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elf: parse and emit Elf relocs for cross section refs for .debug* sections

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This commit is contained in:
Jakub Konka 2024-08-19 08:40:22 +02:00 committed by Jacob Young
parent d3d5ed992c
commit d388d555d5
2 changed files with 57 additions and 16 deletions
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8
src/link/Dwarf.zig
View File

@ -287,7 +287,7 @@ pub const Section = struct {
return sec.getUnit(unit).addEntry(sec, dwarf);
}
fn getUnit(sec: *Section, unit: Unit.Index) *Unit {
pub fn getUnit(sec: *Section, unit: Unit.Index) *Unit {
return &sec.units.items[@intFromEnum(unit)];
}
@ -368,7 +368,7 @@ const Unit = struct {
none = std.math.maxInt(u32),
_,
fn unwrap(uio: Optional) ?Index {
pub fn unwrap(uio: Optional) ?Index {
return if (uio != .none) @enumFromInt(@intFromEnum(uio)) else null;
}
};
@ -614,7 +614,7 @@ const Entry = struct {
none = std.math.maxInt(u32),
_,
fn unwrap(eio: Optional) ?Index {
pub fn unwrap(eio: Optional) ?Index {
return if (eio != .none) @enumFromInt(@intFromEnum(eio)) else null;
}
};
@ -736,7 +736,7 @@ const Entry = struct {
}
}
fn assertNonEmpty(entry: *Entry, unit: *Unit, sec: *Section, dwarf: *Dwarf) *Entry {
pub fn assertNonEmpty(entry: *Entry, unit: *Unit, sec: *Section, dwarf: *Dwarf) *Entry {
if (entry.len > 0) return entry;
if (std.debug.runtime_safety) {
log.err("missing {} from {s}", .{

65
src/link/Elf/ZigObject.zig
View File

@ -195,15 +195,15 @@ pub fn flushModule(self: *ZigObject, elf_file: *Elf, tid: Zcu.PerThread.Id) !voi
self.debug_line_str_index.?,
self.debug_loclists_index.?,
self.debug_rnglists_index.?,
}, [_]Dwarf.Section{
dwarf.debug_info.section,
dwarf.debug_abbrev.section,
dwarf.debug_str.section,
dwarf.debug_aranges.section,
dwarf.debug_line.section,
dwarf.debug_line_str.section,
dwarf.debug_loclists.section,
dwarf.debug_rnglists.section,
}, [_]*Dwarf.Section{
&dwarf.debug_info.section,
&dwarf.debug_abbrev.section,
&dwarf.debug_str.section,
&dwarf.debug_aranges.section,
&dwarf.debug_line.section,
&dwarf.debug_line_str.section,
&dwarf.debug_loclists.section,
&dwarf.debug_rnglists.section,
}) |sym_index, sect| {
const sym = self.symbol(sym_index);
const atom_ptr = self.atom(sym.ref.index).?;
@ -215,11 +215,52 @@ pub fn flushModule(self: *ZigObject, elf_file: *Elf, tid: Zcu.PerThread.Id) !voi
atom_ptr.size = shdr.sh_size;
atom_ptr.alignment = Atom.Alignment.fromNonzeroByteUnits(shdr.sh_addralign);
log.debug("parsing relocs in {s}", .{sym.name(elf_file)});
const relocs = &self.relocs.items[atom_ptr.relocsShndx().?];
for (sect.units.items) |*unit| {
try relocs.ensureUnusedCapacity(gpa, unit.cross_section_relocs.items.len);
for (unit.cross_section_relocs.items) |reloc| {
const target_sym_index = switch (reloc.target_sec) {
.debug_abbrev => self.debug_abbrev_index.?,
.debug_info => self.debug_info_index.?,
.debug_line => self.debug_line_index.?,
.debug_line_str => self.debug_line_str_index.?,
.debug_loclists => self.debug_loclists_index.?,
.debug_rnglists => self.debug_rnglists_index.?,
.debug_str => self.debug_str_index.?,
};
const target_sec = switch (reloc.target_sec) {
inline else => |target_sec| &@field(dwarf, @tagName(target_sec)).section,
};
const target_unit = target_sec.getUnit(reloc.target_unit);
const r_offset = unit.off + reloc.source_off + (if (reloc.source_entry.unwrap()) |source_entry|
unit.header_len + unit.getEntry(source_entry).off
else
0);
const r_addend: i64 = @intCast(reloc.target_off + (if (reloc.target_entry.unwrap()) |target_entry|
target_unit.header_len + target_unit.getEntry(target_entry).assertNonEmpty(unit, sect, dwarf).off
else
0));
const r_type: elf.R_X86_64 = switch (dwarf.format) {
.@"32" => .@"32",
.@"64" => .@"64",
};
log.debug(" {s} <- r_off={x}, r_add={x}, r_type={s}", .{
self.symbol(target_sym_index).name(elf_file),
r_offset,
r_addend,
@tagName(r_type),
});
atom_ptr.addRelocAssumeCapacity(.{
.r_offset = r_offset,
.r_addend = r_addend,
.r_info = (@as(u64, @intCast(target_sym_index)) << 32) | @intFromEnum(r_type),
}, self);
}
try relocs.ensureUnusedCapacity(gpa, unit.external_relocs.items.len);
for (unit.external_relocs.items) |reloc| {
const tsym = self.symbol(reloc.target_sym);
const r_offset = unit.off + unit.header_len + unit.getEntry(reloc.source_entry).off + reloc.source_off;
const r_addend: i64 = @intCast(reloc.target_off);
const r_type: elf.R_X86_64 = switch (dwarf.address_size) {
@ -227,8 +268,8 @@ pub fn flushModule(self: *ZigObject, elf_file: *Elf, tid: Zcu.PerThread.Id) !voi
.@"64" => .@"64",
else => unreachable,
};
log.debug("{s} <- r_off={x}, r_add={x}, r_type={s}\n", .{
tsym.name(elf_file),
log.debug(" {s} <- r_off={x}, r_add={x}, r_type={s}", .{
self.symbol(reloc.target_sym).name(elf_file),
r_offset,
r_addend,
@tagName(r_type),