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readelf: handle disassembling code from ELF-64 files

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This commit is contained in:
Mikael Pettersson
2025-08-13 18:00:43 +02:00
parent 1e92b66d9c
commit 6fe75207e3
1 changed files with 80 additions and 26 deletions
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106
erlang/apps/readelf/src/readelf.erl
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@@ -443,24 +443,24 @@ print_phtab(Opts, {EC, IoDev} = FP, Ehdr) ->
io:format("Program Headers:\n"),
io:format(" Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align\n"),
lists:foreach(fun print_phdr/1, PhTab),
disassemble_phtab(Opts, FP, PhTab),
disassemble_phtab(Opts, FP, PhTab, Ehdr),
io:format("\n");
{error, Reason} ->
escript_runtime:errmsg("Error reading program headers: ~s\n",
[error:format(Reason)])
end.
disassemble_phtab(#options{disassemble = false}, _FP, _PhTab) -> ok;
disassemble_phtab(_Opts, FP, PhTab) -> do_disassemble_phtab(PhTab, 0, FP).
disassemble_phtab(#options{disassemble = false}, _FP, _PhTab, _Ehdr) -> ok;
disassemble_phtab(_Opts, FP, PhTab, Ehdr) -> do_disassemble_phtab(PhTab, 0, FP, Ehdr).
do_disassemble_phtab([], _PhNdx, _FP) -> ok;
do_disassemble_phtab([Phdr | PhTab], PhNdx, FP) ->
case disassemble_phdr(Phdr, PhNdx, FP) of
ok -> do_disassemble_phtab(PhTab, PhNdx + 1, FP);
do_disassemble_phtab([], _PhNdx, _FP, _Ehdr) -> ok;
do_disassemble_phtab([Phdr | PhTab], PhNdx, FP, Ehdr) ->
case disassemble_phdr(Phdr, PhNdx, FP, Ehdr) of
ok -> do_disassemble_phtab(PhTab, PhNdx + 1, FP, Ehdr);
{error, _Reason} = Error -> Error
end.
disassemble_phdr(Phdr, PhNdx, FP) ->
disassemble_phdr(Phdr, PhNdx, FP, Ehdr) ->
case Phdr of
#elf_Phdr{ p_type = ?PT_LOAD
, p_offset = Offset
@@ -468,12 +468,44 @@ disassemble_phdr(Phdr, PhNdx, FP) ->
, p_filesz = Size
, p_flags = Flags
} when (Flags band ?PF_X) =/= 0 ->
io:format("\nDisassembly of segment nr ~.10b:\n", [PhNdx]),
disassemble_unit(Offset, Size, VAddr, FP, _Labels = []);
io:format("\nDisassembly of segment nr ~.10b:\n\n", [PhNdx]),
AvoidRegions = avoid_regions(Offset, Ehdr),
disassemble_unit(Offset, Size, VAddr, FP, _Labels = [], AvoidRegions);
#elf_Phdr{} ->
ok
end.
%% GNU ld tends to create executables with the ELF header and program and section
%% tables mapped into the main PF_X PT_LOAD segment. We need to avoid processing
%% such meta-data as if it was proper PDP-10 encoded code or data.
avoid_regions(_Offset = 0, Ehdr) ->
#elf_Ehdr{ e_phoff = PhOff
, e_shoff = ShOff
, e_ehsize = EhSize
, e_phentsize = PhEntSize
, e_phnum = PhNum
, e_shentsize = ShEntSize
, e_shnum = ShNum
} = Ehdr,
ShArea =
case ShNum of
0 -> [];
_ -> [{ShOff, ShOff + ShNum * ShEntSize - 1}]
end,
PhArea =
case PhNum of
0 -> [];
_ -> [{PhOff, PhOff + PhNum * PhEntSize - 1}]
end,
EhArea = [{0, EhSize - 1}],
EhArea ++ PhArea ++ ShArea;
avoid_regions(_Offset, _Ehdr) -> [].
%% Regions is a very short list (max 3 elements).
avoid_offset(_Offset, _Regions = []) -> false;
avoid_offset(Offset, [{Start, End} | Regions]) ->
(Offset >= Start andalso Offset =< End) orelse avoid_offset(Offset, Regions).
print_phdr(Phdr) ->
io:format(" ~-6s 0~12.8.0b 0~12.8.0b 0~12.8.0b 0x~9.16.0b 0x~9.16.0b ~-3s 0x~.16b\n",
[ p_type(Phdr)
@@ -680,37 +712,59 @@ disassemble_section(Shdr, ShNdx, FP, SymTab) ->
} ->
io:format("Disassembly of section nr ~.10b ~s:\n\n",
[ShNdx, sh_name(Shdr)]),
disassemble_unit(ShOffset, ShSize, ShAddr, FP, labels(SymTab, ShNdx));
disassemble_unit(ShOffset, ShSize, ShAddr, FP, labels(SymTab, ShNdx), []);
#elf_Shdr{} ->
ok
end.
disassemble_unit(FileOffset, Size, VAddr, FP, Labels) ->
disassemble_unit(FileOffset, Size, VAddr, FP, Labels, AvoidRegions) ->
case libelf:fseek(FP, {bof, FileOffset}) of
ok -> disassemble_insns(0, Size, VAddr, FP, Labels);
ok -> disassemble_insns(0, Size, VAddr, FP, Labels, wordsize(FP), AvoidRegions);
{error, _Reason} = Error -> Error
end.
disassemble_insns(Offset, Size, VAddr, FP, Labels) when Offset < Size ->
case read_uint36(FP) of
{ok, InsnWord} ->
RestLabels = print_labels(Labels, Offset),
io:format(" 0~12.8.0b:\t0~12.8.0b\t", [VAddr + Offset, InsnWord]),
disassemble_insn(InsnWord),
disassemble_insns(Offset + 4, Size, VAddr, FP, RestLabels);
disassemble_insns(Offset, Size, VAddr, FP, Labels, Wordsize, AvoidRegions) when Offset < Size ->
case avoid_offset(Offset, AvoidRegions) of
true ->
ok = libelf:fseek(FP, {cur, Wordsize}),
disassemble_insns(Offset + Wordsize, Size, VAddr, FP, Labels, Wordsize, AvoidRegions);
false ->
case read_uint36(FP) of
{ok, InsnWord} ->
RestLabels = print_labels(Labels, Offset),
io:format(" 0~12.8.0b:\t0~12.8.0b\t", [VAddr + Offset, InsnWord]),
disassemble_insn(InsnWord),
disassemble_insns(Offset + Wordsize, Size, VAddr, FP, RestLabels, Wordsize, AvoidRegions);
{error, _Reason} = Error -> Error
end
end;
disassemble_insns(_Offset, _Size, _VAddr, _FP, _Labels, _Wordsize, _AvoidRegions) -> ok.
wordsize({?ELFCLASS64, _}) -> 8;
wordsize(_) -> 4.
read_uint36({?ELFCLASS64, _} = FP) ->
case libelf:fread(8, FP) of
{ok, [B0, B1, B2, B3, B4, B5, B6, B7]} ->
0 = (B0 bor B2 bor B4 bor B6) band bnot 1, % assert
N0 = (B0 bsl 8) bor B1,
N1 = (B2 bsl 8) bor B3,
N2 = (B4 bsl 8) bor B5,
N3 = (B6 bsl 8) bor B7,
{ok, make_uint36(N0, N1, N2, N3)};
eof -> {error, eof};
{error, _Reason} = Error -> Error
end;
disassemble_insns(_Offset, _Size, _VAddr, _FP, _Labels) -> ok.
%% TODO: for ELF-64 read 4 nonets from 8 octets and combine
read_uint36(FP) ->
read_uint36({?ELFCLASS36, _} = FP) ->
case libelf:fread(4, FP) of
{ok, [B0, B1, B2, B3]} ->
{ok, (((((B0 bsl 9) bor B1) bsl 9) bor B2) bsl 9) bor B3};
{ok, [N0, N1, N2, N3]} -> {ok, make_uint36(N0, N1, N2, N3)};
eof -> {error, eof};
{error, _Reason} = Error -> Error
end.
make_uint36(N0, N1, N2, N3) ->
(((((N0 bsl 9) bor N1) bsl 9) bor N2) bsl 9) bor N3.
disassemble_insn(InsnWord) ->
Models = ?PDP10_KL10_271up,
High13 = InsnWord bsr (36 - 13),