mod getcontext;
pub use getcontext::crash_context_getcontext;
/// The full context for a Linux/Android crash
#[repr(C)]
#[derive(Clone)]
pub struct CrashContext {
/// Crashing thread context.
///
/// Note that we use [`crate::ucontext_t`] instead of [`libc::ucontext_t`]
/// as libc's differs between glibc and musl <
https://github.com/rust-lang/libc/pull/1646>
/// even though the ucontext_t received from a signal will be the same
/// regardless of the libc implementation used as it is only arch specific
/// and not libc specific
///
/// Note that we hide `ucontext_t::uc_link` as it is a pointer and thus can't
/// be accessed in a process other than the one the `CrashContext` was created
/// in. This is a just a self-reference so is not useful in practice.
///
/// Note that the same applies to [`mcontext_t::fpregs`], but since that points
/// to floating point registers and _is_ interesting to read in another process,
/// those registers available as [`Self::float_state`], except on the `arm`
/// architecture since they aren't part of `mcontext_t` at all.
pub context: ucontext_t,
/// State of floating point registers.
///
/// This isn't part of the user ABI for Linux arm
#[cfg(not(target_arch = "arm"))]
pub float_state: fpregset_t,
/// The signal info for the crash
pub siginfo: libc::signalfd_siginfo,
/// The id of the crashing process
pub pid: libc::pid_t,
/// The id of the crashing thread
pub tid: libc::pid_t,
}
unsafe impl Send for CrashContext {}
impl CrashContext {
pub fn as_bytes(&self) -> &[u8] {
unsafe {
let size = std::mem::size_of_val(self);
let ptr = (self as *const Self).cast();
std::slice::from_raw_parts(ptr, size)
}
}
pub fn from_bytes(bytes: &[u8]) -> Option<Self> {
if bytes.len() != std::mem::size_of::<Self>() {
return None;
}
unsafe { Some((*bytes.as_ptr().cast::<Self>()).clone()) }
}
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct sigset_t {
#[cfg(target_pointer_width = "32")]
__val: [u32; 32],
#[cfg(target_pointer_width = "64")]
__val: [u64; 16],
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct stack_t {
pub ss_sp: *mut std::ffi::c_void,
pub ss_flags: i32,
pub ss_size: usize,
}
cfg_if::cfg_if! {
if #[cfg(target_arch = "x86_64")] {
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct ucontext_t {
pub uc_flags: u64,
uc_link: *mut ucontext_t,
pub uc_stack: stack_t,
pub uc_mcontext: mcontext_t,
pub uc_sigmask: sigset_t,
__private: [u8; 512],
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct mcontext_t {
pub gregs: [i64; 23],
pub fpregs: *mut fpregset_t,
__reserved: [u64; 8],
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct fpregset_t {
pub cwd: u16,
pub swd: u16,
pub ftw: u16,
pub fop: u16,
pub rip: u64,
pub rdp: u64,
pub mxcsr: u32,
pub mxcr_mask: u32,
pub st_space: [u32; 32],
pub xmm_space: [u32; 64],
__padding: [u64; 12],
}
} else if #[cfg(target_arch = "x86")] {
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct ucontext_t {
pub uc_flags: u32,
uc_link: *mut ucontext_t,
pub uc_stack: stack_t,
pub uc_mcontext: mcontext_t,
pub uc_sigmask: sigset_t,
pub __fpregs_mem: [u32; 28],
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct mcontext_t {
pub gregs: [i32; 23],
pub fpregs: *mut fpregset_t,
pub oldmask: u32,
pub cr2: u32,
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct fpreg_t {
pub significand: [u16; 4],
pub exponent: u16,
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct fpregset_t {
pub cw: u32,
pub sw: u32,
pub tag: u32,
pub ipoff: u32,
pub cssel: u32,
pub dataoff: u32,
pub datasel: u32,
pub _st: [fpreg_t; 8],
pub status: u32,
}
} else if #[cfg(target_arch = "aarch64")] {
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct ucontext_t {
pub uc_flags: u64,
uc_link: *mut ucontext_t,
pub uc_stack: stack_t,
pub uc_sigmask: sigset_t,
pub uc_mcontext: mcontext_t,
}
// Note you might see this defined in C with `unsigned long` or
// `unsigned long long` and think, WTF, those aren't the same! Except
// `long` means either 32-bit _or_ 64-bit depending on the data model,
// and the default data model for C/C++ is LP64 which means long is
// 64-bit. I had forgotten what a trash type long was.
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct mcontext_t {
// Note in the kernel this is just part of regs which is length 32
pub fault_address: u64,
pub regs: [u64; 31],
pub sp: u64,
pub pc: u64,
pub pstate: u64,
// Note that u128 is ABI safe on aarch64, this is actually a
// `long double` in C which Rust doesn't have native support
pub __reserved: [u128; 256],
}
/// Magic value written by the kernel and our custom getcontext
#[doc(hidden)]
pub const FPSIMD_MAGIC: u32 = 0x46508001;
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct _aarch64_ctx {
pub magic: u32,
pub size: u32,
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct fpsimd_context {
pub head: _aarch64_ctx,
pub fpsr: u32,
pub fpcr: u32,
pub vregs: [u128; 32],
}
#[doc(hidden)]
pub type fpregset_t = fpsimd_context;
} else if #[cfg(target_arch = "arm")] {
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct ucontext_t {
pub uc_flags: u32,
uc_link: *mut ucontext_t,
pub uc_stack: stack_t,
// Note that the mcontext_t and sigset_t are swapped compared to
// all of the other arches currently supported :p
pub uc_mcontext: mcontext_t,
pub uc_sigmask: sigset_t,
pub uc_regspace: [u64; 64],
}
#[repr(C)]
#[derive(Clone)]
#[doc(hidden)]
pub struct mcontext_t {
pub trap_no: u32,
pub error_code: u32,
pub oldmask: u32,
pub arm_r0: u32,
pub arm_r1: u32,
pub arm_r2: u32,
pub arm_r3: u32,
pub arm_r4: u32,
pub arm_r5: u32,
pub arm_r6: u32,
pub arm_r7: u32,
pub arm_r8: u32,
pub arm_r9: u32,
pub arm_r10: u32,
pub arm_fp: u32,
pub arm_ip: u32,
pub arm_sp: u32,
pub arm_lr: u32,
pub arm_pc: u32,
pub arm_cpsr: u32,
pub fault_address: u32,
}
}
}
#[cfg(test)]
mod test {
// Musl doesn't contain fpregs in libc because reasons
https://github.com/rust-lang/libc/pull/1646
#[cfg(not(target_env = "musl"))]
#[test]
fn matches_libc() {
assert_eq!(
std::mem::size_of::<libc::ucontext_t>(),
std::mem::size_of::<super::ucontext_t>()
);
}
}
