/* This module handles expression trees. Copyright (C) 1991-2024 Free Software Foundation, Inc. Written by Steve Chamberlain of Cygnus Support <sac@cygnus.com>. This file is part of the GNU Binutils. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ /* This module is in charge of working out the contents of expressions. It has to keep track of the relative/absness of a symbol etc. This is done by keeping all values in a struct (an etree_value_type) which contains a value, a section to which it is relative and a valid bit. */ #include "sysdep.h" #include "bfd.h" #include "bfdlink.h" #include "ctf-api.h" #include "ld.h" #include "ldmain.h" #include "ldmisc.h" #include "ldexp.h" #include "ldlex.h" #include <ldgram.h> #include "ldlang.h" #include "libiberty.h" #include "safe-ctype.h" static void exp_fold_tree_1 (etree_type *); static bfd_vma align_n (bfd_vma, bfd_vma); segment_type *segments; struct ldexp_control expld; /* This structure records symbols for which we need to keep track of definedness for use in the DEFINED () test. It is also used in making absolute symbols section relative late in the link. */ struct definedness_hash_entry { struct bfd_hash_entry root; /* If this symbol was assigned from "dot" outside of an output section statement, the section we'd like it relative to. */ asection *final_sec; /* Low bits of iteration count. Symbols with matching iteration have been defined in this pass over the script. */ unsigned int iteration : 8; /* Symbol was defined by an object file. */ unsigned int by_object : 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 void exp_print_token (token_code_type code, int infix_p) { static const struct { token_code_type code; const char *name; } table[] = { { INT, "int" }, { NAME, "NAME" }, { PLUSEQ, "+=" }, { MINUSEQ, "-=" }, { MULTEQ, "*=" }, { DIVEQ, "/=" }, { LSHIFTEQ, "<<=" }, { RSHIFTEQ, ">>=" }, { ANDEQ, "&=" }, { OREQ, "|=" }, { XOREQ, "^=" }, { OROR, "||" }, { ANDAND, "&&" }, { EQ, "==" }, { NE, "!=" }, { LE, "<=" }, { GE, ">=" }, { LSHIFT, "<<" }, { RSHIFT, ">>" }, { LOG2CEIL, "LOG2CEIL" }, { ALIGN_K, "ALIGN" }, { BLOCK, "BLOCK" }, { QUAD, "QUAD" }, { SQUAD, "SQUAD" }, { LONG, "LONG" }, { SHORT, "SHORT" }, { BYTE, "BYTE" }, { SECTIONS, "SECTIONS" }, { SIZEOF_HEADERS, "SIZEOF_HEADERS" }, { MEMORY, "MEMORY" }, { DEFINED, "DEFINED" }, { TARGET_K, "TARGET" }, { SEARCH_DIR, "SEARCH_DIR" }, { MAP, "MAP" }, { ENTRY, "ENTRY" }, { NEXT, "NEXT" }, { ALIGNOF, "ALIGNOF" }, { SIZEOF, "SIZEOF" }, { ADDR, "ADDR" }, { LOADADDR, "LOADADDR" }, { CONSTANT, "CONSTANT" }, { ABSOLUTE, "ABSOLUTE" }, { MAX_K, "MAX" }, { MIN_K, "MIN" }, { ASSERT_K, "ASSERT" }, { REL, "relocatable" }, { DATA_SEGMENT_ALIGN, "DATA_SEGMENT_ALIGN" }, { DATA_SEGMENT_RELRO_END, "DATA_SEGMENT_RELRO_END" }, { DATA_SEGMENT_END, "DATA_SEGMENT_END" }, { ORIGIN, "ORIGIN" }, { LENGTH, "LENGTH" }, { SEGMENT_START, "SEGMENT_START" } }; unsigned int idx; for (idx = 0; idx < ARRAY_SIZE (table); idx++) if (table[idx].code == code) break; if (infix_p) fputc (' ', config.map_file); if (idx < ARRAY_SIZE (table)) fputs (table[idx].name, config.map_file); else if (code < 127) fputc (code, config.map_file); else fprintf (config.map_file, "<code %d>", code); if (infix_p) fputc (' ', config.map_file); } static void make_log2ceil (void) { bfd_vma value = expld.result.value; bfd_vma result = -1; bool 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) { if (expld.result.section != NULL) expld.result.value += expld.result.section->vma; expld.result.section = bfd_abs_section_ptr; expld.rel_from_abs = false; } static void new_abs (bfd_vma value) { expld.result.valid_p = true; expld.result.section = bfd_abs_section_ptr; expld.result.value = value; expld.result.str = NULL; } etree_type * exp_intop (bfd_vma value) { etree_type *new_e = stat_alloc (sizeof (new_e->value)); new_e->type.node_code = INT; new_e->type.filename = ldlex_filename (); new_e->type.lineno = lineno; new_e->value.value = value; new_e->value.str = NULL; new_e->type.node_class = etree_value; return new_e; } etree_type * exp_bigintop (bfd_vma value, char *str) { etree_type *new_e = stat_alloc (sizeof (new_e->value)); new_e->type.node_code = INT; new_e->type.filename = ldlex_filename (); new_e->type.lineno = lineno; new_e->value.value = value; new_e->value.str = str; new_e->type.node_class = etree_value; return new_e; } /* Build an expression representing an unnamed relocatable value. */ etree_type * exp_relop (asection *section, bfd_vma value) { etree_type *new_e = stat_alloc (sizeof (new_e->rel)); new_e->type.node_code = REL; new_e->type.filename = ldlex_filename (); new_e->type.lineno = lineno; new_e->type.node_class = etree_rel; new_e->rel.section = section; new_e->rel.value = value; return new_e; } static void new_number (bfd_vma value) { expld.result.valid_p = true; expld.result.value = value; expld.result.str = NULL; expld.result.section = NULL; } static void new_rel (bfd_vma value, asection *section) { expld.result.valid_p = true; expld.result.value = value; expld.result.str = NULL; expld.result.section = section; } static void new_rel_from_abs (bfd_vma value) { asection *s = expld.section; expld.rel_from_abs = true; expld.result.valid_p = true; expld.result.value = value - s->vma; expld.result.str = NULL; 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 (_("%F%P: bfd_hash_allocate failed creating symbol %s\n"), name); ret->by_object = 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 bool update_definedness (const char *name, struct bfd_link_hash_entry *h) { bool ret; struct definedness_hash_entry *defentry = (struct definedness_hash_entry *) bfd_hash_lookup (&definedness_table, name, true, false); if (defentry == NULL) einfo (_("%F%P: 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 (!h->ldscript_def && (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 && !bfd_is_abs_section (h->u.def.section) && !h->linker_def) ret = false; } defentry->iteration = lang_statement_iteration; defentry->final_sec = bfd_abs_section_ptr; if (expld.phase == lang_final_phase_enum && expld.rel_from_abs && expld.result.section == bfd_abs_section_ptr) defentry->final_sec = section_for_dot (); return ret; } static void fold_segment_end (void) { seg_align_type *seg = &expld.dataseg; if (expld.phase == lang_first_phase_enum || expld.section != bfd_abs_section_ptr) { expld.result.valid_p = false; } else if (seg->phase == exp_seg_align_seen || seg->phase == exp_seg_relro_seen) { seg->phase = exp_seg_end_seen; seg->end = expld.result.value; } else if (seg->phase == exp_seg_done || seg->phase == exp_seg_adjust || seg->phase == exp_seg_relro_adjust) { /* OK. */ } else expld.result.valid_p = false; } static void fold_unary (etree_type *tree) { exp_fold_tree_1 (tree->unary.child); if (expld.result.valid_p) { switch (tree->type.node_code) { case ALIGN_K: if (expld.phase != lang_first_phase_enum) new_rel_from_abs (align_n (expld.dot, expld.result.value)); else expld.result.valid_p = false; break; case ABSOLUTE: make_abs (); break; case LOG2CEIL: make_log2ceil (); break; case '~': expld.result.value = ~expld.result.value; break; case '!': expld.result.value = !expld.result.value; break; case '-': expld.result.value = -expld.result.value; break; case NEXT: /* Return next place aligned to value. */ if (expld.phase != lang_first_phase_enum) { make_abs (); expld.result.value = align_n (expld.dot, expld.result.value); } else expld.result.valid_p = false; break; case DATA_SEGMENT_END: fold_segment_end (); break; default: FAIL (); break; } } } /* Arithmetic operators, bitwise AND, bitwise OR and XOR keep the section of one of their operands only when the other operand is a plain number. Losing the section when operating on two symbols, ie. a result of a plain number, is required for subtraction and XOR. It's justifiable for the other operations on the grounds that adding, multiplying etc. two section relative values does not really make sense unless they are just treated as numbers. The same argument could be made for many expressions involving one symbol and a number. For example, "1 << x" and "100 / x" probably should not be given the section of x. The trouble is that if we fuss about such things the rules become complex and it is onerous to document ld expression evaluation. */ static void arith_result_section (const etree_value_type *lhs) { if (expld.result.section == lhs->section) { if (expld.section == bfd_abs_section_ptr && !config.sane_expr) /* Duplicate the insanity in exp_fold_tree_1 case etree_value. */ expld.result.section = bfd_abs_section_ptr; else expld.result.section = NULL; } } static void fold_segment_align (etree_value_type *lhs) { seg_align_type *seg = &expld.dataseg; seg->relro = exp_seg_relro_start; if (expld.phase == lang_first_phase_enum || expld.section != bfd_abs_section_ptr) expld.result.valid_p = false; else { bfd_vma maxpage = lhs->value; bfd_vma commonpage = expld.result.value; expld.result.value = align_n (expld.dot, maxpage); if (seg->phase == exp_seg_relro_adjust) expld.result.value = seg->base; else if (seg->phase == exp_seg_adjust) { if (commonpage < maxpage) expld.result.value += ((expld.dot + commonpage - 1) & (maxpage - commonpage)); } else { if (!link_info.relro) expld.result.value += expld.dot & (maxpage - 1); if (seg->phase == exp_seg_done) { /* OK. */ } else if (seg->phase == exp_seg_none) { seg->phase = exp_seg_align_seen; seg->base = expld.result.value; seg->commonpagesize = commonpage; seg->maxpagesize = maxpage; seg->relropagesize = maxpage; seg->relro_end = 0; } else expld.result.valid_p = false; } } } static void fold_segment_relro_end (etree_value_type *lhs) { seg_align_type *seg = &expld.dataseg; /* Operands swapped! XXX_SEGMENT_RELRO_END(offset,exp) has offset in expld.result and exp in lhs. */ seg->relro = exp_seg_relro_end; seg->relro_offset = expld.result.value; if (expld.phase == lang_first_phase_enum || expld.section != bfd_abs_section_ptr) expld.result.valid_p = false; else if (seg->phase == exp_seg_align_seen || seg->phase == exp_seg_adjust || seg->phase == exp_seg_relro_adjust || seg->phase == exp_seg_done) { if (seg->phase == exp_seg_align_seen || seg->phase == exp_seg_relro_adjust) seg->relro_end = lhs->value + expld.result.value; if (seg->phase == exp_seg_relro_adjust && (seg->relro_end & (seg->relropagesize - 1))) { seg->relro_end += seg->relropagesize - 1; seg->relro_end &= ~(seg->relropagesize - 1); expld.result.value = seg->relro_end - expld.result.value; } else expld.result.value = lhs->value; if (seg->phase == exp_seg_align_seen) seg->phase = exp_seg_relro_seen; } else expld.result.valid_p = false; } static void fold_binary (etree_type *tree) { etree_value_type lhs; exp_fold_tree_1 (tree->binary.lhs); /* The SEGMENT_START operator is special because its first operand is a string, not the name of a symbol. Note that the operands have been swapped, so binary.lhs is second (default) operand, binary.rhs is first operand. */ if (expld.result.valid_p && tree->type.node_code == SEGMENT_START) { bfd_vma value = expld.result.value; const char *segment_name; segment_type *seg; /* 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) if (strcmp (seg->name, segment_name) == 0) { if (!seg->used && config.magic_demand_paged && link_info.maxpagesize != 0 && (seg->value % link_info.maxpagesize) != 0) einfo (_("%P: warning: address of `%s' " "isn't multiple of maximum page size\n"), segment_name); seg->used = true; value = seg->value; break; } new_rel_from_abs (value); return; } lhs = expld.result; exp_fold_tree_1 (tree->binary.rhs); expld.result.valid_p &= lhs.valid_p; if (expld.result.valid_p) { if (lhs.section != expld.result.section) { /* If the values are from different sections, and neither is just a number, make both the source arguments absolute. */ if (expld.result.section != NULL && lhs.section != NULL) { make_abs (); lhs.value += lhs.section->vma; lhs.section = bfd_abs_section_ptr; } /* If the rhs is just a number, keep the lhs section. */ else if (expld.result.section == NULL) { expld.result.section = lhs.section; /* Make this NULL so that we know one of the operands was just a number, for later tests. */ lhs.section = NULL; } } /* At this point we know that both operands have the same section, or at least one of them is a plain number. */ switch (tree->type.node_code) { #define BOP(x, y) \ case x: \ expld.result.value = lhs.value y expld.result.value; \ arith_result_section (&lhs); \ break; /* Comparison operators, logical AND, and logical OR always return a plain number. */ #define BOPN(x, y) \ case x: \ expld.result.value = lhs.value y expld.result.value; \ expld.result.section = NULL; \ break; BOP ('+', +); BOP ('*', *); BOP ('-', -); BOP (LSHIFT, <<); BOP (RSHIFT, >>); BOP ('&', &); BOP ('^', ^); BOP ('|', |); BOPN (EQ, ==); BOPN (NE, !=); BOPN ('<', <); BOPN ('>', >); BOPN (LE, <=); BOPN (GE, >=); BOPN (ANDAND, &&); BOPN (OROR, ||); case '%': if (expld.result.value != 0) expld.result.value = ((bfd_signed_vma) lhs.value % (bfd_signed_vma) expld.result.value); else if (expld.phase != lang_mark_phase_enum) einfo (_("%F%P:%pS %% by zero\n"), tree->binary.rhs); arith_result_section (&lhs); break; case '/': if (expld.result.value != 0) expld.result.value = ((bfd_signed_vma) lhs.value / (bfd_signed_vma) expld.result.value); else if (expld.phase != lang_mark_phase_enum) einfo (_("%F%P:%pS / by zero\n"), tree->binary.rhs); arith_result_section (&lhs); break; case MAX_K: if (lhs.value > expld.result.value) expld.result.value = lhs.value; break; case MIN_K: if (lhs.value < expld.result.value) expld.result.value = lhs.value; break; case ALIGN_K: expld.result.value = align_n (lhs.value, expld.result.value); break; case DATA_SEGMENT_ALIGN: fold_segment_align (&lhs); break; case DATA_SEGMENT_RELRO_END: fold_segment_relro_end (&lhs); break; default: FAIL (); } } } static void fold_trinary (etree_type *tree) { struct bfd_link_hash_entry *save = expld.assign_src; exp_fold_tree_1 (tree->trinary.cond); expld.assign_src = save; if (expld.result.valid_p) exp_fold_tree_1 (expld.result.value ? tree->trinary.lhs : tree->trinary.rhs); } static lang_output_section_statement_type * output_section_find (const char *name) { lang_output_section_statement_type *os = lang_output_section_find (name); if (os == NULL && strcmp (name, "NEXT_SECTION") == 0) { os = expld.last_os; if (os != NULL) while ((os = os->next) != NULL) if (os->constraint >= 0 && os->bfd_section != NULL) break; if (os == NULL) os = abs_output_section; } return os; } static void fold_name (etree_type *tree) { struct bfd_link_hash_entry *h; struct definedness_hash_entry *def; memset (&expld.result, 0, sizeof (expld.result)); switch (tree->type.node_code) { case SIZEOF_HEADERS: link_info.load_phdrs = 1; if (expld.phase != lang_first_phase_enum) { bfd_vma hdr_size = 0; /* Don't find the real header size if only marking sections; The bfd function may cache incorrect data. */ if (expld.phase != lang_mark_phase_enum) hdr_size = (bfd_sizeof_headers (link_info.output_bfd, &link_info) / bfd_octets_per_byte (link_info.output_bfd, NULL)); new_number (hdr_size); } break; case DEFINED: h = bfd_wrapped_link_hash_lookup (link_info.output_bfd, &link_info, tree->name.name, false, false, true); new_number (h != NULL && (h->type == bfd_link_hash_defined || h->type == bfd_link_hash_defweak || h->type == bfd_link_hash_common) && (!h->ldscript_def || (def = symbol_defined (tree->name.name)) == NULL || def->by_object || def->iteration == (lang_statement_iteration & 255))); break; case NAME: if (tree->name.name[0] == '.' && tree->name.name[1] == 0) new_rel_from_abs (expld.dot); else { h = bfd_wrapped_link_hash_lookup (link_info.output_bfd, &link_info, tree->name.name, true, false, true); if (!h) { if (expld.phase != lang_first_phase_enum) einfo (_("%F%P: bfd_link_hash_lookup failed: %E\n")); } else if (h->type == bfd_link_hash_defined || h->type == bfd_link_hash_defweak) { asection *output_section; output_section = h->u.def.section->output_section; if (output_section == NULL) { if (expld.phase <= lang_mark_phase_enum) new_rel (h->u.def.value, h->u.def.section); else einfo (_("%X%P:%pS: unresolvable symbol `%s'" " referenced in expression\n"), tree, tree->name.name); } else if (output_section == bfd_abs_section_ptr && (expld.section != bfd_abs_section_ptr || config.sane_expr)) new_number (h->u.def.value + h->u.def.section->output_offset); else new_rel (h->u.def.value + h->u.def.section->output_offset, output_section); } else if (expld.phase == lang_final_phase_enum || (expld.phase != lang_mark_phase_enum && expld.assigning_to_dot)) einfo (_("%F%P:%pS: undefined symbol `%s'" " referenced in expression\n"), tree, tree->name.name); else if (h->type == bfd_link_hash_new) { h->type = bfd_link_hash_undefined; h->u.undef.abfd = NULL; if (h->u.undef.next == NULL && h != link_info.hash->undefs_tail) bfd_link_add_undef (link_info.hash, h); } if (expld.assign_src == NULL) expld.assign_src = h; else expld.assign_src = (struct bfd_link_hash_entry *) - 1; /* Self-assignment is only allowed for absolute symbols defined in a linker script. */ if (expld.assign_name != NULL && strcmp (expld.assign_name, tree->name.name) == 0 && !(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 & 255))) expld.assign_name = NULL; } break; case ADDR: if (expld.phase != lang_first_phase_enum) { lang_output_section_statement_type *os; os = lang_output_section_find (tree->name.name); if (os == NULL) { if (expld.phase == lang_final_phase_enum) einfo (_("%F%P:%pS: undefined section `%s'" " referenced in expression\n"), tree, tree->name.name); } else if (os->processed_vma) new_rel (0, os->bfd_section); } break; case LOADADDR: if (expld.phase != lang_first_phase_enum) { lang_output_section_statement_type *os; os = lang_output_section_find (tree->name.name); if (os == NULL) { if (expld.phase == lang_final_phase_enum) einfo (_("%F%P:%pS: undefined section `%s'" " referenced in expression\n"), tree, tree->name.name); } else if (os->processed_lma) { if (os->load_base == NULL) new_abs (os->bfd_section->lma); else { exp_fold_tree_1 (os->load_base); if (expld.result.valid_p) make_abs (); } } } break; case SIZEOF: case ALIGNOF: if (expld.phase != lang_first_phase_enum) { lang_output_section_statement_type *os; os = output_section_find (tree->name.name); if (os == NULL) { if (expld.phase == lang_final_phase_enum) einfo (_("%F%P:%pS: undefined section `%s'" " referenced in expression\n"), tree, tree->name.name); new_number (0); } else if (os->bfd_section != NULL) { bfd_vma val; if (tree->type.node_code == SIZEOF) { if (os->processed_vma) val = os->bfd_section->size; else /* If we've just called lang_reset_memory_regions, size will be zero and a previous estimate of size will be in rawsize. */ val = os->bfd_section->rawsize; val /= bfd_octets_per_byte (link_info.output_bfd, os->bfd_section); } 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) new_number (mem->length); else einfo (_("%F%P:%pS: undefined MEMORY region `%s'" " referenced in expression\n"), tree, tree->name.name); } break; case ORIGIN: { lang_memory_region_type *mem; mem = lang_memory_region_lookup (tree->name.name, false); if (mem != NULL) new_rel_from_abs (mem->origin); else einfo (_("%F%P:%pS: undefined MEMORY region `%s'" " referenced in expression\n"), tree, tree->name.name); } break; case CONSTANT: if (strcmp (tree->name.name, "MAXPAGESIZE") == 0) new_number (link_info.maxpagesize); else if (strcmp (tree->name.name, "COMMONPAGESIZE") == 0) new_number (link_info.commonpagesize); else einfo (_("%F%P:%pS: unknown constant `%s' referenced in expression\n"), tree, tree->name.name); break; default: FAIL (); break; } } /* Return true if TREE is '.'. */ static bool 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 bool 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 bool 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->iteration == (lang_statement_iteration & 255) && (h = bfd_wrapped_link_hash_lookup (link_info.output_bfd, &link_info, tree->name.name, false, false, true)) != NULL && h->ldscript_def && 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 bool 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 bool 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 bool 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 false; } static void exp_fold_tree_1 (etree_type *tree) { if (tree == NULL) { memset (&expld.result, 0, sizeof (expld.result)); return; } switch (tree->type.node_class) { case etree_value: if (expld.section == bfd_abs_section_ptr && !config.sane_expr) new_abs (tree->value.value); else new_number (tree->value.value); expld.result.str = tree->value.str; break; case etree_rel: if (expld.phase != lang_first_phase_enum) { asection *output_section = tree->rel.section->output_section; new_rel (tree->rel.value + tree->rel.section->output_offset, output_section); } else memset (&expld.result, 0, sizeof (expld.result)); break; case etree_assert: exp_fold_tree_1 (tree->assert_s.child); if (expld.phase == lang_final_phase_enum && !expld.result.value) einfo ("%X%P: %s\n", tree->assert_s.message); break; case etree_unary: fold_unary (tree); break; case etree_binary: fold_binary (tree); break; case etree_trinary: fold_trinary (tree); break; case etree_assign: case etree_provide: case etree_provided: if (tree->assign.dst[0] == '.' && tree->assign.dst[1] == 0) { if (tree->type.node_class != etree_assign) einfo (_("%F%P:%pS can not PROVIDE assignment to" " location counter\n"), tree); 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). We can't ignore all expressions that evaluate to zero because an otherwise empty section might have padding added by an alignment expression that changes with relaxation. Such a section might have zero size before relaxation and so be stripped incorrectly. */ if (expld.phase == lang_mark_phase_enum && expld.section != bfd_abs_section_ptr && expld.section != bfd_und_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 || expld.section == bfd_und_section_ptr) { if (expld.phase != lang_mark_phase_enum) einfo (_("%F%P:%pS invalid assignment to" " location counter\n"), tree); } else if (expld.dotp == NULL) einfo (_("%F%P:%pS assignment to location counter" " 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; nextdot = expld.result.value; if (expld.result.section != NULL) nextdot += expld.result.section->vma; else nextdot += expld.section->vma; if (nextdot < expld.dot && expld.section != bfd_abs_section_ptr) einfo (_("%F%P:%pS cannot move location counter backwards" " (from %V to %V)\n"), tree, expld.dot, nextdot); else { expld.dot = nextdot; *expld.dotp = nextdot; } } } else memset (&expld.result, 0, sizeof (expld.result)); } else { 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_undefweak || h->linker_def)) { /* Do nothing. The symbol was never referenced, or was defined in some object file. Note that undefweak symbols are defined by PROVIDE. This is to support glibc use of __rela_iplt_start and similar weak references. */ break; } } expld.assign_name = tree->assign.dst; expld.assign_src = NULL; exp_fold_tree_1 (tree->assign.src); /* 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.phase == lang_final_phase_enum || expld.phase == lang_fixed_phase_enum || expld.assign_name != NULL) { if (tree->type.node_class == etree_provide) tree->type.node_class = etree_provided; if (h == NULL) { h = bfd_link_hash_lookup (link_info.hash, tree->assign.dst, true, false, true); if (h == NULL) einfo (_("%F%P:%s: hash creation failed\n"), tree->assign.dst); } /* If the expression is not valid then fake a zero value. In the final phase any errors will already have been raised, in earlier phases we want to create this definition so that it can be seen by other expressions. */ if (!expld.result.valid_p && h->type == bfd_link_hash_new) { expld.result.value = 0; expld.result.section = NULL; expld.result.valid_p = true; } if (expld.result.valid_p) { if (expld.result.section == NULL) expld.result.section = expld.section; if (!update_definedness (tree->assign.dst, h) && expld.assign_name != NULL) { /* Symbol was already defined, and the script isn't modifying the symbol value for some reason as in ld-elf/var1 and ld-scripts/pr14962. For now this is only a warning. */ unsigned int warn = link_info.warn_multiple_definition; link_info.warn_multiple_definition = 1; (*link_info.callbacks->multiple_definition) (&link_info, h, link_info.output_bfd, expld.result.section, expld.result.value); link_info.warn_multiple_definition = warn; } if (expld.phase == lang_fixed_phase_enum) { if (h->type == bfd_link_hash_defined) { expld.result.value = h->u.def.value; expld.result.section = h->u.def.section; } } else { h->type = bfd_link_hash_defined; h->u.def.value = expld.result.value; h->u.def.section = expld.result.section; h->linker_def = ! tree->assign.type.lineno; h->ldscript_def = 1; h->rel_from_abs = expld.rel_from_abs; if (tree->assign.hidden) bfd_link_hide_symbol (link_info.output_bfd, &link_info, h); /* Copy the symbol type and set non_ir_ref_regular on the source if this is an expression only referencing a single symbol. (If the expression contains ternary conditions, ignoring symbols on false branches.) */ if (expld.assign_src != NULL && (expld.assign_src != (struct bfd_link_hash_entry *) -1)) { bfd_copy_link_hash_symbol_type (link_info.output_bfd, h, expld.assign_src); expld.assign_src->non_ir_ref_regular = true; } } } } if (expld.phase != lang_fixed_phase_enum) expld.assign_name = NULL; } break; case etree_name: fold_name (tree); break; default: FAIL (); memset (&expld.result, 0, sizeof (expld.result)); break; } } void exp_fold_tree (etree_type *tree, lang_output_section_statement_type *os, asection *current_section, bfd_vma *dotp) { expld.rel_from_abs = false; expld.dot = *dotp; expld.dotp = dotp; expld.section = current_section; expld.last_os = os; exp_fold_tree_1 (tree); } void exp_fold_tree_no_dot (etree_type *tree, lang_output_section_statement_type *os) { expld.rel_from_abs = false; expld.dot = 0; expld.dotp = NULL; expld.section = bfd_abs_section_ptr; expld.last_os = os; exp_fold_tree_1 (tree); } static void exp_value_fold (etree_type *tree) { exp_fold_tree_no_dot (tree, NULL); if (expld.result.valid_p) { tree->type.node_code = INT; tree->value.value = expld.result.value; tree->value.str = NULL; tree->type.node_class = etree_value; } } #define MAX(a, b) ((a) > (b) ? (a) : (b)) etree_type * exp_binop (int code, etree_type *lhs, etree_type *rhs) { etree_type *new_e = stat_alloc (MAX (sizeof (new_e->binary), sizeof (new_e->value))); new_e->type.node_code = code; new_e->type.filename = lhs->type.filename; new_e->type.lineno = lhs->type.lineno; new_e->binary.lhs = lhs; new_e->binary.rhs = rhs; new_e->type.node_class = etree_binary; if (lhs->type.node_class == etree_value && rhs->type.node_class == etree_value && code != ALIGN_K && code != DATA_SEGMENT_ALIGN && code != DATA_SEGMENT_RELRO_END) exp_value_fold (new_e); return new_e; } etree_type * exp_trinop (int code, etree_type *cond, etree_type *lhs, etree_type *rhs) { etree_type *new_e = stat_alloc (MAX (sizeof (new_e->trinary), sizeof (new_e->value))); new_e->type.node_code = code; new_e->type.filename = cond->type.filename; new_e->type.lineno = cond->type.lineno; new_e->trinary.lhs = lhs; new_e->trinary.cond = cond; new_e->trinary.rhs = rhs; new_e->type.node_class = etree_trinary; if (cond->type.node_class == etree_value && lhs->type.node_class == etree_value && rhs->type.node_class == etree_value) exp_value_fold (new_e); return new_e; } etree_type * exp_unop (int code, etree_type *child) { etree_type *new_e = stat_alloc (MAX (sizeof (new_e->unary), sizeof (new_e->value))); new_e->unary.type.node_code = code; new_e->unary.type.filename = child->type.filename; new_e->unary.type.lineno = child->type.lineno; new_e->unary.child = child; new_e->unary.type.node_class = etree_unary; if (child->type.node_class == etree_value && code != ALIGN_K && code != ABSOLUTE && code != NEXT && code != DATA_SEGMENT_END) exp_value_fold (new_e); return new_e; } etree_type * exp_nameop (int code, const char *name) { etree_type *new_e = stat_alloc (sizeof (new_e->name)); new_e->name.type.node_code = code; new_e->name.type.filename = ldlex_filename (); new_e->name.type.lineno = lineno; new_e->name.name = name; new_e->name.type.node_class = etree_name; return new_e; } static etree_type * exp_assop (const char *dst, etree_type *src, enum node_tree_enum class, bool hidden) { etree_type *n; n = stat_alloc (sizeof (n->assign)); n->assign.type.node_code = '='; n->assign.type.filename = src->type.filename; n->assign.type.lineno = src->type.lineno; n->assign.type.node_class = class; n->assign.src = src; n->assign.dst = dst; n->assign.hidden = hidden; return n; } /* Handle linker script assignments and HIDDEN. */ etree_type * exp_assign (const char *dst, etree_type *src, bool hidden) { return exp_assop (dst, src, etree_assign, hidden); } /* Handle --defsym command-line option. */ etree_type * exp_defsym (const char *dst, etree_type *src) { return exp_assop (dst, src, etree_assign, false); } /* Handle PROVIDE. */ etree_type * exp_provide (const char *dst, etree_type *src, bool hidden) { return exp_assop (dst, src, etree_provide, hidden); } /* Handle ASSERT. */ etree_type * exp_assert (etree_type *exp, const char *message) { etree_type *n; n = stat_alloc (sizeof (n->assert_s)); n->assert_s.type.node_code = '!'; n->assert_s.type.filename = exp->type.filename; n->assert_s.type.lineno = exp->type.lineno; n->assert_s.type.node_class = etree_assert; n->assert_s.child = exp; n->assert_s.message = message; return n; } void exp_print_tree (etree_type *tree) { bool function_like; if (config.map_file == NULL) config.map_file = stderr; if (tree == NULL) { minfo ("NULL TREE\n"); return; } switch (tree->type.node_class) { case etree_value: minfo ("0x%v", tree->value.value); return; case etree_rel: if (tree->rel.section->owner != NULL) minfo ("%pB:", tree->rel.section->owner); minfo ("%s+0x%v", tree->rel.section->name, tree->rel.value); return; case etree_assign: fputs (tree->assign.dst, config.map_file); exp_print_token (tree->type.node_code, true); exp_print_tree (tree->assign.src); break; case etree_provide: case etree_provided: fprintf (config.map_file, "PROVIDE (%s = ", tree->assign.dst); exp_print_tree (tree->assign.src); fputc (')', config.map_file); break; case etree_binary: function_like = false; switch (tree->type.node_code) { case MAX_K: case MIN_K: case ALIGN_K: 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) { exp_print_token (tree->type.node_code, false); fputc (' ', config.map_file); } fputc ('(', config.map_file); exp_print_tree (tree->binary.lhs); if (function_like) fprintf (config.map_file, ", "); else exp_print_token (tree->type.node_code, true); exp_print_tree (tree->binary.rhs); fputc (')', config.map_file); break; case etree_trinary: exp_print_tree (tree->trinary.cond); fputc ('?', config.map_file); exp_print_tree (tree->trinary.lhs); fputc (':', config.map_file); exp_print_tree (tree->trinary.rhs); break; case etree_unary: exp_print_token (tree->unary.type.node_code, false); if (tree->unary.child) { fprintf (config.map_file, " ("); exp_print_tree (tree->unary.child); fputc (')', config.map_file); } break; case etree_assert: fprintf (config.map_file, "ASSERT ("); exp_print_tree (tree->assert_s.child); fprintf (config.map_file, ", %s)", tree->assert_s.message); break; case etree_name: if (tree->type.node_code == NAME) fputs (tree->name.name, config.map_file); else { exp_print_token (tree->type.node_code, false); if (tree->name.name) fprintf (config.map_file, " (%s)", tree->name.name); } break; default: FAIL (); break; } } bfd_vma exp_get_vma (etree_type *tree, lang_output_section_statement_type *os, bfd_vma def, char *name) { if (tree != NULL) { exp_fold_tree_no_dot (tree, os); if (expld.result.valid_p) return expld.result.value; else if (name != NULL && expld.phase != lang_mark_phase_enum) einfo (_("%F%P:%pS: nonconstant expression for %s\n"), tree, name); } return def; } /* Return the smallest non-negative integer such that two raised to that power is at least as large as the vma evaluated at TREE, if TREE is a non-NULL expression that can be resolved. If TREE is NULL or cannot be resolved, return -1. */ int exp_get_power (etree_type *tree, lang_output_section_statement_type *os, char *name) { bfd_vma x = exp_get_vma (tree, os, -1, name); bfd_vma p2; int n; if (x == (bfd_vma) -1) return -1; for (n = 0, p2 = 1; p2 < x; ++n, p2 <<= 1) if (p2 == 0) break; return n; } fill_type * exp_get_fill (etree_type *tree, fill_type *def, char *name) { fill_type *fill; size_t len; unsigned int val; if (tree == NULL) return def; exp_fold_tree_no_dot (tree, NULL); if (!expld.result.valid_p) { if (name != NULL && expld.phase != lang_mark_phase_enum) einfo (_("%F%P:%pS: nonconstant expression for %s\n"), tree, name); return def; } if (expld.result.str != NULL && (len = strlen (expld.result.str)) != 0) { unsigned char *dst; unsigned char *s; fill = (fill_type *) xmalloc ((len + 1) / 2 + sizeof (*fill) - 1); fill->size = (len + 1) / 2; dst = fill->data; s = (unsigned char *) expld.result.str; val = 0; do { unsigned int digit; digit = *s++ - '0'; if (digit > 9) digit = (digit - 'A' + '0' + 10) & 0xf; val <<= 4; val += digit; --len; if ((len & 1) == 0) { *dst++ = val; val = 0; } } while (len != 0); } else { fill = (fill_type *) xmalloc (4 + sizeof (*fill) - 1); val = expld.result.value; fill->data[0] = (val >> 24) & 0xff; fill->data[1] = (val >> 16) & 0xff; fill->data[2] = (val >> 8) & 0xff; fill->data[3] = (val >> 0) & 0xff; fill->size = 4; } return fill; } bfd_vma exp_get_abs_int (etree_type *tree, int def, char *name) { if (tree != NULL) { exp_fold_tree_no_dot (tree, NULL); if (expld.result.valid_p) { if (expld.result.section != NULL) expld.result.value += expld.result.section->vma; return expld.result.value; } else if (name != NULL && expld.phase != lang_mark_phase_enum) { einfo (_("%F%P:%pS: nonconstant expression for %s\n"), tree, name); } } return def; } static bfd_vma align_n (bfd_vma value, bfd_vma align) { if (align <= 1) return value; 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 (_("%F%P: can not create hash table: %E\n")); } /* Convert absolute symbols defined by a script from "dot" (also SEGMENT_START or ORIGIN) outside of an output section statement, to section relative. */ static bool set_sym_sections (struct bfd_hash_entry *bh, void *inf ATTRIBUTE_UNUSED) { struct definedness_hash_entry *def = (struct definedness_hash_entry *) bh; if (def->final_sec != bfd_abs_section_ptr) { struct bfd_link_hash_entry *h; h = bfd_link_hash_lookup (link_info.hash, bh->string, false, false, true); if (h != NULL && h->type == bfd_link_hash_defined && h->u.def.section == bfd_abs_section_ptr) { h->u.def.value -= def->final_sec->vma; h->u.def.section = def->final_sec; } } return true; } void ldexp_finalize_syms (void) { bfd_hash_traverse (&definedness_table, set_sym_sections, NULL); } /* Determine whether a symbol is going to remain absolute even after ldexp_finalize_syms() has run. */ bool ldexp_is_final_sym_absolute (const struct bfd_link_hash_entry *h) { if (h->type == bfd_link_hash_defined && h->u.def.section == bfd_abs_section_ptr) { const struct definedness_hash_entry *def; if (!h->ldscript_def) return true; def = symbol_defined (h->root.string); if (def != NULL) return def->final_sec == bfd_abs_section_ptr; } return false; } void ldexp_finish (void) { bfd_hash_table_free (&definedness_table); }