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use std::path::Path;
use crate::backend::MemoryOps;
use crate::dmp::{DmpInfo, DmpMem};
use crate::error::Result;
use crate::host::VmHandle;
use crate::kd::KdMemory;
use crate::memory::TranslationCache;
use crate::types::{Dtb, PhysAddr, VirtAddr};
/// Guest physical memory backed by a live VM process, KD transport, or crash
/// dump. Built once at attach and shared via `Arc`; everything above (address
/// spaces, symbol loading, unwinding) reads through it. `Dmp` is boxed because
/// it is much larger than the live handle.
pub enum PhysMem {
/// Live VM RAM. Reads come straight from the host mapping; writes go
/// through `mediated` when there is one, because poking a guest frame from
/// the host bypasses everything the guest's memory manager knows about
/// that page, including PTE write protection, copy-on-write, residency and
/// dirty tracking, while a target-mediated write is serviced by the guest's own
/// debug-memory path.
///
/// Mediation needs a request/reply exchange, so it only applies while the
/// target is halted. A write to a running guest keeps using the host
/// mapping: it is the only mechanism left, and such a write is already
/// best-effort because the guest may be touching the same bytes.
Live {
host: VmHandle,
mediated: Option<KdMemory>,
},
Dmp(Box<DmpMem>),
Remote(KdMemory),
}
impl PhysMem {
pub fn live() -> Result<Self> {
Ok(Self::Live {
host: VmHandle::new()?,
mediated: None,
})
}
/// Hand guest writes to the target while reads keep coming from the host
/// mapping. A no-op for sources that have no host mapping.
pub fn with_mediated_writes(self, memory: KdMemory) -> Self {
match self {
Self::Live { host, .. } => Self::Live {
host,
mediated: Some(memory),
},
other => other,
}
}
pub fn dmp(path: &Path) -> Result<Self> {
Ok(Self::Dmp(Box::new(DmpMem::open(path)?)))
}
pub fn remote(memory: KdMemory) -> Self {
Self::Remote(memory)
}
pub fn dmp_info(&self) -> Option<&DmpInfo> {
match self {
Self::Dmp(d) => Some(d.info()),
_ => None,
}
}
/// Guest-physical address where RAM starts (below is firmware/MMIO):
/// x86 QEMU/VMware: 0; aarch64 QEMU `virt`: 0x4000_0000 (1 GiB).
pub fn ram_base(&self) -> u64 {
match self {
Self::Live { host, .. } => host.ram_base(),
Self::Dmp(_) | Self::Remote(_) => 0,
}
}
/// Total mapped guest RAM size.
pub fn ram_size(&self) -> u64 {
match self {
Self::Live { host, .. } => host.ram_size(),
Self::Dmp(_) | Self::Remote(_) => 0,
}
}
/// Guest-physical RAM as `(base, len)` runs, for memory sources that know
/// the layout (a live VM process). Empty for KD and dumps, whose callers
/// take the runs from the guest's own `MmPhysicalMemoryBlock`.
pub fn ram_runs(&self) -> Vec<(u64, u64)> {
match self {
Self::Live { host, .. } => host.ram_runs(),
Self::Dmp(_) | Self::Remote(_) => Vec::new(),
}
}
/// Identity of the current halt, for memoizing guest-derived lists: equal
/// values mean the guest has not run in between. `None` when this memory
/// has no resume signal (a live VM process), so nothing may be memoized.
/// A dump never changes, so it is one epoch forever.
pub fn halt_epoch(&self) -> Option<u64> {
match self {
Self::Remote(kd) => kd.translation_cache().map(TranslationCache::halt_epoch),
Self::Dmp(_) => Some(0),
Self::Live { .. } => None,
}
}
}
impl MemoryOps<PhysAddr> for PhysMem {
fn read_bytes(&self, addr: PhysAddr, buf: &mut [u8]) -> Result<()> {
match self {
Self::Live { host, .. } => host.read_bytes(addr, buf),
Self::Dmp(d) => d.read_bytes(addr, buf),
Self::Remote(kd) => kd.read_bytes(addr, buf),
}
}
fn write_bytes(&self, addr: PhysAddr, buf: &[u8]) -> Result<()> {
match self {
Self::Live {
mediated: Some(kd), ..
} if kd.can_mediate_writes() => kd.write_bytes(addr, buf),
// The target cannot service a request while it runs, and the host
// mapping is the only mechanism left. Such a write is already
// best-effort because the guest may be touching the same bytes,
// so it stays available rather than requiring an interrupt.
Self::Live { host, .. } => host.write_bytes(addr, buf),
Self::Dmp(d) => d.write_bytes(addr, buf),
Self::Remote(kd) => kd.write_bytes(addr, buf),
}
}
fn read_virtual_direct(&self, addr: VirtAddr, root: Dtb, buf: &mut [u8]) -> Option<Result<()>> {
match self {
Self::Remote(kd) => kd.read_virtual_direct(addr, root, buf),
// A host mapping is there to be read directly; that is the whole
// point of selecting it.
Self::Live { .. } | Self::Dmp(_) => None,
}
}
fn write_virtual_direct(&self, addr: VirtAddr, root: Dtb, buf: &[u8]) -> Option<Result<()>> {
match self {
Self::Live {
mediated: Some(kd), ..
} if kd.can_mediate_writes() => kd.write_virtual_direct(addr, root, buf),
Self::Remote(kd) => kd.write_virtual_direct(addr, root, buf),
Self::Live { .. } | Self::Dmp(_) => None,
}
}
fn can_mediate_writes(&self) -> bool {
match self {
Self::Live {
mediated: Some(kd), ..
}
| Self::Remote(kd) => kd.can_mediate_writes(),
Self::Live { .. } | Self::Dmp(_) => false,
}
}
fn translation_cache(&self) -> Option<&TranslationCache> {
match self {
Self::Remote(kd) => kd.translation_cache(),
// Host reads are cheap enough to walk every time, and a mediated
// write clears the target's own cache.
Self::Live { .. } | Self::Dmp(_) => None,
}
}
fn read_page_table_bytes(&self, addr: PhysAddr, buf: &mut [u8]) -> Result<()> {
match self {
Self::Remote(kd) => kd.read_page_table_bytes(addr, buf),
Self::Live { .. } | Self::Dmp(_) => self.read_bytes(addr, buf),
}
}
}