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elf: emit valid section headers table when building an object file

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This commit is contained in:
Jakub Konka 2023-11-01 18:01:29 +01:00
parent 74f12d0691
commit 0ee2ab413f
2 changed files with 37 additions and 29 deletions
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42
src/link/Elf.zig
View File

@ -768,15 +768,15 @@ pub fn initMetadata(self: *Elf) !void {
pub fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
const shdr = &self.shdrs.items[shdr_index];
const phdr_index = self.phdr_to_shdr_table.get(shdr_index).?;
const phdr = &self.phdrs.items[phdr_index];
const maybe_phdr = if (self.phdr_to_shdr_table.get(shdr_index)) |phndx| &self.phdrs.items[phndx] else null;
const is_zerofill = shdr.sh_type == elf.SHT_NOBITS;
if (needed_size > self.allocatedSize(shdr.sh_offset) and !is_zerofill) {
const existing_size = shdr.sh_size;
shdr.sh_size = 0;
// Must move the entire section.
const new_offset = self.findFreeSpace(needed_size, self.page_size);
const alignment = if (maybe_phdr) |phdr| phdr.p_align else shdr.sh_addralign;
const new_offset = self.findFreeSpace(needed_size, alignment);
log.debug("new '{s}' file offset 0x{x} to 0x{x}", .{
self.getShString(shdr.sh_name),
@ -789,25 +789,27 @@ pub fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
if (amt != existing_size) return error.InputOutput;
shdr.sh_offset = new_offset;
phdr.p_offset = new_offset;
if (maybe_phdr) |phdr| phdr.p_offset = new_offset;
}
shdr.sh_size = needed_size;
if (!is_zerofill) {
phdr.p_filesz = needed_size;
if (maybe_phdr) |phdr| phdr.p_filesz = needed_size;
}
const mem_capacity = self.allocatedVirtualSize(phdr.p_vaddr);
if (needed_size > mem_capacity) {
var err = try self.addErrorWithNotes(2);
try err.addMsg(self, "fatal linker error: cannot expand load segment phdr({d}) in virtual memory", .{
phdr_index,
});
try err.addNote(self, "TODO: emit relocations to memory locations in self-hosted backends", .{});
try err.addNote(self, "as a workaround, try increasing pre-allocated virtual memory of each segment", .{});
}
if (maybe_phdr) |phdr| {
const mem_capacity = self.allocatedVirtualSize(phdr.p_vaddr);
if (needed_size > mem_capacity) {
var err = try self.addErrorWithNotes(2);
try err.addMsg(self, "fatal linker error: cannot expand load segment phdr({d}) in virtual memory", .{
self.phdr_to_shdr_table.get(shdr_index).?,
});
try err.addNote(self, "TODO: emit relocations to memory locations in self-hosted backends", .{});
try err.addNote(self, "as a workaround, try increasing pre-allocated virtual memory of each segment", .{});
}
phdr.p_memsz = needed_size;
phdr.p_memsz = needed_size;
}
self.markDirty(shdr_index);
}
@ -1499,7 +1501,17 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
pub fn flushObject(self: *Elf, comp: *Compilation) link.File.FlushError!void {
_ = comp;
try self.initSections();
try self.sortShdrs();
try self.updateSectionSizes();
try self.allocateNonAllocSections();
if (build_options.enable_logging) {
state_log.debug("{}", .{self.dumpState()});
}
try self.writeShdrTable();
try self.writeSyntheticSections();
try self.writeHeader();
}

24
src/link/Elf/ZigObject.zig
View File

@ -180,16 +180,16 @@ pub fn flushModule(self: *ZigObject, elf_file: *Elf) !void {
}
if (self.debug_info_header_dirty) {
const text_phdr = &elf_file.phdrs.items[elf_file.phdr_zig_load_re_index.?];
const low_pc = text_phdr.p_vaddr;
const high_pc = text_phdr.p_vaddr + text_phdr.p_memsz;
const text_shdr = elf_file.shdrs.items[elf_file.zig_text_section_index.?];
const low_pc = text_shdr.sh_addr;
const high_pc = text_shdr.sh_addr + text_shdr.sh_size;
try dw.writeDbgInfoHeader(elf_file.base.options.module.?, low_pc, high_pc);
self.debug_info_header_dirty = false;
}
if (self.debug_aranges_section_dirty) {
const text_phdr = &elf_file.phdrs.items[elf_file.phdr_zig_load_re_index.?];
try dw.writeDbgAranges(text_phdr.p_vaddr, text_phdr.p_memsz);
const text_shdr = elf_file.shdrs.items[elf_file.zig_text_section_index.?];
try dw.writeDbgAranges(text_shdr.sh_addr, text_shdr.sh_size);
self.debug_aranges_section_dirty = false;
}
@ -731,9 +731,7 @@ fn updateDeclCode(
const shdr = elf_file.shdrs.items[shdr_index];
if (shdr.sh_type != elf.SHT_NOBITS) {
const phdr_index = elf_file.phdr_to_shdr_table.get(shdr_index).?;
const section_offset = sym.value - elf_file.phdrs.items[phdr_index].p_vaddr;
const file_offset = shdr.sh_offset + section_offset;
const file_offset = shdr.sh_offset + sym.value - shdr.sh_addr;
try elf_file.base.file.?.pwriteAll(code, file_offset);
}
}
@ -940,7 +938,6 @@ fn updateLazySymbol(
.const_data => elf_file.zig_data_rel_ro_section_index.?,
};
const local_sym = elf_file.symbol(symbol_index);
const phdr_index = elf_file.phdr_to_shdr_table.get(output_section_index).?;
local_sym.name_offset = name_str_index;
local_sym.output_section_index = output_section_index;
const local_esym = &self.local_esyms.items(.elf_sym)[local_sym.esym_index];
@ -963,8 +960,8 @@ fn updateLazySymbol(
const gop = try local_sym.getOrCreateZigGotEntry(symbol_index, elf_file);
try elf_file.zig_got.writeOne(elf_file, gop.index);
const section_offset = atom_ptr.value - elf_file.phdrs.items[phdr_index].p_vaddr;
const file_offset = elf_file.shdrs.items[output_section_index].sh_offset + section_offset;
const shdr = elf_file.shdrs.items[output_section_index];
const file_offset = shdr.sh_offset + atom_ptr.value - shdr.sh_addr;
try elf_file.base.file.?.pwriteAll(code, file_offset);
}
@ -1038,7 +1035,6 @@ fn lowerConst(
.fail => |em| return .{ .fail = em },
};
const phdr_index = elf_file.phdr_to_shdr_table.get(output_section_index).?;
const local_sym = elf_file.symbol(sym_index);
const name_str_index = try self.insertString(gpa, name);
local_sym.name_offset = name_str_index;
@ -1061,8 +1057,8 @@ fn lowerConst(
local_sym.value = atom_ptr.value;
local_esym.st_value = atom_ptr.value;
const section_offset = atom_ptr.value - elf_file.phdrs.items[phdr_index].p_vaddr;
const file_offset = elf_file.shdrs.items[output_section_index].sh_offset + section_offset;
const shdr = elf_file.shdrs.items[output_section_index];
const file_offset = shdr.sh_offset + atom_ptr.value - shdr.sh_addr;
try elf_file.base.file.?.pwriteAll(code, file_offset);
return .{ .ok = sym_index };