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elf: misc .eh_frame management fixes

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This commit is contained in:
Jakub Konka 2024-09-03 21:01:12 +02:00
parent fca92fd7c0
commit eeec50d251
5 changed files with 64 additions and 61 deletions
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44
src/link/Elf.zig
View File

@ -621,7 +621,6 @@ pub fn growNonAllocSection(
try self.base.file.?.setEndPos(shdr.sh_offset + needed_size);
}
shdr.sh_size = needed_size;
self.markDirty(shdr_index);
}
@ -2895,28 +2894,25 @@ fn initSyntheticSections(self: *Elf) !void {
const target = self.getTarget();
const ptr_size = self.ptrWidthBytes();
const needs_eh_frame = if (self.zigObjectPtr()) |zo|
zo.eh_frame_index != null
else for (self.objects.items) |index| {
if (self.file(index).?.object.cies.items.len > 0) break true;
} else false;
const needs_eh_frame = blk: {
if (self.zigObjectPtr()) |zo|
if (zo.eh_frame_index != null) break :blk true;
break :blk for (self.objects.items) |index| {
if (self.file(index).?.object.cies.items.len > 0) break true;
} else false;
};
if (needs_eh_frame) {
if (self.eh_frame_section_index == null) {
self.eh_frame_section_index = blk: {
if (self.zigObjectPtr()) |zo| {
if (zo.eh_frame_index) |idx| break :blk zo.symbol(idx).atom(self).?.output_section_index;
}
break :blk try self.addSection(.{
.name = try self.insertShString(".eh_frame"),
.type = if (target.cpu.arch == .x86_64)
elf.SHT_X86_64_UNWIND
else
elf.SHT_PROGBITS,
.flags = elf.SHF_ALLOC,
.addralign = ptr_size,
.offset = std.math.maxInt(u64),
});
};
self.eh_frame_section_index = self.sectionByName(".eh_frame") orelse try self.addSection(.{
.name = try self.insertShString(".eh_frame"),
.type = if (target.cpu.arch == .x86_64)
elf.SHT_X86_64_UNWIND
else
elf.SHT_PROGBITS,
.flags = elf.SHF_ALLOC,
.addralign = ptr_size,
.offset = std.math.maxInt(u64),
});
}
if (comp.link_eh_frame_hdr) {
self.eh_frame_hdr_section_index = try self.addSection(.{
@ -3591,11 +3587,7 @@ fn updateSectionSizes(self: *Elf) !void {
const shdrs = slice.items(.shdr);
if (self.eh_frame_section_index) |index| {
shdrs[index].sh_size = existing_size: {
const zo = self.zigObjectPtr() orelse break :existing_size 0;
const sym = zo.symbol(zo.eh_frame_index orelse break :existing_size 0);
break :existing_size sym.atom(self).?.size;
} + try eh_frame.calcEhFrameSize(self);
shdrs[index].sh_size = try eh_frame.calcEhFrameSize(self);
}
if (self.eh_frame_hdr_section_index) |index| {

1
src/link/Elf/Object.zig
View File

@ -1096,6 +1096,7 @@ pub fn initRelaSections(self: *Object, elf_file: *Elf) !void {
for (self.atoms_indexes.items) |atom_index| {
const atom_ptr = self.atom(atom_index) orelse continue;
if (!atom_ptr.alive) continue;
if (atom_ptr.output_section_index == elf_file.eh_frame_section_index) continue;
const shndx = atom_ptr.relocsShndx() orelse continue;
const shdr = self.shdrs.items[shndx];
const out_shndx = try elf_file.initOutputSection(.{

12
src/link/Elf/ZigObject.zig
View File

@ -111,6 +111,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_str_section_dirty = true;
self.debug_str_index = try self.addSectionSymbol(gpa, ".debug_str", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_str_index.?).ref;
}
if (self.debug_info_index == null) {
@ -121,6 +122,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_info_section_dirty = true;
self.debug_info_index = try self.addSectionSymbol(gpa, ".debug_info", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_info_index.?).ref;
}
if (self.debug_abbrev_index == null) {
@ -131,6 +133,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_abbrev_section_dirty = true;
self.debug_abbrev_index = try self.addSectionSymbol(gpa, ".debug_abbrev", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_abbrev_index.?).ref;
}
if (self.debug_aranges_index == null) {
@ -141,6 +144,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_aranges_section_dirty = true;
self.debug_aranges_index = try self.addSectionSymbol(gpa, ".debug_aranges", .@"16", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_aranges_index.?).ref;
}
if (self.debug_line_index == null) {
@ -151,6 +155,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_line_section_dirty = true;
self.debug_line_index = try self.addSectionSymbol(gpa, ".debug_line", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_line_index.?).ref;
}
if (self.debug_line_str_index == null) {
@ -163,6 +168,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_line_str_section_dirty = true;
self.debug_line_str_index = try self.addSectionSymbol(gpa, ".debug_line_str", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_line_str_index.?).ref;
}
if (self.debug_loclists_index == null) {
@ -173,6 +179,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_loclists_section_dirty = true;
self.debug_loclists_index = try self.addSectionSymbol(gpa, ".debug_loclists", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_loclists_index.?).ref;
}
if (self.debug_rnglists_index == null) {
@ -183,6 +190,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.debug_rnglists_section_dirty = true;
self.debug_rnglists_index = try self.addSectionSymbol(gpa, ".debug_rnglists", .@"1", osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.debug_rnglists_index.?).ref;
}
if (self.eh_frame_index == null) {
@ -197,6 +205,7 @@ pub fn init(self: *ZigObject, elf_file: *Elf, options: InitOptions) !void {
});
self.eh_frame_section_dirty = true;
self.eh_frame_index = try self.addSectionSymbol(gpa, ".eh_frame", Atom.Alignment.fromNonzeroByteUnits(ptr_size), osec);
elf_file.sections.items(.last_atom)[osec] = self.symbol(self.eh_frame_index.?).ref;
}
try dwarf.initMetadata();
@ -1116,6 +1125,9 @@ pub fn getOrCreateMetadataForNav(
return gop.value_ptr.symbol_index;
}
// FIXME: we always create an atom to basically store size and alignment, however, this is only true for
// sections that have a single atom like the debug sections. It would be a better solution to decouple this
// concept from the atom, maybe.
fn addSectionSymbol(
self: *ZigObject,
allocator: Allocator,

18
src/link/Elf/eh_frame.zig
View File

@ -233,7 +233,10 @@ pub fn calcEhFrameSize(elf_file: *Elf) !usize {
const comp = elf_file.base.comp;
const gpa = comp.gpa;
var offset: usize = 0;
var offset: usize = if (elf_file.zigObjectPtr()) |zo| blk: {
const sym = zo.symbol(zo.eh_frame_index orelse break :blk 0);
break :blk sym.atom(elf_file).?.size;
} else 0;
var cies = std.ArrayList(Cie).init(gpa);
defer cies.deinit();
@ -423,9 +426,8 @@ pub fn writeEhFrameRelocatable(elf_file: *Elf, writer: anytype) !void {
}
}
fn emitReloc(elf_file: *Elf, base_offset: u64, sym: *const Symbol, rel: elf.Elf64_Rela) elf.Elf64_Rela {
fn emitReloc(elf_file: *Elf, r_offset: u64, sym: *const Symbol, rel: elf.Elf64_Rela) elf.Elf64_Rela {
const cpu_arch = elf_file.getTarget().cpu.arch;
const r_offset = base_offset + rel.r_offset;
const r_type = rel.r_type();
var r_addend = rel.r_addend;
var r_sym: u32 = 0;
@ -467,7 +469,7 @@ pub fn writeEhFrameRelocs(elf_file: *Elf, writer: anytype) !void {
for (atom_ptr.relocs(elf_file)) |rel| {
const ref = zo.resolveSymbol(rel.r_sym(), elf_file);
const target = elf_file.symbol(ref).?;
const out_rel = emitReloc(elf_file, 0, target, rel);
const out_rel = emitReloc(elf_file, rel.r_offset, target, rel);
try writer.writeStruct(out_rel);
}
}
@ -480,8 +482,8 @@ pub fn writeEhFrameRelocs(elf_file: *Elf, writer: anytype) !void {
for (cie.relocs(elf_file)) |rel| {
const ref = object.resolveSymbol(rel.r_sym(), elf_file);
const sym = elf_file.symbol(ref).?;
const offset = cie.address(elf_file) - cie.offset;
const out_rel = emitReloc(elf_file, offset, sym, rel);
const r_offset = cie.address(elf_file) + rel.r_offset - cie.offset;
const out_rel = emitReloc(elf_file, r_offset, sym, rel);
try writer.writeStruct(out_rel);
}
}
@ -491,8 +493,8 @@ pub fn writeEhFrameRelocs(elf_file: *Elf, writer: anytype) !void {
for (fde.relocs(elf_file)) |rel| {
const ref = object.resolveSymbol(rel.r_sym(), elf_file);
const sym = elf_file.symbol(ref).?;
const offset = fde.address(elf_file) - fde.offset;
const out_rel = emitReloc(elf_file, offset, sym, rel);
const r_offset = fde.address(elf_file) + rel.r_offset - fde.offset;
const out_rel = emitReloc(elf_file, r_offset, sym, rel);
try writer.writeStruct(out_rel);
}
}

50
src/link/Elf/relocatable.zig
View File

@ -302,30 +302,29 @@ fn initSections(elf_file: *Elf) !void {
try msec.initOutputSection(elf_file);
}
const needs_eh_frame = if (elf_file.zigObjectPtr()) |zo|
zo.eh_frame_index != null
else for (elf_file.objects.items) |index| {
if (elf_file.file(index).?.object.cies.items.len > 0) break true;
} else false;
const needs_eh_frame = blk: {
if (elf_file.zigObjectPtr()) |zo|
if (zo.eh_frame_index != null) break :blk true;
break :blk for (elf_file.objects.items) |index| {
if (elf_file.file(index).?.object.cies.items.len > 0) break true;
} else false;
};
if (needs_eh_frame) {
if (elf_file.eh_frame_section_index == null) {
elf_file.eh_frame_section_index = blk: {
if (elf_file.zigObjectPtr()) |zo| {
if (zo.eh_frame_index) |idx| break :blk zo.symbol(idx).atom(elf_file).?.output_section_index;
}
break :blk try elf_file.addSection(.{
.name = try elf_file.insertShString(".eh_frame"),
.type = if (elf_file.getTarget().cpu.arch == .x86_64)
elf.SHT_X86_64_UNWIND
else
elf.SHT_PROGBITS,
.flags = elf.SHF_ALLOC,
.addralign = elf_file.ptrWidthBytes(),
.offset = std.math.maxInt(u64),
});
};
elf_file.eh_frame_section_index = elf_file.sectionByName(".eh_frame") orelse
try elf_file.addSection(.{
.name = try elf_file.insertShString(".eh_frame"),
.type = if (elf_file.getTarget().cpu.arch == .x86_64)
elf.SHT_X86_64_UNWIND
else
elf.SHT_PROGBITS,
.flags = elf.SHF_ALLOC,
.addralign = elf_file.ptrWidthBytes(),
.offset = std.math.maxInt(u64),
});
}
elf_file.eh_frame_rela_section_index = try elf_file.addRelaShdr(
elf_file.eh_frame_rela_section_index = elf_file.sectionByName(".rela.eh_frame") orelse
try elf_file.addRelaShdr(
try elf_file.insertShString(".rela.eh_frame"),
elf_file.eh_frame_section_index.?,
);
@ -367,6 +366,7 @@ fn updateSectionSizes(elf_file: *Elf) !void {
for (slice.items(.shdr), 0..) |*shdr, shndx| {
const atom_list = slice.items(.atom_list)[shndx];
if (shdr.sh_type != elf.SHT_RELA) continue;
if (@as(u32, @intCast(shndx)) == elf_file.eh_frame_section_index) continue;
for (atom_list.items) |ref| {
const atom_ptr = elf_file.atom(ref) orelse continue;
if (!atom_ptr.alive) continue;
@ -378,11 +378,7 @@ fn updateSectionSizes(elf_file: *Elf) !void {
}
if (elf_file.eh_frame_section_index) |index| {
slice.items(.shdr)[index].sh_size = existing_size: {
const zo = elf_file.zigObjectPtr() orelse break :existing_size 0;
const sym = zo.symbol(zo.eh_frame_index orelse break :existing_size 0);
break :existing_size sym.atom(elf_file).?.size;
} + try eh_frame.calcEhFrameSize(elf_file);
slice.items(.shdr)[index].sh_size = try eh_frame.calcEhFrameSize(elf_file);
}
if (elf_file.eh_frame_rela_section_index) |index| {
const shdr = &slice.items(.shdr)[index];
@ -464,8 +460,8 @@ fn writeSyntheticSections(elf_file: *Elf) !void {
for (slice.items(.shdr), slice.items(.atom_list), 0..) |shdr, atom_list, shndx| {
if (shdr.sh_type != elf.SHT_RELA) continue;
if (@as(u32, @intCast(shndx)) == elf_file.eh_frame_rela_section_index) continue;
if (atom_list.items.len == 0) continue;
if (@as(u32, @intCast(shndx)) == elf_file.eh_frame_section_index) continue;
const num_relocs = math.cast(usize, @divExact(shdr.sh_size, shdr.sh_entsize)) orelse
return error.Overflow;