mmu: almost have it working

Just have major stack issues.

Signed-off-by: Sean Cross <sean@xobs.io>

asm.S

@@ -24,3 +24,9 @@ start_kmain:
     add     a6, a7, zero
     add     a7, zero, zero
 	mret    // Return to kmain
+
+.global read_satp
+.text
+read_satp:
+    csrr    a0, satp
+    ret

build.rs

@@ -17,6 +17,7 @@ fn main() {
 
         println!("cargo:rustc-link-lib=static={}", name);
         println!("cargo:rustc-link-search={}", out_dir.display());
+        println!("cargo:rerun-if-changed=bin/{}.a", target);
     }
 
     // Put the linker script somewhere the linker can find it

src/main.rs

@@ -19,7 +19,7 @@ pub use irq::sys_interrupt_claim;
 use core::panic::PanicInfo;
 use mem::MemoryManager;
 use processtable::ProcessTable;
-use vexriscv::register::{mcause, mie, mstatus, vmim, vmip};
+use vexriscv::register::{mcause, mepc, mie, mstatus, vmim, vmip};
 use xous_kernel_riscv_rt::xous_kernel_entry;
 
 #[panic_handler]
@@ -50,11 +50,10 @@ fn xous_main() -> ! {
     sys_interrupt_claim(2, debug::irq).unwrap();
 
     println!("Creating memory manager...");
-    let mut mm = MemoryManager::new();
+    let mm = MemoryManager::new();
 
     println!("Creating process table...");
     ProcessTable::new(mm, kmain);
-    panic!("fell off main");
 }
 
 fn kmain(mm: MemoryManager, pt: ProcessTable) -> ! {
@@ -76,6 +75,8 @@ pub fn trap_handler() {
     let irqs_pending = vmip::read();
 
     if mc.is_exception() {
+        println!("CPU Exception");
+        println!("{:?} @ PC: {:08x}", mc.cause(), mepc::read());
         unsafe { vexriscv::asm::ebreak() };
         loop {}
     }

src/mem.rs

@@ -134,14 +134,14 @@ impl MemoryManager {
         // the MMU
         unsafe { mstatus::clear_mie() };
 
-        let ranges = [
+        let mut ranges = [
             mem_range!(&_sbss, &_ebss),
             mem_range!(&_sdata, &_edata),
             mem_range!(&_estack, &_sstack), // NOTE: Stack is reversed
             mem_range!(&_stext, &_etext),
         ];
-        for range in &ranges {
-            for region in range.clone() {
+        for range in &mut ranges {
+            for region in range {
                 mm.claim_page(region & !0xfff, 1)
                     .expect("Unable to claim region for PID 1");
             }
@@ -190,11 +190,12 @@ impl MemoryManager {
         phys: usize,
         virt: usize,
     ) -> Result<(), XousError> {
-        let ppn1 = (phys >> 20) & ((1 << 12) - 1);
-        let ppn0 = (phys >> 10) & ((1 << 10) - 1);
+        let ppn1 = (phys >> 22) & ((1 << 12) - 1);
+        let ppn0 = (phys >> 12) & ((1 << 10) - 1);
         let ppo = (phys >> 0) & ((1 << 12) - 1);
+
         let vpn1 = (virt >> 22) & ((1 << 10) - 1);
-        let vpn0 = (virt >> 10) & ((1 << 10) - 1);
+        let vpn0 = (virt >> 12) & ((1 << 10) - 1);
         let vpo = (virt >> 0) & ((1 << 12) - 1);
 
         println!(
@@ -213,7 +214,10 @@ impl MemoryManager {
 
         // Allocate a new level 1 pagetable entry if one doesn't exist.
         if l1_pt[vpn1] & 1 == 0 {
-            println!("    top-level VPN1 {:04x}: {:08x} (will allocate a new one)", vpn1, l1_pt[vpn1]);
+            println!(
+                "    top-level VPN1 {:04x}: {:08x} (will allocate a new one)",
+                vpn1, l1_pt[vpn1]
+            );
             // Allocate the page to the kernel (PID 1)
             let new_addr = self.alloc_page(1)?.get();
             println!(
@@ -223,64 +227,65 @@ impl MemoryManager {
 
             // Mark this entry as a leaf node (WRX as 0), and indicate
             // it is a valid page by setting "V".
-            l1_pt[vpn1] = (((new_addr >> 10) & ((1 << 22) - 1)) << 10) | 1;
+            let ppn = new_addr >> 12;
+            l1_pt[vpn1] = (ppn << 10) | 1;
             println!("    New top-level page entry: {:08x}", l1_pt[vpn1]);
         }
 
-        let mut l0_pt = unsafe {
-            let tmp = (l1_pt[vpn1] & ((1 << 10) - 1)) as *mut PageTable;
-            (*tmp).entries
-        };
+        let l0_pt_idx =
+            unsafe { &mut (*(((l1_pt[vpn1] << 2) & !((1 << 12) - 1)) as *mut PageTable)) };
+        let ref mut l0_pt = l0_pt_idx.entries;
+        println!("    l0_pt is at {:p}  ({:p})", &l0_pt, &l0_pt[vpn0]);
 
         // Allocate a new level 0 pagetable entry if one doesn't exist.
         if l0_pt[vpn0] & 1 != 0 {
-            panic!("Page already allocated!");
+            println!("Page already allocated!");
         }
-        l0_pt[vpn0] = (ppn1 << 20) | (ppn0 << 10) | 1 | 0xe;
+        l0_pt[vpn0] = (ppn1 << 20) | (ppn0 << 10) | 1 | 0xe | 0xc0;
         Ok(())
     }
 
     /// Create an identity mapping, copying the kernel to itself
     pub fn create_identity(&mut self, process: &Process) -> Result<(), XousError> {
-        let root_page = (process.satp & ((1 << 22) - 1)) << 9;
+        let root_page = (process.satp & ((1 << 22) - 1)) << 12;
         let pt = unsafe { &mut (*(root_page as *mut PageTable)) };
-        println!("SATP value: {:08x}  Root page: {:08x}  pt: {:p}  pt: {:p}", process.satp, root_page, &pt, pt);
+        println!(
+            "SATP value: {:08x}  Root page: {:08x}  pt: {:p}  pt: {:p}",
+            process.satp, root_page, &pt, pt
+        );
 
-        let ranges = [
+        let mut ranges = [
             mem_range!(&_sbss, &_ebss),
             mem_range!(&_sdata, &_edata),
             mem_range!(&_estack, &_sstack), // NOTE: Stack is reversed
             mem_range!(&_stext, &_etext),
         ];
-        for range in &ranges {
-            for region in range.clone() {
+        for range in &mut ranges {
+            for region in range {
                 // mm.claim_page(region & !0xfff, 1)
                 // .expect("Unable to claim region for PID 1");
-                self.map_page(
-                    pt,
-                    region,
-                    region,
-                )?;
-                print!("Entries mapped: >");
-                let mut i = 0;
-                for (entry_idx, entry) in pt.entries.iter().enumerate() {
-                    i = i + 1;
-                    if *entry != 0 {
-                        print!(" {}:{:08x}", entry_idx, entry);
-                    }
-                }
-                println!(" < ({})", i);
+                self.map_page(pt, region, region)?;
+                // print!("Entries mapped: >");
+                // let mut i = 0;
+                // for (entry_idx, entry) in pt.entries.iter().enumerate() {
+                //     i = i + 1;
+                //     if *entry != 0 {
+                //         print!(" {}:{:08x}", entry_idx, entry);
+                //     }
+                // }
+                // println!(" < ({})", i);
                 println!("");
             }
         }
+        self.map_page(pt, 0xE000_1800, 0xE000_1800)?;
         // let flash_orig = self.flash.clone();
         // for (flash_idx, flash_pid) in flash_orig.iter().enumerate() {
         //     if *flash_pid == pid {
-                // println!(
-                //     "Flash addr {:08x} owned by PID {}, mapping it as ident",
-                //     flash_idx * PAGE_SIZE + FLASH_START,
-                //     pid
-                // );
+        // println!(
+        //     "Flash addr {:08x} owned by PID {}, mapping it as ident",
+        //     flash_idx * PAGE_SIZE + FLASH_START,
+        //     pid
+        // );
         //     }
         // }
 

src/processtable.rs

@@ -33,6 +33,9 @@ extern "Rust" {
         pt: ProcessTable,
     ) -> !;
 }
+extern "C" {
+    fn read_satp() -> usize;
+}
 
 impl ProcessTable {
     pub fn new(mut mm: MemoryManager, kmain: fn(MemoryManager, ProcessTable) -> !) -> ! {
@@ -43,7 +46,7 @@ impl ProcessTable {
         // Allocate a root page table for PID 1.  Also mark the "ASID" as "1"
         // for "PID 1"
         let root_page = mm.alloc_page(1).unwrap().get();
-        pt.processes[1].satp = (root_page >> 9) | (1 << 22);
+        pt.processes[1].satp = (root_page >> 12) | (1 << 22);
         mm.create_identity(&pt.processes[1])
             .expect("Unable to create identity mapping");
         println!("PID 1: {:?} root page @ {:08x}", pt.processes[1], root_page);
@@ -60,6 +63,7 @@ impl ProcessTable {
             mstatus::set_mpp(mstatus::MPP::Supervisor);
         };
         println!("MMU enabled, jumping to kmain");
+        println!("SATP: {:08x}", unsafe { read_satp() });
         unsafe { start_kmain(kmain, mm, pt) }
     }
 }