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feat(adapter): higher-half kernel (linked at PHYS_OFFSET, boot trampoline, no low mappings), fix SBI ecall clobbers

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This commit is contained in:
Gabriel Kaszewski
2026-10-27 00:25:20 +01:00
parent 55758ae5b2
commit b87a62475f
20 changed files with 208 additions and 143 deletions
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16
crates/adapter-riscv/src/platform.rs
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@@ -53,7 +53,7 @@ impl Platform for RiscVPlatform {
.page_tables
.get_mut(process.raw() as usize)
.ok_or(MapError::NoAddressSpace)?;
// SAFETY: the kernel page table is identity mapped and lives forever.
// SAFETY: the kernel page table lives in the boot heap forever.
let kernel_root = unsafe { &*(self.kernel_pt as *const mmu::PageTable) };
*slot = mmu::create_user_root(kernel_root, frames)?;
Ok(())
@@ -66,7 +66,7 @@ impl Platform for RiscVPlatform {
// The caller may be tearing down the space we are running on; get
// off it before the kernel frees its frames.
if mmu::active_root() == root {
// SAFETY: the kernel page table is identity mapped and lives forever.
// SAFETY: the kernel page table lives in the boot heap forever.
mmu::activate(unsafe { &*(self.kernel_pt as *const mmu::PageTable) });
}
self.page_tables[process.raw() as usize] = 0;
@@ -99,9 +99,11 @@ impl Platform for RiscVPlatform {
}
fn zero_frame(&mut self, pa: PhysicalAddress) {
// SAFETY: pool frames are identity mapped kernel RAM and the kernel
// only zeroes frames it has just allocated.
unsafe { core::ptr::write_bytes(pa.raw() as *mut u8, 0, mmu::PAGE_SIZE) };
// SAFETY: pool frames are RAM, mapped at `phys_to_virt`, and the
// kernel only zeroes frames it has just allocated.
unsafe {
core::ptr::write_bytes(mmu::phys_to_virt(pa.raw()) as *mut u8, 0, mmu::PAGE_SIZE)
};
}
fn enable_user_mode(&mut self, entry: EntryPoint, stack: StackPointer) -> ! {
@@ -160,8 +162,8 @@ impl Platform for RiscVPlatform {
unsafe {
core::arch::asm!(
"ecall",
in("a0") 0usize,
in("a1") 0usize,
inlateout("a0") 0usize => _,
inlateout("a1") 0usize => _,
in("a7") 0x53525354usize,
in("a6") 0usize,
);