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macho: handle all jumps in stubs on aarch64

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This commit is contained in:
Jakub Konka 2021-03-16 23:00:10 +01:00
parent 3019676440
commit 643b4898f5
1 changed files with 48 additions and 7 deletions
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55
src/link/MachO.zig
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@ -1597,7 +1597,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
};
const stub_size: u4 = switch (self.base.options.target.cpu.arch) {
.x86_64 => 6,
.aarch64 => 2 * @sizeOf(u32),
.aarch64 => 3 * @sizeOf(u32),
else => unreachable, // unhandled architecture type
};
const flags = macho.S_SYMBOL_STUBS | macho.S_ATTR_PURE_INSTRUCTIONS | macho.S_ATTR_SOME_INSTRUCTIONS;
@ -2525,9 +2525,12 @@ fn writeStub(self: *MachO, index: u32) !void {
const stub_off = stubs.offset + index * stubs.reserved2;
const stub_addr = stubs.addr + index * stubs.reserved2;
const la_ptr_addr = la_symbol_ptr.addr + index * @sizeOf(u64);
log.debug("writing stub at 0x{x}", .{stub_off});
var code = try self.base.allocator.alloc(u8, stubs.reserved2);
defer self.base.allocator.free(code);
switch (self.base.options.target.cpu.arch) {
.x86_64 => {
assert(la_ptr_addr >= stub_addr + stubs.reserved2);
@ -2539,12 +2542,50 @@ fn writeStub(self: *MachO, index: u32) !void {
},
.aarch64 => {
assert(la_ptr_addr >= stub_addr);
const displacement = try math.divExact(u64, la_ptr_addr - stub_addr, 4);
const literal = try math.cast(u19, displacement);
mem.writeIntLittle(u32, code[0..4], aarch64.Instruction.ldr(.x16, .{
.literal = literal,
}).toU32());
mem.writeIntLittle(u32, code[4..8], aarch64.Instruction.br(.x16).toU32());
outer: {
const this_addr = stub_addr;
const target_addr = la_ptr_addr;
inner: {
const displacement = math.divExact(u64, target_addr - this_addr, 4) catch |_| break :inner;
const literal = math.cast(u18, displacement) catch |_| break :inner;
// ldr x16, literal
mem.writeIntLittle(u32, code[0..4], aarch64.Instruction.ldr(.x16, .{
.literal = literal,
}).toU32());
// nop
mem.writeIntLittle(u32, code[4..8], aarch64.Instruction.nop().toU32());
break :outer;
}
inner: {
const new_this_addr = this_addr + @sizeOf(u32);
const displacement = math.divExact(u64, target_addr - new_this_addr, 4) catch |_| break :inner;
const literal = math.cast(u18, displacement) catch |_| break :inner;
// nop
mem.writeIntLittle(u32, code[0..4], aarch64.Instruction.nop().toU32());
// ldr x16, literal
mem.writeIntLittle(u32, code[4..8], aarch64.Instruction.ldr(.x16, .{
.literal = literal,
}).toU32());
break :outer;
}
// Use adrp followed by ldr(register).
const this_page = @intCast(i32, this_addr >> 12);
const target_page = @intCast(i32, target_addr >> 12);
const pages = @intCast(i21, target_page - this_page);
// adrp x16, pages
mem.writeIntLittle(u32, code[0..4], aarch64.Instruction.adrp(.x16, pages).toU32());
const narrowed = @truncate(u12, target_addr);
const offset = try math.divExact(u12, narrowed, 8);
// ldr x16, x16, offset
mem.writeIntLittle(u32, code[4..8], aarch64.Instruction.ldr(.x16, .{
.register = .{
.rn = .x16,
.offset = aarch64.Instruction.LoadStoreOffset.imm(offset),
},
}).toU32());
}
// br x16
mem.writeIntLittle(u32, code[8..12], aarch64.Instruction.br(.x16).toU32());
},
else => unreachable,
}