Commit 8e6a62ba10326e48eaefd40f89c9452d92f39c9d | zig

author	Casey Banner <kcbanner@gmail.com> 2023-07-19 02:06:17-04:00
committer	Casey Banner <kcbanner@gmail.com> 2023-07-20 22:58:16-04:00
log	8e6a62ba10326e48eaefd40f89c9452d92f39c9d
tree	9d0baca4c2209676996c3ce0a0530541f989ae51
parent	6d87bb370a6d9075b2b6628f5f8c09171f25e4e9

test: disable omit_frame_pointer unwinding tests on aarch64-macos

dwarf: handle signal frame CIE flag

6 files changed, 119 insertions(+), 110 deletions(-)

lib
- std
  - debug.zig
  - dwarf.zig
test
- standalone
  - stack_iterator
    build.zig
    shared_lib_unwind.zig
    unwind.zig
    zig_unwind.zig

lib/std/debug.zig+1-1

...	...	@@ -882,7 +882,7 @@ fn printUnknownSource(debug_info: *DebugInfo, out_stream: anytype, address: usiz
882	882	pub fn printUnwindError(debug_info: *DebugInfo, out_stream: anytype, address: usize, err: UnwindError, tty_config: io.tty.Config) !void {
883	883	const module_name = debug_info.getModuleNameForAddress(address) orelse "???";
884	884	try tty_config.setColor(out_stream, .dim);
885		try out_stream.print("Unwind information for `{s}:{}` was not available ({}), trace may be incomplete\n\n", .{ module_name, address, err });
	885	try out_stream.print("Unwind information for `{s}:0x{x}` was not available ({}), trace may be incomplete\n\n", .{ module_name, address, err });
886	886	try tty_config.setColor(out_stream, .reset);
887	887	}
888	888

lib/std/dwarf.zig+9-6

...	...	@@ -1659,8 +1659,6 @@ pub const DwarfInfo = struct {
1659	1659	if (!comptime abi.isSupportedArch(builtin.target.cpu.arch)) return error.UnsupportedCpuArchitecture;
1660	1660	if (context.pc == 0) return 0;
1661	1661
1662		// TODO: Handle unwinding from a signal frame (ie. use_prev_instr in libunwind)
1663
1664	1662	// Find the FDE and CIE
1665	1663	var cie: CommonInformationEntry = undefined;
1666	1664	var fde: FrameDescriptionEntry = undefined;
...	...	@@ -1828,11 +1826,16 @@ pub const DwarfInfo = struct {
1828	1826
1829	1827	(try abi.regValueNative(usize, context.thread_context, abi.ipRegNum(), context.reg_context)).* = context.pc;
1830	1828
1831		// The call instruction will have pushed the address of the instruction that follows the call as the return address
1832		// However, this return address may be past the end of the function if the caller was `noreturn`. By subtracting one,
1833		// then `context.pc` will always point to an instruction within the FDE for the previous function.
	1829	// The call instruction will have pushed the address of the instruction that follows the call as the return address.
	1830	// This next instruction may be past the end of the function if the caller was `noreturn` (ie. the last instruction in
	1831	// the function was the call). If we were to look up an FDE entry using the return address directly, it could end up
	1832	// either not finding an FDE at all, or using the next FDE in the program, producing incorrect results. To prevent this,
	1833	// we subtract one so that the next lookup is guaranteed to land inside the
	1834	//
	1835	// The exception to this rule is signal frames, where we return execution would be returned to the instruction
	1836	// that triggered the handler.
1834	1837	const return_address = context.pc;
1835		if (context.pc > 0) context.pc -= 1;
	1838	if (context.pc > 0 and !cie.isSignalFrame()) context.pc -= 1;
1836	1839
1837	1840	return return_address;
1838	1841	}

test/standalone/stack_iterator/build.zig+6-7

...	...	@@ -7,7 +7,7 @@ pub fn build(b: *std.Build) void {
7	7	const target = b.standardTargetOptions(.{});
8	8	const optimize = b.standardOptimizeOption(.{});
9	9
10		// Unwinding pure zig code, with a frame pointer
	10	// Unwinding with a frame pointer
11	11	//
12	12	// getcontext version: zig std
13	13	//
...	...	@@ -18,8 +18,8 @@ pub fn build(b: *std.Build) void {
18	18	// - aarch64: FRAME, DWARF
19	19	{
20	20	const exe = b.addExecutable(.{
21		.name = "zig_unwind_fp",
22		.root_source_file = .{ .path = "zig_unwind.zig" },
	21	.name = "unwind_fp",
	22	.root_source_file = .{ .path = "unwind.zig" },
23	23	.target = target,
24	24	.optimize = optimize,
25	25	});
...	...	@@ -31,7 +31,7 @@ pub fn build(b: *std.Build) void {
31	31	test_step.dependOn(&run_cmd.step);
32	32	}
33	33
34		// Unwinding pure zig code, without a frame pointer.
	34	// Unwinding without a frame pointer
35	35	//
36	36	// getcontext version: zig std
37	37	//
...	...	@@ -42,13 +42,12 @@ pub fn build(b: *std.Build) void {
42	42	// - aarch64: FRAMELESS, DWARF
43	43	{
44	44	const exe = b.addExecutable(.{
45		.name = "zig_unwind_nofp",
46		.root_source_file = .{ .path = "zig_unwind.zig" },
	45	.name = "unwind_nofp",
	46	.root_source_file = .{ .path = "unwind.zig" },
47	47	.target = target,
48	48	.optimize = optimize,
49	49	});
50	50
51		if (target.isDarwin()) exe.unwind_tables = true;
52	51	exe.omit_frame_pointer = true;
53	52	exe.unwind_tables = true;
54	53

test/standalone/stack_iterator/shared_lib_unwind.zig+4

...	...	@@ -1,4 +1,5 @@
1	1	const std = @import("std");
	2	const builtin = @import("builtin");
2	3	const debug = std.debug;
3	4	const testing = std.testing;
4	5
...	...	@@ -34,6 +35,9 @@ extern fn frame0(
34	35	) void;
35	36
36	37	pub fn main() !void {
	38	// Disabled until the DWARF unwinder bugs on .aarch64 are solved
	39	if (builtin.omit_frame_pointer and comptime builtin.target.isDarwin() and builtin.cpu.arch == .aarch64) return;
	40
37	41	if (!std.debug.have_ucontext or !std.debug.have_getcontext) return;
38	42
39	43	var expected: [5]usize = undefined;

test/standalone/stack_iterator/unwind.zig created+99

...	...	@@ -0,0 +1,99 @@
	1	const std = @import("std");
	2	const builtin = @import("builtin");
	3	const debug = std.debug;
	4	const testing = std.testing;
	5
	6	noinline fn frame3(expected: [4]usize, unwound: [4]usize) void {
	7	expected[0] = @returnAddress();
	8
	9	var context: debug.ThreadContext = undefined;
	10	testing.expect(debug.getContext(&context)) catch @panic("failed to getContext");
	11
	12	var debug_info = debug.getSelfDebugInfo() catch @panic("failed to openSelfDebugInfo");
	13	var it = debug.StackIterator.initWithContext(expected[0], debug_info, &context) catch @panic("failed to initWithContext");
	14	defer it.deinit();
	15
	16	for (unwound) \|*addr\| {
	17	if (it.next()) \|return_address\| addr.* = return_address;
	18	}
	19	}
	20
	21	noinline fn frame2(expected: [4]usize, unwound: [4]usize) void {
	22	// Excercise different __unwind_info / DWARF CFI encodings by forcing some registers to be restored
	23	if (builtin.target.ofmt != .c) {
	24	switch (builtin.cpu.arch) {
	25	.x86 => {
	26	if (builtin.omit_frame_pointer) {
	27	asm volatile (
	28	\\movl $3, %%ebx
	29	\\movl $1, %%ecx
	30	\\movl $2, %%edx
	31	\\movl $7, %%edi
	32	\\movl $6, %%esi
	33	\\movl $5, %%ebp
	34	::: "ebx", "ecx", "edx", "edi", "esi", "ebp");
	35	} else {
	36	asm volatile (
	37	\\movl $3, %%ebx
	38	\\movl $1, %%ecx
	39	\\movl $2, %%edx
	40	\\movl $7, %%edi
	41	\\movl $6, %%esi
	42	::: "ebx", "ecx", "edx", "edi", "esi");
	43	}
	44	},
	45	.x86_64 => {
	46	if (builtin.omit_frame_pointer) {
	47	asm volatile (
	48	\\movq $3, %%rbx
	49	\\movq $12, %%r12
	50	\\movq $13, %%r13
	51	\\movq $14, %%r14
	52	\\movq $15, %%r15
	53	\\movq $6, %%rbp
	54	::: "rbx", "r12", "r13", "r14", "r15", "rbp");
	55	} else {
	56	asm volatile (
	57	\\movq $3, %%rbx
	58	\\movq $12, %%r12
	59	\\movq $13, %%r13
	60	\\movq $14, %%r14
	61	\\movq $15, %%r15
	62	::: "rbx", "r12", "r13", "r14", "r15");
	63	}
	64	},
	65	else => {},
	66	}
	67	}
	68
	69	expected[1] = @returnAddress();
	70	frame3(expected, unwound);
	71	}
	72
	73	noinline fn frame1(expected: [4]usize, unwound: [4]usize) void {
	74	expected[2] = @returnAddress();
	75
	76	// Use a stack frame that is too big to encode in __unwind_info's stack-immediate encoding
	77	// to exercise the stack-indirect encoding path
	78	var pad: [std.math.maxInt(u8) * @sizeOf(usize) + 1]u8 = undefined;
	79	_ = pad;
	80
	81	frame2(expected, unwound);
	82	}
	83
	84	noinline fn frame0(expected: [4]usize, unwound: [4]usize) void {
	85	expected[3] = @returnAddress();
	86	frame1(expected, unwound);
	87	}
	88
	89	pub fn main() !void {
	90	// Disabled until the DWARF unwinder bugs on .aarch64 are solved
	91	if (builtin.omit_frame_pointer and comptime builtin.target.isDarwin() and builtin.cpu.arch == .aarch64) return;
	92
	93	if (!std.debug.have_ucontext or !std.debug.have_getcontext) return;
	94
	95	var expected: [4]usize = undefined;
	96	var unwound: [4]usize = undefined;
	97	frame0(&expected, &unwound);
	98	try testing.expectEqual(expected, unwound);
	99	}

test/standalone/stack_iterator/zig_unwind.zig deleted-96

...	...	@@ -1,96 +0,0 @@
1		const std = @import("std");
2		const builtin = @import("builtin");
3		const debug = std.debug;
4		const testing = std.testing;
5
6		noinline fn frame3(expected: [4]usize, unwound: [4]usize) void {
7		expected[0] = @returnAddress();
8
9		var context: debug.ThreadContext = undefined;
10		testing.expect(debug.getContext(&context)) catch @panic("failed to getContext");
11
12		var debug_info = debug.getSelfDebugInfo() catch @panic("failed to openSelfDebugInfo");
13		var it = debug.StackIterator.initWithContext(expected[0], debug_info, &context) catch @panic("failed to initWithContext");
14		defer it.deinit();
15
16		for (unwound) \|*addr\| {
17		if (it.next()) \|return_address\| addr.* = return_address;
18		}
19		}
20
21		noinline fn frame2(expected: [4]usize, unwound: [4]usize) void {
22		// Excercise different __unwind_info / DWARF CFI encodings by forcing some registers to be restored
23		if (builtin.target.ofmt != .c) {
24		switch (builtin.cpu.arch) {
25		.x86 => {
26		if (builtin.omit_frame_pointer) {
27		asm volatile (
28		\\movl $3, %%ebx
29		\\movl $1, %%ecx
30		\\movl $2, %%edx
31		\\movl $7, %%edi
32		\\movl $6, %%esi
33		\\movl $5, %%ebp
34		::: "ebx", "ecx", "edx", "edi", "esi", "ebp");
35		} else {
36		asm volatile (
37		\\movl $3, %%ebx
38		\\movl $1, %%ecx
39		\\movl $2, %%edx
40		\\movl $7, %%edi
41		\\movl $6, %%esi
42		::: "ebx", "ecx", "edx", "edi", "esi");
43		}
44		},
45		.x86_64 => {
46		if (builtin.omit_frame_pointer) {
47		asm volatile (
48		\\movq $3, %%rbx
49		\\movq $12, %%r12
50		\\movq $13, %%r13
51		\\movq $14, %%r14
52		\\movq $15, %%r15
53		\\movq $6, %%rbp
54		::: "rbx", "r12", "r13", "r14", "r15", "rbp");
55		} else {
56		asm volatile (
57		\\movq $3, %%rbx
58		\\movq $12, %%r12
59		\\movq $13, %%r13
60		\\movq $14, %%r14
61		\\movq $15, %%r15
62		::: "rbx", "r12", "r13", "r14", "r15");
63		}
64		},
65		else => {},
66		}
67		}
68
69		expected[1] = @returnAddress();
70		frame3(expected, unwound);
71		}
72
73		noinline fn frame1(expected: [4]usize, unwound: [4]usize) void {
74		expected[2] = @returnAddress();
75
76		// Use a stack frame that is too big to encode in __unwind_info's stack-immediate encoding
77		// to exercise the stack-indirect encoding path
78		var pad: [std.math.maxInt(u8) * @sizeOf(usize) + 1]u8 = undefined;
79		_ = pad;
80
81		frame2(expected, unwound);
82		}
83
84		noinline fn frame0(expected: [4]usize, unwound: [4]usize) void {
85		expected[3] = @returnAddress();
86		frame1(expected, unwound);
87		}
88
89		pub fn main() !void {
90		if (!std.debug.have_ucontext or !std.debug.have_getcontext) return;
91
92		var expected: [4]usize = undefined;
93		var unwound: [4]usize = undefined;
94		frame0(&expected, &unwound);
95		try testing.expectEqual(expected, unwound);
96		}