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Merge pull request #17304 from ziglang/elf-grow-vm-2

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elf: grow segments in virtual memory if they exceed allocated capacity
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Jakub Konka 2023-09-28 14:29:35 +02:00 committed by GitHub
commit 1063035be6
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6 changed files with 267 additions and 106 deletions
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265
src/link/Elf.zig
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@ -1,4 +1,5 @@
base: link.File,
dwarf: ?Dwarf = null,
ptr_width: PtrWidth,
@ -103,6 +104,7 @@ phdr_table_dirty: bool = false,
shdr_table_dirty: bool = false,
shstrtab_dirty: bool = false,
strtab_dirty: bool = false,
got_dirty: bool = false,
debug_strtab_dirty: bool = false,
debug_abbrev_section_dirty: bool = false,
@ -411,21 +413,31 @@ fn findFreeSpace(self: *Elf, object_size: u64, min_alignment: u64) u64 {
const AllocateSegmentOpts = struct {
size: u64,
alignment: u64,
addr: ?u64 = null, // TODO find free VM space
addr: ?u64 = null,
flags: u32 = elf.PF_R,
};
pub fn allocateSegment(self: *Elf, opts: AllocateSegmentOpts) error{OutOfMemory}!u16 {
const gpa = self.base.allocator;
const index = @as(u16, @intCast(self.phdrs.items.len));
try self.phdrs.ensureUnusedCapacity(self.base.allocator, 1);
try self.phdrs.ensureUnusedCapacity(gpa, 1);
const off = self.findFreeSpace(opts.size, opts.alignment);
// Memory is always allocated in sequence.
// TODO is this correct? Or should we implement something similar to `findFreeSpace`?
// How would that impact HCS?
// Currently, we automatically allocate memory in sequence by finding the largest
// allocated virtual address and going from there.
// TODO we want to keep machine code segment in the furthest memory range among all
// segments as it is most likely to grow.
const addr = opts.addr orelse blk: {
assert(self.phdr_table_load_index != null);
const phdr = &self.phdrs.items[index - 1];
break :blk mem.alignForward(u64, phdr.p_vaddr + phdr.p_memsz, opts.alignment);
const reserved_capacity = self.calcImageBase() * 4;
// Calculate largest VM address
const count = self.phdrs.items.len;
var addresses = std.ArrayList(u64).init(gpa);
defer addresses.deinit();
try addresses.ensureTotalCapacityPrecise(count);
for (self.phdrs.items) |phdr| {
addresses.appendAssumeCapacity(phdr.p_vaddr + reserved_capacity);
}
mem.sort(u64, addresses.items, {}, std.sort.asc(u64));
break :blk mem.alignForward(u64, addresses.items[count - 1], opts.alignment);
};
log.debug("allocating phdr({d})({c}{c}{c}) from 0x{x} to 0x{x} (0x{x} - 0x{x})", .{
index,
@ -530,6 +542,8 @@ pub fn populateMissingMetadata(self: *Elf) !void {
.p64 => false,
};
const ptr_size: u8 = self.ptrWidthBytes();
const is_linux = self.base.options.target.os.tag == .linux;
const large_addrspace = self.base.options.target.ptrBitWidth() >= 32;
const image_base = self.calcImageBase();
if (self.phdr_table_index == null) {
@ -577,13 +591,10 @@ pub fn populateMissingMetadata(self: *Elf) !void {
}
if (self.phdr_got_index == null) {
// TODO instead of hard coding the vaddr, make a function to find a vaddr to put things at.
// we'll need to re-use that function anyway, in case the GOT grows and overlaps something
// else in virtual memory.
const addr: u64 = if (self.base.options.target.ptrBitWidth() >= 32) 0x4000000 else 0x8000;
const addr: u64 = if (large_addrspace) 0x4000000 else 0x8000;
// We really only need ptr alignment but since we are using PROGBITS, linux requires
// page align.
const alignment = if (self.base.options.target.os.tag == .linux) self.page_size else @as(u16, ptr_size);
const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
self.phdr_got_index = try self.allocateSegment(.{
.addr = addr,
.size = @as(u64, ptr_size) * self.base.options.symbol_count_hint,
@ -593,10 +604,8 @@ pub fn populateMissingMetadata(self: *Elf) !void {
}
if (self.phdr_load_ro_index == null) {
// TODO Same as for GOT
const addr: u64 = if (self.base.options.target.ptrBitWidth() >= 32) 0xc000000 else 0xa000;
// Same reason as for GOT
const alignment = if (self.base.options.target.os.tag == .linux) self.page_size else @as(u16, ptr_size);
const addr: u64 = if (large_addrspace) 0xc000000 else 0xa000;
const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
self.phdr_load_ro_index = try self.allocateSegment(.{
.addr = addr,
.size = 1024,
@ -606,10 +615,8 @@ pub fn populateMissingMetadata(self: *Elf) !void {
}
if (self.phdr_load_rw_index == null) {
// TODO Same as for GOT
const addr: u64 = if (self.base.options.target.ptrBitWidth() >= 32) 0x10000000 else 0xc000;
// Same reason as for GOT
const alignment = if (self.base.options.target.os.tag == .linux) self.page_size else @as(u16, ptr_size);
const addr: u64 = if (large_addrspace) 0x10000000 else 0xc000;
const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
self.phdr_load_rw_index = try self.allocateSegment(.{
.addr = addr,
.size = 1024,
@ -619,9 +626,8 @@ pub fn populateMissingMetadata(self: *Elf) !void {
}
if (self.phdr_load_zerofill_index == null) {
// TODO Same as for GOT
const addr: u64 = if (self.base.options.target.ptrBitWidth() >= 32) 0x14000000 else 0xf000;
const alignment = if (self.base.options.target.os.tag == .linux) self.page_size else @as(u16, ptr_size);
const addr: u64 = if (large_addrspace) 0x14000000 else 0xf000;
const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
self.phdr_load_zerofill_index = try self.allocateSegment(.{
.addr = addr,
.size = 0,
@ -803,7 +809,7 @@ pub fn populateMissingMetadata(self: *Elf) !void {
}
if (self.base.options.module) |module| {
if (self.zig_module_index == null) {
if (self.zig_module_index == null and !self.base.options.use_llvm) {
const index = @as(File.Index, @intCast(try self.files.addOne(gpa)));
self.files.set(index, .{ .zig_module = .{
.index = index,
@ -858,7 +864,30 @@ pub fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
}
const mem_capacity = self.allocatedVirtualSize(phdr.p_vaddr);
assert(needed_size <= mem_capacity); // TODO grow section in virtual memory
if (needed_size > mem_capacity) {
// We are exceeding our allocated VM capacity so we need to shift everything in memory
// and grow.
{
const dirty_addr = phdr.p_vaddr + phdr.p_memsz;
self.got_dirty = for (self.got.entries.items) |entry| {
if (self.symbol(entry.symbol_index).value >= dirty_addr) break true;
} else false;
// TODO mark relocs dirty
}
try self.growSegment(shdr_index, needed_size);
if (self.zig_module_index != null) {
// TODO self-hosted backends cannot yet handle this condition correctly as the linker
// cannot update emitted virtual addresses of symbols already committed to the final file.
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", .{});
}
}
shdr.sh_size = needed_size;
phdr.p_memsz = needed_size;
@ -870,6 +899,62 @@ pub fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
self.markDirty(shdr_index, phdr_index);
}
fn growSegment(self: *Elf, shndx: u16, needed_size: u64) !void {
const phdr_index = self.phdr_to_shdr_table.get(shndx).?;
const phdr = &self.phdrs.items[phdr_index];
const increased_size = padToIdeal(needed_size);
const end_addr = phdr.p_vaddr + phdr.p_memsz;
const old_aligned_end = phdr.p_vaddr + mem.alignForward(u64, phdr.p_memsz, phdr.p_align);
const new_aligned_end = phdr.p_vaddr + mem.alignForward(u64, increased_size, phdr.p_align);
const diff = new_aligned_end - old_aligned_end;
log.debug("growing phdr({d}) in memory by {x}", .{ phdr_index, diff });
// Update symbols and atoms.
var files = std.ArrayList(File.Index).init(self.base.allocator);
defer files.deinit();
try files.ensureTotalCapacityPrecise(self.objects.items.len + 1);
if (self.zig_module_index) |index| files.appendAssumeCapacity(index);
files.appendSliceAssumeCapacity(self.objects.items);
for (files.items) |index| {
const file_ptr = self.file(index).?;
for (file_ptr.locals()) |sym_index| {
const sym = self.symbol(sym_index);
const atom_ptr = sym.atom(self) orelse continue;
if (!atom_ptr.flags.alive or !atom_ptr.flags.allocated) continue;
if (sym.value >= end_addr) sym.value += diff;
}
for (file_ptr.globals()) |sym_index| {
const sym = self.symbol(sym_index);
if (sym.file_index != index) continue;
const atom_ptr = sym.atom(self) orelse continue;
if (!atom_ptr.flags.alive or !atom_ptr.flags.allocated) continue;
if (sym.value >= end_addr) sym.value += diff;
}
for (file_ptr.atoms()) |atom_index| {
const atom_ptr = self.atom(atom_index) orelse continue;
if (!atom_ptr.flags.alive or !atom_ptr.flags.allocated) continue;
if (atom_ptr.value >= end_addr) atom_ptr.value += diff;
}
}
// Finally, update section headers.
for (self.shdrs.items, 0..) |*other_shdr, other_shndx| {
if (other_shdr.sh_flags & elf.SHF_ALLOC == 0) continue;
if (other_shndx == shndx) continue;
const other_phdr_index = self.phdr_to_shdr_table.get(@intCast(other_shndx)) orelse continue;
const other_phdr = &self.phdrs.items[other_phdr_index];
if (other_phdr.p_vaddr < end_addr) continue;
other_shdr.sh_addr += diff;
other_phdr.p_vaddr += diff;
other_phdr.p_paddr += diff;
}
}
pub fn growNonAllocSection(
self: *Elf,
shdr_index: u16,
@ -1143,7 +1228,7 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
if (self.zig_module_index) |index| {
for (self.file(index).?.zig_module.atoms.keys()) |atom_index| {
const atom_ptr = self.atom(atom_index).?;
if (!atom_ptr.alive) continue;
if (!atom_ptr.flags.alive) continue;
const shdr = &self.shdrs.items[atom_ptr.outputShndx().?];
const file_offset = shdr.sh_offset + atom_ptr.value - shdr.sh_addr;
const size = math.cast(usize, atom_ptr.size) orelse return error.Overflow;
@ -1157,6 +1242,15 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
}
try self.writeObjects();
if (self.got_dirty) {
const shdr = &self.shdrs.items[self.got_section_index.?];
var buffer = try std.ArrayList(u8).initCapacity(gpa, self.got.size(self));
defer buffer.deinit();
try self.got.writeAllEntries(self, buffer.writer());
try self.base.file.?.pwriteAll(buffer.items, shdr.sh_offset);
self.got_dirty = false;
}
// Look for entry address in objects if not set by the incremental compiler.
if (self.entry_addr == null) {
const entry: ?[]const u8 = entry: {
@ -1537,7 +1631,7 @@ fn resolveSymbols(self: *Elf) error{Overflow}!void {
for (try object.comdatGroupMembers(cg.shndx)) |shndx| {
const atom_index = object.atoms.items[shndx];
if (self.atom(atom_index)) |atom_ptr| {
atom_ptr.alive = false;
atom_ptr.flags.alive = false;
// atom_ptr.markFdesDead(self);
}
}
@ -1645,25 +1739,26 @@ fn scanRelocs(self: *Elf) !void {
fn allocateObjects(self: *Elf) !void {
for (self.objects.items) |index| {
const object = self.file(index).?.object;
for (object.atoms.items) |atom_index| {
const atom_ptr = self.atom(atom_index) orelse continue;
if (!atom_ptr.alive) continue;
if (!atom_ptr.flags.alive or atom_ptr.flags.allocated) continue;
try atom_ptr.allocate(self);
}
for (object.locals()) |local_index| {
const local = self.symbol(local_index);
const atom_ptr = local.atom(self) orelse continue;
if (!atom_ptr.alive) continue;
local.value += atom_ptr.value;
if (!atom_ptr.flags.alive) continue;
local.value = local.elfSym(self).st_value + atom_ptr.value;
}
for (object.globals()) |global_index| {
const global = self.symbol(global_index);
const atom_ptr = global.atom(self) orelse continue;
if (!atom_ptr.alive) continue;
if (!atom_ptr.flags.alive) continue;
if (global.file_index == index) {
global.value += atom_ptr.value;
global.value = global.elfSym(self).st_value + atom_ptr.value;
}
}
}
@ -1676,7 +1771,7 @@ fn writeObjects(self: *Elf) !void {
const object = self.file(index).?.object;
for (object.atoms.items) |atom_index| {
const atom_ptr = self.atom(atom_index) orelse continue;
if (!atom_ptr.alive) continue;
if (!atom_ptr.flags.alive) continue;
const shdr = &self.shdrs.items[atom_ptr.outputShndx().?];
if (shdr.sh_type == elf.SHT_NOBITS) continue;
@ -2650,7 +2745,7 @@ fn updateDeclCode(
atom_ptr.output_section_index = shdr_index;
sym.name_offset = try self.strtab.insert(gpa, decl_name);
atom_ptr.alive = true;
atom_ptr.flags.alive = true;
atom_ptr.name_offset = sym.name_offset;
esym.st_name = sym.name_offset;
esym.st_info |= stt_bits;
@ -2681,11 +2776,6 @@ fn updateDeclCode(
} else {
try atom_ptr.allocate(self);
errdefer self.freeDeclMetadata(sym_index);
log.debug("allocated atom for {s} at 0x{x} to 0x{x}", .{
decl_name,
atom_ptr.value,
atom_ptr.value + atom_ptr.size,
});
sym.value = atom_ptr.value;
esym.st_value = atom_ptr.value;
@ -2873,7 +2963,6 @@ fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.
defer gpa.free(name);
break :blk try self.strtab.insert(gpa, name);
};
const name = self.strtab.get(name_str_index).?;
const src = if (sym.ty.getOwnerDeclOrNull(mod)) |owner_decl|
mod.declPtr(owner_decl).srcLoc(mod)
@ -2913,7 +3002,7 @@ fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.
local_esym.st_info |= elf.STT_OBJECT;
local_esym.st_size = code.len;
const atom_ptr = local_sym.atom(self).?;
atom_ptr.alive = true;
atom_ptr.flags.alive = true;
atom_ptr.name_offset = name_str_index;
atom_ptr.alignment = required_alignment;
atom_ptr.size = code.len;
@ -2922,12 +3011,6 @@ fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.
try atom_ptr.allocate(self);
errdefer self.freeDeclMetadata(symbol_index);
log.debug("allocated atom for {s} at 0x{x} to 0x{x}", .{
name,
atom_ptr.value,
atom_ptr.value + atom_ptr.size,
});
local_sym.value = atom_ptr.value;
local_esym.st_value = atom_ptr.value;
@ -2961,7 +3044,6 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
defer gpa.free(name);
break :blk try self.strtab.insert(gpa, name);
};
const name = self.strtab.get(name_str_index).?;
const zig_module = self.file(self.zig_module_index.?).?.zig_module;
const sym_index = try zig_module.addAtom(self);
@ -2992,7 +3074,7 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
local_esym.st_info |= elf.STT_OBJECT;
local_esym.st_size = code.len;
const atom_ptr = local_sym.atom(self).?;
atom_ptr.alive = true;
atom_ptr.flags.alive = true;
atom_ptr.name_offset = name_str_index;
atom_ptr.alignment = required_alignment;
atom_ptr.size = code.len;
@ -3001,8 +3083,6 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
try atom_ptr.allocate(self);
errdefer self.freeDeclMetadata(sym_index);
log.debug("allocated atom for {s} at 0x{x} to 0x{x}", .{ name, atom_ptr.value, atom_ptr.value + atom_ptr.size });
local_sym.value = atom_ptr.value;
local_esym.st_value = atom_ptr.value;
@ -3931,6 +4011,50 @@ pub fn comdatGroupOwner(self: *Elf, index: ComdatGroupOwner.Index) *ComdatGroupO
return &self.comdat_groups_owners.items[index];
}
const ErrorWithNotes = struct {
/// Allocated index in misc_errors array.
index: usize,
/// Next available note slot.
note_slot: usize = 0,
pub fn addMsg(
err: ErrorWithNotes,
elf_file: *Elf,
comptime format: []const u8,
args: anytype,
) error{OutOfMemory}!void {
const gpa = elf_file.base.allocator;
const err_msg = &elf_file.misc_errors.items[err.index];
err_msg.msg = try std.fmt.allocPrint(gpa, format, args);
}
pub fn addNote(
err: *ErrorWithNotes,
elf_file: *Elf,
comptime format: []const u8,
args: anytype,
) error{OutOfMemory}!void {
const gpa = elf_file.base.allocator;
const err_msg = &elf_file.misc_errors.items[err.index];
assert(err.note_slot < err_msg.notes.len);
err_msg.notes[err.note_slot] = .{ .msg = try std.fmt.allocPrint(gpa, format, args) };
err.note_slot += 1;
}
};
fn addErrorWithNotes(self: *Elf, note_count: usize) error{OutOfMemory}!ErrorWithNotes {
try self.misc_errors.ensureUnusedCapacity(self.base.allocator, 1);
return self.addErrorWithNotesAssumeCapacity(note_count);
}
fn addErrorWithNotesAssumeCapacity(self: *Elf, note_count: usize) error{OutOfMemory}!ErrorWithNotes {
const index = self.misc_errors.items.len;
const err = self.misc_errors.addOneAssumeCapacity();
err.* = .{ .msg = undefined, .notes = try self.base.allocator.alloc(link.File.ErrorMsg, note_count) };
return .{ .index = index };
}
fn reportUndefined(self: *Elf, undefs: anytype) !void {
const gpa = self.base.allocator;
const max_notes = 4;
@ -3941,33 +4065,22 @@ fn reportUndefined(self: *Elf, undefs: anytype) !void {
while (it.next()) |entry| {
const undef_index = entry.key_ptr.*;
const atoms = entry.value_ptr.*.items;
const nnotes = @min(atoms.len, max_notes);
const natoms = @min(atoms.len, max_notes);
const nnotes = natoms + @intFromBool(atoms.len > max_notes);
var notes = try std.ArrayList(link.File.ErrorMsg).initCapacity(gpa, max_notes + 1);
defer notes.deinit();
var err = try self.addErrorWithNotesAssumeCapacity(nnotes);
try err.addMsg(self, "undefined symbol: {s}", .{self.symbol(undef_index).name(self)});
for (atoms[0..nnotes]) |atom_index| {
for (atoms[0..natoms]) |atom_index| {
const atom_ptr = self.atom(atom_index).?;
const file_ptr = self.file(atom_ptr.file_index).?;
const note = try std.fmt.allocPrint(gpa, "referenced by {s}:{s}", .{
file_ptr.fmtPath(),
atom_ptr.name(self),
});
notes.appendAssumeCapacity(.{ .msg = note });
try err.addNote(self, "referenced by {s}:{s}", .{ file_ptr.fmtPath(), atom_ptr.name(self) });
}
if (atoms.len > max_notes) {
const remaining = atoms.len - max_notes;
const note = try std.fmt.allocPrint(gpa, "referenced {d} more times", .{remaining});
notes.appendAssumeCapacity(.{ .msg = note });
try err.addNote(self, "referenced {d} more times", .{remaining});
}
var err_msg = link.File.ErrorMsg{
.msg = try std.fmt.allocPrint(gpa, "undefined symbol: {s}", .{self.symbol(undef_index).name(self)}),
};
err_msg.notes = try notes.toOwnedSlice();
self.misc_errors.appendAssumeCapacity(err_msg);
}
}
@ -4003,15 +4116,9 @@ fn reportParseError(
comptime format: []const u8,
args: anytype,
) error{OutOfMemory}!void {
const gpa = self.base.allocator;
try self.misc_errors.ensureUnusedCapacity(gpa, 1);
var notes = try gpa.alloc(link.File.ErrorMsg, 1);
errdefer gpa.free(notes);
notes[0] = .{ .msg = try std.fmt.allocPrint(gpa, "while parsing {s}", .{path}) };
self.misc_errors.appendAssumeCapacity(.{
.msg = try std.fmt.allocPrint(gpa, format, args),
.notes = notes,
});
var err = try self.addErrorWithNotes(1);
try err.addMsg(self, format, args);
try err.addNote(self, "while parsing {s}", .{path});
}
fn fmtShdrs(self: *Elf) std.fmt.Formatter(formatShdrs) {

53
src/link/Elf/Atom.zig
View File

@ -25,11 +25,8 @@ relocs_section_index: Index = 0,
/// Index of this atom in the linker's atoms table.
atom_index: Index = 0,
/// Specifies whether this atom is alive or has been garbage collected.
alive: bool = false,
/// Specifies if the atom has been visited during garbage collection.
visited: bool = false,
/// Flags we use for state tracking.
flags: Flags = .{},
/// Start index of FDEs referencing this atom.
fde_start: u32 = 0,
@ -48,8 +45,12 @@ pub fn name(self: Atom, elf_file: *Elf) []const u8 {
return elf_file.strtab.getAssumeExists(self.name_offset);
}
pub fn file(self: Atom, elf_file: *Elf) ?File {
return elf_file.file(self.file_index);
}
pub fn inputShdr(self: Atom, elf_file: *Elf) elf.Elf64_Shdr {
const object = elf_file.file(self.file_index).?.object;
const object = self.file(elf_file).?.object;
return object.shdrs.items[self.input_section_index];
}
@ -59,7 +60,7 @@ pub fn outputShndx(self: Atom) ?u16 {
}
pub fn codeInObject(self: Atom, elf_file: *Elf) error{Overflow}![]const u8 {
const object = elf_file.file(self.file_index).?.object;
const object = self.file(elf_file).?.object;
return object.shdrContents(self.input_section_index);
}
@ -91,7 +92,7 @@ pub fn codeInObjectUncompressAlloc(self: Atom, elf_file: *Elf) ![]u8 {
}
pub fn priority(self: Atom, elf_file: *Elf) u64 {
const index = elf_file.file(self.file_index).?.index();
const index = self.file(elf_file).?.index();
return (@as(u64, @intCast(index)) << 32) | @as(u64, @intCast(self.input_section_index));
}
@ -178,6 +179,13 @@ pub fn allocate(self: *Atom, elf_file: *Elf) !void {
}
};
log.debug("allocated atom({d}) : '{s}' at 0x{x} to 0x{x}", .{
self.atom_index,
self.name(elf_file),
self.value,
self.value + self.size,
});
const expand_section = if (atom_placement) |placement_index|
elf_file.atom(placement_index).?.next_index == 0
else
@ -222,6 +230,8 @@ pub fn allocate(self: *Atom, elf_file: *Elf) !void {
if (free_list_removal) |i| {
_ = free_list.swapRemove(i);
}
self.flags.allocated = true;
}
pub fn shrink(self: *Atom, elf_file: *Elf) void {
@ -238,7 +248,7 @@ pub fn free(self: *Atom, elf_file: *Elf) void {
log.debug("freeAtom {d} ({s})", .{ self.atom_index, self.name(elf_file) });
const gpa = elf_file.base.allocator;
const zig_module = elf_file.file(self.file_index).?.zig_module;
const zig_module = self.file(elf_file).?.zig_module;
const shndx = self.outputShndx().?;
const meta = elf_file.last_atom_and_free_list_table.getPtr(shndx).?;
const free_list = &meta.free_list;
@ -294,7 +304,7 @@ pub fn free(self: *Atom, elf_file: *Elf) void {
}
pub fn relocs(self: Atom, elf_file: *Elf) error{Overflow}![]align(1) const elf.Elf64_Rela {
return switch (elf_file.file(self.file_index).?) {
return switch (self.file(elf_file).?) {
.zig_module => |x| x.relocs.items[self.relocs_section_index].items,
.object => |x| x.getRelocs(self.relocs_section_index),
else => unreachable,
@ -303,7 +313,7 @@ pub fn relocs(self: Atom, elf_file: *Elf) error{Overflow}![]align(1) const elf.E
pub fn addReloc(self: Atom, elf_file: *Elf, reloc: elf.Elf64_Rela) !void {
const gpa = elf_file.base.allocator;
const file_ptr = elf_file.file(self.file_index).?;
const file_ptr = self.file(elf_file).?;
assert(file_ptr == .zig_module);
const zig_module = file_ptr.zig_module;
const rels = &zig_module.relocs.items[self.relocs_section_index];
@ -311,14 +321,14 @@ pub fn addReloc(self: Atom, elf_file: *Elf, reloc: elf.Elf64_Rela) !void {
}
pub fn freeRelocs(self: Atom, elf_file: *Elf) void {
const file_ptr = elf_file.file(self.file_index).?;
const file_ptr = self.file(elf_file).?;
assert(file_ptr == .zig_module);
const zig_module = file_ptr.zig_module;
zig_module.relocs.items[self.relocs_section_index].clearRetainingCapacity();
}
pub fn scanRelocs(self: Atom, elf_file: *Elf, undefs: anytype) !void {
const file_ptr = elf_file.file(self.file_index).?;
const file_ptr = self.file(elf_file).?;
const rels = try self.relocs(elf_file);
var i: usize = 0;
while (i < rels.len) : (i += 1) {
@ -392,7 +402,7 @@ fn reportUndefined(
rel: elf.Elf64_Rela,
undefs: anytype,
) !void {
const rel_esym = switch (elf_file.file(self.file_index).?) {
const rel_esym = switch (self.file(elf_file).?) {
.zig_module => |x| x.elfSym(rel.r_sym()).*,
.object => |x| x.symtab[rel.r_sym()],
else => unreachable,
@ -416,7 +426,7 @@ fn reportUndefined(
pub fn resolveRelocs(self: Atom, elf_file: *Elf, code: []u8) !void {
relocs_log.debug("0x{x}: {s}", .{ self.value, self.name(elf_file) });
const file_ptr = elf_file.file(self.file_index).?;
const file_ptr = self.file(elf_file).?;
var stream = std.io.fixedBufferStream(code);
const cwriter = stream.writer();
@ -619,7 +629,7 @@ fn format2(
// try writer.writeAll(" }");
// }
const gc_sections = if (elf_file.base.options.gc_sections) |gc_sections| gc_sections else false;
if (gc_sections and !atom.alive) {
if (gc_sections and !atom.flags.alive) {
try writer.writeAll(" : [*]");
}
}
@ -629,6 +639,17 @@ fn format2(
// future.
pub const Index = u16;
pub const Flags = packed struct {
/// Specifies whether this atom is alive or has been garbage collected.
alive: bool = false,
/// Specifies if the atom has been visited during garbage collection.
visited: bool = false,
/// Specifies whether this atom has been allocated in the output section.
allocated: bool = false,
};
const x86_64 = struct {
pub fn relaxGotpcrelx(code: []u8) !void {
const old_inst = disassemble(code) orelse return error.RelaxFail;

12
src/link/Elf/Object.zig
View File

@ -180,7 +180,7 @@ fn addAtom(
atom.file_index = self.index;
atom.input_section_index = shndx;
atom.output_section_index = try self.getOutputSectionIndex(elf_file, shdr);
atom.alive = true;
atom.flags.alive = true;
self.atoms.items[shndx] = atom_index;
if (shdr.sh_flags & elf.SHF_COMPRESSED != 0) {
@ -424,7 +424,7 @@ fn filterRelocs(
pub fn scanRelocs(self: *Object, elf_file: *Elf, undefs: anytype) !void {
for (self.atoms.items) |atom_index| {
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
if (!atom.flags.alive) continue;
const shdr = atom.inputShdr(elf_file);
if (shdr.sh_flags & elf.SHF_ALLOC == 0) continue;
if (shdr.sh_type == elf.SHT_NOBITS) continue;
@ -458,7 +458,7 @@ pub fn resolveSymbols(self: *Object, elf_file: *Elf) void {
if (esym.st_shndx != elf.SHN_ABS and esym.st_shndx != elf.SHN_COMMON) {
const atom_index = self.atoms.items[esym.st_shndx];
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
if (!atom.flags.alive) continue;
}
const global = elf_file.symbol(index);
@ -553,7 +553,7 @@ pub fn checkDuplicates(self: *Object, elf_file: *Elf) void {
if (this_sym.st_shndx != elf.SHN_ABS) {
const atom_index = self.atoms.items[this_sym.st_shndx];
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
if (!atom.flags.alive) continue;
}
elf_file.base.fatal("multiple definition: {}: {}: {s}", .{
@ -628,7 +628,7 @@ pub fn convertCommonSymbols(self: *Object, elf_file: *Elf) !void {
pub fn updateSymtabSize(self: *Object, elf_file: *Elf) void {
for (self.locals()) |local_index| {
const local = elf_file.symbol(local_index);
if (local.atom(elf_file)) |atom| if (!atom.alive) continue;
if (local.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
const esym = local.elfSym(elf_file);
switch (esym.st_type()) {
elf.STT_SECTION, elf.STT_NOTYPE => continue,
@ -641,7 +641,7 @@ pub fn updateSymtabSize(self: *Object, elf_file: *Elf) void {
for (self.globals()) |global_index| {
const global = elf_file.symbol(global_index);
if (global.file(elf_file)) |file| if (file.index() != self.index) continue;
if (global.atom(elf_file)) |atom| if (!atom.alive) continue;
if (global.atom(elf_file)) |atom| if (!atom.flags.alive) continue;
global.flags.output_symtab = true;
if (global.isLocal()) {
self.output_symtab_size.nlocals += 1;

12
src/link/Elf/ZigModule.zig
View File

@ -53,17 +53,19 @@ pub fn addAtom(self: *ZigModule, elf_file: *Elf) !Symbol.Index {
const gpa = elf_file.base.allocator;
const atom_index = try elf_file.addAtom();
const symbol_index = try elf_file.addSymbol();
const esym_index = try self.addLocalEsym(gpa);
try self.atoms.putNoClobber(gpa, atom_index, {});
try self.local_symbols.append(gpa, symbol_index);
const atom_ptr = elf_file.atom(atom_index).?;
atom_ptr.file_index = self.index;
const symbol_index = try elf_file.addSymbol();
try self.local_symbols.append(gpa, symbol_index);
const symbol_ptr = elf_file.symbol(symbol_index);
symbol_ptr.file_index = self.index;
symbol_ptr.atom_index = atom_index;
const esym_index = try self.addLocalEsym(gpa);
const esym = &self.local_esyms.items[esym_index];
esym.st_shndx = atom_index;
symbol_ptr.esym_index = esym_index;
@ -86,7 +88,7 @@ pub fn resolveSymbols(self: *ZigModule, elf_file: *Elf) void {
if (esym.st_shndx != elf.SHN_ABS and esym.st_shndx != elf.SHN_COMMON) {
const atom_index = esym.st_shndx;
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
if (!atom.flags.alive) continue;
}
const global = elf_file.symbol(index);
@ -141,7 +143,7 @@ pub fn claimUnresolved(self: *ZigModule, elf_file: *Elf) void {
pub fn scanRelocs(self: *ZigModule, elf_file: *Elf, undefs: anytype) !void {
for (self.atoms.keys()) |atom_index| {
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.alive) continue;
if (!atom.flags.alive) continue;
try atom.scanRelocs(elf_file, undefs);
}
}

16
src/link/Elf/file.zig
View File

@ -89,6 +89,21 @@ pub const File = union(enum) {
}
}
pub fn atoms(file: File) []const Atom.Index {
return switch (file) {
.linker_defined => unreachable,
.zig_module => |x| x.atoms.keys(),
.object => |x| x.atoms.items,
};
}
pub fn locals(file: File) []const Symbol.Index {
return switch (file) {
.linker_defined => unreachable,
inline else => |x| x.locals(),
};
}
pub fn globals(file: File) []const Symbol.Index {
return switch (file) {
inline else => |x| x.globals(),
@ -110,6 +125,7 @@ const std = @import("std");
const elf = std.elf;
const Allocator = std.mem.Allocator;
const Atom = @import("Atom.zig");
const Elf = @import("../Elf.zig");
const LinkerDefined = @import("LinkerDefined.zig");
const Object = @import("Object.zig");

15
src/link/Elf/synthetic_sections.zig
View File

@ -169,6 +169,21 @@ pub const GotSection = struct {
}
}
pub fn writeAllEntries(got: GotSection, elf_file: *Elf, writer: anytype) !void {
assert(!got.dirty);
const entry_size: u16 = elf_file.archPtrWidthBytes();
const endian = elf_file.base.options.target.cpu.arch.endian();
for (got.entries.items) |entry| {
const value = elf_file.symbol(entry.symbol_index).value;
switch (entry_size) {
2 => try writer.writeInt(u16, @intCast(value), endian),
4 => try writer.writeInt(u32, @intCast(value), endian),
8 => try writer.writeInt(u64, @intCast(value), endian),
else => unreachable,
}
}
}
// pub fn write(got: GotSection, elf_file: *Elf, writer: anytype) !void {
// const is_shared = elf_file.options.output_mode == .lib;
// const apply_relocs = elf_file.options.apply_dynamic_relocs;