srctree

Alexandre Janon parent aecd9cc6 25f1526f
Fix ELF alignment for freestanding targets (#19766)

* Fix the ELF binaries for freestanding target created with the self-hosted linker.
The ELF specification (generic ABI) states that loadable process segments must have congruent
values for p_vaddr and p_offset, modulo the page size''. Linux refuses to load binaries that

don't meet this requirement (execve() fails with EINVAL).

src/link/Elf.zig added: 5, removed: 8, total 0

@@ -648,7 +648,6 @@ pub fn initMetadata(self: *Elf, options: InitMetadataOptions) !void {

const ptr_size = self.ptrWidthBytes();

const target = self.base.comp.root_mod.resolved_target.result;

const ptr_bit_width = target.ptrBitWidth();

const has_os = target.os.tag != .freestanding;

const zig_object = self.zigObjectPtr().?;

const fillSection = struct {

@@ -684,9 +683,7 @@ pub fn initMetadata(self: *Elf, options: InitMetadataOptions) !void {

}

if (self.phdr_zig_got_index == null) {

// We really only need ptr alignment but since we are using PROGBITS, linux requires

// page align.

const alignment = if (has_os) self.page_size else @as(u16, ptr_size);

const alignment = self.page_size;

const filesz = @as(u64, ptr_size) * options.symbol_count_hint;

const off = self.findFreeSpace(filesz, alignment);

self.phdr_zig_got_index = try self.addPhdr(.{

@@ -701,7 +698,7 @@ pub fn initMetadata(self: *Elf, options: InitMetadataOptions) !void {

}

if (self.phdr_zig_load_ro_index == null) {

const alignment = if (has_os) self.page_size else @as(u16, ptr_size);

const alignment = self.page_size;

const filesz: u64 = 1024;

const off = self.findFreeSpace(filesz, alignment);

self.phdr_zig_load_ro_index = try self.addPhdr(.{

@@ -716,7 +713,7 @@ pub fn initMetadata(self: *Elf, options: InitMetadataOptions) !void {

}

if (self.phdr_zig_load_rw_index == null) {

const alignment = if (has_os) self.page_size else @as(u16, ptr_size);

const alignment = self.page_size;

const filesz: u64 = 1024;

const off = self.findFreeSpace(filesz, alignment);

self.phdr_zig_load_rw_index = try self.addPhdr(.{

@@ -731,7 +728,7 @@ pub fn initMetadata(self: *Elf, options: InitMetadataOptions) !void {

}

if (self.phdr_zig_load_zerofill_index == null) {

const alignment = if (has_os) self.page_size else @as(u16, ptr_size);

const alignment = self.page_size;

self.phdr_zig_load_zerofill_index = try self.addPhdr(.{

.type = elf.PT_LOAD,

.addr = if (ptr_bit_width >= 32) 0x14000000 else 0xf000,