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plan9 linker: correct runtime vs file offset converting code
This commit is contained in:
Jacob G-W
Andrew Kelley
parent
72bb6bb143
commit
166dffb088
@ -19,37 +19,73 @@ const assert = std.debug.assert;
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base: link.File,
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ptr_width: PtrWidth,
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error_flags: File.ErrorFlags = File.ErrorFlags{},
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bases: Bases,
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decl_table: std.AutoArrayHashMapUnmanaged(*Module.Decl, void) = .{},
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/// is just casted down when 32 bit
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syms: std.ArrayListUnmanaged(aout.Sym64) = .{},
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syms: std.ArrayListUnmanaged(aout.Sym) = .{},
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call_relocs: std.ArrayListUnmanaged(CallReloc) = .{},
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text_buf: std.ArrayListUnmanaged(u8) = .{},
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data_buf: std.ArrayListUnmanaged(u8) = .{},
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cur_decl: *Module.Decl = undefined,
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hdr: aout.ExecHdr = undefined,
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const Bases = struct { text: u32, data: u32 };
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fn getAddr(self: Plan9, addr: u32, t: aout.SymType) u32 {
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return addr + switch (t) {
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.T, .t => self.bases.text,
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.D, .d, .B, .b => self.bases.data,
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else => @panic("get address for more symbol types"),
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};
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}
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/// opposite of getAddr
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fn takeAddr(self: Plan9, addr: u32, t: aout.SymType) u32 {
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return addr - switch (t) {
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.T, .t => self.bases.text,
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.D, .d, .B, .b => self.bases.data, // TODO is .b correct here?
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else => @panic("take address for more symbol types"),
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};
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}
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fn getSymAddr(self: Plan9, s: aout.Sym) u32 {
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return self.getAddr(@intCast(u32, s.value), s.type);
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}
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fn headerSize(self: Plan9) u32 {
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// fat header (currently unused)
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const fat: u8 = if (self.ptr_width == .p64) 8 else 0;
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return @sizeOf(aout.ExecHdr) + fat;
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}
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pub const DeclBlock = struct {
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type: enum { text, data },
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type: aout.SymType,
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// offset in the text or data sects
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offset: u32,
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// offset into syms
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sym_index: ?usize,
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pub const empty = DeclBlock{
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.type = .text,
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.type = .t,
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.offset = 0,
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.sym_index = null,
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};
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};
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// TODO change base addr based on target (and section?) (right now it just works on amd64)
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const default_base_addr = 0x00200028;
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pub fn defaultBaseAddrs(arch: std.Target.Cpu.Arch) Bases {
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return switch (arch) {
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.x86_64 => .{
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// 0x28 => 40 == header size
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.text = 0x200028,
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.data = 0x400000,
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},
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.i386 => .{
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// 0x20 => 32 == header size
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.text = 0x200020,
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.data = 0x400000,
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},
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else => std.debug.panic("find default base address for {}", .{arch}),
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};
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}
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pub const CallReloc = struct {
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caller: *Module.Decl,
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@ -76,6 +112,7 @@ pub fn createEmpty(gpa: *Allocator, options: link.Options) !*Plan9 {
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.file = null,
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},
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.ptr_width = ptr_width,
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.bases = undefined,
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};
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return self;
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}
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@ -115,31 +152,25 @@ pub fn flushModule(self: *Plan9, comp: *Compilation) !void {
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self.cur_decl = decl;
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const is_fn = (decl.ty.zigTypeTag() == .Fn);
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decl.link.plan9 = if (is_fn) .{
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.offset = @intCast(u32, self.text_buf.items.len),
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.type = .text,
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.offset = self.getAddr(@intCast(u32, self.text_buf.items.len), .t),
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.type = .t,
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.sym_index = decl.link.plan9.sym_index,
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} else .{
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.offset = @intCast(u32, self.data_buf.items.len),
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.type = .data,
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.offset = self.getAddr(@intCast(u32, self.data_buf.items.len), .d),
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.type = .t,
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.sym_index = decl.link.plan9.sym_index,
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};
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if (decl.link.plan9.sym_index == null) {
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try self.syms.append(self.base.allocator, .{
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.value = decl.link.plan9.offset,
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.type = switch (decl.link.plan9.type) {
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.text => .t,
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.data => .d,
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},
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.type = decl.link.plan9.type,
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.name = mem.span(decl.name),
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});
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decl.link.plan9.sym_index = self.syms.items.len - 1;
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} else {
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self.syms.items[decl.link.plan9.sym_index.?] = .{
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.value = decl.link.plan9.offset,
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.type = switch (decl.link.plan9.type) {
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.text => .t,
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.data => .d,
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},
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.type = decl.link.plan9.type,
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.name = mem.span(decl.name),
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};
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}
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@ -174,21 +205,21 @@ pub fn flushModule(self: *Plan9, comp: *Compilation) !void {
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assert(l.sym_index != null); // we didn't process it already
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const endian = self.base.options.target.cpu.arch.endian();
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if (self.ptr_width == .p32) {
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const callee_offset = @truncate(u32, reloc.callee.link.plan9.offset + default_base_addr); // TODO this is different if its data
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const off = reloc.offset_in_caller + l.offset;
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const callee_offset = @intCast(u32, reloc.callee.link.plan9.offset);
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const off = self.takeAddr(@intCast(u32, reloc.offset_in_caller) + l.offset, reloc.caller.link.plan9.type);
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std.mem.writeInt(u32, self.text_buf.items[off - 4 ..][0..4], callee_offset, endian);
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} else {
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const callee_offset = reloc.callee.link.plan9.offset + default_base_addr; // TODO this is different if its data
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const off = reloc.offset_in_caller + l.offset;
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const callee_offset = reloc.callee.link.plan9.offset;
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const off = self.takeAddr(@intCast(u32, reloc.offset_in_caller) + l.offset, reloc.caller.link.plan9.type);
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std.mem.writeInt(u64, self.text_buf.items[off - 8 ..][0..8], callee_offset, endian);
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}
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}
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}
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// edata, end, etext
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self.syms.items[0].value = 0x200000; // TODO make this number other place, and what is it?
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self.syms.items[1].value = 0x200000; // TODO make this number other place, and what is it?
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self.syms.items[2].value = self.text_buf.items.len;
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self.syms.items[0].value = self.getAddr(0x0, .b); // what is this number
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self.syms.items[1].value = self.getAddr(0x0, .b); // what is this number
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self.syms.items[2].value = self.getAddr(@intCast(u32, self.text_buf.items.len), .t);
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var sym_buf = std.ArrayList(u8).init(self.base.allocator);
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defer sym_buf.deinit();
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@ -248,25 +279,19 @@ pub fn updateDeclExports(
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}
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}
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if (std.mem.eql(u8, exp.options.name, "_start")) {
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std.debug.assert(decl.link.plan9.type == .text); // we tried to link a non-function as _start
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self.hdr.entry = Plan9.default_base_addr + self.headerSize() + decl.link.plan9.offset;
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std.debug.assert(decl.link.plan9.type == .t); // we tried to link a non-function as _start
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self.hdr.entry = self.bases.text + decl.link.plan9.offset;
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}
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if (exp.link.plan9) |i| {
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self.syms.items[i] = .{
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.value = decl.link.plan9.offset,
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.type = switch (decl.link.plan9.type) {
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.text => .T,
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.data => .D,
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},
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.value = self.getAddr(decl.link.plan9.offset, decl.link.plan9.type),
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.type = decl.link.plan9.type.toGlobal(),
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.name = exp.options.name,
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};
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} else {
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try self.syms.append(self.base.allocator, .{
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.value = decl.link.plan9.offset,
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.type = switch (decl.link.plan9.type) {
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.text => .T,
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.data => .D,
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},
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.value = self.getAddr(decl.link.plan9.offset, decl.link.plan9.type),
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.type = decl.link.plan9.type.toGlobal(),
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.name = exp.options.name,
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});
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exp.link.plan9 = self.syms.items.len - 1;
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@ -300,6 +325,8 @@ pub fn openPath(allocator: *Allocator, sub_path: []const u8, options: link.Optio
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if (std.builtin.mode == .Debug or std.builtin.mode == .ReleaseSafe)
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self.hdr.entry = 0x0;
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self.bases = defaultBaseAddrs(options.target.cpu.arch);
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// first 3 symbols in our table are edata, end, etext
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try self.syms.appendSlice(self.base.allocator, &.{
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.{
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@ -333,9 +360,9 @@ pub fn writeSyms(self: *Plan9, buf: *std.ArrayList(u8)) !void {
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const writer = buf.writer();
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for (self.syms.items) |sym| {
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if (self.ptr_width == .p32) {
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try writer.writeIntBig(u32, @intCast(u32, sym.value) + default_base_addr);
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try writer.writeIntBig(u32, @intCast(u32, sym.value));
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} else {
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try writer.writeIntBig(u64, sym.value + default_base_addr);
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try writer.writeIntBig(u64, sym.value);
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}
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try writer.writeByte(@enumToInt(sym.type));
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try writer.writeAll(std.mem.span(sym.name));
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@ -46,18 +46,10 @@ pub const ExecHdr = extern struct {
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}
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};
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// uchar value[4];
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// char type;
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// char name[n]; /* NUL-terminated */
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pub const Sym32 = struct {
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value: u32, // big endian in the file
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type: SymType,
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name: []const u8,
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};
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// uchar value[8];
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// char type;
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// char name[n]; /* NUL-terminated */
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pub const Sym64 = struct {
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pub const Sym = struct {
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value: u64, // big endian in the file
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type: SymType,
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name: []const u8,
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@ -93,6 +85,14 @@ pub const SymType = enum(u8) {
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z = 0x80 | 'z',
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Z = 0x80 | 'Z',
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m = 0x80 | 'm',
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pub fn toGlobal(self: SymType) SymType {
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return switch (self) {
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.t => .T,
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.b => .B,
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.d => .D,
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else => unreachable,
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};
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}
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};
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pub const HDR_MAGIC = 0x00008000;
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