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

crates/adapter-riscv/src/boot/loader.rs

@@ -75,7 +75,7 @@ pub fn load_server(
 pub fn enter_userspace(pid: ProcessId, entry: usize, shared_buf_va: usize) -> ! {
     let pt_addr = kern().platform_mut().page_table_for(pid);
     if pt_addr != 0 {
-        mmu::activate(unsafe { &*(pt_addr as *const mmu::PageTable) });
+        mmu::activate(mmu::page_table::table_at(pt_addr));
     }
 
     let kernel_sp: usize;
@@ -120,11 +120,11 @@ fn copy_to_user(pid: ProcessId, va: usize, data: &[u8]) -> bool {
         };
         let len = (PAGE_SIZE - offset).min(data.len() - done);
         // SAFETY: `pa` is a pool frame the kernel just mapped for `pid`;
-        // pool frames are identity mapped kernel RAM.
+        // pool frames are RAM, mapped at `phys_to_virt`.
         unsafe {
             core::ptr::copy_nonoverlapping(
                 data.as_ptr().add(done),
-                (pa.raw() as *mut u8).add(offset),
+                (mmu::phys_to_virt(pa.raw()) as *mut u8).add(offset),
                 len,
             );
         }