Remove naked_functions feature usage for x86

Given that this function has no generics, it could easily use `global_asm!`
instead.

build.rs

@@ -83,14 +83,10 @@ fn main() {
  // x86 our asm support requires naked functions. On PowerPC and MIPS,
  // Rust's inline asm is considered experimental, so only use it if
  // `--cfg=rustix_use_experimental_asm` is given.
- if (arch != "x86" || has_feature("naked_functions"))
- && ((arch != "powerpc64" && arch != "mips" && arch != "mips64")
- || rustix_use_experimental_asm)
+ if (arch != "powerpc64" && arch != "mips" && arch != "mips64")
+ || rustix_use_experimental_asm
  {
  use_feature("asm");
- if arch == "x86" {
- use_feature("naked_functions");
- }
  if rustix_use_experimental_asm {
  use_feature("asm_experimental_arch");
  }

src/backend/linux_raw/vdso_wrappers.rs

@@ -12,8 +12,8 @@
 #[cfg(target_arch = "x86")]
 use super::reg::{ArgReg, RetReg, SyscallNumber, A0, A1, A2, A3, A4, A5, R0};
 use super::vdso;
-#[cfg(all(asm, target_arch = "x86"))]
-use core::arch::asm;
+#[cfg(target_arch = "x86")]
+use core::arch::global_asm;
 use core::mem::transmute;
 use core::ptr::null_mut;
 use core::sync::atomic::AtomicPtr;
@@ -310,21 +310,34 @@ unsafe fn _rustix_clock_gettime_via_syscall(
  ret(syscall!(__NR_clock_gettime, c_int(clockid), res))
 }
 
-/// A symbol pointing to an `int 0x80` instruction. This “function” is only
-/// called from assembly, and only with the x86 syscall calling convention,
-/// so its signature here is not its true signature.
-#[cfg(all(asm, target_arch = "x86"))]
-#[naked]
-unsafe extern "C" fn rustix_int_0x80() {
- asm!("int $$0x80", "ret", options(noreturn))
-}
-
-// The outline version of the `rustix_int_0x80` above.
-#[cfg(all(not(asm), target_arch = "x86"))]
+#[cfg(target_arch = "x86")]
 extern "C" {
+ /// A symbol pointing to an `int 0x80` instruction. This “function” is only
+ /// called from assembly, and only with the x86 syscall calling convention.
+ /// so its signature here is not its true signature.
+ ///
+ /// This extern block and the `global_asm!` below can be replaced with
+ /// `#[naked]` if it's stabilized.
  fn rustix_int_0x80();
 }
 
+#[cfg(target_arch = "x86")]
+global_asm!(
+ r#"
+ .section .text.rustix_int_0x80,"ax",@progbits
+ .p2align 4
+ .weak rustix_int_0x80
+ .hidden rustix_int_0x80
+ .type rustix_int_0x80, @function
+rustix_int_0x80:
+ .cfi_startproc
+ int 0x80
+ ret
+ .cfi_endproc
+ .size rustix_int_0x80, .-rustix_int_0x80
+"#
+);
+
 fn minimal_init() {
  // SAFETY: Store default function addresses in static storage so that if we
  // end up making any system calls while we read the vDSO, they'll work.

src/lib.rs

@@ -100,10 +100,6 @@
 #![cfg_attr(rustc_attrs, feature(rustc_attrs))]
 #![cfg_attr(doc_cfg, feature(doc_cfg))]
 #![cfg_attr(all(wasi_ext, target_os = "wasi", feature = "std"), feature(wasi_ext))]
-#![cfg_attr(
- all(linux_raw, naked_functions, target_arch = "x86"),
- feature(naked_functions)
-)]
 #![cfg_attr(core_ffi_c, feature(core_ffi_c))]
 #![cfg_attr(core_c_str, feature(core_c_str))]
 #![cfg_attr(alloc_c_string, feature(alloc_ffi))]