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trace.zig
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trace.zig
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const std = @import("std");
const print = std.debug.print;
const libbpf = @cImport({
@cInclude("libbpf.h");
});
const bpf = @import("bpf");
const vmlinux = @import("vmlinux");
const TRACE_RECORD = bpf.Args.TRACE_RECORD;
const is_pointer = bpf.Args.is_pointer;
const cast = bpf.Args.cast;
const process = std.process;
const kprobes = @import("build_options").kprobes;
const syscalls = @import("build_options").syscalls;
var exiting = false;
fn usage() void {
print(
\\ Usage:
\\ --timeout [seconds]
\\ --help
++ "\n", .{});
}
fn nextArg(args: [][]const u8, idx: *usize) ?[]const u8 {
if (idx.* >= args.len) return null;
defer idx.* += 1;
return args[idx.*];
}
pub fn main() !void {
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer arena.deinit();
const allocator = arena.allocator();
const args = try process.argsAlloc(allocator);
defer process.argsFree(allocator, args);
var arg_idx: usize = 1; // skip exe name
const bytes = @embedFile("@bpf_prog");
var seconds: ?usize = null;
while (nextArg(args, &arg_idx)) |arg| {
if (std.mem.eql(u8, arg, "--timeout")) {
const s = nextArg(args, &arg_idx) orelse {
usage();
return error.ARGS;
};
seconds = try std.fmt.parseUnsigned(usize, s, 0);
} else if (std.mem.eql(u8, arg, "--help")) {
usage();
return;
} else {
print("unknown parameter\n", .{});
usage();
return error.ARGS;
}
}
const obj = libbpf.bpf_object__open_mem(bytes.ptr, bytes.len, null);
if (obj == null) {
print("failed to open bpf object: {}\n", .{std.posix.errno(-1)});
return error.OPEN;
}
defer libbpf.bpf_object__close(obj);
var ret = libbpf.bpf_object__load(obj);
if (ret != 0) {
print("failed to load bpf object: {}\n", .{std.posix.errno(-1)});
return error.LOAD;
}
var links = std.ArrayList(*libbpf.bpf_link).init(allocator);
defer {
for (links.items) |link| {
_ = libbpf.bpf_link__destroy(link);
}
links.deinit();
}
var cur_prog: ?*libbpf.bpf_program = null;
while (libbpf.bpf_object__next_program(obj, cur_prog)) |prog| : (cur_prog = prog) {
try links.append(libbpf.bpf_program__attach(prog) orelse {
print("failed to attach prog {s}: {}\n", .{ libbpf.bpf_program__name(prog), std.posix.errno(-1) });
return error.ATTACH;
});
}
var ctx: Ctx = .{
.stdout = std.io.getStdOut().writer(),
};
// setup events ring buffer
const events = libbpf.bpf_object__find_map_by_name(obj, "events").?;
const ring_buf = libbpf.ring_buffer__new(libbpf.bpf_map__fd(events), on_sample, &ctx, null).?;
defer libbpf.ring_buffer__free(ring_buf);
try setup_ctrl_c();
const begin_ts = std.time.timestamp();
while (!exiting) {
ret = libbpf.ring_buffer__poll(ring_buf, 100);
if (ret < 0) {
return error.POLL;
}
if (seconds) |timeout| {
const cur_ts = std.time.timestamp();
if (cur_ts - begin_ts > timeout) break;
}
}
}
fn interrupt_handler(_: c_int) callconv(.C) void {
exiting = true;
}
fn setup_ctrl_c() !void {
const act = std.posix.Sigaction{
.handler = .{ .handler = interrupt_handler },
.mask = std.posix.empty_sigset,
.flags = 0,
};
try std.posix.sigaction(std.posix.SIG.INT, &act, null);
}
const Ctx = struct {
stdout: std.fs.File.Writer,
};
fn on_sample(_ctx: ?*anyopaque, data: ?*anyopaque, _: usize) callconv(.C) c_int {
const ctx: *Ctx = @alignCast(@ptrCast(_ctx));
const record: *TRACE_RECORD = @alignCast(@ptrCast(data.?));
// kprobes at first, then syscalls
switch (record.id) {
inline 0...kprobes.len + syscalls.len - 1 => |i| {
const for_kprobe = i < kprobes.len;
const func_name = if (for_kprobe) kprobes[i] else syscalls[i - kprobes.len];
const tracked_func = if (for_kprobe) bpf.Kprobe{ .name = func_name } else bpf.Ksyscall{ .name = func_name };
const T = tracked_func.Ctx();
const args: *T = @ptrCast(&record.regs);
const pid: u32 = @truncate(record.tpid);
ctx.stdout.print("pid: {}, {s} {s}: ", .{ pid, if (for_kprobe) "kprobe" else "syscall", func_name }) catch return -1;
if (comptime @hasDecl(T, "arg0")) {
const v = args.arg0();
ctx.stdout.print("arg0: " ++ (if (is_pointer(@TypeOf(v))) "{any}" else "{}"), .{v}) catch return -1;
}
if (comptime @hasDecl(T, "arg1")) {
const v = args.arg1();
ctx.stdout.print(", arg1: " ++ (if (is_pointer(@TypeOf(v))) "{any}" else "{}"), .{v}) catch return -1;
}
if (comptime @hasDecl(T, "arg2")) {
const v = args.arg2();
ctx.stdout.print(", arg2: " ++ (if (is_pointer(@TypeOf(v))) "{any}" else "{}"), .{v}) catch return -1;
}
if (comptime @hasDecl(T, "arg3")) {
const v = args.arg3();
ctx.stdout.print(", arg3: " ++ (if (is_pointer(@TypeOf(v))) "{any}" else "{}"), .{v}) catch return -1;
}
if (comptime @hasDecl(T, "arg4")) {
const v = args.arg4();
ctx.stdout.print("arg4: " ++ (if (is_pointer(@TypeOf(v))) "{any}" else "{}"), .{v}) catch return -1;
}
if (comptime @hasDecl(T, "ret")) {
const v = args.ret();
ctx.stdout.print(", ret: " ++ (if (is_pointer(@TypeOf(v))) "{any}" else "{}"), .{v}) catch return -1;
}
ctx.stdout.print("\n", .{}) catch return -1;
},
else => ctx.stdout.print("Unknown function id: {}\n", .{record.id}) catch return -1,
}
return 0;
}