tiny.tldr.formats.elf.addressing.symbol

1pub const symbol = @import("symbol.zig");

1const std = @import("std");2const root = @import("../../../root.zig");3const elf = @import("../root.zig");4const boundary = @import("boundary.zig");5const cache = @import("cache.zig");67const model = root.model;8const format = elf.format;9const layout = elf.layout;10const merge = elf.merge;11const section_state = elf.section_state;1213const Access = cache.Access;14const Cache = cache.Cache;15const GlobalSymbol = layout.GlobalSymbol;16const ObjectFile = elf.parser.ObjectFile;17const ObjectLayout = layout.ObjectLayout;18const OutputSection = layout.OutputSection;19const Symbol = format.Symbol;20const SymbolRef = layout.SymbolRef;21const contributionAt = layout.contributionAt;22const foldedSection = section_state.foldedSection;23const symbolSectionDiscarded = section_state.symbolSectionDiscarded;2425pub fn address(26    comptime cache_access: Access,27    objects: []const ObjectFile,28    layouts: []const ObjectLayout,29    output_sections: []const OutputSection,30    globals: *const std.StringHashMapUnmanaged(GlobalSymbol),31    symbol_addresses: *Cache,32    object_index: usize,33    symbol_index: usize,34) model.Error!u64 {35    if (symbol_index >= objects[object_index].symbols.len) return error.UndefinedSymbol;36    const cached = symbol_addresses.slot(object_index, symbol_index);37    const cached_value = cache.load(cache_access, cached);38    if (cached_value != Cache.missing) return cached_value;3940    const symbol_record = objects[object_index].symbols[symbol_index];41    if (symbol_record.isUndefined()) {42        const global = globals.get(symbol_record.name) orelse {43            if (boundary.forSymbol(symbol_record.name)) |symbol_boundary| {44                if (symbol_addresses.syntheticBoundaryAddress(symbol_boundary)) |boundary_address| {45                    return cache.store(cache_access, cached, boundary_address);46                }47            }48            if (symbol_record.isWeakUndefined()) {49                return cache.store(cache_access, cached, 0);50            }51            return error.UndefinedSymbol;52        };53        const resolved = try address(54            cache_access,55            objects,56            layouts,57            output_sections,58            globals,59            symbol_addresses,60            global.ref.object_index,61            global.ref.symbol_index,62        );63        return cache.store(cache_access, cached, resolved);64    }65    if (symbolSectionDiscarded(objects[object_index], symbol_record) and symbol_record.name.len != 0) {66        const global = globals.get(symbol_record.name) orelse return error.MissingSection;67        const current_ref = SymbolRef{ .object_index = object_index, .symbol_index = symbol_index };68        if (global.ref.eql(current_ref)) return error.MissingSection;69        const resolved = try address(70            cache_access,71            objects,72            layouts,73            output_sections,74            globals,75            symbol_addresses,76            global.ref.object_index,77            global.ref.symbol_index,78        );79        return cache.store(cache_access, cached, resolved);80    }81    if (symbol_record.isCommon() and symbol_record.name.len != 0) {82        const global = globals.get(symbol_record.name) orelse return error.UndefinedSymbol;83        const current_ref = SymbolRef{ .object_index = object_index, .symbol_index = symbol_index };84        if (!global.ref.eql(current_ref)) {85            const resolved = try address(cache_access, objects, layouts, output_sections, globals, symbol_addresses, global.ref.object_index, global.ref.symbol_index);86            return cache.store(cache_access, cached, resolved);87        }88    }89    if (symbol_record.isAbsolute()) return cache.store(cache_access, cached, symbol_record.value);90    if (symbol_record.isCommon()) {91        const object_layout = layouts[object_index];92        if (symbol_index >= object_layout.common_symbols.len) return error.UnsupportedRelocation;93        const common_contribution = contributionAt(object_layout.common_symbols, symbol_index) orelse return error.MissingSection;94        const output = output_sections[common_contribution.outputIndex()];95        return cache.store(cache_access, cached, output.address + common_contribution.offset);96    }97    return sectionAddress(cache_access, objects, layouts, output_sections, cached, object_index, symbol_record);98}99100pub fn relocation(101    comptime cache_access: Access,102    objects: []const ObjectFile,103    layouts: []const ObjectLayout,104    output_sections: []const OutputSection,105    globals: *const std.StringHashMapUnmanaged(GlobalSymbol),106    symbol_addresses: *Cache,107    object_index: usize,108    symbol_index: usize,109) model.Error!i128 {110    if (symbol_index >= objects[object_index].symbols.len) return error.UndefinedSymbol;111112    const symbol_record = objects[object_index].symbols[symbol_index];113    if (symbol_record.isUndefined()) {114        const global = globals.get(symbol_record.name) orelse {115            if (boundary.forSymbol(symbol_record.name)) |symbol_boundary| {116                if (symbol_addresses.syntheticBoundaryAddress(symbol_boundary)) |boundary_address| {117                    return @intCast(boundary_address);118                }119            }120            if (symbol_record.isWeakUndefined()) return 0;121            return error.UndefinedSymbol;122        };123        return relocation(124            cache_access,125            objects,126            layouts,127            output_sections,128            globals,129            symbol_addresses,130            global.ref.object_index,131            global.ref.symbol_index,132        );133    }134    if (symbolSectionDiscarded(objects[object_index], symbol_record) and symbol_record.name.len != 0) {135        const global = globals.get(symbol_record.name) orelse return error.MissingSection;136        const current_ref = SymbolRef{ .object_index = object_index, .symbol_index = symbol_index };137        if (global.ref.eql(current_ref)) return error.MissingSection;138        return relocation(139            cache_access,140            objects,141            layouts,142            output_sections,143            globals,144            symbol_addresses,145            global.ref.object_index,146            global.ref.symbol_index,147        );148    }149    if (symbol_record.isCommon() and symbol_record.name.len != 0) {150        const global = globals.get(symbol_record.name) orelse return error.UndefinedSymbol;151        const current_ref = SymbolRef{ .object_index = object_index, .symbol_index = symbol_index };152        if (!global.ref.eql(current_ref)) {153            return relocation(cache_access, objects, layouts, output_sections, globals, symbol_addresses, global.ref.object_index, global.ref.symbol_index);154        }155    }156    if (symbol_record.isAbsolute()) return signedAbsoluteValue(symbol_record.value);157    if (symbol_record.isCommon()) return @intCast(try address(cache_access, objects, layouts, output_sections, globals, symbol_addresses, object_index, symbol_index));158    return @intCast(try sectionSymbolAddress(cache_access, objects, layouts, output_sections, symbol_addresses, object_index, symbol_index, symbol_record));159}160161pub fn isUnresolvedWeak(162    object: ObjectFile,163    symbol_index: usize,164    globals: *const std.StringHashMapUnmanaged(GlobalSymbol),165) bool {166    if (symbol_index >= object.symbols.len) return false;167    const symbol_record = object.symbols[symbol_index];168    return symbol_record.isWeakUndefined() and !globals.contains(symbol_record.name);169}170171pub fn sectionSymbolAddress(172    comptime cache_access: Access,173    objects: []const ObjectFile,174    layouts: []const ObjectLayout,175    output_sections: []const OutputSection,176    symbol_addresses: *Cache,177    object_index: usize,178    symbol_index: usize,179    symbol_record: Symbol,180) model.Error!u64 {181    const cached = symbol_addresses.slot(object_index, symbol_index);182    const cached_value = cache.load(cache_access, cached);183    if (cached_value != Cache.missing) return cached_value;184    return sectionAddress(cache_access, objects, layouts, output_sections, cached, object_index, symbol_record);185}186187fn sectionAddress(188    comptime cache_access: Access,189    objects: []const ObjectFile,190    layouts: []const ObjectLayout,191    output_sections: []const OutputSection,192    cached: *u64,193    object_index: usize,194    symbol_record: Symbol,195) model.Error!u64 {196    const object = objects[object_index];197    const object_layout = layouts[object_index];198    if (symbol_record.section_index >= object.sections.len) return error.UnsupportedRelocation;199    if (merge.piece(object_layout, object, symbol_record.section_index, symbol_record.value)) |entry| {200        const output = output_sections[entry.contribution.outputIndex()];201        const resolved = output.address + entry.contribution.offset + entry.intra_offset;202        return cache.store(cache_access, cached, resolved);203    }204    const symbol_contribution = if (foldedSection(object, symbol_record.section_index)) |canonical|205        (contributionAt(layouts[canonical.object_index].sections, canonical.section_index) orelse return error.MissingSection).*206    else207        (contributionAt(object_layout.sections, symbol_record.section_index) orelse return error.MissingSection).*;208    const output = output_sections[symbol_contribution.outputIndex()];209    const resolved = output.address + symbol_contribution.offset + symbol_record.value;210    return cache.store(cache_access, cached, resolved);211}212213fn signedAbsoluteValue(value: u64) i128 {214    return @as(i64, @bitCast(value));215}