mirror of
https://github.com/mikpe/pdp10-tools.git
synced 2026-03-10 04:44:31 +00:00
ld_phase2: 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 2 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 +17,34 @@
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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 second phase, sections should be assigned to segments or other units
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%%% based on their attribute flags. Sections of each particular unrecognized type
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%%% should be assigned to the same unit unless prevented by incompatible flags,
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%%% and within a unit, sections of the same unrecognized type should be placed
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%%% together if possible."
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%%%
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%%% The output consists of the following segments, each containing the indicated
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%%% sections in that order:
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%%%
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%%% * Text Segment (PT_LOAD, PF_R+PF_X)
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%%% - .text*
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%%% - other SHT_PROGBITS, SHF_ALLOC+SHF_EXECINSTR sections
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%%%
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%%% * Rodata Segment (PT_LOAD, PF_R)
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%%% - .rodata*
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%%% - other SHT_PROGBITS, SHF_ALLOC sections
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%%%
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%%% * Data Segment (PT_LOAD, PF_R+PR_W)
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%%% - .data*
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%%% - other SHT_PROGBITS, SHF_ALLOC+SHF_WRITE sections
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%%%
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%%% * BSS Segment (PT_LOAD, PF_R+PF_W)
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%%% - .bss*
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%%% - other SHT_NOBITS, SHF_ALLOC+SHF_WRITE sections
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-module(ld_phase2).
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@@ -25,82 +53,55 @@
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-include("ld_internal.hrl").
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%% Phase 2 =====================================================================
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%%
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%% Citing The System V Application Binary Interface, Ch. 4 Sections:
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%% "In the second phase, sections should be assigned to segments or other units
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%% based on their attribute flags. Sections of each particular unrecognized type
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%% should be assigned to the same unit unless prevented by incompatible flags,
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%% and within a unit, sections of the same unrecognized type should be placed
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%% together if possible."
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%%
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%% The output consists of the following segments, each containing the indicated
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%% sections in that order:
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%%
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%% * Text Segment (PT_LOAD, PF_R+PF_X)
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%% - .text*
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%% - other SHT_PROGBITS, SHF_ALLOC+SHF_EXECINSTR sections
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%%
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%% * Rodata Segment (PT_LOAD, PF_R)
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%% - .rodata*
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%% - other SHT_PROGBITS, SHF_ALLOC sections
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%%
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%% * Data Segment (PT_LOAD, PF_R+PR_W)
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%% - .data*
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%% - other SHT_PROGBITS, SHF_ALLOC+SHF_WRITE sections
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%%
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%% * BSS Segment (PT_LOAD, PF_R+PF_W)
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%% - .bss*
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%% - other SHT_NOBITS, SHF_ALLOC+SHF_WRITE sections
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-record(pre_segment,
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{ p_flags :: non_neg_integer()
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, sections :: [#section{}]
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}).
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-record(pre_segments,
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{ text :: #pre_segment{}
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, rodata :: #pre_segment{}
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, data :: #pre_segment{}
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, bss :: #pre_segment{}
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}).
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%% Linking Phase 2 =============================================================
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-spec phase2([#section{}]) -> [#segment{}].
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phase2(Sections) ->
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segments_to_list(
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lists:foldl(fun segment_add_section/2, segments_new(), Sections)).
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%% Segment indices in segments tuple.
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-define(SEG_TEXT, 1).
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-define(SEG_RODATA, 2).
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-define(SEG_DATA, 3).
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-define(SEG_BSS, 4).
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-define(SEG__MAX, ?SEG_BSS).
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lists:foldl(fun segments_add_section/2, segments_new(), Sections)).
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segments_new() ->
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list_to_tuple([segment_new(Index) || Index <- lists:seq(1, ?SEG__MAX)]).
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#pre_segments
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{ text = #pre_segment{p_flags = ?PF_R bor ?PF_X, sections = []}
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, rodata = #pre_segment{p_flags = ?PF_R, sections = []}
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, data = #pre_segment{p_flags = ?PF_R bor ?PF_W, sections = []}
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, bss = #pre_segment{p_flags = ?PF_R bor ?PF_W, sections = []}
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}.
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segment_new(Index) ->
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{segment_props(Index), []}.
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segments_add_section(Section, Segments) ->
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Index = section_segment_index(Section),
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#pre_segment{sections = Sections} = PreSegment = element(Index, Segments),
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setelement(Index, Segments, PreSegment#pre_segment{sections = [Section | Sections]}).
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segment_props(Index) ->
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case Index of
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?SEG_TEXT -> {?PT_LOAD, ?PF_R bor ?PF_X};
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?SEG_RODATA -> {?PT_LOAD, ?PF_R};
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?SEG_DATA -> {?PT_LOAD, ?PF_R bor ?PF_W};
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?SEG_BSS -> {?PT_LOAD, ?PF_R bor ?PF_W}
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end.
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segment_add_section(Section, Segments) ->
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Index = section_index(Section),
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{Props, Sections} = element(Index, Segments),
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setelement(Index, Segments, {Props, [Section | Sections]}).
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section_index(Section) ->
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section_segment_index(Section) ->
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#section{shdr = #elf36_Shdr{sh_type = Type, sh_flags = Flags}} = Section,
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case {Type, Flags} of
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{?SHT_PROGBITS, ?SHF_ALLOC bor ?SHF_EXECINSTR} -> ?SEG_TEXT;
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{?SHT_PROGBITS, ?SHF_ALLOC bor ?SHF_WRITE} -> ?SEG_DATA;
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{?SHT_PROGBITS, ?SHF_ALLOC} -> ?SEG_RODATA;
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{?SHT_NOBITS, ?SHF_ALLOC bor ?SHF_WRITE} -> ?SEG_BSS
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{?SHT_PROGBITS, ?SHF_ALLOC bor ?SHF_EXECINSTR} -> #pre_segments.text;
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{?SHT_PROGBITS, ?SHF_ALLOC bor ?SHF_WRITE} -> #pre_segments.data;
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{?SHT_PROGBITS, ?SHF_ALLOC} -> #pre_segments.rodata;
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{?SHT_NOBITS, ?SHF_ALLOC bor ?SHF_WRITE} -> #pre_segments.bss
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end.
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segments_to_list(Segments) ->
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lists:append([segment_to_list(Segment) || Segment <- tuple_to_list(Segments)]).
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segments_to_list(#pre_segments{text = Text, rodata = Rodata, data = Data, bss = Bss}) ->
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lists:append([segment_to_list(Segment) || Segment <- [Text, Rodata, Data, Bss]]).
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segment_to_list({_Props, _Sections = []}) -> [];
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segment_to_list({{Type, Flags}, Sections0}) ->
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segment_to_list(#pre_segment{sections = []}) -> [];
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segment_to_list(#pre_segment{p_flags = Flags, sections = Sections0}) ->
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Sections1 = lists:sort(fun sections_le/2, Sections0),
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{Sections, FileSz, MemSz, Align} = sections_layout(Sections1),
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Phdr = #elf36_Phdr{ p_type = Type
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Phdr = #elf36_Phdr{ p_type = ?PT_LOAD
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, p_offset = 0
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, p_vaddr = 0
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, p_paddr = 0
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@@ -132,6 +133,12 @@ name_known(Name) ->
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_ -> false
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end.
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%% Compute final layout of the sections in a segment ===========================
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%%
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%% Given a sequence of sections that make up a segment, taking into account their
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%% sizes and alignment, compute their offsets in the segment. Also compute the
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%% segment's final filesz, memsz, and alignment.
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sections_layout(Sections0) ->
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Init = {_Sections = [], _FileSz = 0, _MemSz = 0, _Align = 1},
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{Sections, FileSz, MemSz, Align} =
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