From 1757d35c8a35d77fd631705589024456c6030966 Mon Sep 17 00:00:00 2001 From: Cary Coutant Date: Tue, 25 Aug 2015 17:41:19 -0700 Subject: [PATCH] Fix internal error in gold when script uses section address in assignment. When processing assignment expressions in a linker script, gold processes absolute assignments early, but when one of those assignments involves the address of a section that has not yet been finalized, we get an internal error in address. This patch fixes the problem by gracefully returning from expression evaluation even if the address is not yet valid, and deferring the assignment in such a case. gold/ PR gold/14746 * expression.cc (Expression::Expression_eval_info): Add is_valid_pointer field. (Expression::eval_maybe_dot): Add is_valid_pointer parameter. Adjust all callers. (Addr_expression::value_from_output_section): Check whether address is valid. * script.cc (Symbol_assignment::set_if_absolute): Defer assignment if evaluation failed due to address that is not yet valid. * script.h: (Expression::eval_maybe_dot): Add is_valid_pointer parameter. --- gold/ChangeLog | 14 ++++++++++++++ gold/expression.cc | 44 ++++++++++++++++++++++++++++++++++---------- gold/script.cc | 7 ++++--- gold/script.h | 2 +- 4 files changed, 53 insertions(+), 14 deletions(-) diff --git a/gold/ChangeLog b/gold/ChangeLog index 5190e7e0d1..ebed52b2ee 100644 --- a/gold/ChangeLog +++ b/gold/ChangeLog @@ -1,3 +1,17 @@ +2015-08-25 Cary Coutant + + PR gold/14746 + * expression.cc (Expression::Expression_eval_info): Add + is_valid_pointer field. + (Expression::eval_maybe_dot): Add is_valid_pointer parameter. + Adjust all callers. + (Addr_expression::value_from_output_section): Check whether address + is valid. + * script.cc (Symbol_assignment::set_if_absolute): Defer assignment + if evaluation failed due to address that is not yet valid. + * script.h: (Expression::eval_maybe_dot): Add is_valid_pointer + parameter. + 2015-08-25 Cary Coutant PR gold/18866 diff --git a/gold/expression.cc b/gold/expression.cc index a64fa42302..484a49341d 100644 --- a/gold/expression.cc +++ b/gold/expression.cc @@ -74,6 +74,10 @@ struct Expression::Expression_eval_info elfcpp::STV* vis_pointer; // Pointer to where the rest of the symbol's st_other field should be stored. unsigned char* nonvis_pointer; + // Whether the value is valid. In Symbol_assignment::set_if_absolute, we + // may be trying to evaluate the address of a section whose address is not + // yet finalized, and we need to fail the evaluation gracefully. + bool *is_valid_pointer; }; // Evaluate an expression. @@ -83,7 +87,7 @@ Expression::eval(const Symbol_table* symtab, const Layout* layout, bool check_assertions) { return this->eval_maybe_dot(symtab, layout, check_assertions, false, 0, - NULL, NULL, NULL, NULL, NULL, NULL, false); + NULL, NULL, NULL, NULL, NULL, NULL, false, NULL); } // Evaluate an expression which may refer to the dot symbol. @@ -99,7 +103,7 @@ Expression::eval_with_dot(const Symbol_table* symtab, const Layout* layout, return this->eval_maybe_dot(symtab, layout, check_assertions, true, dot_value, dot_section, result_section_pointer, result_alignment_pointer, NULL, NULL, NULL, - is_section_dot_assignment); + is_section_dot_assignment, NULL); } // Evaluate an expression which may or may not refer to the dot @@ -114,7 +118,8 @@ Expression::eval_maybe_dot(const Symbol_table* symtab, const Layout* layout, elfcpp::STT* type_pointer, elfcpp::STV* vis_pointer, unsigned char* nonvis_pointer, - bool is_section_dot_assignment) + bool is_section_dot_assignment, + bool* is_valid_pointer) { Expression_eval_info eei; eei.symtab = symtab; @@ -138,8 +143,18 @@ Expression::eval_maybe_dot(const Symbol_table* symtab, const Layout* layout, eei.result_alignment_pointer = result_alignment_pointer; + // Assume the value is valid until we try to evaluate an expression + // that can't be evaluated yet. + bool is_valid = true; + eei.is_valid_pointer = &is_valid; + uint64_t val = this->value(&eei); + if (is_valid_pointer != NULL) + *is_valid_pointer = is_valid; + else + gold_assert(is_valid); + // If this is an assignment to dot within a section, and the value // is absolute, treat it as a section-relative offset. if (is_section_dot_assignment && *result_section_pointer == NULL) @@ -295,7 +310,8 @@ class Unary_expression : public Expression NULL, NULL, NULL, - false); + false, + eei->is_valid_pointer); } void @@ -378,7 +394,8 @@ class Binary_expression : public Expression NULL, NULL, NULL, - false); + false, + eei->is_valid_pointer); } uint64_t @@ -396,7 +413,8 @@ class Binary_expression : public Expression NULL, NULL, NULL, - false); + false, + eei->is_valid_pointer); } void @@ -550,7 +568,8 @@ class Trinary_expression : public Expression NULL, NULL, NULL, - false); + false, + eei->is_valid_pointer); } uint64_t @@ -568,7 +587,8 @@ class Trinary_expression : public Expression NULL, NULL, NULL, - false); + false, + eei->is_valid_pointer); } uint64_t @@ -586,7 +606,8 @@ class Trinary_expression : public Expression NULL, NULL, NULL, - false); + false, + eei->is_valid_pointer); } void @@ -945,7 +966,10 @@ class Addr_expression : public Section_expression { if (eei->result_section_pointer != NULL) *eei->result_section_pointer = os; - return os->address(); + if (os->is_address_valid()) + return os->address(); + *eei->is_valid_pointer = false; + return 0; } uint64_t diff --git a/gold/script.cc b/gold/script.cc index 56f126c738..cfa3116e18 100644 --- a/gold/script.cc +++ b/gold/script.cc @@ -987,7 +987,7 @@ Symbol_assignment::sized_finalize(Symbol_table* symtab, const Layout* layout, is_dot_available, dot_value, dot_section, §ion, NULL, &type, - &vis, &nonvis, false); + &vis, &nonvis, false, NULL); Sized_symbol* ssym = symtab->get_sized_symbol(this->sym_); ssym->set_value(final_val); ssym->set_type(type); @@ -1009,11 +1009,12 @@ Symbol_assignment::set_if_absolute(Symbol_table* symtab, const Layout* layout, return; Output_section* val_section; + bool is_valid; uint64_t val = this->val_->eval_maybe_dot(symtab, layout, false, is_dot_available, dot_value, dot_section, &val_section, NULL, - NULL, NULL, NULL, false); - if (val_section != NULL && val_section != dot_section) + NULL, NULL, NULL, false, &is_valid); + if (!is_valid || (val_section != NULL && val_section != dot_section)) return; if (parameters->target().get_size() == 32) diff --git a/gold/script.h b/gold/script.h index 1731985d83..739baf16ed 100644 --- a/gold/script.h +++ b/gold/script.h @@ -113,7 +113,7 @@ class Expression Output_section* dot_section, Output_section** result_section, uint64_t* result_alignment, elfcpp::STT* type, elfcpp::STV* vis, unsigned char* nonvis, - bool is_section_dot_assignment); + bool is_section_dot_assignment, bool* is_valid_pointer); // Print the expression to the FILE. This is for debugging. virtual void