Rollup merge of rust-lang#156548 - jchlanda:jakub/pac_lib, r=davidtwco

 Library support for aarch64-unknown-linux-pauthtest target

This is a follow up to rust-lang#155722, adding library support for the target.

Author: JonathanBrouwer

library/std/src/sys/personality/gcc.rs

@@ -204,6 +204,35 @@ cfg_select! {
         }
     }
     _ => {
+        #[rustc_force_inline]
+        unsafe fn sign_lpad(context: *mut uw::_Unwind_Context, lpad: *const u8) -> *const u8 {
+            cfg_select! {
+                all(target_abi = "pauthtest", target_arch = "aarch64") => {
+                    // DWARF register number for SP on AArch64.
+                    const SP_REG: i32 = 31;
+
+                    unsafe {
+                        let sp = uw::_Unwind_GetGR(context, SP_REG).addr() as u64;
+                        let mut addr = lpad.addr();
+
+                        // `pacib` corresponds to `ptrauth_key_process_dependent_code` in <ptrauth.h>.
+                        core::arch::asm!(
+                            "pacib {addr}, {sp}",
+                            addr = inout(reg) addr,
+                            sp = in(reg) sp,
+                            options(nostack, preserves_flags)
+                        );
+
+                        lpad.with_addr(addr)
+                    }
+                }
+                _ => {
+                    let _ = context;
+                    lpad
+                }
+            }
+        }
+
         /// Default personality routine, which is used directly on most targets
         /// and indirectly on Windows x86_64 and AArch64 via SEH.
         unsafe extern "C" fn rust_eh_personality_impl(
@@ -239,7 +268,8 @@ cfg_select! {
                                 exception_object.cast(),
                             );
                             uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, core::ptr::null());
-                            uw::_Unwind_SetIP(context, lpad);
+                            let maybe_signed_lpad = sign_lpad(context, lpad);
+                            uw::_Unwind_SetIP(context, maybe_signed_lpad);
                             uw::_URC_INSTALL_CONTEXT
                         }
                         EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR,

library/std/tests/pipe_subprocess.rs

@@ -13,10 +13,16 @@ fn main() {
 
         fn parent() {
             let me = env::current_exe().unwrap();
+            // If a custom `runner` is set up for the current target, we'll be
+            // executing `./runner ./test`, not just `./test`. For such a case,
+            // use the same arguments for child to avoid executing `runner`
+            // without an actual executable.
+            let args = env::args();
 
             let (rx, tx) = pipe().unwrap();
             assert!(
                 process::Command::new(me)
+                    .args(args)
                     .env("I_AM_THE_CHILD", "1")
                     .stdout(tx)
                     .status()

library/std/tests/process_spawning.rs

@@ -26,8 +26,16 @@ fn issue_15149() {
         env::join_paths(paths).unwrap()
     };
 
-    let child_output =
-        process::Command::new("mytest").env("PATH", &path).arg("child").output().unwrap();
+    // If a custom `runner` is set up for the current target, we'll be executing `./runner ./test`,
+    // not just `./test`. For such a case, use the same arguments for child to avoid executing
+    // `runner` without an actual executable.
+    let args = env::args();
+    let child_output = process::Command::new("mytest")
+        .args(args)
+        .env("PATH", &path)
+        .arg("child")
+        .output()
+        .unwrap();
 
     assert!(
         child_output.status.success(),

library/unwind/src/lib.rs

@@ -56,7 +56,14 @@ cfg_select! {
     }
 }
 
-#[cfg(target_env = "musl")]
+// `target_abi = "pauthtest"` is currently only used by the Linux/musl
+// `aarch64-unknown-linux-pauthtest` target. That target only supports unwinding
+// via libunwind.
+#[cfg(target_abi = "pauthtest")]
+#[link(name = "unwind")]
+unsafe extern "C" {}
+
+#[cfg(all(target_env = "musl", not(target_abi = "pauthtest")))]
 cfg_select! {
     all(feature = "llvm-libunwind", feature = "system-llvm-libunwind") => {
         compile_error!("`llvm-libunwind` and `system-llvm-libunwind` cannot be enabled at the same time");