aya: enforce valid perf_event type & config combos

Add guardrails for when setting event type and config for perf_event
programs. The `PerfEventConfig` enum now defines the event `type` and
`config` of interest.

Remove public re-exports, and add idiomatic Rust types for:
- perf_hw_id => HardwareEvent
- perf_sw_ids => SoftwareEvent
- perf_hw_cache_id => HwCacheEvent
- perf_hw_cache_op_id => HwCacheOp
- perf_hw_cache_op_result_id => HwCacheResult

The motivation behind this is mainly for the `type` and `config` fields
of `bpf_link_info.perf_event.event`. The newly added enums are planned
to also be used in the `bpf_link_info` metadata.

Although `Breakpoint`/`PERF_TYPE_BREAKPOINT` variant exists, it is not
fully implemented. It's only usage at the moment is in link info.

aya/src/programs/mod.rs

@@ -98,7 +98,7 @@ pub use crate::programs::{
     links::{CgroupAttachMode, Link, LinkOrder},
     lirc_mode2::LircMode2,
     lsm::Lsm,
-    perf_event::{PerfEvent, PerfEventScope, PerfTypeId, SamplePolicy},
+    perf_event::{PerfEvent, PerfEventScope, SamplePolicy},
     probe::ProbeKind,
     raw_trace_point::RawTracePoint,
     sk_lookup::SkLookup,

aya/src/programs/perf_event.rs

@@ -2,13 +2,11 @@
 
 use std::os::fd::AsFd as _;
 
-pub use crate::generated::{
-    perf_hw_cache_id, perf_hw_cache_op_id, perf_hw_cache_op_result_id, perf_hw_id, perf_sw_ids,
-};
 use crate::{
     generated::{
         bpf_link_type,
         bpf_prog_type::BPF_PROG_TYPE_PERF_EVENT,
+        perf_hw_cache_id, perf_hw_cache_op_id, perf_hw_cache_op_result_id, perf_hw_id, perf_sw_ids,
         perf_type_id::{
             PERF_TYPE_BREAKPOINT, PERF_TYPE_HARDWARE, PERF_TYPE_HW_CACHE, PERF_TYPE_RAW,
             PERF_TYPE_SOFTWARE, PERF_TYPE_TRACEPOINT,
@@ -23,22 +21,195 @@ use crate::{
     sys::{bpf_link_get_info_by_fd, perf_event_open, SyscallError},
 };
 
-/// The type of perf event
-#[repr(u32)]
+/// The type of perf event and their respective configuration.
+#[doc(alias = "perf_type_id")]
 #[derive(Debug, Clone)]
-pub enum PerfTypeId {
-    /// PERF_TYPE_HARDWARE
-    Hardware = PERF_TYPE_HARDWARE as u32,
-    /// PERF_TYPE_SOFTWARE
-    Software = PERF_TYPE_SOFTWARE as u32,
-    /// PERF_TYPE_TRACEPOINT
-    TracePoint = PERF_TYPE_TRACEPOINT as u32,
-    /// PERF_TYPE_HW_CACHE
-    HwCache = PERF_TYPE_HW_CACHE as u32,
-    /// PERF_TYPE_RAW
-    Raw = PERF_TYPE_RAW as u32,
-    /// PERF_TYPE_BREAKPOINT
-    Breakpoint = PERF_TYPE_BREAKPOINT as u32,
+pub enum PerfEventConfig {
+    /// The hardware event to report.
+    #[doc(alias = "PERF_TYPE_HARDWARE")]
+    Hardware(HardwareEvent),
+    /// The software event to report.
+    #[doc(alias = "PERF_TYPE_SOFTWARE")]
+    Software(SoftwareEvent),
+    /// The kernel trace point event to report.
+    #[doc(alias = "PERF_TYPE_TRACEPOINT")]
+    TracePoint {
+        /// The ID of the tracing event. This can be obtained from
+        /// `/sys/kernel/debug/tracing/events/*/*/id` if `ftrace` is enabled in the kernel.
+        event_id: u64,
+    },
+    /// The hardware cache event to report.
+    #[doc(alias = "PERF_TYPE_HW_CACHE")]
+    HwCache {
+        /// The hardware cache event.
+        event: HwCacheEvent,
+        /// The hardware cache operation.
+        operation: HwCacheOp,
+        /// The hardware cache result of interest.
+        result: HwCacheResult,
+    },
+    /// The "raw" implementation-specific event to report.
+    #[doc(alias = "PERF_TYPE_RAW")]
+    Raw {
+        /// The "raw" event value, which is not covered by the "generalized" events. This is CPU
+        /// implementation defined events.
+        event_id: u64,
+    },
+    /// A hardware breakpoint.
+    ///
+    /// Note: this variant is not fully implemented at the moment.
+    // TODO: Variant not fully implemented due to additional `perf_event_attr` fields like
+    //       `bp_type`, `bp_addr`, etc.
+    #[doc(alias = "PERF_TYPE_BREAKPOINT")]
+    Breakpoint,
+    /// The dynamic PMU (Performance Monitor Unit) event to report.
+    ///
+    /// Available PMU's may be found under `/sys/bus/event_source/devices`.
+    Pmu {
+        /// The PMU type.
+        ///
+        /// This value can extracted from `/sys/bus/event_source/devices/*/type`.
+        pmu_type: u32,
+        /// The PMU config option.
+        ///
+        /// This value can extracted from `/sys/bus/event_source/devices/*/format/`, where the
+        /// `config:<value>` indicates the bit position to set.
+        ///
+        /// For example, `config:3` => `config = 1 << 3`.
+        config: u64,
+    },
+}
+
+/// The "generalized" hardware CPU events provided by the kernel.
+#[doc(alias = "perf_hw_id")]
+#[derive(Debug, Clone, Copy)]
+pub enum HardwareEvent {
+    /// The total CPU cycles.
+    #[doc(alias = "PERF_COUNT_HW_CPU_CYCLES")]
+    CpuCycles = perf_hw_id::PERF_COUNT_HW_CPU_CYCLES as isize,
+    /// Number of retired instructions.
+    #[doc(alias = "PERF_COUNT_HW_INSTRUCTIONS")]
+    Instructions = perf_hw_id::PERF_COUNT_HW_INSTRUCTIONS as isize,
+    /// Number of cache accesses.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_REFERENCES")]
+    CacheReferences = perf_hw_id::PERF_COUNT_HW_CACHE_REFERENCES as isize,
+    /// Number of cache misses.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_MISSES")]
+    CacheMisses = perf_hw_id::PERF_COUNT_HW_CACHE_MISSES as isize,
+    /// Number of retired branch instructions.
+    #[doc(alias = "PERF_COUNT_HW_BRANCH_INSTRUCTIONS")]
+    BranchInstructions = perf_hw_id::PERF_COUNT_HW_BRANCH_INSTRUCTIONS as isize,
+    /// Number of mispredicted branch instructions.
+    #[doc(alias = "PERF_COUNT_HW_BRANCH_MISSES")]
+    BranchMisses = perf_hw_id::PERF_COUNT_HW_BRANCH_MISSES as isize,
+    /// Number of bus cycles.
+    #[doc(alias = "PERF_COUNT_HW_BUS_CYCLES")]
+    BusCycles = perf_hw_id::PERF_COUNT_HW_BUS_CYCLES as isize,
+    /// Number of stalled cycles during issue.
+    #[doc(alias = "PERF_COUNT_HW_STALLED_CYCLES_FRONTEND")]
+    StalledCyclesFrontend = perf_hw_id::PERF_COUNT_HW_STALLED_CYCLES_FRONTEND as isize,
+    /// Number of stalled cycles during retirement.
+    #[doc(alias = "PERF_COUNT_HW_STALLED_CYCLES_BACKEND")]
+    StalledCyclesBackend = perf_hw_id::PERF_COUNT_HW_STALLED_CYCLES_BACKEND as isize,
+    /// The total CPU cycles, which is not affected by CPU frequency scaling.
+    #[doc(alias = "PERF_COUNT_HW_REF_CPU_CYCLES")]
+    RefCpuCycles = perf_hw_id::PERF_COUNT_HW_REF_CPU_CYCLES as isize,
+}
+
+/// The software-defined events provided by the kernel.
+#[doc(alias = "perf_sw_ids")]
+#[derive(Debug, Clone, Copy)]
+pub enum SoftwareEvent {
+    /// The CPU clock timer.
+    #[doc(alias = "PERF_COUNT_SW_CPU_CLOCK")]
+    CpuClock = perf_sw_ids::PERF_COUNT_SW_CPU_CLOCK as isize,
+    /// The clock count specific to the task that is running.
+    #[doc(alias = "PERF_COUNT_SW_TASK_CLOCK")]
+    TaskClock = perf_sw_ids::PERF_COUNT_SW_TASK_CLOCK as isize,
+    /// Number of page faults.
+    #[doc(alias = "PERF_COUNT_SW_PAGE_FAULTS")]
+    PageFaults = perf_sw_ids::PERF_COUNT_SW_PAGE_FAULTS as isize,
+    /// Numer of context switches.
+    #[doc(alias = "PERF_COUNT_SW_CONTEXT_SWITCHES")]
+    ContextSwitches = perf_sw_ids::PERF_COUNT_SW_CONTEXT_SWITCHES as isize,
+    /// Number of times the process has migrated to a new CPU.
+    #[doc(alias = "PERF_COUNT_SW_CPU_MIGRATIONS")]
+    CpuMigrations = perf_sw_ids::PERF_COUNT_SW_CPU_MIGRATIONS as isize,
+    /// Number of minor page faults.
+    #[doc(alias = "PERF_COUNT_SW_PAGE_FAULTS_MIN")]
+    PageFaultsMin = perf_sw_ids::PERF_COUNT_SW_PAGE_FAULTS_MIN as isize,
+    /// Number of major page faults.
+    #[doc(alias = "PERF_COUNT_SW_PAGE_FAULTS_MAJ")]
+    PageFaultsMaj = perf_sw_ids::PERF_COUNT_SW_PAGE_FAULTS_MAJ as isize,
+    /// Number of alignment faults.
+    #[doc(alias = "PERF_COUNT_SW_ALIGNMENT_FAULTS")]
+    AlignmentFaults = perf_sw_ids::PERF_COUNT_SW_ALIGNMENT_FAULTS as isize,
+    /// Number of emulation faults.
+    #[doc(alias = "PERF_COUNT_SW_EMULATION_FAULTS")]
+    EmulationFaults = perf_sw_ids::PERF_COUNT_SW_EMULATION_FAULTS as isize,
+    /// Placeholder event that counts nothing.
+    #[doc(alias = "PERF_COUNT_SW_DUMMY")]
+    Dummy = perf_sw_ids::PERF_COUNT_SW_DUMMY as isize,
+    /// Generates raw sample data from BPF.
+    #[doc(alias = "PERF_COUNT_SW_BPF_OUTPUT")]
+    BpfOutput = perf_sw_ids::PERF_COUNT_SW_BPF_OUTPUT as isize,
+    /// Number of context switches to a task when switching to a different cgroup.
+    #[doc(alias = "PERF_COUNT_SW_CGROUP_SWITCHES")]
+    CgroupSwitches = perf_sw_ids::PERF_COUNT_SW_CGROUP_SWITCHES as isize,
+}
+
+/// The hardware CPU cache events.
+#[doc(alias = "perf_hw_cache_id")]
+#[derive(Debug, Clone, Copy)]
+pub enum HwCacheEvent {
+    /// Measures Level 1 data cache.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_L1D")]
+    L1d = perf_hw_cache_id::PERF_COUNT_HW_CACHE_L1D as isize,
+    /// Measures Level 1 data cache.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_L1I")]
+    L1i = perf_hw_cache_id::PERF_COUNT_HW_CACHE_L1I as isize,
+    /// Measures Last-level cache.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_LL")]
+    Ll = perf_hw_cache_id::PERF_COUNT_HW_CACHE_LL as isize,
+    /// Measures Data TLB (Translation Lookaside Buffer).
+    #[doc(alias = "PERF_COUNT_HW_CACHE_DTLB")]
+    Dtlb = perf_hw_cache_id::PERF_COUNT_HW_CACHE_DTLB as isize,
+    /// Measures Instruction TLB (Translation Lookaside Buffer).
+    #[doc(alias = "PERF_COUNT_HW_CACHE_ITLB")]
+    Itlb = perf_hw_cache_id::PERF_COUNT_HW_CACHE_ITLB as isize,
+    /// Measures branch prediction.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_BPU")]
+    Bpu = perf_hw_cache_id::PERF_COUNT_HW_CACHE_BPU as isize,
+    /// Measures local memory accesses.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_NODE")]
+    Node = perf_hw_cache_id::PERF_COUNT_HW_CACHE_NODE as isize,
+}
+
+/// The hardware CPU cache operations.
+#[doc(alias = "perf_hw_cache_op_id")]
+#[derive(Debug, Clone, Copy)]
+pub enum HwCacheOp {
+    /// Read access.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_OP_READ")]
+    Read = perf_hw_cache_op_id::PERF_COUNT_HW_CACHE_OP_READ as isize,
+    /// Write access.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_OP_WRITE")]
+    Write = perf_hw_cache_op_id::PERF_COUNT_HW_CACHE_OP_WRITE as isize,
+    /// Prefetch access.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_OP_PREFETCH")]
+    Prefetch = perf_hw_cache_op_id::PERF_COUNT_HW_CACHE_OP_PREFETCH as isize,
+}
+
+/// The hardware CPU cache result.
+#[doc(alias = "perf_hw_cache_op_result_id")]
+#[derive(Debug, Clone, Copy)]
+pub enum HwCacheResult {
+    /// Cache accesses.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_RESULT_ACCESS")]
+    Access = perf_hw_cache_op_result_id::PERF_COUNT_HW_CACHE_RESULT_ACCESS as isize,
+    /// Cache missed accesses.
+    #[doc(alias = "PERF_COUNT_HW_CACHE_RESULT_MISS")]
+    Miss = perf_hw_cache_op_result_id::PERF_COUNT_HW_CACHE_RESULT_MISS as isize,
 }
 
 /// Sample Policy
@@ -100,19 +271,21 @@ pub enum PerfEventScope {
 /// #     #[error(transparent)]
 /// #     Ebpf(#[from] aya::EbpfError)
 /// # }
-/// # let mut bpf = aya::Ebpf::load(&[])?;
-/// use aya::util::online_cpus;
-/// use aya::programs::perf_event::{
-///     perf_sw_ids::PERF_COUNT_SW_CPU_CLOCK, PerfEvent, PerfEventScope, PerfTypeId, SamplePolicy,
+/// use aya::{
+///     util::online_cpus,
+///     programs::perf_event::{
+///         PerfEvent, PerfEventConfig, PerfEventScope, SamplePolicy, SoftwareEvent,
+///     },
 /// };
 ///
+/// # let mut bpf = aya::Ebpf::load(&[])?;
 /// let prog: &mut PerfEvent = bpf.program_mut("observe_cpu_clock").unwrap().try_into()?;
 /// prog.load()?;
 ///
+/// let perf_type = PerfEventConfig::Software(SoftwareEvent::CpuClock);
 /// for cpu in online_cpus().map_err(|(_, error)| error)? {
 ///     prog.attach(
-///         PerfTypeId::Software,
-///         PERF_COUNT_SW_CPU_CLOCK as u64,
+///         perf_type.clone(),
 ///         PerfEventScope::AllProcessesOneCpu { cpu },
 ///         SamplePolicy::Period(1000000),
 ///         true,
@@ -134,25 +307,45 @@ impl PerfEvent {
 
     /// Attaches to the given perf event.
     ///
-    /// The possible values and encoding of the `config` argument depends on the
-    /// `perf_type`. See `perf_sw_ids`, `perf_hw_id`, `perf_hw_cache_id`,
-    /// `perf_hw_cache_op_id` and `perf_hw_cache_op_result_id`.
-    ///
-    /// The `scope` argument determines which processes are sampled. If `inherit`
-    /// is true, any new processes spawned by those processes will also
+    /// The [`perf_type`](PerfEventConfig) defines the event `type` and `config` of interest.
+    /// The [`scope`](PerfEventScope) argument determines which processes are sampled.
+    /// If `inherit` is `true`, any new processes spawned by those processes will also
     /// automatically get sampled.
     ///
     /// The returned value can be used to detach, see [PerfEvent::detach].
     pub fn attach(
         &mut self,
-        perf_type: PerfTypeId,
-        config: u64,
+        perf_type: PerfEventConfig,
         scope: PerfEventScope,
         sample_policy: SamplePolicy,
         inherit: bool,
     ) -> Result<PerfEventLinkId, ProgramError> {
         let prog_fd = self.fd()?;
         let prog_fd = prog_fd.as_fd();
+
+        let (event_type, config) = match perf_type {
+            PerfEventConfig::Pmu { pmu_type, config } => (pmu_type, config),
+            // To handle `perf_type_id` event_type together
+            _ => {
+                let (event_type, config) = match perf_type {
+                    PerfEventConfig::Hardware(hw_event) => (PERF_TYPE_HARDWARE, hw_event as u64),
+                    PerfEventConfig::Software(sw_event) => (PERF_TYPE_SOFTWARE, sw_event as u64),
+                    PerfEventConfig::TracePoint { event_id } => (PERF_TYPE_TRACEPOINT, event_id),
+                    PerfEventConfig::HwCache {
+                        event,
+                        operation,
+                        result,
+                    } => (
+                        PERF_TYPE_HW_CACHE,
+                        (event as u64) | ((operation as u64) << 8) | ((result as u64) << 16),
+                    ),
+                    PerfEventConfig::Raw { event_id } => (PERF_TYPE_RAW, event_id),
+                    PerfEventConfig::Breakpoint => (PERF_TYPE_BREAKPOINT, 0),
+                    PerfEventConfig::Pmu { .. } => unreachable!(), // not possible due to earlier match
+                };
+                (event_type as u32, config)
+            }
+        };
         let (sample_period, sample_frequency) = match sample_policy {
             SamplePolicy::Period(period) => (period, None),
             SamplePolicy::Frequency(frequency) => (0, Some(frequency)),
@@ -165,7 +358,7 @@ impl PerfEvent {
             PerfEventScope::AllProcessesOneCpu { cpu } => (-1, cpu as i32),
         };
         let fd = perf_event_open(
-            perf_type as u32,
+            event_type,
             config,
             pid,
             cpu,