mirror of
https://github.com/mikpe/pdp10-tools.git
synced 2026-03-10 12:48:31 +00:00
ld_phase1: cleanups
This commit is contained in:
Mikael Pettersson
@@ -1,7 +1,7 @@
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%%% -*- erlang-indent-level: 2 -*-
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%%%
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%%% linking phase 1 for pdp10-elf ld
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%%% Copyright (C) 2020 Mikael Pettersson
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%%% Copyright (C) 2020-2023 Mikael Pettersson
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%%%
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%%% This file is part of pdp10-tools.
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%%%
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@@ -17,6 +17,15 @@
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%%%
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%%% You should have received a copy of the GNU General Public License
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%%% along with pdp10-tools. If not, see <http://www.gnu.org/licenses/>.
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%%%
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%%%=============================================================================
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%%%
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%%% Citing The System V Application Binary Interface, Ch. 4 Sections:
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%%% "In the first phase, input sections that match in name, type and attribute
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%%% flags should be concatenated into single sections. The concatenation order
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%%% should satisfy the requirements of any known input section attributes (e.g,
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%%% SHF_MERGE and SHF_LINK_ORDER). When not otherwise constrained, sections
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%%% should be emitted in input order."
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-module(ld_phase1).
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@@ -25,41 +34,44 @@
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-include("ld_internal.hrl").
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-record(section_key,
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{ sh_name :: string()
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, sh_type :: non_neg_integer()
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, sh_flags :: non_neg_integer()
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}).
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-record(output, % accumulates fragments for a given section
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{ nr :: non_neg_integer() % determines output order
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, shdr :: #elf36_Shdr{}
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, frags :: [#sectfrag{}]
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}).
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-type outputsmap() :: #{#section_key{} => #output{}}.
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-type relocsmap() :: #{non_neg_integer() => #elf36_Shdr{}}.
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%% Linking Phase 1 =============================================================
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%%
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%% Citing The System V Application Binary Interface, Ch. 4 Sections:
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%% "In the first phase, input sections that match in name, type and attribute
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%% flags should be concatenated into single sections. The concatenation order
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%% should satisfy the requirements of any known input section attributes (e.g,
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%% SHF_MERGE and SHF_LINK_ORDER). When not otherwise constrained, sections
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%% should be emitted in input order."
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-spec phase1([#input{}]) -> [#section{}].
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phase1(Inputs) ->
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phase1(Inputs, _OutputMap = maps:new()).
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OutputsMap = lists:foldl(fun phase1/2, _OutputsMap = maps:new(), Inputs),
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UnsortedOutputs = maps:values(OutputsMap),
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SortedOutputs = lists:keysort(#output.nr, UnsortedOutputs),
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lists:map(fun output_to_section/1, SortedOutputs).
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phase1([Input | Inputs], OutputsMap) ->
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output_to_section(#output{shdr = Shdr, frags = Frags}) ->
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#section{shdr = Shdr, frags = lists:reverse(Frags)}.
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-spec phase1(#input{}, outputsmap()) -> outputsmap().
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phase1(Input, OutputsMap0) ->
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#input{file = File, shtab = ShTab, stshndx = StShNdx} = Input,
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NewOutputsMap = phase1(File, ShTab, StShNdx, OutputsMap),
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phase1(Inputs, NewOutputsMap);
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phase1([], OutputsMap) ->
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Sections1 = maps:values(OutputsMap),
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Sections2 = lists:map(fun({Nr, Shdr, Frags}) ->
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{Nr, #section{shdr = Shdr, frags = lists:reverse(Frags)}}
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end, Sections1),
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Sections3 = lists:keysort(1, Sections2),
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lists:map(fun({_Nr, Section}) -> Section end, Sections3).
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phase1(File, ShTab, StShNdx, OutputsMap) ->
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RelocsMap = relocs_map(ShTab, StShNdx),
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phase1(ShTab, _ShNdx = 0, File, RelocsMap, OutputsMap).
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phase1([], _ShNdx, _File, _RelocsMap, OutputsMap) ->
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OutputsMap;
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phase1([Shdr | ShTab], ShNdx, File, RelocsMap, OutputsMap) ->
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NewOutputsMap =
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maybe_output_section(Shdr, ShNdx, File, RelocsMap, OutputsMap),
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phase1(ShTab, ShNdx + 1, File, RelocsMap, NewOutputsMap).
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{_NewShNdx, NewOutputsMap} =
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lists:foldl(
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fun(Shdr, {ShNdx, OutputsMap}) ->
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{ShNdx + 1, maybe_output_section(Shdr, ShNdx, File, RelocsMap, OutputsMap)}
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end, {_ShNdx = 0, OutputsMap0}, ShTab),
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NewOutputsMap.
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maybe_output_section(Shdr, ShNdx, File, RelocsMap, OutputsMap) ->
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case should_output_section(Shdr) of
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@@ -67,71 +79,9 @@ maybe_output_section(Shdr, ShNdx, File, RelocsMap, OutputsMap) ->
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false -> OutputsMap
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end.
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output_section(Shdr, ShNdx, File, RelocsMap, OutputsMap) ->
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SectionKey = section_key(Shdr),
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Output = output_get(SectionKey, OutputsMap, Shdr),
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Relocs = maps:get(ShNdx, RelocsMap, false),
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NewOutput = output_append(Output, File, Shdr, ShNdx, Relocs),
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maps:put(SectionKey, NewOutput, OutputsMap).
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output_get(SectionKey, OutputsMap, Shdr) ->
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case maps:get(SectionKey, OutputsMap, false) of
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{_Nr, _Shdr, _Frags} = Output -> Output;
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false ->
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OutputShdr = Shdr#elf36_Shdr{ sh_addr = 0
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, sh_offset = 0
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, sh_size = 0
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, sh_link = 0
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, sh_info = 0
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, sh_addralign = 0
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},
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{_Nr = maps:size(OutputsMap), OutputShdr, _Frags = []}
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end.
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output_append({Nr, OutputShdr, Frags}, File, Shdr, ShNdx, Relocs) ->
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OutputAlignment = section_alignment(OutputShdr),
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FragAlignment = section_alignment(Shdr),
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NewAlignment = max(OutputAlignment, FragAlignment),
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OutputSize = section_size(OutputShdr),
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FragSize = section_size(Shdr),
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FragOffset = align(OutputSize, FragAlignment),
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NewSize = FragOffset + FragSize,
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NewOutputShdr = OutputShdr#elf36_Shdr{ sh_size = NewSize
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, sh_addralign = NewAlignment
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},
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Frag = #sectfrag{file = File, shdr = Shdr, shndx = ShNdx, relocs = Relocs, offset = FragOffset},
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{Nr, NewOutputShdr, [Frag | Frags]}.
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section_alignment(Shdr) ->
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case Shdr#elf36_Shdr.sh_addralign of
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0 -> 1;
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Alignment -> Alignment
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end.
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section_size(Shdr) ->
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Shdr#elf36_Shdr.sh_size.
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align(Offset, Alignment) ->
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(Offset + Alignment - 1) band bnot (Alignment - 1).
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relocs_map(ShTab, StShNdx) ->
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lists:foldl(fun(Shdr, RelocsMap) -> relocs_map(Shdr, RelocsMap, StShNdx) end,
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maps:new(), ShTab).
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relocs_map(Shdr, RelocsMap, StShNdx) -> % FIXME: ok | error
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case Shdr of
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#elf36_Shdr{sh_type = ?SHT_RELA, sh_link = Link, sh_info = Info} ->
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Link = StShNdx, % assert
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maps:put(Info, Shdr, RelocsMap);
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#elf36_Shdr{} -> RelocsMap
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end.
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should_output_section(Shdr) ->
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#elf36_Shdr{sh_type = Type, sh_flags = Flags} = Shdr,
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case should_output_type(Type) of
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true -> should_output_flags(Flags);
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false -> false
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end.
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should_output_type(Type) andalso should_output_flags(Flags).
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should_output_type(Type) ->
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case Type of
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@@ -153,6 +103,80 @@ should_output_flags(Flags) ->
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?SHF_STRINGS bor
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?SHF_TLS)) =:= 0.
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%% Append a section to the outputs accumulator =================================
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output_section(Shdr, ShNdx, File, RelocsMap, OutputsMap) ->
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SectionKey = section_key(Shdr),
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Output = output_get(SectionKey, OutputsMap, Shdr),
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Relocs = relocs_get(ShNdx, RelocsMap),
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NewOutput = output_append(Output, File, Shdr, ShNdx, Relocs),
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maps:put(SectionKey, NewOutput, OutputsMap).
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output_get(SectionKey, OutputsMap, Shdr) ->
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case maps:get(SectionKey, OutputsMap, false) of
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false ->
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OutputShdr = Shdr#elf36_Shdr{ sh_addr = 0
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, sh_offset = 0
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, sh_size = 0
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, sh_link = 0
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, sh_info = 0
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, sh_addralign = 0
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},
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#output{nr = maps:size(OutputsMap), shdr = OutputShdr, frags = []};
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Output -> Output
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end.
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output_append(Output, File, Shdr, ShNdx, Relocs) ->
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#output{shdr = OutputShdr, frags = Frags} = Output,
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OutputAlignment = section_alignment(OutputShdr),
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FragAlignment = section_alignment(Shdr),
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NewAlignment = max(OutputAlignment, FragAlignment),
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OutputSize = section_size(OutputShdr),
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FragSize = section_size(Shdr),
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FragOffset = align(OutputSize, FragAlignment),
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NewSize = FragOffset + FragSize,
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NewOutputShdr = OutputShdr#elf36_Shdr{ sh_size = NewSize
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, sh_addralign = NewAlignment
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},
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Frag = #sectfrag{file = File, shdr = Shdr, shndx = ShNdx, relocs = Relocs, offset = FragOffset},
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Output#output{shdr = NewOutputShdr, frags = [Frag | Frags]}.
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section_alignment(Shdr) ->
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case Shdr#elf36_Shdr.sh_addralign of
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0 -> 1;
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Alignment -> Alignment
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end.
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section_size(Shdr) ->
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Shdr#elf36_Shdr.sh_size.
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align(Offset, Alignment) ->
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(Offset + Alignment - 1) band bnot (Alignment - 1).
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section_key(Shdr) ->
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#elf36_Shdr{sh_name = Name, sh_type = Type, sh_flags = Flags} = Shdr,
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{Name, Type, Flags}.
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#section_key{sh_name = Name, sh_type = Type, sh_flags = Flags}.
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%% Relocs Map ==================================================================
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%%
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%% The Relocs Map is a mapping from a section's section header index to the section
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%% header for the SHT_RELA which applies to that section, if any.
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-spec relocs_map([#elf36_Shdr{}], non_neg_integer()) -> relocsmap().
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relocs_map(ShTab, StShNdx) ->
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lists:foldl(
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fun(Shdr, RelocsMap) ->
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relocs_map(Shdr, RelocsMap, StShNdx)
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end, maps:new(), ShTab).
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relocs_map(Shdr, RelocsMap, StShNdx) -> % FIXME: ok | error
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case Shdr of
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#elf36_Shdr{sh_type = ?SHT_RELA, sh_link = Link, sh_info = Info} ->
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Link = StShNdx, % assert
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maps:put(Info, Shdr, RelocsMap);
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#elf36_Shdr{} -> RelocsMap
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end.
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-spec relocs_get(non_neg_integer(), relocsmap()) -> #elf36_Shdr{} | false.
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relocs_get(ShNdx, RelocsMap) ->
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maps:get(ShNdx, RelocsMap, false).
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