ci: Fix bpf-linker installation on macOS

LLVM 19 is not packaged in brew or any other package repository for
macOS. Use LLVM tarball from Rust CI instead, to make sure we use the
newest LLVM.

Also, install LLVM 19 on Linux for consistency.

Co-authored-by: tyrone-wu <wudevelops@gmail.com>

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ on:
 
 env:
   CARGO_TERM_COLOR: always
-  LLVM_VERSION: 18
+  LLVM_VERSION: 19
 
 jobs:
   lint:
@@ -183,19 +183,51 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        runner:
+        include:
           # macos-14 is arm64 per
           # https://github.com/actions/runner-images#available-images which
           # doesn't support nested virtualization per
           # https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners/about-github-hosted-runners#limitations-for-arm64-macos-runners
-          - macos-13
-          - ubuntu-22.04
-    runs-on: ${{ matrix.runner }}
+          - target: x86_64-apple-darwin
+            os: macos-13
+          - target: x86_64-unknown-linux-gnu
+            os: ubuntu-22.04
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
         with:
           submodules: recursive
 
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+          components: rust-src
+          targets: aarch64-unknown-linux-musl,x86_64-unknown-linux-musl
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Install LLVM
+        run: |
+          set -euxo pipefail
+          # Use LLVM tarball from Rust CI, for two reasons:
+          #
+          # - LLVM packaged in brew or any other package repository for macOS
+          #   is usually too old for bpf-linker.
+          # - Packages from apt.llvm.org, even though they follow new LLVM
+          #   releases, are are often buggy.
+
+          # Get the partial SHA from Rust nightly.
+          rustc_sha=$(rustc +nightly --version | grep -oE '[a-f0-9]{7,40}')
+          # Get the full SHA from GitHub.
+          rustc_sha=$(curl -s https://api.github.com/repos/rust-lang/rust/commits/$rustc_sha \
+            --header 'authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' \
+            --header 'content-type: application/json' \
+            | jq -r '.sha')
+          mkdir -p /usr/local/lib/rustc-llvm
+          wget -q -O - https://ci-artifacts.rust-lang.org/rustc-builds/$rustc_sha/rust-dev-nightly-${{ matrix.target }}.tar.xz | \
+            tar -xJ --strip-components 2 -C /usr/local/lib/rustc-llvm
+          echo /usr/local/lib/rust-llvm >> $GITHUB_PATH
+
       - name: Install prerequisites
         if: runner.os == 'Linux'
         # ubuntu-22.04 comes with clang 14[0] which doesn't include support for signed and 64bit
@@ -210,11 +242,8 @@ jobs:
         # [1] https://github.com/llvm/llvm-project/commit/dc1c43d
         run: |
           set -euxo pipefail
-          wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | sudo tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc
-          echo deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-${{ env.LLVM_VERSION }} main | sudo tee /etc/apt/sources.list.d/llvm.list
           sudo apt update
-          sudo apt -y install clang-${{ env.LLVM_VERSION }} gcc-multilib llvm-${{ env.LLVM_VERSION }} locate qemu-system-{arm,x86}
-          echo /usr/lib/llvm-${{ env.LLVM_VERSION }}/bin >> $GITHUB_PATH
+          sudo apt -y install gcc-multilib locate qemu-system-{arm,x86}
 
       - name: bpf-linker
         if: runner.os == 'Linux'
@@ -227,32 +256,23 @@ jobs:
         # The tar shipped on macOS doesn't support --wildcards, so we need GNU tar.
         #
         # The clang shipped on macOS doesn't support BPF, so we need LLVM from brew.
-        #
-        # We also need LLVM for bpf-linker, see comment below.
         run: |
           set -euxo pipefail
           brew update
           # https://github.com/actions/setup-python/issues/577
           find /usr/local/bin -type l -exec sh -c 'readlink -f "$1" \
           | grep -q ^/Library/Frameworks/Python.framework/Versions/' _ {} \; -exec rm -v {} \;
           HOMEBREW_NO_INSTALLED_DEPENDENTS_CHECK=1 \
-          brew install dpkg findutils gnu-tar llvm pkg-config qemu
+          brew install dpkg findutils gnu-tar llvm pkg-config qemu          
           echo $(brew --prefix)/opt/findutils/libexec/gnubin >> $GITHUB_PATH
           echo $(brew --prefix)/opt/gnu-tar/libexec/gnubin >> $GITHUB_PATH
           echo $(brew --prefix)/opt/llvm/bin >> $GITHUB_PATH
 
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: nightly
-          components: rust-src
-          targets: aarch64-unknown-linux-musl,x86_64-unknown-linux-musl
-
-      - uses: Swatinem/rust-cache@v2
-
       - name: bpf-linker
         if: runner.os == 'macOS'
         # NB: rustc doesn't ship libLLVM.so on macOS, so disable proxying (default feature). We also
-        # --force so that bpf-linker gets always relinked against the latest LLVM installed by brew.
+        # --force so that bpf-linker gets always relinked against the latest LLVM from the latest
+        # LLVM downloaded above.
         run: cargo install --force bpf-linker --git https://github.com/aya-rs/bpf-linker.git --no-default-features
 
       - name: Download debian kernels

test/integration-ebpf/src/test.rs

@@ -3,8 +3,10 @@
 
 use aya_ebpf::{
     bindings::xdp_action,
+    bpf_printk,
     macros::{kprobe, kretprobe, tracepoint, uprobe, uretprobe, xdp},
     programs::{ProbeContext, RetProbeContext, TracePointContext, XdpContext},
+    EbpfContext,
 };
 
 #[xdp]
@@ -30,8 +32,20 @@ pub fn test_kretprobe(_ctx: RetProbeContext) -> u32 {
 }
 
 #[tracepoint]
-pub fn test_tracepoint(_ctx: TracePointContext) -> u32 {
-    0
+pub fn test_tracepoint(ctx: TracePointContext) -> u32 {
+    // Some arbitrary work, to make the program running for some time and have
+    // a real `run_time` in `test_program_info`.
+    let mut res = ctx.uid().wrapping_add(ctx.pid());
+    for _ in 0..10_000 {
+        res = res.wrapping_mul(123);
+        res ^= (ctx.pid() << 3) ^ (ctx.uid() << 4);
+        res = res.rotate_left(2);
+        res = res.reverse_bits();
+        res = res.swap_bytes();
+        res = res.count_ones();
+        unsafe { bpf_printk!(b"number %u", res) };
+    }
+    res
 }
 
 #[uprobe]

test/integration-test/src/tests/info.rs

@@ -214,6 +214,12 @@ fn test_prog_stats() {
         .unwrap();
     prog.load().unwrap();
     prog.attach("syscalls", "sys_enter_bpf").unwrap();
+
+    // Executing bpf syscalls to trigger `sys_enter_bpf`
+    for _ in 0..5 {
+        let _ = loaded_programs().collect::<Vec<_>>();
+    }
+
     let test_prog = prog.info().unwrap();
 
     kernel_assert!(