diff --git a/src/link/Coff.zig b/src/link/Coff.zig index 87ad1085aa..a7ca47c151 100644 --- a/src/link/Coff.zig +++ b/src/link/Coff.zig @@ -781,24 +781,47 @@ fn writeAtom(self: *Coff, atom_index: Atom.Index, code: []u8) !void { const sym = atom.getSymbol(self); const section = self.sections.get(@enumToInt(sym.section_number) - 1); const file_offset = section.header.pointer_to_raw_data + sym.value - section.header.virtual_address; + log.debug("writing atom for symbol {s} at file offset 0x{x} to 0x{x}", .{ atom.getName(self), file_offset, file_offset + code.len, }); + const gpa = self.base.allocator; + + // Gather relocs which can be resolved. + // We need to do this as we will be applying different slide values depending + // if we are running in hot-code swapping mode or not. + // TODO: how crazy would it be to try and apply the actual image base of the loaded + // process for the in-file values rather than the Windows defaults? + var relocs = std.ArrayList(*Relocation).init(gpa); + defer relocs.deinit(); + + if (self.relocs.getPtr(atom_index)) |rels| { + try relocs.ensureTotalCapacityPrecise(rels.items.len); + for (rels.items) |*reloc| { + if (reloc.isResolvable(self)) relocs.appendAssumeCapacity(reloc); + } + } + if (self.base.child_pid) |handle| { const slide = @ptrToInt(self.hot_state.loaded_base_address.?); - const mem_code = try self.base.allocator.dupe(u8, code); - defer self.base.allocator.free(mem_code); - self.resolveRelocs(atom_index, mem_code, slide); + const mem_code = try gpa.dupe(u8, code); + defer gpa.free(mem_code); + self.resolveRelocs(atom_index, relocs.items, mem_code, slide); const vaddr = sym.value + slide; const pvaddr = @intToPtr(*anyopaque, vaddr); + log.debug("writing to memory at address {x}", .{vaddr}); + + if (build_options.enable_logging) { + try debugMem(gpa, handle, pvaddr, mem_code); + } + if (section.header.flags.MEM_WRITE == 0) { - log.debug("page not mapped for write access; re-mapping...", .{}); writeMemProtected(handle, pvaddr, mem_code) catch |err| { log.warn("writing to protected memory failed with error: {s}", .{@errorName(err)}); }; @@ -809,25 +832,29 @@ fn writeAtom(self: *Coff, atom_index: Atom.Index, code: []u8) !void { } } - self.resolveRelocs(atom_index, code, self.getImageBase()); + self.resolveRelocs(atom_index, relocs.items, code, self.getImageBase()); try self.base.file.?.pwriteAll(code, file_offset); + + // Now we can mark the relocs as resolved. + while (relocs.popOrNull()) |reloc| { + reloc.dirty = false; + } } fn debugMem(allocator: Allocator, handle: std.ChildProcess.Id, pvaddr: std.os.windows.LPVOID, code: []const u8) !void { var buffer = try allocator.alloc(u8, code.len); defer allocator.free(buffer); const memread = try std.os.windows.ReadProcessMemory(handle, pvaddr, buffer); - log.debug("in memory: {x}", .{std.fmt.fmtSliceHexLower(memread)}); log.debug("to write: {x}", .{std.fmt.fmtSliceHexLower(code)}); + log.debug("in memory: {x}", .{std.fmt.fmtSliceHexLower(memread)}); } fn writeMemProtected(handle: std.ChildProcess.Id, pvaddr: std.os.windows.LPVOID, code: []const u8) !void { - var old_prot: std.os.windows.DWORD = undefined; - try std.os.windows.VirtualProtectEx(handle, pvaddr, code.len, std.os.windows.PAGE_EXECUTE_WRITECOPY, &old_prot); + const old_prot = try std.os.windows.VirtualProtectEx(handle, pvaddr, code.len, std.os.windows.PAGE_EXECUTE_WRITECOPY); try writeMem(handle, pvaddr, code); // TODO: We can probably just set the pages writeable and leave it at that without having to restore the attributes. // For that though, we want to track which page has already been modified. - try std.os.windows.VirtualProtectEx(handle, pvaddr, code.len, old_prot, null); + _ = try std.os.windows.VirtualProtectEx(handle, pvaddr, code.len, old_prot); } fn writeMem(handle: std.ChildProcess.Id, pvaddr: std.os.windows.LPVOID, code: []const u8) !void { @@ -868,16 +895,10 @@ fn markRelocsDirtyByAddress(self: *Coff, addr: u32) void { } } -fn resolveRelocs(self: *Coff, atom_index: Atom.Index, code: []u8, image_base: u64) void { - const relocs = self.relocs.getPtr(atom_index) orelse return; - +fn resolveRelocs(self: *Coff, atom_index: Atom.Index, relocs: []*const Relocation, code: []u8, image_base: u64) void { log.debug("relocating '{s}'", .{self.getAtom(atom_index).getName(self)}); - - for (relocs.items) |*reloc| { - if (!reloc.dirty) continue; - if (reloc.resolve(atom_index, code, image_base, self)) { - reloc.dirty = false; - } + for (relocs) |reloc| { + reloc.resolve(atom_index, code, image_base, self); } } @@ -1488,7 +1509,7 @@ pub fn flushModule(self: *Coff, comp: *Compilation, prog_node: *std.Progress.Nod for (self.relocs.keys(), self.relocs.values()) |atom_index, relocs| { const needs_update = for (relocs.items) |reloc| { - if (reloc.dirty) break true; + if (reloc.isResolvable(self)) break true; } else false; if (!needs_update) continue; diff --git a/src/link/Coff/Relocation.zig b/src/link/Coff/Relocation.zig index 6b35de93f4..2fafa0bbdc 100644 --- a/src/link/Coff/Relocation.zig +++ b/src/link/Coff/Relocation.zig @@ -72,14 +72,18 @@ pub fn getTargetAddress(self: Relocation, coff_file: *const Coff) ?u32 { } } -/// Returns `false` if obtaining the target address has been deferred until `flushModule`. -/// This can happen when trying to resolve address of an import table entry ahead of time. -pub fn resolve(self: Relocation, atom_index: Atom.Index, code: []u8, image_base: u64, coff_file: *Coff) bool { +/// Returns true if and only if the reloc is dirty AND the target address is available. +pub fn isResolvable(self: Relocation, coff_file: *Coff) bool { + _ = self.getTargetAddress(coff_file) orelse return false; + return self.dirty; +} + +pub fn resolve(self: Relocation, atom_index: Atom.Index, code: []u8, image_base: u64, coff_file: *Coff) void { const atom = coff_file.getAtom(atom_index); const source_sym = atom.getSymbol(coff_file); const source_vaddr = source_sym.value + self.offset; - const target_vaddr = self.getTargetAddress(coff_file) orelse return false; + const target_vaddr = self.getTargetAddress(coff_file).?; // Oops, you didn't check if the relocation can be resolved with isResolvable(). const target_vaddr_with_addend = target_vaddr + self.addend; log.debug(" ({x}: [() => 0x{x} ({s})) ({s}) ", .{ @@ -102,8 +106,6 @@ pub fn resolve(self: Relocation, atom_index: Atom.Index, code: []u8, image_base: .x86, .x86_64 => self.resolveX86(ctx), else => unreachable, // unhandled target architecture } - - return true; } const Context = struct {