Commit f56054d129d19a006ff19c56b48bc9c7d9c04593 | zig

author	Jakub Konka <kubkon@jakubkonka.com> 2023-04-26 13:04:24+02:00
committer	Jacob Young <jacobly@ziglang.org> 2023-04-26 19:08:38-04:00
log	f56054d129d19a006ff19c56b48bc9c7d9c04593
tree	aa2880b4c127a39563232b7db8c851d13def8596
parent	bc69d5a00fb197a7bafc716b84c8675382074c19

coff: invalidate GOT relocs after segment shift in memory

2 files changed, 37 insertions(+), 19 deletions(-)

src
- link
  - Coff.zig
  - Coff
    Relocation.zig

src/link/Coff.zig+19-7

 @@ -492,7 +492,7 @@ fn growSection(self: *Coff, sect_id: u32, needed_size: u32) !void {
     const sect_vm_capacity = self.allocatedVirtualSize(header.virtual_address);
     if (needed_size > sect_vm_capacity) {
-        self.markRelocsDirtyByAddress(header.virtual_address + needed_size);
+        self.markRelocsDirtyByAddress(header.virtual_address + header.virtual_size);
         try self.growSectionVirtualMemory(sect_id, needed_size);
     }
 @@ -759,7 +759,9 @@ fn writeAtom(self: *Coff, atom_index: Atom.Index, code: []u8) !void {
     if (self.relocs.getPtr(atom_index)) |rels| {
         try relocs.ensureTotalCapacityPrecise(rels.items.len);
         for (rels.items) |*reloc| {
-            if (reloc.isResolvable(self)) relocs.appendAssumeCapacity(reloc);
+            if (reloc.isResolvable(self) and reloc.dirty) {
+                relocs.appendAssumeCapacity(reloc);
+            }
         }
     }
 @@ -904,18 +906,28 @@ fn markRelocsDirtyByTarget(self: *Coff, target: SymbolWithLoc) void {
 }
 fn markRelocsDirtyByAddress(self: *Coff, addr: u32) void {
+    const got_moved = blk: {
+        const sect_id = self.got_section_index orelse break :blk false;
+        break :blk self.sections.items(.header)[sect_id].virtual_address > addr;
+    };
+    // TODO: dirty relocations targeting import table if that got moved in memory
     for (self.relocs.values()) |*relocs| {
         for (relocs.items) |*reloc| {
-            const target_vaddr = reloc.getTargetAddress(self) orelse continue;
+            if (reloc.isGotIndirection()) {
-            if (target_vaddr < addr) continue;
+                reloc.dirty = reloc.dirty or got_moved;
-            reloc.dirty = true;
+            } else {
+                const target_vaddr = reloc.getTargetAddress(self) orelse continue;
+                if (target_vaddr > addr) reloc.dirty = true;
+            }
         }
     }
     // TODO: dirty only really affected GOT cells
     for (self.got_table.entries.items) |entry| {
         const target_addr = self.getSymbol(entry).value;
-        if (target_addr >= addr) {
+        if (target_addr > addr) {
             self.got_table_contents_dirty = true;
             break;
         }
 @@ -1624,7 +1636,7 @@ pub fn flushModule(self: *Coff, comp: *Compilation, prog_node: *std.Progress.Nod
     for (self.relocs.keys(), self.relocs.values()) |atom_index, relocs| {
         const needs_update = for (relocs.items) |reloc| {
-            if (reloc.isResolvable(self)) break true;
+            if (reloc.dirty) break true;
         } else false;
         if (!needs_update) continue;

src/link/Coff/Relocation.zig+18-12

 @@ -45,6 +45,19 @@ pcrel: bool,
 length: u2,
 dirty: bool = true,
+/// Returns true if and only if the reloc can be resolved.
+pub fn isResolvable(self: Relocation, coff_file: *Coff) bool {
+    _ = self.getTargetAddress(coff_file) orelse return false;
+    return true;
+}
+pub fn isGotIndirection(self: Relocation) bool {
+    return switch (self.type) {
+        .got, .got_page, .got_pageoff => true,
+        else => false,
+    };
+}
 /// Returns address of the target if any.
 pub fn getTargetAddress(self: Relocation, coff_file: *const Coff) ?u32 {
     switch (self.type) {
 @@ -53,11 +66,6 @@ pub fn getTargetAddress(self: Relocation, coff_file: *const Coff) ?u32 {
             const header = coff_file.sections.items(.header)[coff_file.got_section_index.?];
             return header.virtual_address + got_index * coff_file.ptr_width.size();
         },
-        .direct, .page, .pageoff => {
-            const target_atom_index = coff_file.getAtomIndexForSymbol(self.target) orelse return null;
-            const target_atom = coff_file.getAtom(target_atom_index);
-            return target_atom.getSymbol(coff_file).value;
-        },
         .import, .import_page, .import_pageoff => {
             const sym = coff_file.getSymbol(self.target);
             const index = coff_file.import_tables.getIndex(sym.value) orelse return null;
 @@ -68,16 +76,14 @@ pub fn getTargetAddress(self: Relocation, coff_file: *const Coff) ?u32 {
                 .name_off = sym.value,
             });
         },
+        else => {
+            const target_atom_index = coff_file.getAtomIndexForSymbol(self.target) orelse return null;
+            const target_atom = coff_file.getAtom(target_atom_index);
+            return target_atom.getSymbol(coff_file).value;
+        },
     }
 }
-/// Returns true if and only if the reloc is dirty AND the target address is available.
-pub fn isResolvable(self: Relocation, coff_file: *Coff) bool {
-    const addr = self.getTargetAddress(coff_file) orelse return false;
-    if (addr == 0) return false;
-    return self.dirty;
-}
 pub fn resolve(self: Relocation, atom_index: Atom.Index, code: []u8, image_base: u64, coff_file: *Coff) void {
     const atom = coff_file.getAtom(atom_index);
     const source_sym = atom.getSymbol(coff_file);