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start: Don't artificially limit some posixCallMainAndExit() logic to Linux.

Browse source 
This code applies to ~any POSIX OS where we don't link libc. For example, it'll
be useful for FreeBSD and NetBSD.

As part of this, move std.os.linux.pie to std.pie since there's really nothing
Linux-specific about what that file is doing.
This commit is contained in:
Alex Rønne Petersen 2025-05-18 02:01:37 +02:00
parent 8e72a25285
commit 74a3ae4927
4 changed files with 38 additions and 38 deletions
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1
lib/std/os/linux.zig
View file

@ -115,7 +115,6 @@ pub const user_desc = arch_bits.user_desc;
pub const getcontext = arch_bits.getcontext;
pub const tls = @import("linux/tls.zig");
pub const pie = @import("linux/pie.zig");
pub const BPF = @import("linux/bpf.zig");
pub const IOCTL = @import("linux/ioctl.zig");
pub const SECCOMP = @import("linux/seccomp.zig");

0
lib/std/os/linux/pie.zig → lib/std/pie.zig
View file

74
lib/std/start.zig
View file

@ -325,7 +325,7 @@ fn _start() callconv(.naked) noreturn {
,
.csky =>
// The CSKY ABI assumes that `gb` is set to the address of the GOT in order for
// position-independent code to work. We depend on this in `std.os.linux.pie` to locate
// position-independent code to work. We depend on this in `std.pie` to locate
// `_DYNAMIC` as well.
// r8 = FP
\\ grs t0, 1f
@ -514,33 +514,33 @@ fn posixCallMainAndExit(argc_argv_ptr: [*]usize) callconv(.c) noreturn {
while (envp_optional[envp_count]) |_| : (envp_count += 1) {}
const envp = @as([*][*:0]u8, @ptrCast(envp_optional))[0..envp_count];
if (native_os == .linux) {
// Find the beginning of the auxiliary vector
const auxv: [*]elf.Auxv = @ptrCast(@alignCast(envp.ptr + envp_count + 1));
// Find the beginning of the auxiliary vector
const auxv: [*]elf.Auxv = @ptrCast(@alignCast(envp.ptr + envp_count + 1));
var at_hwcap: usize = 0;
const phdrs = init: {
var i: usize = 0;
var at_phdr: usize = 0;
var at_phnum: usize = 0;
while (auxv[i].a_type != elf.AT_NULL) : (i += 1) {
switch (auxv[i].a_type) {
elf.AT_PHNUM => at_phnum = auxv[i].a_un.a_val,
elf.AT_PHDR => at_phdr = auxv[i].a_un.a_val,
elf.AT_HWCAP => at_hwcap = auxv[i].a_un.a_val,
else => continue,
}
var at_hwcap: usize = 0;
const phdrs = init: {
var i: usize = 0;
var at_phdr: usize = 0;
var at_phnum: usize = 0;
while (auxv[i].a_type != elf.AT_NULL) : (i += 1) {
switch (auxv[i].a_type) {
elf.AT_PHNUM => at_phnum = auxv[i].a_un.a_val,
elf.AT_PHDR => at_phdr = auxv[i].a_un.a_val,
elf.AT_HWCAP => at_hwcap = auxv[i].a_un.a_val,
else => continue,
}
break :init @as([*]elf.Phdr, @ptrFromInt(at_phdr))[0..at_phnum];
};
// Apply the initial relocations as early as possible in the startup process. We cannot
// make calls yet on some architectures (e.g. MIPS) *because* they haven't been applied yet,
// so this must be fully inlined.
if (builtin.position_independent_executable) {
@call(.always_inline, std.os.linux.pie.relocate, .{phdrs});
}
break :init @as([*]elf.Phdr, @ptrFromInt(at_phdr))[0..at_phnum];
};
// Apply the initial relocations as early as possible in the startup process. We cannot
// make calls yet on some architectures (e.g. MIPS) *because* they haven't been applied yet,
// so this must be fully inlined.
if (builtin.position_independent_executable) {
@call(.always_inline, std.pie.relocate, .{phdrs});
}
if (native_os == .linux) {
// This must be done after PIE relocations have been applied or we may crash
// while trying to access the global variable (happens on MIPS at least).
std.os.linux.elf_aux_maybe = auxv;
@ -567,20 +567,20 @@ fn posixCallMainAndExit(argc_argv_ptr: [*]usize) callconv(.c) noreturn {
// Here we look for the stack size in our program headers and use setrlimit
// to ask for more stack space.
expandStackSize(phdrs);
}
const opt_init_array_start = @extern([*]*const fn () callconv(.c) void, .{
.name = "__init_array_start",
.linkage = .weak,
});
const opt_init_array_end = @extern([*]*const fn () callconv(.c) void, .{
.name = "__init_array_end",
.linkage = .weak,
});
if (opt_init_array_start) |init_array_start| {
const init_array_end = opt_init_array_end.?;
const slice = init_array_start[0 .. init_array_end - init_array_start];
for (slice) |func| func();
}
const opt_init_array_start = @extern([*]*const fn () callconv(.c) void, .{
.name = "__init_array_start",
.linkage = .weak,
});
const opt_init_array_end = @extern([*]*const fn () callconv(.c) void, .{
.name = "__init_array_end",
.linkage = .weak,
});
if (opt_init_array_start) |init_array_start| {
const init_array_end = opt_init_array_end.?;
const slice = init_array_start[0 .. init_array_end - init_array_start];
for (slice) |func| func();
}
std.posix.exit(callMainWithArgs(argc, argv, envp));

1
lib/std/std.zig
View file

@ -79,6 +79,7 @@ pub const net = @import("net.zig");
pub const os = @import("os.zig");
pub const once = @import("once.zig").once;
pub const pdb = @import("pdb.zig");
pub const pie = @import("pie.zig");
pub const posix = @import("posix.zig");
pub const process = @import("process.zig");
pub const sort = @import("sort.zig");