diff options
Diffstat (limited to 'gold/x86_64.cc')
| -rw-r--r-- | gold/x86_64.cc | 90 |
1 files changed, 79 insertions, 11 deletions
diff --git a/gold/x86_64.cc b/gold/x86_64.cc index 419746d..46e879d 100644 --- a/gold/x86_64.cc +++ b/gold/x86_64.cc @@ -120,7 +120,8 @@ class Target_x86_64 : public Target_freebsd<64, false> bool needs_special_offset_handling, unsigned char* view, elfcpp::Elf_types<64>::Elf_Addr view_address, - section_size_type view_size); + section_size_type view_size, + const Reloc_symbol_changes*); // Scan the relocs during a relocatable link. void @@ -162,6 +163,13 @@ class Target_x86_64 : public Target_freebsd<64, false> do_is_defined_by_abi(const Symbol* sym) const { return strcmp(sym->name(), "__tls_get_addr") == 0; } + // Adjust -fstack-split code which calls non-stack-split code. + void + do_calls_non_split(Relobj* object, unsigned int shndx, + section_offset_type fnoffset, section_size_type fnsize, + unsigned char* view, section_size_type view_size, + std::string* from, std::string* to) const; + // Return the size of the GOT section. section_size_type got_size() @@ -2417,15 +2425,17 @@ Target_x86_64::Relocate::tls_ie_to_le(const Relocate_info<64, false>* relinfo, // Relocate section data. void -Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo, - unsigned int sh_type, - const unsigned char* prelocs, - size_t reloc_count, - Output_section* output_section, - bool needs_special_offset_handling, - unsigned char* view, - elfcpp::Elf_types<64>::Elf_Addr address, - section_size_type view_size) +Target_x86_64::relocate_section( + const Relocate_info<64, false>* relinfo, + unsigned int sh_type, + const unsigned char* prelocs, + size_t reloc_count, + Output_section* output_section, + bool needs_special_offset_handling, + unsigned char* view, + elfcpp::Elf_types<64>::Elf_Addr address, + section_size_type view_size, + const Reloc_symbol_changes* reloc_symbol_changes) { gold_assert(sh_type == elfcpp::SHT_RELA); @@ -2439,7 +2449,8 @@ Target_x86_64::relocate_section(const Relocate_info<64, false>* relinfo, needs_special_offset_handling, view, address, - view_size); + view_size, + reloc_symbol_changes); } // Return the size of a relocation while scanning during a relocatable @@ -2657,6 +2668,63 @@ Target_x86_64::do_code_fill(section_size_type length) const return std::string(nops[length], length); } +// FNOFFSET in section SHNDX in OBJECT is the start of a function +// compiled with -fstack-split. The function calls non-stack-split +// code. We have to change the function so that it always ensures +// that it has enough stack space to run some random function. + +void +Target_x86_64::do_calls_non_split(Relobj* object, unsigned int shndx, + section_offset_type fnoffset, + section_size_type fnsize, + unsigned char* view, + section_size_type view_size, + std::string* from, + std::string* to) const +{ + // The function starts with a comparison of the stack pointer and a + // field in the TCB. This is followed by a jump. + + // cmp %fs:NN,%rsp + if (this->match_view(view, view_size, fnoffset, "\x64\x48\x3b\x24\x25", 5) + && fnsize > 9) + { + // We will call __morestack if the carry flag is set after this + // comparison. We turn the comparison into an stc instruction + // and some nops. + view[fnoffset] = '\xf9'; + this->set_view_to_nop(view, view_size, fnoffset + 1, 8); + } + // lea NN(%rsp),%r10 + else if (this->match_view(view, view_size, fnoffset, "\x4c\x8d\x94\x24", 4) + && fnsize > 8) + { + // This is loading an offset from the stack pointer for a + // comparison. The offset is negative, so we decrease the + // offset by the amount of space we need for the stack. This + // means we will avoid calling __morestack if there happens to + // be plenty of space on the stack already. + unsigned char* pval = view + fnoffset + 4; + uint32_t val = elfcpp::Swap_unaligned<32, false>::readval(pval); + val -= parameters->options().split_stack_adjust_size(); + elfcpp::Swap_unaligned<32, false>::writeval(pval, val); + } + else + { + if (!object->has_no_split_stack()) + object->error(_("failed to match split-stack sequence at " + "section %u offset %0zx"), + shndx, fnoffset); + return; + } + + // We have to change the function so that it calls + // __morestack_non_split instead of __morestack. The former will + // allocate additional stack space. + *from = "__morestack"; + *to = "__morestack_non_split"; +} + // The selector for x86_64 object files. class Target_selector_x86_64 : public Target_selector_freebsd |