perf-event-open 0.6.3

use std::ffi::c_long;
use std::io::Result;

use super::EventConfig;
use crate::ffi::bindings as b;

/// Hardware breakpoint event provided by the CPU.
///
/// Breakpoints can be read/write accesses to an address as well as execution of an
/// instruction address.
///
/// # Examples
///
/// Count writes to a variable by watching its address:
///
/// ```rust
/// use perf_event_open::config::{Cpu, Opts, Proc};
/// use perf_event_open::count::Counter;
/// use perf_event_open::event::bp::{Breakpoint, Len, Type};
///
/// let mut var = 0u64;
///
/// // Count 8-byte writes to the address of `var`.
/// let event = Breakpoint {
///     ty: Type::W(Len::_8),
///     addr: &var as *const u64 as u64,
/// };
/// let target = (Proc::CURRENT, Cpu::ALL);
///
/// let counter = Counter::new(event, target, Opts::default()).unwrap();
///
/// counter.enable().unwrap(); // Start the counter.
/// for i in 0..10 {
///     var = i;
///     std::hint::black_box(var);
/// }
/// counter.disable().unwrap(); // Stop the counter.
///
/// let writes = counter.stat().unwrap().count;
/// assert_eq!(writes, 10);
/// ```
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Breakpoint {
    /// Breakpoint type.
    pub ty: Type,
    /// Breakpoint address.
    pub addr: u64,
}

/// Breakpoint type.
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum Type {
    /// Count when we read the memory location.
    R(Len),
    /// Count when we write the memory location.
    W(Len),
    /// Count when we read or write the memory location.
    Rw(Len),
    /// Count when we execute code at the memory location.
    X,
}

/// Breakpoint size (in bytes).
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum Len {
    /// 1 byte.
    _1,
    /// 2 bytes.
    _2,
    /// 3 bytes.
    ///
    /// Since `linux-4.10`: <https://github.com/torvalds/linux/commit/651be3cb085341a21847e47c694c249c3e1e4e5b>
    _3,
    /// 4 bytes.
    _4,
    /// 5 bytes.
    ///
    /// Since `linux-4.10`: <https://github.com/torvalds/linux/commit/651be3cb085341a21847e47c694c249c3e1e4e5b>
    _5,
    /// 6 bytes.
    ///
    /// Since `linux-4.10`: <https://github.com/torvalds/linux/commit/651be3cb085341a21847e47c694c249c3e1e4e5b>
    _6,
    /// 7 bytes.
    ///
    /// Since `linux-4.10`: <https://github.com/torvalds/linux/commit/651be3cb085341a21847e47c694c249c3e1e4e5b>
    _7,
    /// 8 bytes.
    _8,
}

impl Len {
    #[cfg(feature = "linux-4.10")]
    pub(crate) const fn as_bp_len(&self) -> Result<u64> {
        let bp_len = match self {
            Self::_1 => b::HW_BREAKPOINT_LEN_1,
            Self::_2 => b::HW_BREAKPOINT_LEN_2,
            Self::_3 => b::HW_BREAKPOINT_LEN_3,
            Self::_4 => b::HW_BREAKPOINT_LEN_4,
            Self::_5 => b::HW_BREAKPOINT_LEN_5,
            Self::_6 => b::HW_BREAKPOINT_LEN_6,
            Self::_7 => b::HW_BREAKPOINT_LEN_7,
            Self::_8 => b::HW_BREAKPOINT_LEN_8,
        };
        Ok(bp_len as _)
    }

    #[cfg(not(feature = "linux-4.10"))]
    pub(crate) fn as_bp_len(&self) -> Result<u64> {
        let bp_len = match self {
            Self::_1 => b::HW_BREAKPOINT_LEN_1,
            Self::_2 => b::HW_BREAKPOINT_LEN_2,
            Self::_4 => b::HW_BREAKPOINT_LEN_4,
            Self::_8 => b::HW_BREAKPOINT_LEN_8,
            _ => crate::config::unsupported!(),
        };
        Ok(bp_len as _)
    }
}

super::try_from!(Breakpoint, value, {
    let (bp_type, bp_len) = match &value.ty {
        Type::R(l) => (b::HW_BREAKPOINT_R, l.as_bp_len()?),
        Type::W(l) => (b::HW_BREAKPOINT_W, l.as_bp_len()?),
        Type::Rw(l) => (b::HW_BREAKPOINT_RW, l.as_bp_len()?),
        Type::X => (b::HW_BREAKPOINT_X, size_of::<c_long>() as u64),
    };
    let event_cfg = EventConfig {
        ty: b::PERF_TYPE_BREAKPOINT,
        config: 0,
        config1: value.addr,
        config2: bp_len,
        config3: 0,
        bp_type,
    };
    Ok(Self(event_cfg))
});