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+//! Frequently used first boot stage dynamic information on RISC-V.
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+
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+use core::ops::Range;
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+use core::sync::atomic::{AtomicBool, Ordering};
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+
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+use super::BootInfo;
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+use crate::fail;
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+use crate::riscv_spec::current_hartid;
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+
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+use riscv::register::mstatus;
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+
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+pub fn get_boot_info(opaque: usize, nonstandard_a2: usize) -> BootInfo {
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+ static GENESIS: AtomicBool = AtomicBool::new(true);
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+ let info = read_paddr(nonstandard_a2).unwrap_or_else(fail::no_dynamic_info_available);
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+ let is_boot_hart = if info.boot_hart == usize::MAX {
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+ GENESIS.swap(false, Ordering::AcqRel)
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+ } else {
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+ current_hartid() == info.boot_hart
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+ };
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+ let (mpp, next_addr) = mpp_next_addr(&info).unwrap_or_else(fail::invalid_dynamic_data);
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+ BootInfo {
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+ fdt_address: opaque,
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+ next_address: next_addr,
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+ mpp,
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+ is_boot_hart,
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+ }
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+}
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+
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+/// M-mode firmware dynamic information.
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+#[derive(Clone, Copy)]
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+#[repr(C)]
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+pub struct DynamicInfo {
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+ /// Dynamic information magic value.
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+ pub magic: usize,
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+ /// Version of dynamic information.
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+ pub version: usize,
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+ /// Address of the next boot-loading stage.
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+ pub next_addr: usize,
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+ /// RISC-V privilege mode of the next boot-loading stage.
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+ pub next_mode: usize,
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+ /// M-mode firmware options; its definition varies between SBI implementations.
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+ pub options: usize,
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+ /// Boot hart ID of current environment.
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+ pub boot_hart: usize,
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+}
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+
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+// Definition of `boot_hart` can be found at:
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+// https://github.com/riscv-software-src/opensbi/blob/019a8e69a1dc0c0f011fabd0372e1ba80e40dd7c/include/sbi/fw_dynamic.h#L75
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+
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+const DYNAMIC_INFO_INVALID_ADDRESSES: usize = 0x00000000;
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+const NEXT_ADDR_VALID_ADDRESSES: Range<usize> = 0x80000000..0x90000000;
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+pub(crate) const MAGIC: usize = 0x4942534f;
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+const SUPPORTED_VERSION: Range<usize> = 2..3;
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+
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+pub struct DynamicReadError {
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+ pub bad_paddr: Option<usize>,
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+ pub bad_magic: Option<usize>,
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+ pub bad_version: Option<usize>,
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+}
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+
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+// TODO unconstrained lifetime
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+pub fn read_paddr(paddr: usize) -> Result<DynamicInfo, DynamicReadError> {
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+ let mut error = DynamicReadError {
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+ bad_paddr: None,
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+ bad_magic: None,
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+ bad_version: None,
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+ };
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+ // check pointer before dereference
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+ if DYNAMIC_INFO_INVALID_ADDRESSES == paddr {
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+ error.bad_paddr = Some(paddr);
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+ return Err(error);
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+ }
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+ let ans = unsafe { *(paddr as *const DynamicInfo) };
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+
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+ if ans.magic != MAGIC {
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+ error.bad_magic = Some(ans.magic);
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+ }
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+ if !SUPPORTED_VERSION.contains(&ans.version) {
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+ error.bad_version = Some(ans.version);
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+ }
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+ if error.bad_magic.is_some() || error.bad_version.is_some() {
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+ return Err(error);
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+ }
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+ Ok(ans)
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+}
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+
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+pub struct DynamicError<'a> {
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+ pub invalid_mpp: bool,
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+ pub invalid_next_addr: bool,
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+ pub bad_info: &'a DynamicInfo,
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+}
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+
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+pub fn mpp_next_addr(info: &DynamicInfo) -> Result<(mstatus::MPP, usize), DynamicError> {
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+ let mut error = DynamicError {
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+ invalid_mpp: false,
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+ invalid_next_addr: false,
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+ bad_info: info,
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+ };
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+
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+ // fail safe, errors will be aggregated after whole checking process.
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+ let next_addr_valid = NEXT_ADDR_VALID_ADDRESSES.contains(&info.next_addr);
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+ let mpp_valid = matches!(info.next_mode, 0 | 1 | 3);
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+
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+ if !next_addr_valid {
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+ error.invalid_next_addr = true;
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+ }
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+ if !mpp_valid {
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+ error.invalid_mpp = true;
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+ }
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+
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+ if !next_addr_valid || !mpp_valid {
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+ return Err(error);
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+ }
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+
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+ let mpp = match info.next_mode {
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+ 3 => mstatus::MPP::Machine,
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+ 1 => mstatus::MPP::Supervisor,
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+ // pattern `_` avoids `unreachable!`` which introduces panic handler.
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+ // pattern 0 and _
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+ _ => mstatus::MPP::User,
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+ };
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+
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+ Ok((mpp, info.next_addr))
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+}
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Woshiluo Luo