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create btf sanitizer to fixup invalid btf generated from zig
Signed-off-by: Tw <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,124 @@ | ||
| const std = @import("std"); | ||
| const print = std.debug.print; | ||
| pub const c = @cImport({ | ||
| @cInclude("btf.h"); | ||
| @cInclude("libelf.h"); | ||
| }); | ||
|
|
||
| // btf_sanitizer src_obj dst_obj | ||
| pub fn main() !void { | ||
| var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator); | ||
| defer arena.deinit(); | ||
|
|
||
| const allocator = arena.allocator(); | ||
|
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| var it = std.process.args(); | ||
| _ = it.skip(); // skip process name | ||
| const src_obj_path = it.next().?; | ||
| const dst_obj_path = it.next().?; | ||
|
|
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| try std.fs.copyFileAbsolute(src_obj_path, dst_obj_path, .{}); | ||
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| const src_obj = try std.fs.openFileAbsolute(src_obj_path, .{ .mode = .read_only }); | ||
| defer src_obj.close(); | ||
| const dst_obj = try std.fs.openFileAbsolute(dst_obj_path, .{ .mode = .read_write }); | ||
| defer dst_obj.close(); | ||
|
|
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| const src_btf = c.btf__parse(src_obj_path, null) orelse { | ||
| print("failed to get source BTF: {}\n", .{std.posix.errno(-1)}); | ||
| return error.PARSE; | ||
| }; | ||
| var sz: c_uint = undefined; | ||
|
|
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| var buf = c.btf__raw_data(src_btf, &sz); | ||
| const dst_btf = c.btf__new(buf, sz) orelse { | ||
| print("create empty dest BTF failed: {}\n", .{std.posix.errno(-1)}); | ||
| return error.PARSE; | ||
| }; | ||
| defer c.btf__free(dst_btf); | ||
|
|
||
| // sanitize | ||
| _ = c.btf__find_str(dst_btf, ""); // ensure btf is in modifiable/splited state | ||
| for (0..c.btf__type_cnt(dst_btf)) |i| { | ||
| const t: *c.btf_type = @constCast(c.btf__type_by_id(dst_btf, @intCast(i))); | ||
|
|
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| if (c.btf_is_fwd(t) or c.btf_is_struct(t)) { | ||
| // replace non-alphabet with '_' | ||
| const name: [:0]u8 = @constCast(std.mem.sliceTo(c.btf__name_by_offset(dst_btf, t.name_off), 0)); | ||
| for (name) |*ch| { | ||
| if (!std.ascii.isAlphabetic(ch.*)) { | ||
| ch.* = '_'; | ||
| } | ||
| } | ||
| } else if (c.btf_is_ptr(t)) { | ||
| // null pointer type name | ||
| t.name_off = 0; | ||
| } else if (c.btf_is_func_proto(t)) { | ||
| // add function parameter's name with 'argX' | ||
| const vlen: usize = @intCast(c.BTF_INFO_VLEN(@as(c_int, @bitCast(t.info)))); | ||
| const params: [*c]c.btf_param = @ptrFromInt(@intFromPtr(t) + @sizeOf(c.btf_type)); | ||
|
|
||
| for (0..vlen) |pi| { | ||
| if (params[pi].name_off == 0) { | ||
| const name = try std.fmt.allocPrintZ(allocator, "arg{}", .{pi}); | ||
| var off = c.btf__find_str(dst_btf, name.ptr); | ||
| if (off < 0) { | ||
| off = c.btf__add_str(dst_btf, name.ptr); | ||
| if (off < 0) { | ||
| print("failed to add str\n", .{}); | ||
| return error.OOM; | ||
| } | ||
| } | ||
|
|
||
| params[pi].name_off = @intCast(off); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| buf = c.btf__raw_data(dst_btf, &sz); | ||
|
|
||
| // update BTF section in elf | ||
| const elf = c.elf_begin(dst_obj.handle, c.ELF_C_RDWR, null) orelse { | ||
| print("failed to open dst elf: {}\n", .{std.posix.errno(-1)}); | ||
| return error.PARSE; | ||
| }; | ||
| defer { | ||
| _ = c.elf_update(elf, c.ELF_C_WRITE); | ||
| _ = c.elf_end(elf); | ||
| } | ||
|
|
||
| var stridx: usize = undefined; | ||
| const ret = c.elf_getshdrstrndx(elf, &stridx); | ||
| if (ret != 0) { | ||
| print("failed to get string section idx: {}\n", .{std.posix.errno(-1)}); | ||
| return error.PARSE; | ||
| } | ||
| var scn = c.elf_nextscn(elf, null); | ||
| const btf_section_name = ".BTF"; | ||
| while (scn) |section| : (scn = c.elf_nextscn(elf, scn)) { | ||
| const shdr: *c.Elf64_Shdr = c.elf64_getshdr(section) orelse { | ||
| print("failed to get section header: {}\n", .{std.posix.errno(-1)}); | ||
| return error.PARSE; | ||
| }; | ||
| const name = c.elf_strptr(elf, stridx, shdr.sh_name) orelse { | ||
| print("failed to get section name: {}\n", .{std.posix.errno(-1)}); | ||
| return error.PARSE; | ||
| }; | ||
| if (std.mem.eql(u8, name[0..btf_section_name.len], btf_section_name)) { | ||
| var data: *c.Elf_Data = c.elf_newdata(section) orelse { | ||
| print("failed to create section data: {}\n", .{std.posix.errno(-1)}); | ||
| return error.OOM; | ||
| }; | ||
|
|
||
| data.d_type = c.ELF_T_BYTE; | ||
| data.d_version = c.EV_CURRENT; | ||
| data.d_buf = @constCast(buf); | ||
| data.d_size = sz; | ||
|
|
||
| break; | ||
| } | ||
| } else { | ||
| print("failed to find BTF section in elf\n", .{}); | ||
| return error.PARSE; | ||
| } | ||
| } |