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linker: remove -z noexecstack option

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Note that the current documentation for the `-z noexecstack` is
incorrect. This indicates that an object *does not* require an
executable stack.

This is actually the default of LLD, and there has never been a way to
override this default by passing `-z execstack` to LLD.

This commit removes the redundant `-z noexecstack` option from
zig build-exe/build-lib/build-obj and ignores the option if passed
to zig cc for compatibility.

As far as I can tell, there is no reason for code to require an
executable stack. This option only exists because the stack was
originally executable by default and some programs came to depend
on that behavior. Instead, mprotect(2) may be used to make memory
pages executable.
This commit is contained in:
Isaac Freund 2022-06-09 00:06:16 +02:00 committed by Andrew Kelley
parent f1cff4fa4a
commit 5816d3eaec
4 changed files with 1 additions and 15 deletions
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3
src/Compilation.zig
View File

@ -762,7 +762,6 @@ pub const InitOptions = struct {
linker_z_notext: bool = false,
linker_z_defs: bool = false,
linker_z_origin: bool = false,
linker_z_noexecstack: bool = false,
linker_z_now: bool = true,
linker_z_relro: bool = true,
linker_z_nocopyreloc: bool = false,
@ -1602,7 +1601,6 @@ pub fn create(gpa: Allocator, options: InitOptions) !*Compilation {
.z_defs = options.linker_z_defs,
.z_origin = options.linker_z_origin,
.z_nocopyreloc = options.linker_z_nocopyreloc,
.z_noexecstack = options.linker_z_noexecstack,
.z_now = options.linker_z_now,
.z_relro = options.linker_z_relro,
.tsaware = options.linker_tsaware,
@ -2350,7 +2348,6 @@ fn addNonIncrementalStuffToCacheManifest(comp: *Compilation, man: *Cache.Manifes
man.hash.add(comp.bin_file.options.z_defs);
man.hash.add(comp.bin_file.options.z_origin);
man.hash.add(comp.bin_file.options.z_nocopyreloc);
man.hash.add(comp.bin_file.options.z_noexecstack);
man.hash.add(comp.bin_file.options.z_now);
man.hash.add(comp.bin_file.options.z_relro);
man.hash.add(comp.bin_file.options.hash_style);

1
src/link.zig
View File

@ -113,7 +113,6 @@ pub const Options = struct {
z_defs: bool,
z_origin: bool,
z_nocopyreloc: bool,
z_noexecstack: bool,
z_now: bool,
z_relro: bool,
tsaware: bool,

5
src/link/Elf.zig
View File

@ -1333,7 +1333,6 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v
man.hash.add(self.base.options.z_defs);
man.hash.add(self.base.options.z_origin);
man.hash.add(self.base.options.z_nocopyreloc);
man.hash.add(self.base.options.z_noexecstack);
man.hash.add(self.base.options.z_now);
man.hash.add(self.base.options.z_relro);
man.hash.add(self.base.options.hash_style);
@ -1512,10 +1511,6 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v
try argv.append("-z");
try argv.append("nocopyreloc");
}
if (self.base.options.z_noexecstack) {
try argv.append("-z");
try argv.append("noexecstack");
}
if (self.base.options.z_now) {
// LLD defaults to -zlazy
try argv.append("-znow");

7
src/main.zig
View File

@ -433,7 +433,6 @@ const usage_build_generic =
\\ defs Force a fatal error if any undefined symbols remain
\\ origin Indicate that the object must have its origin processed
\\ nocopyreloc Disable the creation of copy relocations
\\ noexecstack Indicate that the object requires an executable stack
\\ now (default) Force all relocations to be processed on load
\\ lazy Don't force all relocations to be processed on load
\\ relro (default) Force all relocations to be read-only after processing
@ -656,7 +655,6 @@ fn buildOutputType(
var linker_z_notext = false;
var linker_z_defs = false;
var linker_z_origin = false;
var linker_z_noexecstack = false;
var linker_z_now = true;
var linker_z_relro = true;
var linker_tsaware = false;
@ -1207,8 +1205,6 @@ fn buildOutputType(
linker_z_defs = true;
} else if (mem.eql(u8, z_arg, "origin")) {
linker_z_origin = true;
} else if (mem.eql(u8, z_arg, "noexecstack")) {
linker_z_noexecstack = true;
} else if (mem.eql(u8, z_arg, "now")) {
linker_z_now = true;
} else if (mem.eql(u8, z_arg, "lazy")) {
@ -1694,7 +1690,7 @@ fn buildOutputType(
} else if (mem.eql(u8, z_arg, "origin")) {
linker_z_origin = true;
} else if (mem.eql(u8, z_arg, "noexecstack")) {
linker_z_noexecstack = true;
// noexecstack is the default when linking with LLD
} else if (mem.eql(u8, z_arg, "now")) {
linker_z_now = true;
} else if (mem.eql(u8, z_arg, "lazy")) {
@ -2719,7 +2715,6 @@ fn buildOutputType(
.linker_z_notext = linker_z_notext,
.linker_z_defs = linker_z_defs,
.linker_z_origin = linker_z_origin,
.linker_z_noexecstack = linker_z_noexecstack,
.linker_z_now = linker_z_now,
.linker_z_relro = linker_z_relro,
.linker_tsaware = linker_tsaware,