authorgravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2021-01-19 22:54:34+01:00
committergravatar for kubkon@jakubkonka.comJakub Konka <kubkon@jakubkonka.com> 2021-01-19 22:54:34+01:00
loga26ab9afeeeca405118fb3411dce0810ca723b5f
treea748d51c0fe3e477e9afba5df63aef62ea34b8c8
parent0e56d4cc02ce1a09670bf6c50149cb59fd80e9d1

Backport Elf changes from d5d0619

3 files changed, 38 insertions(+), 47 deletions(-)

src/link/MachO.zig+24-29
......@@ -143,11 +143,11 @@ string_table_needs_relocation: bool = false,
143143/// or removed from the freelist.
144144///
145145/// A text block has surplus capacity when its overcapacity value is greater than
146/// minimum_text_block_size * alloc_num / alloc_den. That is, when it has so
146/// padToIdeal(minimum_text_block_size). That is, when it has so
147147/// much extra capacity, that we could fit a small new symbol in it, itself with
148148/// ideal_capacity or more.
149149///
150/// Ideal capacity is defined by size * alloc_num / alloc_den.
150/// Ideal capacity is defined by size + (size / ideal_factor).
151151///
152152/// Overcapacity is measured by actual_capacity - ideal_capacity. Note that
153153/// overcapacity can be negative. A simple way to have negative overcapacity is to
......@@ -192,9 +192,9 @@ pub const StubFixup = struct {
192192 len: usize,
193193};
194194
195/// `alloc_num / alloc_den` is the factor of padding when allocating.
196pub const alloc_num = 4;
197pub const alloc_den = 3;
195/// When allocating, the ideal_capacity is calculated by
196/// actual_capacity + (actual_capacity / ideal_factor)
197const ideal_factor = 2;
198198
199199/// Default path to dyld
200200/// TODO instead of hardcoding it, we should probably look through some env vars and search paths
......@@ -214,7 +214,7 @@ const LIB_SYSTEM_PATH: [*:0]const u8 = DEFAULT_LIB_SEARCH_PATH ++ "/libSystem.B.
214214/// it as a possible place to put new symbols, it must have enough room for this many bytes
215215/// (plus extra for reserved capacity).
216216const minimum_text_block_size = 64;
217const min_text_capacity = minimum_text_block_size * alloc_num / alloc_den;
217const min_text_capacity = padToIdeal(minimum_text_block_size);
218218
219219pub const TextBlock = struct {
220220 /// Each decl always gets a local symbol with the fully qualified name.
......@@ -277,7 +277,7 @@ pub const TextBlock = struct {
277277 const self_sym = macho_file.local_symbols.items[self.local_sym_index];
278278 const next_sym = macho_file.local_symbols.items[next.local_sym_index];
279279 const cap = next_sym.n_value - self_sym.n_value;
280 const ideal_cap = self.size * alloc_num / alloc_den;
280 const ideal_cap = padToIdeal(self.size);
281281 if (cap <= ideal_cap) return false;
282282 const surplus = cap - ideal_cap;
283283 return surplus >= min_text_capacity;
......@@ -873,7 +873,7 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
873873 const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
874874 const text_section = text_segment.sections.items[self.text_section_index.?];
875875 const after_last_cmd_offset = self.header.?.sizeofcmds + @sizeOf(macho.mach_header_64);
876 const needed_size = @sizeOf(macho.linkedit_data_command) * alloc_num / alloc_den;
876 const needed_size = padToIdeal(@sizeOf(macho.linkedit_data_command));
877877
878878 if (needed_size + after_last_cmd_offset > text_section.offset) {
879879 log.err("Unable to extend padding between the end of load commands and start of __text section.", .{});
......@@ -943,7 +943,7 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
943943 const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
944944 const text_section = text_segment.sections.items[self.text_section_index.?];
945945 const after_last_cmd_offset = self.header.?.sizeofcmds + @sizeOf(macho.mach_header_64);
946 const needed_size = @sizeOf(macho.linkedit_data_command) * alloc_num / alloc_den;
946 const needed_size = padToIdeal(@sizeOf(macho.linkedit_data_command));
947947
948948 if (needed_size + after_last_cmd_offset > text_section.offset) {
949949 log.err("Unable to extend padding between the end of load commands and start of __text section.", .{});
......@@ -1491,7 +1491,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
14911491 const program_code_size_hint = self.base.options.program_code_size_hint;
14921492 const offset_table_size_hint = @sizeOf(u64) * self.base.options.symbol_count_hint;
14931493 const ideal_size = self.header_pad + program_code_size_hint + 3 * offset_table_size_hint;
1494 const needed_size = mem.alignForwardGeneric(u64, satMul(ideal_size, alloc_num) / alloc_den, self.page_size);
1494 const needed_size = mem.alignForwardGeneric(u64, padToIdeal(ideal_size), self.page_size);
14951495
14961496 log.debug("found __TEXT segment free space 0x{x} to 0x{x}", .{ 0, needed_size });
14971497
......@@ -1656,7 +1656,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
16561656 const address_and_offset = self.nextSegmentAddressAndOffset();
16571657
16581658 const ideal_size = @sizeOf(u64) * self.base.options.symbol_count_hint;
1659 const needed_size = mem.alignForwardGeneric(u64, satMul(ideal_size, alloc_num) / alloc_den, self.page_size);
1659 const needed_size = mem.alignForwardGeneric(u64, padToIdeal(ideal_size), self.page_size);
16601660
16611661 log.debug("found __DATA_CONST segment free space 0x{x} to 0x{x}", .{ address_and_offset.offset, address_and_offset.offset + needed_size });
16621662
......@@ -1713,7 +1713,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
17131713 const address_and_offset = self.nextSegmentAddressAndOffset();
17141714
17151715 const ideal_size = 2 * @sizeOf(u64) * self.base.options.symbol_count_hint;
1716 const needed_size = mem.alignForwardGeneric(u64, satMul(ideal_size, alloc_num) / alloc_den, self.page_size);
1716 const needed_size = mem.alignForwardGeneric(u64, padToIdeal(ideal_size), self.page_size);
17171717
17181718 log.debug("found __DATA segment free space 0x{x} to 0x{x}", .{ address_and_offset.offset, address_and_offset.offset + needed_size });
17191719
......@@ -2133,7 +2133,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
21332133fn allocateTextBlock(self: *MachO, text_block: *TextBlock, new_block_size: u64, alignment: u64) !u64 {
21342134 const text_segment = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
21352135 const text_section = &text_segment.sections.items[self.text_section_index.?];
2136 const new_block_ideal_capacity = new_block_size * alloc_num / alloc_den;
2136 const new_block_ideal_capacity = padToIdeal(new_block_size);
21372137
21382138 // We use these to indicate our intention to update metadata, placing the new block,
21392139 // and possibly removing a free list node.
......@@ -2153,13 +2153,8 @@ fn allocateTextBlock(self: *MachO, text_block: *TextBlock, new_block_size: u64,
21532153 // Is it enough that we could fit this new text block?
21542154 const sym = self.local_symbols.items[big_block.local_sym_index];
21552155 const capacity = big_block.capacity(self.*);
2156 const ideal_capacity_end_vaddr: u64 = ideal_cap: {
2157 if (math.mul(u64, @divTrunc(capacity, alloc_den), alloc_num)) |cap| {
2158 break :ideal_cap math.add(u64, sym.n_value, cap) catch math.maxInt(u64);
2159 } else |_| {
2160 break :ideal_cap math.maxInt(u64);
2161 }
2162 };
2156 const ideal_capacity = padToIdeal(capacity);
2157 const ideal_capacity_end_vaddr = sym.n_value + ideal_capacity;
21632158 const capacity_end_vaddr = sym.n_value + capacity;
21642159 const new_start_vaddr_unaligned = capacity_end_vaddr - new_block_ideal_capacity;
21652160 const new_start_vaddr = mem.alignBackwardGeneric(u64, new_start_vaddr_unaligned, alignment);
......@@ -2190,7 +2185,7 @@ fn allocateTextBlock(self: *MachO, text_block: *TextBlock, new_block_size: u64,
21902185 const last_symbol = self.local_symbols.items[last.local_sym_index];
21912186 // TODO We should pad out the excess capacity with NOPs. For executables,
21922187 // no padding seems to be OK, but it will probably not be for objects.
2193 const ideal_capacity = last.size * alloc_num / alloc_den;
2188 const ideal_capacity = padToIdeal(last.size);
21942189 const ideal_capacity_end_vaddr = last_symbol.n_value + ideal_capacity;
21952190 const new_start_vaddr = mem.alignForwardGeneric(u64, ideal_capacity_end_vaddr, alignment);
21962191 block_placement = last;
......@@ -2365,7 +2360,7 @@ fn allocatedSizeLinkedit(self: *MachO, start: u64) u64 {
23652360}
23662361
23672362inline fn checkForCollision(start: u64, end: u64, off: u64, size: u64) ?u64 {
2368 const increased_size = satMul(size, alloc_num) / alloc_den;
2363 const increased_size = padToIdeal(size);
23692364 const test_end = off + increased_size;
23702365 if (end > off and start < test_end) {
23712366 return test_end;
......@@ -2374,7 +2369,7 @@ inline fn checkForCollision(start: u64, end: u64, off: u64, size: u64) ?u64 {
23742369}
23752370
23762371fn detectAllocCollisionLinkedit(self: *MachO, start: u64, size: u64) ?u64 {
2377 const end = start + satMul(size, alloc_num) / alloc_den;
2372 const end = start + padToIdeal(size);
23782373
23792374 // __LINKEDIT is a weird segment where sections get their own load commands so we
23802375 // special-case it.
......@@ -2455,12 +2450,6 @@ fn findFreeSpaceLinkedit(self: *MachO, object_size: u64, min_alignment: u16, sta
24552450 return st;
24562451}
24572452
2458/// Saturating multiplication
2459pub fn satMul(a: anytype, b: anytype) @TypeOf(a, b) {
2460 const T = @TypeOf(a, b);
2461 return std.math.mul(T, a, b) catch std.math.maxInt(T);
2462}
2463
24642453fn writeOffsetTableEntry(self: *MachO, index: usize) !void {
24652454 const text_segment = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
24662455 const sect = &text_segment.sections.items[self.got_section_index.?];
......@@ -3275,3 +3264,9 @@ fn fixupInfoCommon(self: *MachO, buffer: []u8, dylib_ordinal: u32) !void {
32753264 }
32763265 }
32773266}
3267
3268pub fn padToIdeal(actual_size: anytype) @TypeOf(actual_size) {
3269 // TODO https://github.com/ziglang/zig/issues/1284
3270 return std.math.add(@TypeOf(actual_size), actual_size, actual_size / ideal_factor) catch
3271 std.math.maxInt(@TypeOf(actual_size));
3272}
src/link/MachO/DebugSymbols.zig+11-13
......@@ -18,9 +18,7 @@ const link = @import("../../link.zig");
1818const MachO = @import("../MachO.zig");
1919const SrcFn = MachO.SrcFn;
2020const TextBlock = MachO.TextBlock;
21const satMul = MachO.satMul;
22const alloc_num = MachO.alloc_num;
23const alloc_den = MachO.alloc_den;
21const padToIdeal = MachO.padToIdeal;
2422const makeStaticString = MachO.makeStaticString;
2523
2624usingnamespace @import("commands.zig");
......@@ -207,7 +205,7 @@ pub fn populateMissingMetadata(self: *DebugSymbols, allocator: *Allocator) !void
207205
208206 const linkedit = self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
209207 const ideal_size: u16 = 200 + 128 + 160 + 250;
210 const needed_size = mem.alignForwardGeneric(u64, satMul(ideal_size, alloc_num) / alloc_den, page_size);
208 const needed_size = mem.alignForwardGeneric(u64, padToIdeal(ideal_size), page_size);
211209 const off = linkedit.inner.fileoff + linkedit.inner.filesize;
212210 const vmaddr = linkedit.inner.vmaddr + linkedit.inner.vmsize;
213211
......@@ -804,7 +802,7 @@ fn allocatedSizeLinkedit(self: *DebugSymbols, start: u64) u64 {
804802}
805803
806804fn detectAllocCollisionLinkedit(self: *DebugSymbols, start: u64, size: u64) ?u64 {
807 const end = start + satMul(size, alloc_num) / alloc_den;
805 const end = start + padToIdeal(size);
808806
809807 if (self.symtab_cmd_index) |idx| outer: {
810808 if (self.load_commands.items.len == idx) break :outer;
......@@ -812,7 +810,7 @@ fn detectAllocCollisionLinkedit(self: *DebugSymbols, start: u64, size: u64) ?u64
812810 {
813811 // Symbol table
814812 const symsize = symtab.nsyms * @sizeOf(macho.nlist_64);
815 const increased_size = satMul(symsize, alloc_num) / alloc_den;
813 const increased_size = padToIdeal(symsize);
816814 const test_end = symtab.symoff + increased_size;
817815 if (end > symtab.symoff and start < test_end) {
818816 return test_end;
......@@ -820,7 +818,7 @@ fn detectAllocCollisionLinkedit(self: *DebugSymbols, start: u64, size: u64) ?u64
820818 }
821819 {
822820 // String table
823 const increased_size = satMul(symtab.strsize, alloc_num) / alloc_den;
821 const increased_size = padToIdeal(symtab.strsize);
824822 const test_end = symtab.stroff + increased_size;
825823 if (end > symtab.stroff and start < test_end) {
826824 return test_end;
......@@ -1099,7 +1097,7 @@ pub fn commitDeclDebugInfo(
10991097 last.next = src_fn;
11001098 self.dbg_line_fn_last = src_fn;
11011099
1102 src_fn.off = last.off + (last.len * alloc_num / alloc_den);
1100 src_fn.off = last.off + padToIdeal(last.len);
11031101 }
11041102 } else if (src_fn.prev == null) {
11051103 // Append new function.
......@@ -1108,14 +1106,14 @@ pub fn commitDeclDebugInfo(
11081106 last.next = src_fn;
11091107 self.dbg_line_fn_last = src_fn;
11101108
1111 src_fn.off = last.off + (last.len * alloc_num / alloc_den);
1109 src_fn.off = last.off + padToIdeal(last.len);
11121110 }
11131111 } else {
11141112 // This is the first function of the Line Number Program.
11151113 self.dbg_line_fn_first = src_fn;
11161114 self.dbg_line_fn_last = src_fn;
11171115
1118 src_fn.off = self.dbgLineNeededHeaderBytes(module) * alloc_num / alloc_den;
1116 src_fn.off = padToIdeal(self.dbgLineNeededHeaderBytes(module));
11191117 }
11201118
11211119 const last_src_fn = self.dbg_line_fn_last.?;
......@@ -1259,7 +1257,7 @@ fn updateDeclDebugInfoAllocation(
12591257 last.dbg_info_next = text_block;
12601258 self.dbg_info_decl_last = text_block;
12611259
1262 text_block.dbg_info_off = last.dbg_info_off + (last.dbg_info_len * alloc_num / alloc_den);
1260 text_block.dbg_info_off = last.dbg_info_off + padToIdeal(last.dbg_info_len);
12631261 }
12641262 } else if (text_block.dbg_info_prev == null) {
12651263 // Append new Decl.
......@@ -1268,14 +1266,14 @@ fn updateDeclDebugInfoAllocation(
12681266 last.dbg_info_next = text_block;
12691267 self.dbg_info_decl_last = text_block;
12701268
1271 text_block.dbg_info_off = last.dbg_info_off + (last.dbg_info_len * alloc_num / alloc_den);
1269 text_block.dbg_info_off = last.dbg_info_off + padToIdeal(last.dbg_info_len);
12721270 }
12731271 } else {
12741272 // This is the first Decl of the .debug_info
12751273 self.dbg_info_decl_first = text_block;
12761274 self.dbg_info_decl_last = text_block;
12771275
1278 text_block.dbg_info_off = self.dbgInfoNeededHeaderBytes() * alloc_num / alloc_den;
1276 text_block.dbg_info_off = padToIdeal(self.dbgInfoNeededHeaderBytes());
12791277 }
12801278}
12811279
src/link/MachO/commands.zig+3-5
......@@ -10,9 +10,7 @@ const assert = std.debug.assert;
1010const Allocator = std.mem.Allocator;
1111const MachO = @import("../MachO.zig");
1212const makeStaticString = MachO.makeStaticString;
13const satMul = MachO.satMul;
14const alloc_num = MachO.alloc_num;
15const alloc_den = MachO.alloc_den;
13const padToIdeal = MachO.padToIdeal;
1614
1715pub const LoadCommand = union(enum) {
1816 Segment: SegmentCommand,
......@@ -214,9 +212,9 @@ pub const SegmentCommand = struct {
214212 }
215213
216214 fn detectAllocCollision(self: SegmentCommand, start: u64, size: u64) ?u64 {
217 const end = start + satMul(size, alloc_num) / alloc_den;
215 const end = start + padToIdeal(size);
218216 for (self.sections.items) |section| {
219 const increased_size = satMul(section.size, alloc_num) / alloc_den;
217 const increased_size = padToIdeal(section.size);
220218 const test_end = section.offset + increased_size;
221219 if (end > section.offset and start < test_end) {
222220 return test_end;