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pmp: add PMP struct #2064

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Aug 13, 2020
Merged

pmp: add PMP struct #2064

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072351a
pmp: add PMP struct
bradjc Jul 31, 2020
0175fb9
Update arch/rv32i/src/pmp.rs
bradjc Aug 13, 2020
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56 changes: 30 additions & 26 deletions arch/rv32i/src/pmp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,22 @@ register_bitfields![u8,
]
];

/// Main PMP struct.
pub struct PMP {
/// The application that the MPU was last configured for. Used (along with
/// the `is_dirty` flag) to determine if MPU can skip writing the
/// configuration to hardware.
last_configured_for: MapCell<AppId>,
}

impl PMP {
pub const unsafe fn new() -> PMP {
PMP {
last_configured_for: MapCell::empty(),
}
}
}

/// Struct storing configuration for a RISC-V PMP region.
#[derive(Copy, Clone)]
pub struct PMPRegion {
Expand Down Expand Up @@ -136,37 +152,28 @@ impl PMPRegion {
}
}

pub trait PMPConfigType: Default + Copy + Clone + Sized {}

/// Struct storing region configuration for RISCV PMP.
pub struct PMPConfig<N: PMPConfigType> {
pub struct PMPConfig {
Comment on lines -142 to +156
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This change is fine, but just noting that it is moving us more towards the macro approach as we get further away from the array generators.

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For general awareness, the minimum subset of const generics that will be stabilized now has its own feature gate (rust-lang/rust#74877). Its not stable yet, but clearly on the fast track now.

/// Array of PMP regions. Each region requires two physical entries.
regions: N,
regions: [Option<PMPRegion>; $x / 2],
/// Indicates if the configuration has changed since the last time it was
/// written to hardware.
is_dirty: Cell<bool>,
/// The application that the MPU was last configured for. Used (along with
/// the `is_dirty` flag) to determine if MPU can skip writing the
/// configuration to hardware.
last_configured_for: MapCell<AppId>,
/// Which region index is used for app memory (if it has been configured).
app_memory_region: OptionalCell<usize>,
}

impl PMPConfigType for [Option<PMPRegion>; $x / 2] {}

impl Default for PMPConfig<[Option<PMPRegion>; $x / 2]> {
impl Default for PMPConfig {
fn default() -> Self {
PMPConfig {
regions: [None; $x / 2],
is_dirty: Cell::new(true),
last_configured_for: MapCell::empty(),
app_memory_region: OptionalCell::empty(),
}
}
}

impl fmt::Display for PMPConfig<[Option<PMPRegion>; $x / 2]> {
impl fmt::Display for PMPConfig {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
writeln!(f, "PMP regions:")?;
for (n, region) in self.regions.iter().enumerate() {
Expand All @@ -179,7 +186,7 @@ impl fmt::Display for PMPConfig<[Option<PMPRegion>; $x / 2]> {
}
}

impl PMPConfig<[Option<PMPRegion>; $x / 2]> {
impl PMPConfig {
fn unused_region_number(&self) -> Option<usize> {
for (number, region) in self.regions.iter().enumerate() {
if self.app_memory_region.contains(&number) {
Expand Down Expand Up @@ -234,18 +241,15 @@ impl PMPConfig<[Option<PMPRegion>; $x / 2]> {
}
}

impl kernel::mpu::MPU for PMPConfig<[Option<PMPRegion>; $x / 2]> {
type MpuConfig = PMPConfig<[Option<PMPRegion>; $x / 2]>;
impl kernel::mpu::MPU for PMP {
type MpuConfig = PMPConfig;

fn enable_mpu(&self) {}

fn disable_mpu(&self) {
// The length of `self.regions` here refers to the number of memory
// slices we can protect with the PMP. Each slice requires two PMP
// entries to protect, so this is half of the number physical hardware
// PMP configuration entries. Therefore, we double the number of regions
// to clear all the relevant `pmpcfg` entries.
for x in 0..(self.regions.len() * 2) {
// We want to disable all of the hardware entries, so we use `$x` here,
// and not `$x / 2`.
for x in 0..$x {
match x % 4 {
0 => {
csr::CSR.pmpcfg[x / 4].modify(
Expand Down Expand Up @@ -300,7 +304,7 @@ impl kernel::mpu::MPU for PMPConfig<[Option<PMPRegion>; $x / 2]> {
}

fn number_total_regions(&self) -> usize {
self.regions.len()
$x / 2
}

fn allocate_region(
Expand Down Expand Up @@ -464,7 +468,7 @@ impl kernel::mpu::MPU for PMPConfig<[Option<PMPRegion>; $x / 2]> {
// Skip PMP configuration if it is already configured for this app and the MPU
// configuration of this app has not changed.
if !last_configured_for_this_app || config.is_dirty.get() {
for (x, region) in self.regions.iter().enumerate() {
for (x, region) in config.regions.iter().enumerate() {
match region {
Some(r) => {
let cfg_val = r.cfg.value as u32;
Expand Down Expand Up @@ -514,6 +518,6 @@ impl kernel::mpu::MPU for PMPConfig<[Option<PMPRegion>; $x / 2]> {
self.last_configured_for.put(*app_id);
}
}
}
};
}
};
}
6 changes: 3 additions & 3 deletions chips/arty_e21_chip/src/chip.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ extern "C" {
}

pub struct ArtyExx {
pmp: pmp::PMPConfig<[Option<pmp::PMPRegion>; 2]>,
pmp: pmp::PMP,
userspace_kernel_boundary: rv32i::syscall::SysCall,
clic: rv32i::clic::Clic,
}
Expand All @@ -27,7 +27,7 @@ impl ArtyExx {
let in_use_interrupts: u64 = 0x1FFFF0080;

ArtyExx {
pmp: pmp::PMPConfig::default(),
pmp: pmp::PMP::new(),
userspace_kernel_boundary: rv32i::syscall::SysCall::new(),
clic: rv32i::clic::Clic::new(in_use_interrupts),
}
Expand Down Expand Up @@ -106,7 +106,7 @@ impl ArtyExx {
}

impl kernel::Chip for ArtyExx {
type MPU = pmp::PMPConfig<[Option<pmp::PMPRegion>; 2]>;
type MPU = pmp::PMP;
type UserspaceKernelBoundary = rv32i::syscall::SysCall;
type SchedulerTimer = ();
type WatchDog = ();
Expand Down
6 changes: 3 additions & 3 deletions chips/e310x/src/chip.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,15 +19,15 @@ PMPConfigMacro!(8);

pub struct E310x<A: 'static + Alarm<'static>> {
userspace_kernel_boundary: rv32i::syscall::SysCall,
pmp: PMPConfig<[Option<PMPRegion>; 4]>,
pmp: PMP,
scheduler_timer: kernel::VirtualSchedulerTimer<A>,
}

impl<A: 'static + Alarm<'static>> E310x<A> {
pub unsafe fn new(alarm: &'static A) -> Self {
Self {
userspace_kernel_boundary: rv32i::syscall::SysCall::new(),
pmp: PMPConfig::default(),
pmp: PMP::new(),
scheduler_timer: kernel::VirtualSchedulerTimer::new(alarm),
}
}
Expand All @@ -54,7 +54,7 @@ impl<A: 'static + Alarm<'static>> E310x<A> {
}

impl<A: 'static + Alarm<'static>> kernel::Chip for E310x<A> {
type MPU = PMPConfig<[Option<PMPRegion>; 4]>;
type MPU = PMP;
type UserspaceKernelBoundary = rv32i::syscall::SysCall;
type SchedulerTimer = kernel::VirtualSchedulerTimer<A>;
type WatchDog = ();
Expand Down
6 changes: 3 additions & 3 deletions chips/earlgrey/src/chip.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -27,15 +27,15 @@ pub const CHIP_FREQ: u32 = CONFIG.chip_freq;

pub struct EarlGrey<A: 'static + Alarm<'static>> {
userspace_kernel_boundary: SysCall,
pmp: PMPConfig<[Option<PMPRegion>; 2]>,
pmp: PMP,
scheduler_timer: kernel::VirtualSchedulerTimer<A>,
}

impl<A: 'static + Alarm<'static>> EarlGrey<A> {
pub unsafe fn new(alarm: &'static A) -> Self {
Self {
userspace_kernel_boundary: SysCall::new(),
pmp: PMPConfig::default(),
pmp: PMP::new(),
scheduler_timer: kernel::VirtualSchedulerTimer::new(alarm),
}
}
Expand Down Expand Up @@ -110,7 +110,7 @@ impl<A: 'static + Alarm<'static>> EarlGrey<A> {
}

impl<A: 'static + Alarm<'static>> kernel::Chip for EarlGrey<A> {
type MPU = PMPConfig<[Option<PMPRegion>; 2]>;
type MPU = PMP;
type UserspaceKernelBoundary = SysCall;
type SchedulerTimer = kernel::VirtualSchedulerTimer<A>;
type WatchDog = ();
Expand Down