Revert "ci: remove cross toolchain"

Turns out this was actually being used through magic.

Remove mips since it is a tier 3 target that is only supported on
nightly and dtolnay/rust-toolchain doesn't seem to handle installing
targets without std.

Exclude xtask since it depends on `ring` which doesn't build on all
targets.

Fix compilation on armv7 which had rotted.

This reverts commit d92fc95c39773f08d8dbf95c21cd8c6d11bafa03.

.github/workflows/ci.yml

@@ -71,10 +71,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        bpf_target_arch:
+        arch:
           - aarch64-unknown-linux-gnu
           - armv7-unknown-linux-gnueabi
-          - mips-unknown-linux-gnu
           - powerpc64le-unknown-linux-gnu
           - riscv64gc-unknown-linux-gnu
           - s390x-unknown-linux-gnu
@@ -84,11 +83,18 @@ jobs:
       - uses: actions/checkout@v4
 
       - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: ${{ matrix.arch }}
 
       - uses: Swatinem/rust-cache@v2
 
       - uses: taiki-e/install-action@cargo-hack
 
+      # This is magic, it sets `$CARGO_BUILD_TARGET`.
+      - uses: taiki-e/setup-cross-toolchain-action@v1
+        with:
+          target: ${{ matrix.arch }}
+
       - name: Build
         run: |
           set -euxo pipefail
@@ -97,6 +103,7 @@ jobs:
             --exclude aya-ebpf-bindings \
             --exclude aya-log-ebpf \
             --exclude integration-ebpf \
+            --exclude xtask \
             --workspace
 
       - name: Test
@@ -110,6 +117,7 @@ jobs:
             --exclude aya-log-ebpf \
             --exclude integration-ebpf \
             --exclude integration-test \
+            --exclude xtask \
             --workspace
 
       - name: Doctests
@@ -124,6 +132,7 @@ jobs:
             --exclude init \
             --exclude integration-ebpf \
             --exclude integration-test \
+            --exclude xtask \
             --workspace
 
   build-test-aya-ebpf:

aya/src/sys/bpf.rs

@@ -1,6 +1,6 @@
 use std::{
     cmp,
-    ffi::{CStr, CString, c_char, c_long},
+    ffi::{CStr, CString, c_char},
     io, iter,
     mem::{self, MaybeUninit},
     os::fd::{AsFd as _, AsRawFd as _, BorrowedFd, FromRawFd as _, RawFd},
@@ -1079,7 +1079,7 @@ fn bpf_prog_load(attr: &mut bpf_attr) -> io::Result<crate::MockableFd> {
     unsafe { fd_sys_bpf(bpf_cmd::BPF_PROG_LOAD, attr) }
 }
 
-fn sys_bpf(cmd: bpf_cmd, attr: &mut bpf_attr) -> io::Result<c_long> {
+fn sys_bpf(cmd: bpf_cmd, attr: &mut bpf_attr) -> io::Result<i64> {
     syscall(Syscall::Ebpf { cmd, attr }).map_err(|(code, io_error)| {
         assert_eq!(code, -1);
         io_error

aya/src/sys/mod.rs

@@ -8,7 +8,7 @@ mod perf_event;
 mod fake;
 
 use std::{
-    ffi::{c_int, c_long, c_void},
+    ffi::{c_int, c_void},
     io,
     os::fd::{BorrowedFd, OwnedFd},
 };
@@ -23,7 +23,7 @@ pub(crate) use netlink::*;
 pub(crate) use perf_event::*;
 use thiserror::Error;
 
-pub(crate) type SysResult = Result<c_long, (c_long, io::Error)>;
+pub(crate) type SysResult = Result<i64, (i64, io::Error)>;
 
 #[cfg_attr(test, expect(dead_code))]
 #[derive(Debug)]
@@ -139,6 +139,9 @@ fn syscall(call: Syscall<'_>) -> SysResult {
                 }
             }
         };
+        // c_long is i32 on armv7.
+        #[allow(clippy::useless_conversion)]
+        let ret: i64 = ret.into();
 
         match ret {
             0.. => Ok(ret),