chore: Fix clippy panic_handler warnings

Working with aya in vscode will currently show a number of warnings
along the lines of:

```
found duplicate lang item `panic_impl`
the lang item is first defined in crate `std` (which `aya` depends on)
...
second definition in the local crate (`bpf_probe_read`)
```

This comes from feature unification.
integration-test requires the integration-common user feature, which
requires aya, which in turn brings in std.

For this same reason we avoid running clippy across the whole workspace.

We can avoid this issue by using the panic handler from the panic_halt
crate, which implements the same loop {} panic handler we use today.

However, it seems rustc is happy to conditionally link the panic handler
from an external crate without issuing warnings.

Signed-off-by: Dave Tucker <dave@dtucker.co.uk>

Cargo.toml

@@ -80,11 +80,13 @@ indoc = { version = "2.0", default-features = false }
 libc = { version = "0.2.105", default-features = false }
 log = { version = "0.4", default-features = false }
 netns-rs = { version = "0.1", default-features = false }
+network-types = { version = "0.0.7", default-features = false }
 nix = { version = "0.29.0", default-features = false }
 num_enum = { version = "0.7", default-features = false }
 object = { version = "0.36", default-features = false }
 octorust = { version = "0.10", default-features = false }
 once_cell = { version = "1.20.1", default-features = false }
+panic-halt = { version = "1", default-features = false }
 proc-macro2 = { version = "1", default-features = false }
 proc-macro2-diagnostics = { version = "0.10.1", default-features = false }
 public-api = { version = "0.44.0", default-features = false }

clippy.sh

@@ -2,11 +2,6 @@
 
 set -eux
 
-# We cannot run clippy over the whole workspace at once due to feature unification. Since both
-# integration-test and integration-ebpf depend on integration-common and integration-test activates
-# integration-common's aya dependency, we end up trying to compile the panic handler twice: once
-# from the bpf program, and again from std via aya.
-# 
 # `-C panic=abort` because "unwinding panics are not supported without std"; integration-ebpf
 # contains `#[no_std]` binaries.
 # 
@@ -16,5 +11,4 @@ set -eux
 # unwinding behavior.
 # 
 # `+nightly` because "the option `Z` is only accepted on the nightly compiler".
-cargo +nightly hack clippy "$@" --exclude integration-ebpf --all-targets --feature-powerset --workspace -- --deny warnings
-cargo +nightly hack clippy "$@" --package integration-ebpf --all-targets --feature-powerset -- --deny warnings -C panic=abort -Zpanic_abort_tests
+cargo +nightly hack clippy "$@" --all-targets --feature-powerset -- --deny warnings -C panic=abort -Zpanic_abort_tests

test/integration-ebpf/Cargo.toml

@@ -17,7 +17,8 @@ workspace = true
 aya-ebpf = { path = "../../ebpf/aya-ebpf" }
 aya-log-ebpf = { path = "../../ebpf/aya-log-ebpf" }
 integration-common = { path = "../integration-common" }
-network-types = "0.0.7"
+network-types = { workspace = true }
+panic-halt = { workspace = true }
 
 [build-dependencies]
 which = { workspace = true }

test/integration-ebpf/src/bpf_probe_read.rs

@@ -8,6 +8,8 @@ use aya_ebpf::{
     programs::ProbeContext,
 };
 use integration_common::bpf_probe_read::{RESULT_BUF_LEN, TestResult};
+#[cfg(not(test))]
+use panic_halt as _;
 
 fn read_str_bytes(
     fun: unsafe fn(*const u8, &mut [u8]) -> Result<&[u8], i64>,
@@ -71,9 +73,3 @@ pub fn test_bpf_probe_read_kernel_str_bytes(ctx: ProbeContext) {
         ctx.arg::<usize>(0),
     );
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/log.rs

@@ -5,6 +5,8 @@ use core::net::{IpAddr, Ipv4Addr, Ipv6Addr};
 
 use aya_ebpf::{macros::uprobe, programs::ProbeContext};
 use aya_log_ebpf::{debug, error, info, trace, warn};
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[uprobe]
 pub fn test_log(ctx: ProbeContext) {
@@ -81,9 +83,3 @@ pub fn test_log(ctx: ProbeContext) {
         debug!(&ctx, "{:x}", no_copy.consume());
     }
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/map_test.rs

@@ -9,6 +9,8 @@ use aya_ebpf::{
     maps::{Array, HashMap},
     programs::SkBuffContext,
 };
+#[cfg(not(test))]
+use panic_halt as _;
 
 // Introduced in kernel v3.19.
 #[map]
@@ -35,9 +37,3 @@ pub fn simple_prog(_ctx: SkBuffContext) -> i64 {
 
     0
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/memmove_test.rs

@@ -13,6 +13,8 @@ use network_types::{
     eth::{EthHdr, EtherType},
     ip::Ipv6Hdr,
 };
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[inline(always)]
 fn ptr_at<T>(ctx: &XdpContext, offset: usize) -> Result<*const T, ()> {
@@ -53,9 +55,3 @@ fn try_do_dnat(ctx: XdpContext) -> Result<u32, ()> {
     }
     Ok(xdp_action::XDP_PASS)
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/name_test.rs

@@ -2,6 +2,8 @@
 #![no_main]
 
 use aya_ebpf::{bindings::xdp_action, macros::xdp, programs::XdpContext};
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[xdp]
 pub fn ihaveaverylongname(ctx: XdpContext) -> u32 {
@@ -14,9 +16,3 @@ pub fn ihaveaverylongname(ctx: XdpContext) -> u32 {
 unsafe fn try_pass(_ctx: XdpContext) -> Result<u32, u32> {
     Ok(xdp_action::XDP_PASS)
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/pass.rs

@@ -2,6 +2,8 @@
 #![no_main]
 
 use aya_ebpf::{bindings::xdp_action, macros::xdp, programs::XdpContext};
+#[cfg(not(test))]
+use panic_halt as _;
 
 // Note: the `frags` attribute causes this probe to be incompatible with kernel versions < 5.18.0.
 // See https://github.com/torvalds/linux/commit/c2f2cdb.
@@ -16,9 +18,3 @@ pub fn pass(ctx: XdpContext) -> u32 {
 unsafe fn try_pass(_ctx: XdpContext) -> Result<u32, u32> {
     Ok(xdp_action::XDP_PASS)
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/raw_tracepoint.rs

@@ -7,6 +7,8 @@ use aya_ebpf::{
     programs::RawTracePointContext,
 };
 use integration_common::raw_tracepoint::SysEnterEvent;
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[map]
 static RESULT: Array<SysEnterEvent> = Array::with_max_entries(1, 0);
@@ -25,9 +27,3 @@ pub fn sys_enter(ctx: RawTracePointContext) -> i32 {
 
     0
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/redirect.rs

@@ -7,6 +7,8 @@ use aya_ebpf::{
     maps::{Array, CpuMap, DevMap, DevMapHash, XskMap},
     programs::XdpContext,
 };
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[map]
 static SOCKS: XskMap = XskMap::with_max_entries(1, 0);
@@ -74,9 +76,3 @@ fn inc_hit(index: u32) {
         unsafe { *hit += 1 };
     }
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/relocations.rs

@@ -8,6 +8,8 @@ use aya_ebpf::{
     maps::Array,
     programs::ProbeContext,
 };
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[map]
 static RESULTS: Array<u64> = Array::with_max_entries(3, 0);
@@ -38,9 +40,3 @@ fn set_result(index: u32, value: u64) {
 fn set_result_backward(index: u32, value: u64) {
     set_result(index, value);
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/ring_buf.rs

@@ -7,6 +7,8 @@ use aya_ebpf::{
     programs::ProbeContext,
 };
 use integration_common::ring_buf::Registers;
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[map]
 static RING_BUF: RingBuf = RingBuf::with_byte_size(0, 0);
@@ -45,9 +47,3 @@ pub fn ring_buf_test(ctx: ProbeContext) {
         entry.discard(0);
     }
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/simple_prog.rs

@@ -5,15 +5,11 @@
 #![no_main]
 
 use aya_ebpf::{macros::socket_filter, programs::SkBuffContext};
+#[cfg(not(test))]
+use panic_halt as _;
 
 // Introduced in kernel v3.19.
 #[socket_filter]
 pub fn simple_prog(_ctx: SkBuffContext) -> i64 {
     0
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/strncmp.rs

@@ -9,6 +9,8 @@ use aya_ebpf::{
     programs::ProbeContext,
 };
 use integration_common::strncmp::TestResult;
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[map]
 static RESULT: Array<TestResult> = Array::with_max_entries(1, 0);
@@ -26,9 +28,3 @@ pub fn test_bpf_strncmp(ctx: ProbeContext) -> Result<(), c_long> {
 
     Ok(())
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/tcx.rs

@@ -2,14 +2,10 @@
 #![no_main]
 
 use aya_ebpf::{bindings::tcx_action_base::TCX_NEXT, macros::classifier, programs::TcContext};
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[classifier]
 pub fn tcx_next(_ctx: TcContext) -> i32 {
     TCX_NEXT
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/test.rs

@@ -8,6 +8,8 @@ use aya_ebpf::{
         FlowDissectorContext, ProbeContext, RetProbeContext, TracePointContext, XdpContext,
     },
 };
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[xdp]
 pub fn pass(ctx: XdpContext) -> u32 {
@@ -52,9 +54,3 @@ pub fn test_flow(_ctx: FlowDissectorContext) -> u32 {
     // Linux kernel for inspiration.
     bpf_ret_code::BPF_FLOW_DISSECTOR_CONTINUE
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/two_progs.rs

@@ -4,6 +4,8 @@
 #![no_main]
 
 use aya_ebpf::{macros::tracepoint, programs::TracePointContext};
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[tracepoint]
 pub fn test_tracepoint_one(_ctx: TracePointContext) -> u32 {
@@ -13,9 +15,3 @@ pub fn test_tracepoint_one(_ctx: TracePointContext) -> u32 {
 pub fn test_tracepoint_two(_ctx: TracePointContext) -> u32 {
     0
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/uprobe_cookie.rs

@@ -7,6 +7,8 @@ use aya_ebpf::{
     maps::RingBuf,
     programs::ProbeContext,
 };
+#[cfg(not(test))]
+use panic_halt as _;
 
 #[map]
 static RING_BUF: RingBuf = RingBuf::with_byte_size(0, 0);
@@ -17,9 +19,3 @@ pub fn uprobe_cookie(ctx: ProbeContext) {
     let cookie_bytes = cookie.to_le_bytes();
     let _res = RING_BUF.output(&cookie_bytes, 0);
 }
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}

test/integration-ebpf/src/xdp_sec.rs

@@ -2,6 +2,8 @@
 #![no_main]
 
 use aya_ebpf::{bindings::xdp_action::XDP_PASS, macros::xdp, programs::XdpContext};
+#[cfg(not(test))]
+use panic_halt as _;
 
 macro_rules! probe {
     ($name:ident, ($($arg:ident $(= $value:literal)?),*) ) => {
@@ -18,9 +20,3 @@ probe!(xdp_cpumap, (map = "cpumap"));
 probe!(xdp_devmap, (map = "devmap"));
 probe!(xdp_frags_cpumap, (frags, map = "cpumap"));
 probe!(xdp_frags_devmap, (frags, map = "devmap"));
-
-#[cfg(not(test))]
-#[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {}
-}