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wasm-linker: fix debug info relocation

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This corrects calculating the offsets to the code section as we now
correctly allocate the code atoms during write taking the 'size' into
account. We also handle dead symbols which are garbage-collected by
writing -2 and -1 to skip ranges, loc and other sections respectively.
This commit is contained in:
Luuk de Gram 2024-01-10 06:55:12 +01:00
parent 7fe629a812
commit 3f22bb96f3
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GPG Key ID: A8CFE58E4DC7D664
1 changed files with 30 additions and 10 deletions
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40
src/link/Wasm/Atom.zig
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@ -111,7 +111,7 @@ pub fn resolveRelocs(atom: *Atom, wasm_bin: *const Wasm) void {
.R_WASM_GLOBAL_INDEX_I32,
.R_WASM_MEMORY_ADDR_I32,
.R_WASM_SECTION_OFFSET_I32,
=> std.mem.writeInt(u32, atom.code.items[reloc.offset - atom.original_offset ..][0..4], @as(u32, @intCast(value)), .little),
=> std.mem.writeInt(u32, atom.code.items[reloc.offset - atom.original_offset ..][0..4], @as(u32, @truncate(value)), .little),
.R_WASM_TABLE_INDEX_I64,
.R_WASM_MEMORY_ADDR_I64,
=> std.mem.writeInt(u64, atom.code.items[reloc.offset - atom.original_offset ..][0..8], value, .little),
@ -124,7 +124,7 @@ pub fn resolveRelocs(atom: *Atom, wasm_bin: *const Wasm) void {
.R_WASM_TABLE_NUMBER_LEB,
.R_WASM_TYPE_INDEX_LEB,
.R_WASM_MEMORY_ADDR_TLS_SLEB,
=> leb.writeUnsignedFixed(5, atom.code.items[reloc.offset - atom.original_offset ..][0..5], @as(u32, @intCast(value))),
=> leb.writeUnsignedFixed(5, atom.code.items[reloc.offset - atom.original_offset ..][0..5], @as(u32, @truncate(value))),
.R_WASM_MEMORY_ADDR_LEB64,
.R_WASM_MEMORY_ADDR_SLEB64,
.R_WASM_TABLE_INDEX_SLEB64,
@ -140,6 +140,13 @@ pub fn resolveRelocs(atom: *Atom, wasm_bin: *const Wasm) void {
fn relocationValue(atom: Atom, relocation: types.Relocation, wasm_bin: *const Wasm) u64 {
const target_loc = (Wasm.SymbolLoc{ .file = atom.file, .index = relocation.index }).finalLoc(wasm_bin);
const symbol = target_loc.getSymbol(wasm_bin);
if (relocation.relocation_type != .R_WASM_TYPE_INDEX_LEB and
symbol.tag != .section and
symbol.isDead())
{
const val = atom.thombstone(wasm_bin) orelse relocation.addend;
return @bitCast(val);
}
switch (relocation.relocation_type) {
.R_WASM_FUNCTION_INDEX_LEB => return symbol.index,
.R_WASM_TABLE_NUMBER_LEB => return symbol.index,
@ -170,30 +177,43 @@ fn relocationValue(atom: Atom, relocation: types.Relocation, wasm_bin: *const Wa
if (symbol.isUndefined()) {
return 0;
}
const va = @as(i64, @intCast(symbol.virtual_address));
const va: i33 = @intCast(symbol.virtual_address);
return @intCast(va + relocation.addend);
},
.R_WASM_EVENT_INDEX_LEB => return symbol.index,
.R_WASM_SECTION_OFFSET_I32 => {
const target_atom_index = wasm_bin.symbol_atom.get(target_loc).?;
const target_atom = wasm_bin.getAtom(target_atom_index);
const rel_value: i32 = @intCast(target_atom.offset);
const rel_value: i33 = @intCast(target_atom.offset);
return @intCast(rel_value + relocation.addend);
},
.R_WASM_FUNCTION_OFFSET_I32 => {
const target_atom_index = wasm_bin.symbol_atom.get(target_loc) orelse {
return @as(u32, @bitCast(@as(i32, -1)));
};
if (symbol.isUndefined()) {
const val = atom.thombstone(wasm_bin) orelse relocation.addend;
return @bitCast(val);
}
const target_atom_index = wasm_bin.symbol_atom.get(target_loc).?;
const target_atom = wasm_bin.getAtom(target_atom_index);
const offset: u32 = 11 + Wasm.getULEB128Size(target_atom.size); // Header (11 bytes fixed-size) + body size (leb-encoded)
const rel_value: i32 = @intCast(target_atom.offset + offset);
const rel_value: i33 = @intCast(target_atom.offset);
return @intCast(rel_value + relocation.addend);
},
.R_WASM_MEMORY_ADDR_TLS_SLEB,
.R_WASM_MEMORY_ADDR_TLS_SLEB64,
=> {
const va: i32 = @intCast(symbol.virtual_address);
const va: i33 = @intCast(symbol.virtual_address);
return @intCast(va + relocation.addend);
},
}
}
// For a given `Atom` returns whether it has a thombstone value or not.
/// This defines whether we want a specific value when a section is dead.
fn thombstone(atom: Atom, wasm: *const Wasm) ?i64 {
const atom_name = atom.symbolLoc().getName(wasm);
if (std.mem.eql(u8, atom_name, ".debug_ranges") or std.mem.eql(u8, atom_name, ".debug_loc")) {
return -2;
} else if (std.mem.startsWith(u8, atom_name, ".debug_")) {
return -1;
}
return null;
}