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dwarf: add abi.stripInstructionPtrAuthCode

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This commit is contained in:
kcbanner 2023-07-14 02:50:43 -04:00
parent ec96095efd
commit ba813d00f5
3 changed files with 34 additions and 6 deletions
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10
lib/std/dwarf.zig
View File

@ -1758,12 +1758,16 @@ pub const DwarfInfo = struct {
}
if (has_next_ip) {
context.pc = mem.readIntSliceNative(usize, try abi.regBytes(context.thread_context, cie.return_address_register, context.reg_context));
context.pc = abi.stripInstructionPtrAuthCode(mem.readIntSliceNative(usize, try abi.regBytes(
context.thread_context,
cie.return_address_register,
context.reg_context,
)));
} else {
context.pc = 0;
}
mem.writeIntSliceNative(usize, try abi.regBytes(context.thread_context, abi.spRegNum(context.reg_context), context.reg_context), context.cfa.?);
(try abi.regValueNative(usize, context.thread_context, abi.spRegNum(context.reg_context), context.reg_context)).* = context.cfa.?;
// The call instruction will have pushed the address of the instruction that follows the call as the return address
// However, this return address may be past the end of the function if the caller was `noreturn`. By subtracting one,
@ -1786,7 +1790,7 @@ pub const UnwindContext = struct {
stack_machine: expressions.StackMachine(.{ .call_frame_context = true }) = .{},
pub fn init(allocator: mem.Allocator, thread_context: *const debug.ThreadContext, isValidMemory: *const fn (address: usize) bool) !UnwindContext {
const pc = mem.readIntSliceNative(usize, try abi.regBytes(thread_context, abi.ipRegNum(), null));
const pc = abi.stripInstructionPtrAuthCode((try abi.regValueNative(usize, thread_context, abi.ipRegNum(), null)).*);
const context_copy = try allocator.create(debug.ThreadContext);
debug.copyContext(thread_context, context_copy);

28
lib/std/dwarf/abi.zig
View File

@ -45,6 +45,27 @@ pub fn spRegNum(reg_context: RegisterContext) u8 {
};
}
/// Some platforms use pointer authentication - the upper bits of instruction pointers contain a signature.
/// This function clears these signature bits to make the pointer usable.
pub inline fn stripInstructionPtrAuthCode(ptr: usize) usize {
if (builtin.cpu.arch == .aarch64) {
// `hint 0x07` maps to `xpaclri` (or `nop` if the hardware doesn't support it)
// The save / restore is because `xpaclri` operates on x30 (LR)
return asm (
\\mov x16, x30
\\mov x30, x15
\\hint 0x07
\\mov x15, x30
\\mov x30, x16
: [ret] "={x15}" (-> usize),
: [ptr] "{x15}" (ptr),
: "x16"
);
}
return ptr;
}
pub const RegisterContext = struct {
eh_frame: bool,
is_macho: bool,
@ -160,7 +181,6 @@ pub fn regBytes(
if (!std.debug.have_ucontext) return error.ThreadContextNotSupported;
const ucontext_ptr = thread_context_ptr;
var m = &ucontext_ptr.mcontext;
return switch (builtin.cpu.arch) {
.x86 => switch (builtin.os.tag) {
.linux, .netbsd, .solaris => switch (reg_number) {
@ -216,7 +236,7 @@ pub fn regBytes(
14 => mem.asBytes(&ucontext_ptr.mcontext.gregs[os.REG.R14]),
15 => mem.asBytes(&ucontext_ptr.mcontext.gregs[os.REG.R15]),
16 => mem.asBytes(&ucontext_ptr.mcontext.gregs[os.REG.RIP]),
17...32 => |i| mem.asBytes(&m.fpregs.xmm[i - 17]),
17...32 => |i| mem.asBytes(&ucontext_ptr.mcontext.fpregs.xmm[i - 17]),
else => error.InvalidRegister,
},
.freebsd => switch (reg_number) {
@ -313,6 +333,10 @@ pub fn regBytes(
30 => mem.asBytes(&ucontext_ptr.mcontext.ss.lr),
31 => mem.asBytes(&ucontext_ptr.mcontext.ss.sp),
32 => mem.asBytes(&ucontext_ptr.mcontext.ss.pc),
// TODO: Find storage for this state
//34 => mem.asBytes(&ucontext_ptr.ra_sign_state),
// V0-V31
64...95 => mem.asBytes(&ucontext_ptr.mcontext.ns.q[reg_number - 64]),
else => error.InvalidRegister,

2
lib/std/macho.zig
View File

@ -2459,7 +2459,7 @@ pub fn unwindFrame(context: *dwarf.UnwindContext, unwind_info: []const u8, modul
else => return error.UnimplementedArch,
};
context.pc = new_ip;
context.pc = dwarf.abi.stripInstructionPtrAuthCode(new_ip);
if (context.pc > 0) context.pc -= 1;
return new_ip;
}