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dwarf: fix the unwinder using the incorrect row from the FDE in certain cases

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This commit is contained in:
kcbanner 2023-07-18 01:21:45 -04:00
parent 1a2bb70956
commit d99b40d38b
2 changed files with 19 additions and 11 deletions
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18
lib/std/dwarf.zig
View File

@ -1740,8 +1740,20 @@ pub const DwarfInfo = struct {
context.reg_context.eh_frame = cie.version != 4;
context.reg_context.is_macho = di.is_macho;
_ = try context.vm.runToNative(context.allocator, context.pc, cie, fde);
const row = &context.vm.current_row;
if (comptime builtin.target.isDarwin()) {
std.debug.print(" state before:\n", .{});
std.debug.print(" cfa {?x}:\n", .{context.cfa});
for (context.thread_context.mcontext.ss.regs, 0..) |reg, i| {
std.debug.print(" {}:0x{x}\n", .{i, reg});
}
std.debug.print(" fp:0x{x}\n", .{context.thread_context.mcontext.ss.fp});
std.debug.print(" lr:0x{x}\n", .{context.thread_context.mcontext.ss.lr});
std.debug.print(" sp:0x{x}\n", .{context.thread_context.mcontext.ss.sp});
std.debug.print(" pc:0x{x}\n", .{context.thread_context.mcontext.ss.pc});
}
const row = try context.vm.runToNative(context.allocator, context.pc, cie, fde);
std.debug.print(" ran to 0x{x}\n", .{row.offset + fde.pc_begin});
context.cfa = switch (row.cfa.rule) {
.val_offset => |offset| blk: {
@ -1785,7 +1797,7 @@ pub const DwarfInfo = struct {
var update_tail: ?*RegisterUpdate = null;
var has_next_ip = false;
for (context.vm.rowColumns(row.*)) |column| {
for (context.vm.rowColumns(row)) |column| {
if (column.register) |register| {
if (register == cie.return_address_register) {
has_next_ip = column.rule != .undefined;

12
lib/std/dwarf/call_frame.zig
View File

@ -395,9 +395,7 @@ pub const VirtualMachine = struct {
}
/// Runs the CIE instructions, then the FDE instructions. Execution halts
/// once the row that corresponds to `pc` is known (and set as `current_row`).
///
/// The state of the row prior to the last execution step is returned.
/// once the row that corresponds to `pc` is known, and the row is returned.
pub fn runTo(
self: *VirtualMachine,
allocator: std.mem.Allocator,
@ -419,17 +417,15 @@ pub const VirtualMachine = struct {
&fde_stream,
};
outer: for (&streams, 0..) |stream, i| {
for (&streams, 0..) |stream, i| {
while (stream.pos < stream.buffer.len) {
const instruction = try dwarf.call_frame.Instruction.read(stream, addr_size_bytes, endian);
prev_row = try self.step(allocator, cie, i == 0, instruction);
if (pc < fde.pc_begin + self.current_row.offset) {
break :outer;
}
if (pc < fde.pc_begin + self.current_row.offset) return prev_row;
}
}
return prev_row;
return self.current_row;
}
pub fn runToNative(