE. */
static const struct
{
token_code_type code;
- char * name;
+ const char * name;
}
table[] =
{
{ GE, ">=" },
{ LSHIFT, "<<" },
{ RSHIFT, ">>" },
+ { LOG2CEIL, "LOG2CEIL" },
{ ALIGN_K, "ALIGN" },
{ BLOCK, "BLOCK" },
{ QUAD, "QUAD" },
fputc (' ', config.map_file);
}
+static void
+make_log2ceil (void)
+{
+ bfd_vma value = expld.result.value;
+ bfd_vma result = -1;
+ bfd_boolean round_up = FALSE;
+
+ do
+ {
+ result++;
+ /* If more than one bit is set in the value we will need to round up. */
+ if ((value > 1) && (value & 1))
+ round_up = TRUE;
+ }
+ while (value >>= 1);
+
+ if (round_up)
+ result += 1;
+ expld.result.section = NULL;
+ expld.result.value = result;
+}
+
static void
make_abs (void)
{
static void
new_rel_from_abs (bfd_vma value)
{
+ asection *s = expld.section;
+
+ if (s == bfd_abs_section_ptr && expld.phase == lang_final_phase_enum)
+ s = section_for_dot ();
expld.result.valid_p = TRUE;
- expld.result.value = value - expld.section->vma;
+ expld.result.value = value - s->vma;
expld.result.str = NULL;
- expld.result.section = expld.section;
+ expld.result.section = s;
+}
+
+/* New-function for the definedness hash table. */
+
+static struct bfd_hash_entry *
+definedness_newfunc (struct bfd_hash_entry *entry,
+ struct bfd_hash_table *table ATTRIBUTE_UNUSED,
+ const char *name ATTRIBUTE_UNUSED)
+{
+ struct definedness_hash_entry *ret = (struct definedness_hash_entry *) entry;
+
+ if (ret == NULL)
+ ret = (struct definedness_hash_entry *)
+ bfd_hash_allocate (table, sizeof (struct definedness_hash_entry));
+
+ if (ret == NULL)
+ einfo (_("%P%F: bfd_hash_allocate failed creating symbol %s\n"), name);
+
+ ret->by_object = 0;
+ ret->by_script = 0;
+ ret->iteration = 0;
+ return &ret->root;
+}
+
+/* Called during processing of linker script script expressions.
+ For symbols assigned in a linker script, return a struct describing
+ where the symbol is defined relative to the current expression,
+ otherwise return NULL. */
+
+static struct definedness_hash_entry *
+symbol_defined (const char *name)
+{
+ return ((struct definedness_hash_entry *)
+ bfd_hash_lookup (&definedness_table, name, FALSE, FALSE));
+}
+
+/* Update the definedness state of NAME. Return FALSE if script symbol
+ is multiply defining a strong symbol in an object. */
+
+static bfd_boolean
+update_definedness (const char *name, struct bfd_link_hash_entry *h)
+{
+ bfd_boolean ret;
+ struct definedness_hash_entry *defentry
+ = (struct definedness_hash_entry *)
+ bfd_hash_lookup (&definedness_table, name, TRUE, FALSE);
+
+ if (defentry == NULL)
+ einfo (_("%P%F: bfd_hash_lookup failed creating symbol %s\n"), name);
+
+ /* If the symbol was already defined, and not by a script, then it
+ must be defined by an object file or by the linker target code. */
+ ret = TRUE;
+ if (!defentry->by_script
+ && (h->type == bfd_link_hash_defined
+ || h->type == bfd_link_hash_defweak
+ || h->type == bfd_link_hash_common))
+ {
+ defentry->by_object = 1;
+ if (h->type == bfd_link_hash_defined
+ && h->u.def.section->output_section != NULL
+ && !h->linker_def)
+ ret = FALSE;
+ }
+
+ defentry->by_script = 1;
+ defentry->iteration = lang_statement_iteration;
+ return ret;
}
static void
make_abs ();
break;
+ case LOG2CEIL:
+ make_log2ceil ();
+ break;
+
case '~':
expld.result.value = ~expld.result.value;
break;
/* Check to see if the user has overridden the default
value. */
segment_name = tree->binary.rhs->name.name;
- for (seg = segments; seg; seg = seg->next)
+ for (seg = segments; seg; seg = seg->next)
if (strcmp (seg->name, segment_name) == 0)
{
if (!seg->used
break;
case DEFINED:
- if (expld.phase == lang_first_phase_enum)
- lang_track_definedness (tree->name.name);
- else
+ if (expld.phase != lang_first_phase_enum)
{
struct bfd_link_hash_entry *h;
- int def_iteration
- = lang_symbol_definition_iteration (tree->name.name);
+ struct definedness_hash_entry *def;
h = bfd_wrapped_link_hash_lookup (link_info.output_bfd,
&link_info,
&& (h->type == bfd_link_hash_defined
|| h->type == bfd_link_hash_defweak
|| h->type == bfd_link_hash_common)
- && (def_iteration == lang_statement_iteration
- || def_iteration == -1));
+ && ((def = symbol_defined (tree->name.name)) == NULL
+ || def->by_object
+ || def->iteration == (lang_statement_iteration & 1)));
}
break;
case NAME:
+ if (expld.assign_name != NULL
+ && strcmp (expld.assign_name, tree->name.name) == 0)
+ {
+ /* Self-assignment is only allowed for absolute symbols
+ defined in a linker script. */
+ struct bfd_link_hash_entry *h;
+ struct definedness_hash_entry *def;
+
+ h = bfd_wrapped_link_hash_lookup (link_info.output_bfd,
+ &link_info,
+ tree->name.name,
+ FALSE, FALSE, TRUE);
+ if (!(h != NULL
+ && (h->type == bfd_link_hash_defined
+ || h->type == bfd_link_hash_defweak)
+ && h->u.def.section == bfd_abs_section_ptr
+ && (def = symbol_defined (tree->name.name)) != NULL
+ && def->iteration == (lang_statement_iteration & 1)))
+ expld.assign_name = NULL;
+ }
if (expld.phase == lang_first_phase_enum)
;
else if (tree->name.name[0] == '.' && tree->name.name[1] == 0)
output_section);
}
else if (expld.phase == lang_final_phase_enum
- || expld.assigning_to_dot)
+ || (expld.phase != lang_mark_phase_enum
+ && expld.assigning_to_dot))
einfo (_("%F%S: undefined symbol `%s'"
" referenced in expression\n"),
tree, tree->name.name);
tree, tree->name.name);
new_number (0);
}
- else if (os->processed_vma)
+ else if (os->bfd_section != NULL)
{
bfd_vma val;
/ bfd_octets_per_byte (link_info.output_bfd));
else
val = (bfd_vma)1 << os->bfd_section->alignment_power;
-
+
new_number (val);
}
+ else
+ new_number (0);
}
break;
case LENGTH:
{
lang_memory_region_type *mem;
-
- mem = lang_memory_region_lookup (tree->name.name, FALSE);
- if (mem != NULL)
+
+ mem = lang_memory_region_lookup (tree->name.name, FALSE);
+ if (mem != NULL)
new_number (mem->length);
- else
+ else
einfo (_("%F%S: undefined MEMORY region `%s'"
" referenced in expression\n"),
tree, tree->name.name);
if (expld.phase != lang_first_phase_enum)
{
lang_memory_region_type *mem;
-
- mem = lang_memory_region_lookup (tree->name.name, FALSE);
- if (mem != NULL)
+
+ mem = lang_memory_region_lookup (tree->name.name, FALSE);
+ if (mem != NULL)
new_rel_from_abs (mem->origin);
- else
+ else
einfo (_("%F%S: undefined MEMORY region `%s'"
" referenced in expression\n"),
tree, tree->name.name);
}
}
+/* Return true if TREE is '.'. */
+
+static bfd_boolean
+is_dot (const etree_type *tree)
+{
+ return (tree->type.node_class == etree_name
+ && tree->type.node_code == NAME
+ && tree->name.name[0] == '.'
+ && tree->name.name[1] == 0);
+}
+
+/* Return true if TREE is a constant equal to VAL. */
+
+static bfd_boolean
+is_value (const etree_type *tree, bfd_vma val)
+{
+ return (tree->type.node_class == etree_value
+ && tree->value.value == val);
+}
+
+/* Return true if TREE is an absolute symbol equal to VAL defined in
+ a linker script. */
+
+static bfd_boolean
+is_sym_value (const etree_type *tree, bfd_vma val)
+{
+ struct bfd_link_hash_entry *h;
+ struct definedness_hash_entry *def;
+
+ return (tree->type.node_class == etree_name
+ && tree->type.node_code == NAME
+ && (def = symbol_defined (tree->name.name)) != NULL
+ && def->by_script
+ && def->iteration == (lang_statement_iteration & 1)
+ && (h = bfd_wrapped_link_hash_lookup (link_info.output_bfd,
+ &link_info,
+ tree->name.name,
+ FALSE, FALSE, TRUE)) != NULL
+ && h->type == bfd_link_hash_defined
+ && h->u.def.section == bfd_abs_section_ptr
+ && h->u.def.value == val);
+}
+
+/* Return true if TREE is ". != 0". */
+
+static bfd_boolean
+is_dot_ne_0 (const etree_type *tree)
+{
+ return (tree->type.node_class == etree_binary
+ && tree->type.node_code == NE
+ && is_dot (tree->binary.lhs)
+ && is_value (tree->binary.rhs, 0));
+}
+
+/* Return true if TREE is ". = . + 0" or ". = . + sym" where sym is an
+ absolute constant with value 0 defined in a linker script. */
+
+static bfd_boolean
+is_dot_plus_0 (const etree_type *tree)
+{
+ return (tree->type.node_class == etree_binary
+ && tree->type.node_code == '+'
+ && is_dot (tree->binary.lhs)
+ && (is_value (tree->binary.rhs, 0)
+ || is_sym_value (tree->binary.rhs, 0)));
+}
+
+/* Return true if TREE is "ALIGN (. != 0 ? some_expression : 1)". */
+
+static bfd_boolean
+is_align_conditional (const etree_type *tree)
+{
+ if (tree->type.node_class == etree_unary
+ && tree->type.node_code == ALIGN_K)
+ {
+ tree = tree->unary.child;
+ return (tree->type.node_class == etree_trinary
+ && is_dot_ne_0 (tree->trinary.cond)
+ && is_value (tree->trinary.rhs, 1));
+ }
+ return 0;
+}
+
static void
exp_fold_tree_1 (etree_type *tree)
{
if (tree->type.node_class != etree_assign)
einfo (_("%F%S can not PROVIDE assignment to"
" location counter\n"), tree);
- /* After allocation, assignment to dot should not be done inside
- an output section since allocation adds a padding statement
- that effectively duplicates the assignment. */
- if (expld.phase == lang_mark_phase_enum
- || expld.phase == lang_allocating_phase_enum
- || ((expld.phase == lang_assigning_phase_enum
- || expld.phase == lang_final_phase_enum)
- && expld.section == bfd_abs_section_ptr))
+ if (expld.phase != lang_first_phase_enum)
{
/* Notify the folder that this is an assignment to dot. */
expld.assigning_to_dot = TRUE;
exp_fold_tree_1 (tree->assign.src);
expld.assigning_to_dot = FALSE;
+ /* If we are assigning to dot inside an output section
+ arrange to keep the section, except for certain
+ expressions that evaluate to zero. We ignore . = 0,
+ . = . + 0, and . = ALIGN (. != 0 ? expr : 1). */
+ if (expld.phase == lang_mark_phase_enum
+ && expld.section != bfd_abs_section_ptr
+ && !(expld.result.valid_p
+ && expld.result.value == 0
+ && (is_value (tree->assign.src, 0)
+ || is_sym_value (tree->assign.src, 0)
+ || is_dot_plus_0 (tree->assign.src)
+ || is_align_conditional (tree->assign.src))))
+ expld.section->flags |= SEC_KEEP;
+
if (!expld.result.valid_p)
{
if (expld.phase != lang_mark_phase_enum)
}
else if (expld.dotp == NULL)
einfo (_("%F%S assignment to location counter"
- " invalid outside of SECTION\n"), tree);
- else
+ " invalid outside of SECTIONS\n"), tree);
+
+ /* After allocation, assignment to dot should not be
+ done inside an output section since allocation adds a
+ padding statement that effectively duplicates the
+ assignment. */
+ else if (expld.phase <= lang_allocating_phase_enum
+ || expld.section == bfd_abs_section_ptr)
{
bfd_vma nextdot;
}
else
{
- etree_type *name;
-
struct bfd_link_hash_entry *h = NULL;
if (tree->type.node_class == etree_provide)
h = bfd_link_hash_lookup (link_info.hash, tree->assign.dst,
FALSE, FALSE, TRUE);
if (h == NULL
- || (h->type != bfd_link_hash_new
- && h->type != bfd_link_hash_undefined
- && h->type != bfd_link_hash_common))
+ || !(h->type == bfd_link_hash_new
+ || h->type == bfd_link_hash_undefined
+ || h->linker_def))
{
- /* Do nothing. The symbol was never referenced, or was
- defined by some object. */
+ /* Do nothing. The symbol was never referenced, or
+ was defined in some object file. Undefined weak
+ symbols stay undefined. */
break;
}
}
- name = tree->assign.src;
- if (name->type.node_class == etree_trinary)
- {
- exp_fold_tree_1 (name->trinary.cond);
- if (expld.result.valid_p)
- name = (expld.result.value
- ? name->trinary.lhs : name->trinary.rhs);
- }
-
- if (name->type.node_class == etree_name
- && name->type.node_code == NAME
- && strcmp (tree->assign.dst, name->name.name) == 0)
- /* Leave it alone. Do not replace a symbol with its own
- output address, in case there is another section sizing
- pass. Folding does not preserve input sections. */
- break;
-
+ expld.assign_name = tree->assign.dst;
exp_fold_tree_1 (tree->assign.src);
- if (expld.result.valid_p
+ /* expld.assign_name remaining equal to tree->assign.dst
+ below indicates the evaluation of tree->assign.src did
+ not use the value of tree->assign.dst. We don't allow
+ self assignment until the final phase for two reasons:
+ 1) Expressions are evaluated multiple times. With
+ relaxation, the number of times may vary.
+ 2) Section relative symbol values cannot be correctly
+ converted to absolute values, as is required by many
+ expressions, until final section sizing is complete. */
+ if ((expld.result.valid_p
+ && (expld.phase == lang_final_phase_enum
+ || expld.assign_name != NULL))
|| (expld.phase <= lang_mark_phase_enum
&& tree->type.node_class == etree_assign
- && tree->assign.hidden))
+ && tree->assign.defsym))
{
if (h == NULL)
{
tree->assign.dst);
}
- /* FIXME: Should we worry if the symbol is already
- defined? */
- lang_update_definedness (tree->assign.dst, h);
- h->type = bfd_link_hash_defined;
- h->u.def.value = expld.result.value;
if (expld.result.section == NULL)
expld.result.section = expld.section;
+ if (!update_definedness (tree->assign.dst, h) && 0)
+ {
+ /* Symbol was already defined. For now this error
+ is disabled because it causes failures in the ld
+ testsuite: ld-elf/var1, ld-scripts/defined5, and
+ ld-scripts/pr14962. Some of these no doubt
+ reflect scripts used in the wild. */
+ (*link_info.callbacks->multiple_definition)
+ (&link_info, h, link_info.output_bfd,
+ expld.result.section, expld.result.value);
+ }
+ h->type = bfd_link_hash_defined;
+ h->u.def.value = expld.result.value;
h->u.def.section = expld.result.section;
if (tree->type.node_class == etree_provide)
tree->type.node_class = etree_provided;
/* Copy the symbol type if this is a simple assignment of
- one symbol to another. This could be more general
+ one symbol to another. This could be more general
(e.g. a ?: operator with NAMEs in each branch). */
if (tree->assign.src->type.node_class == etree_name)
{
&& h->type == bfd_link_hash_new)
h->type = bfd_link_hash_undefined;
}
+ expld.assign_name = NULL;
}
break;
exp_assop (const char *dst,
etree_type *src,
enum node_tree_enum class,
+ bfd_boolean defsym,
bfd_boolean hidden)
{
etree_type *n;
n->assign.type.node_class = class;
n->assign.src = src;
n->assign.dst = dst;
+ n->assign.defsym = defsym;
n->assign.hidden = hidden;
return n;
}
+/* Handle linker script assignments and HIDDEN. */
+
etree_type *
-exp_assign (const char *dst, etree_type *src)
+exp_assign (const char *dst, etree_type *src, bfd_boolean hidden)
{
- return exp_assop (dst, src, etree_assign, FALSE);
+ return exp_assop (dst, src, etree_assign, FALSE, hidden);
}
+/* Handle --defsym command-line option. */
+
etree_type *
exp_defsym (const char *dst, etree_type *src)
{
- return exp_assop (dst, src, etree_assign, TRUE);
+ return exp_assop (dst, src, etree_assign, TRUE, FALSE);
}
/* Handle PROVIDE. */
etree_type *
exp_provide (const char *dst, etree_type *src, bfd_boolean hidden)
{
- return exp_assop (dst, src, etree_provide, hidden);
+ return exp_assop (dst, src, etree_provide, FALSE, hidden);
}
/* Handle ASSERT. */
case DATA_SEGMENT_ALIGN:
case DATA_SEGMENT_RELRO_END:
function_like = TRUE;
+ break;
+ case SEGMENT_START:
+ /* Special handling because arguments are in reverse order and
+ the segment name is quoted. */
+ exp_print_token (tree->type.node_code, FALSE);
+ fputs (" (\"", config.map_file);
+ exp_print_tree (tree->binary.rhs);
+ fputs ("\", ", config.map_file);
+ exp_print_tree (tree->binary.lhs);
+ fputc (')', config.map_file);
+ return;
}
if (function_like)
{
value = (value + align - 1) / align;
return value * align;
}
+
+void
+ldexp_init (void)
+{
+ /* The value "13" is ad-hoc, somewhat related to the expected number of
+ assignments in a linker script. */
+ if (!bfd_hash_table_init_n (&definedness_table,
+ definedness_newfunc,
+ sizeof (struct definedness_hash_entry),
+ 13))
+ einfo (_("%P%F: can not create hash table: %E\n"));
+}
+
+void
+ldexp_finish (void)
+{
+ bfd_hash_table_free (&definedness_table);
+}
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