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elf: preallocate offsets for PT_PHDR and PT_LOAD (empty) segment

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Otherwise, we will be using `undefined` as the offset to allocate
remaining phdrs and shdrs.
This commit is contained in:
Jakub Konka 2023-04-03 18:30:48 +02:00
parent 5900dc0580
commit c0e9b84997
1 changed files with 17 additions and 12 deletions
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29
src/link/Elf.zig
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@ -110,7 +110,7 @@ program_headers: std.ArrayListUnmanaged(elf.Elf64_Phdr) = .{},
phdr_table_index: ?u16 = null,
/// The index into the program headers of the PT_LOAD program header containing the phdr
/// Most linkers would merge this with phdr_load_ro_index,
/// but hot swap means we can't ensure they are consecutive.
/// but incremental linking means we can't ensure they are consecutive.
phdr_table_load_index: ?u16 = null,
/// The index into the program headers of a PT_LOAD program header with Read and Execute flags
phdr_load_re_index: ?u16 = null,
@ -473,18 +473,19 @@ pub fn populateMissingMetadata(self: *Elf) !void {
var new_phdr_table_index: ?u16 = null;
if (self.phdr_table_index == null) {
new_phdr_table_index = @intCast(u16, self.program_headers.items.len);
const phalign: u16 = switch (self.ptr_width) {
const p_align: u16 = switch (self.ptr_width) {
.p32 => @alignOf(elf.Elf32_Phdr),
.p64 => @alignOf(elf.Elf64_Phdr),
};
const off = self.findFreeSpace(1, p_align);
try self.program_headers.append(gpa, .{
.p_type = elf.PT_PHDR,
.p_offset = undefined,
.p_filesz = undefined,
.p_vaddr = undefined,
.p_paddr = undefined,
.p_memsz = undefined,
.p_align = phalign,
.p_offset = off,
.p_filesz = 1,
.p_vaddr = 0,
.p_paddr = 0,
.p_memsz = 0,
.p_align = p_align,
.p_flags = elf.PF_R,
});
self.phdr_table_dirty = true;
@ -494,14 +495,18 @@ pub fn populateMissingMetadata(self: *Elf) !void {
self.phdr_table_load_index = @intCast(u16, self.program_headers.items.len);
// TODO Same as for GOT
const phdr_addr: u64 = if (self.base.options.target.cpu.arch.ptrBitWidth() >= 32) 0x1000000 else 0x1000;
const p_align = self.page_size;
const off = self.findFreeSpace(1, p_align);
const file_size: u32 = 1;
log.debug("found PT_LOAD free space 0x{x} to 0x{x}", .{ off, off + file_size });
try self.program_headers.append(gpa, .{
.p_type = elf.PT_LOAD,
.p_offset = undefined,
.p_filesz = undefined,
.p_offset = off,
.p_filesz = file_size,
.p_vaddr = phdr_addr,
.p_paddr = phdr_addr,
.p_memsz = undefined,
.p_align = self.page_size,
.p_memsz = file_size,
.p_align = p_align,
.p_flags = elf.PF_R,
});
self.phdr_table_dirty = true;