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macho: make atom address relative wrt defining section

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This commit is contained in:
Jakub Konka 2024-02-02 22:55:30 +01:00
parent e10a2018a7
commit 9fc1685c1c
5 changed files with 68 additions and 53 deletions
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64
src/link/MachO.zig
View File

@ -636,7 +636,7 @@ pub fn flushModule(self: *MachO, arena: Allocator, prog_node: *std.Progress.Node
return error.FlushFailure;
},
};
const file_offset = sect.offset + atom.value - sect.addr;
const file_offset = sect.offset + atom.value;
atom.resolveRelocs(self, code) catch |err| switch (err) {
error.ResolveFailed => has_resolve_error = true,
else => |e| {
@ -2393,16 +2393,7 @@ fn allocateSegments(self: *MachO) void {
}
pub fn allocateAtoms(self: *MachO) void {
const slice = self.sections.slice();
for (slice.items(.header), slice.items(.atoms)) |header, atoms| {
if (atoms.items.len == 0) continue;
for (atoms.items) |atom_index| {
const atom = self.getAtom(atom_index).?;
assert(atom.flags.alive);
atom.value += header.addr;
}
}
// TODO: redo this like atoms
for (self.thunks.items) |*thunk| {
const header = self.sections.items(.header)[thunk.out_n_sect];
thunk.value += header.addr;
@ -2603,7 +2594,7 @@ fn writeAtoms(self: *MachO) !void {
for (atoms.items) |atom_index| {
const atom = self.getAtom(atom_index).?;
assert(atom.flags.alive);
const off = math.cast(usize, atom.value - header.addr) orelse return error.Overflow;
const off = math.cast(usize, atom.value) orelse return error.Overflow;
const atom_size = math.cast(usize, atom.size) orelse return error.Overflow;
try atom.getData(self, buffer[off..][0..atom_size]);
atom.resolveRelocs(self, buffer[off..][0..atom_size]) catch |err| switch (err) {
@ -2825,7 +2816,7 @@ pub fn writeDataInCode(self: *MachO, base_address: u64, off: u32) !u32 {
if (atom.flags.alive) for (in_dices[start_dice..next_dice]) |dice| {
dices.appendAssumeCapacity(.{
.offset = @intCast(atom.value + dice.offset - start_off - base_address),
.offset = @intCast(atom.getAddress(self) + dice.offset - start_off - base_address),
.length = dice.length,
.kind = dice.kind,
});
@ -3318,7 +3309,7 @@ fn allocatedSize(self: *MachO, start: u64) u64 {
return min_pos - start;
}
fn allocatedVirtualSize(self: *MachO, start: u64) u64 {
fn allocatedSizeVirtual(self: *MachO, start: u64) u64 {
if (start == 0) return 0;
var min_pos: u64 = std.math.maxInt(u64);
for (self.segments.items) |seg| {
@ -3518,22 +3509,39 @@ pub fn growSection(self: *MachO, sect_index: u8, needed_size: u64) !void {
sect.size = 0;
// Must move the entire section.
const alignment = if (self.base.isRelocatable())
try math.powi(u32, 2, sect.@"align")
else
self.getPageSize();
const new_offset = self.findFreeSpace(needed_size, alignment);
if (self.base.isRelocatable()) {
const alignment = try math.powi(u32, 2, sect.@"align");
const new_offset = self.findFreeSpace(needed_size, alignment);
const new_addr = self.findFreeSpaceVirtual(needed_size, alignment);
log.debug("new '{s},{s}' file offset 0x{x} to 0x{x}", .{
sect.segName(),
sect.sectName(),
new_offset,
new_offset + existing_size,
});
log.debug("new '{s},{s}' file offset 0x{x} to 0x{x} (0x{x} - 0x{x})", .{
sect.segName(),
sect.sectName(),
new_offset,
new_offset + existing_size,
new_addr,
new_addr + existing_size,
});
try self.copyRangeAllZeroOut(sect.offset, new_offset, existing_size);
try self.copyRangeAll(sect.offset, new_offset, existing_size);
sect.offset = @intCast(new_offset);
sect.offset = @intCast(new_offset);
sect.addr = new_addr;
} else {
const alignment = self.getPageSize();
const new_offset = self.findFreeSpace(needed_size, alignment);
log.debug("new '{s},{s}' file offset 0x{x} to 0x{x}", .{
sect.segName(),
sect.sectName(),
new_offset,
new_offset + existing_size,
});
try self.copyRangeAllZeroOut(sect.offset, new_offset, existing_size);
sect.offset = @intCast(new_offset);
}
}
sect.size = needed_size;
@ -3547,7 +3555,7 @@ pub fn growSection(self: *MachO, sect_index: u8, needed_size: u64) !void {
seg.filesize = needed_size;
}
const mem_capacity = self.allocatedVirtualSize(seg.vmaddr);
const mem_capacity = self.allocatedSizeVirtual(seg.vmaddr);
if (needed_size > mem_capacity) {
var err = try self.addErrorWithNotes(2);
try err.addMsg(self, "fatal linker error: cannot expand segment seg({d})({s}) in virtual memory", .{

39
src/link/MachO/Atom.zig
View File

@ -1,4 +1,4 @@
/// Address allocated for this Atom.
/// Address offset allocated for this Atom wrt to its section start address.
value: u64 = 0,
/// Name of this Atom.
@ -84,6 +84,11 @@ pub fn getInputAddress(self: Atom, macho_file: *MachO) u64 {
return self.getInputSection(macho_file).addr + self.off;
}
pub fn getAddress(self: Atom, macho_file: *MachO) u64 {
const header = macho_file.sections.items(.header)[self.out_n_sect];
return header.addr + self.value;
}
pub fn getPriority(self: Atom, macho_file: *MachO) u64 {
const file = self.getFile(macho_file);
return (@as(u64, @intCast(file.getIndex())) << 32) | @as(u64, @intCast(self.n_sect));
@ -189,14 +194,17 @@ pub fn initOutputSection(sect: macho.section_64, macho_file: *MachO) !u8 {
/// File offset relocation happens transparently, so it is not included in
/// this calculation.
pub fn capacity(self: Atom, macho_file: *MachO) u64 {
const next_value = if (macho_file.getAtom(self.next_index)) |next| next.value else std.math.maxInt(u32);
return next_value - self.value;
const next_addr = if (macho_file.getAtom(self.next_index)) |next|
next.getAddress(macho_file)
else
std.math.maxInt(u32);
return next_addr - self.getAddress(macho_file);
}
pub fn freeListEligible(self: Atom, macho_file: *MachO) bool {
// No need to keep a free list node for the last block.
const next = macho_file.getAtom(self.next_index) orelse return false;
const cap = next.value - self.value;
const cap = next.getAddress(macho_file) - self.getAddress(macho_file);
const ideal_cap = MachO.padToIdeal(self.size);
if (cap <= ideal_cap) return false;
const surplus = cap - ideal_cap;
@ -263,15 +271,15 @@ pub fn allocate(self: *Atom, macho_file: *MachO) !void {
atom_placement = last.atom_index;
break :blk new_start_vaddr;
} else {
break :blk sect.addr;
break :blk 0;
}
};
log.debug("allocated atom({d}) : '{s}' at 0x{x} to 0x{x}", .{
self.atom_index,
self.getName(macho_file),
self.value,
self.value + self.size,
self.getAddress(macho_file),
self.getAddress(macho_file) + self.size,
});
const expand_section = if (atom_placement) |placement_index|
@ -279,7 +287,7 @@ pub fn allocate(self: *Atom, macho_file: *MachO) !void {
else
true;
if (expand_section) {
const needed_size = (self.value + self.size) - sect.addr;
const needed_size = self.value + self.size;
try macho_file.growSection(self.out_n_sect, needed_size);
last_atom_index.* = self.atom_index;
@ -544,7 +552,7 @@ pub fn resolveRelocs(self: Atom, macho_file: *MachO, buffer: []u8) !void {
const name = self.getName(macho_file);
const relocs = self.getRelocs(macho_file);
relocs_log.debug("{x}: {s}", .{ self.value, name });
relocs_log.debug("{x}: {s}", .{ self.getAddress(macho_file), name });
var has_error = false;
var stream = std.io.fixedBufferStream(buffer);
@ -569,7 +577,7 @@ pub fn resolveRelocs(self: Atom, macho_file: *MachO, buffer: []u8) !void {
try macho_file.reportParseError2(
file.getIndex(),
"{s}: 0x{x}: 0x{x}: failed to relax relocation: type {s}, target {s}",
.{ name, self.value, rel.offset, @tagName(rel.type), target },
.{ name, self.getAddress(macho_file), rel.offset, @tagName(rel.type), target },
);
has_error = true;
},
@ -604,7 +612,7 @@ fn resolveRelocInner(
const rel_offset = math.cast(usize, rel.offset - self.off) orelse return error.Overflow;
const seg_id = macho_file.sections.items(.segment_id)[self.out_n_sect];
const seg = macho_file.segments.items[seg_id];
const P = @as(i64, @intCast(self.value)) + @as(i64, @intCast(rel_offset));
const P = @as(i64, @intCast(self.getAddress(macho_file))) + @as(i64, @intCast(rel_offset));
const A = rel.addend + rel.getRelocAddend(cpu_arch);
const S: i64 = @intCast(rel.getTargetAddress(macho_file));
const G: i64 = @intCast(rel.getGotTargetAddress(macho_file));
@ -919,7 +927,7 @@ const x86_64 = struct {
var err = try macho_file.addErrorWithNotes(2);
try err.addMsg(macho_file, "{s}: 0x{x}: 0x{x}: failed to relax relocation of type {s}", .{
self.getName(macho_file),
self.value,
self.getAddress(macho_file),
rel.offset,
@tagName(rel.type),
});
@ -990,12 +998,11 @@ pub fn writeRelocs(self: Atom, macho_file: *MachO, code: []u8, buffer: *std.Arra
const cpu_arch = macho_file.getTarget().cpu.arch;
const relocs = self.getRelocs(macho_file);
const sect = macho_file.sections.items(.header)[self.out_n_sect];
var stream = std.io.fixedBufferStream(code);
for (relocs) |rel| {
const rel_offset = rel.offset - self.off;
const r_address: i32 = math.cast(i32, self.value + rel_offset - sect.addr) orelse return error.Overflow;
const r_address: i32 = math.cast(i32, self.value + rel_offset) orelse return error.Overflow;
const r_symbolnum = r_symbolnum: {
const r_symbolnum: u32 = switch (rel.tag) {
.local => rel.getTargetAtom(macho_file).out_n_sect + 1,
@ -1062,7 +1069,7 @@ pub fn writeRelocs(self: Atom, macho_file: *MachO, code: []u8, buffer: *std.Arra
.x86_64 => {
if (rel.meta.pcrel) {
if (rel.tag == .local) {
addend -= @as(i64, @intCast(self.value + rel_offset));
addend -= @as(i64, @intCast(self.getAddress(macho_file) + rel_offset));
} else {
addend += 4;
}
@ -1144,7 +1151,7 @@ fn format2(
const atom = ctx.atom;
const macho_file = ctx.macho_file;
try writer.print("atom({d}) : {s} : @{x} : sect({d}) : align({x}) : size({x}) : nreloc({d}) : thunk({d})", .{
atom.atom_index, atom.getName(macho_file), atom.value,
atom.atom_index, atom.getName(macho_file), atom.getAddress(macho_file),
atom.out_n_sect, atom.alignment, atom.size,
atom.getRelocs(macho_file).len, atom.thunk_index,
});

4
src/link/MachO/Symbol.zig
View File

@ -118,7 +118,7 @@ pub fn getAddress(symbol: Symbol, opts: struct {
return symbol.getObjcStubsAddress(macho_file);
}
}
if (symbol.getAtom(macho_file)) |atom| return atom.value + symbol.value;
if (symbol.getAtom(macho_file)) |atom| return atom.getAddress(macho_file) + symbol.value;
return symbol.value;
}
@ -145,7 +145,7 @@ pub fn getObjcSelrefsAddress(symbol: Symbol, macho_file: *MachO) u64 {
const extra = symbol.getExtra(macho_file).?;
const atom = macho_file.getAtom(extra.objc_selrefs).?;
assert(atom.flags.alive);
return atom.value;
return atom.getAddress(macho_file);
}
pub fn getTlvPtrAddress(symbol: Symbol, macho_file: *MachO) u64 {

10
src/link/MachO/ZigObject.zig
View File

@ -154,7 +154,7 @@ pub fn getAtomData(self: ZigObject, macho_file: *MachO, atom: Atom, buffer: []u8
@memset(buffer, 0);
},
else => {
const file_offset = sect.offset + atom.value - sect.addr;
const file_offset = sect.offset + atom.value;
const amt = try macho_file.base.file.?.preadAll(buffer, file_offset);
if (amt != buffer.len) return error.InputOutput;
},
@ -715,7 +715,7 @@ fn updateDeclCode(
} else if (code.len < old_size) {
atom.shrink(macho_file);
} else if (macho_file.getAtom(atom.next_index) == null) {
const needed_size = atom.value + code.len - sect.addr;
const needed_size = atom.value + code.len;
sect.size = needed_size;
}
} else {
@ -733,7 +733,7 @@ fn updateDeclCode(
}
if (!sect.isZerofill()) {
const file_offset = sect.offset + atom.value - sect.addr;
const file_offset = sect.offset + atom.value;
try macho_file.base.file.?.pwriteAll(code, file_offset);
}
}
@ -1036,7 +1036,7 @@ fn lowerConst(
nlist.n_value = 0;
const sect = macho_file.sections.items(.header)[output_section_index];
const file_offset = sect.offset + atom.value - sect.addr;
const file_offset = sect.offset + atom.value;
try macho_file.base.file.?.pwriteAll(code, file_offset);
return .{ .ok = sym_index };
@ -1213,7 +1213,7 @@ fn updateLazySymbol(
}
const sect = macho_file.sections.items(.header)[output_section_index];
const file_offset = sect.offset + atom.value - sect.addr;
const file_offset = sect.offset + atom.value;
try macho_file.base.file.?.pwriteAll(code, file_offset);
}

4
src/link/MachO/relocatable.zig
View File

@ -328,7 +328,7 @@ fn writeAtoms(macho_file: *MachO) !void {
for (atoms.items) |atom_index| {
const atom = macho_file.getAtom(atom_index).?;
assert(atom.flags.alive);
const off = math.cast(usize, atom.value - header.addr) orelse return error.Overflow;
const off = math.cast(usize, atom.value) orelse return error.Overflow;
const atom_size = math.cast(usize, atom.size) orelse return error.Overflow;
try atom.getData(macho_file, code[off..][0..atom_size]);
try atom.writeRelocs(macho_file, code[off..][0..atom_size], &relocs);
@ -386,7 +386,7 @@ fn writeAtoms(macho_file: *MachO) !void {
return error.FlushFailure;
},
};
const file_offset = header.offset + atom.value - header.addr;
const file_offset = header.offset + atom.value;
const rels = relocs.getPtr(atom.out_n_sect).?;
try atom.writeRelocs(macho_file, code, rels);
try macho_file.base.file.?.pwriteAll(code, file_offset);