Rename rustix_int_0x80 and protect it from multiple definitions. (#1396)

* Rename `rustix_int_0x80` and protect it from multiple definitions.

In lto builds, multiple versions of the `rustix_int_0x80` assembly code
can be included in the same .s file. To avoid conflicts when one of them
comes from an older version of rustix, rename the symbol to
`rustix_x86_int_0x80`, and to avoid conflicts with future versions, enclose
the code in an `ifndef` block.

Fixes #1394.

* Fix compilation of tests/event/port.rs

When libc/extra_trais is not enabled, `libc::timespec` does not have a
`PartialEq` implementation, so compare the fields directly.

Author: sunfishcode

src/backend/linux_raw/vdso_wrappers.rs

@@ -410,29 +410,34 @@ unsafe extern "C" fn getcpu_via_syscall(
 
 #[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.
+    /// A symbol pointing to an x86 `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();
+    fn rustix_x86_int_0x80();
 }
 
+// This uses `.weak` so that it doesn't conflict if multiple versions of rustix
+// are linked in in non-lto builds, and `.ifndef` so that it doesn't conflict
+// if multiple versions of rustix are linked in in lto builds.
 #[cfg(target_arch = "x86")]
 global_asm!(
     r#"
-    .section    .text.rustix_int_0x80,"ax",@progbits
+    .ifndef     rustix_x86_int_0x80
+    .section    .text.rustix_x86_int_0x80,"ax",@progbits
     .p2align    4
-    .weak       rustix_int_0x80
-    .hidden     rustix_int_0x80
-    .type       rustix_int_0x80, @function
-rustix_int_0x80:
+    .weak       rustix_x86_int_0x80
+    .hidden     rustix_x86_int_0x80
+    .type       rustix_x86_int_0x80, @function
+rustix_x86_int_0x80:
     .cfi_startproc
     int    0x80
     ret
     .cfi_endproc
-    .size rustix_int_0x80, .-rustix_int_0x80
+    .size rustix_x86_int_0x80, .-rustix_x86_int_0x80
+    .endif
 "#
 );
 
@@ -478,7 +483,7 @@ fn minimal_init() {
         SYSCALL
             .compare_exchange(
                 null_mut(),
-                rustix_int_0x80 as *mut Function,
+                rustix_x86_int_0x80 as *mut Function,
                 Relaxed,
                 Relaxed,
             )

tests/event/port.rs

@@ -37,7 +37,10 @@ fn test_port_timeout_assumption() {
         assert_eq!(libc_errno::errno().0, libc::ETIME);
         assert_eq!(r, -1);
 
-        assert_eq!(timeout, orig_timeout);
+        assert_eq!(
+            (timeout.tv_sec, timeout.tv_nsec),
+            (orig_timeout.tv_sec, orig_timeout.tv_nsec)
+        );
     }
 }
 
@@ -72,7 +75,10 @@ fn test_port_event_assumption() {
         let r = libc::port_get(port, &mut event, &mut timeout);
         assert_ne!(r, -1);
 
-        assert_eq!(timeout, orig_timeout);
+        assert_eq!(
+            (timeout.tv_sec, timeout.tv_nsec),
+            (orig_timeout.tv_sec, orig_timeout.tv_nsec)
+        );
         assert_eq!(event.portev_user, 7 as *mut c_void);
     }
 }
@@ -154,7 +160,10 @@ fn test_port_delay_assumption() {
             let r = libc::port_get(port, &mut event, &mut timeout);
             assert_ne!(r, -1, "port_get: {:?}", std::io::Error::last_os_error());
 
-            assert_eq!(timeout, orig_timeout);
+            assert_eq!(
+                (timeout.tv_sec, timeout.tv_nsec),
+                (orig_timeout.tv_sec, orig_timeout.tv_nsec)
+            );
             assert_eq!(event.portev_user, (9 + i) as *mut c_void);
 
             let mut buf = [0_u8; 1];