mmu: first attempt to get it enabled

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

asm.S

@@ -0,0 +1,26 @@
+#if __riscv_xlen == 64
+# define STORE    sd
+# define LOAD     ld
+# define LOG_REGBYTES 3
+#else
+# define STORE    sw
+# define LOAD     lw
+# define LOG_REGBYTES 2
+#endif
+#define REGBYTES (1 << LOG_REGBYTES)
+
+.global start_kmain
+.text
+start_kmain:
+    li		t0, (1 << 11) | (1 << 5)
+	csrw	mstatus, t0
+	csrw	mepc, a0
+    add     a0, a1, zero
+    add     a1, a2, zero
+    add     a2, a3, zero
+    add     a3, a4, zero
+    add     a4, a5, zero
+    add     a5, a6, zero
+    add     a6, a7, zero
+    add     a7, zero, zero
+	mret    // Return to kmain

assemble.ps1

@@ -0,0 +1,17 @@
+# remove existing blobs because otherwise this will append object files to the old blobs
+Remove-Item -Force bin/*.a
+
+$crate = "xous-kernel"
+
+riscv64-unknown-elf-gcc -ggdb3 -c -mabi=ilp32 -march=rv32imac asm.S -o bin/$crate.o
+riscv64-unknown-elf-ar crs bin/riscv32imac-unknown-none-elf.a bin/$crate.o
+riscv64-unknown-elf-ar crs bin/riscv32imc-unknown-none-elf.a bin/$crate.o
+
+riscv64-unknown-elf-gcc -ggdb3 -c -mabi=ilp32 -march=rv32i asm.S -DSKIP_MULTICORE -o bin/$crate.o
+riscv64-unknown-elf-ar crs bin/riscv32i-unknown-none-elf.a bin/$crate.o
+
+riscv64-unknown-elf-gcc -ggdb3 -c -mabi=lp64 -march=rv64imac asm.S -o bin/$crate.o
+riscv64-unknown-elf-ar crs bin/riscv64imac-unknown-none-elf.a bin/$crate.o
+riscv64-unknown-elf-ar crs bin/riscv64gc-unknown-none-elf.a bin/$crate.o
+
+Remove-Item bin/$crate.o

assemble.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+crate=xous-kernel
+
+# remove existing blobs because otherwise this will append object files to the old blobs
+mkdir -p bin
+rm -f bin/*.a
+
+riscv64-unknown-elf-gcc -ggdb3 -c -mabi=ilp32 -march=rv32imac asm.S -o bin/$crate.o
+ar crs bin/riscv32imac-unknown-none-elf.a bin/$crate.o
+ar crs bin/riscv32imc-unknown-none-elf.a bin/$crate.o
+
+riscv64-unknown-elf-gcc -ggdb3 -c -mabi=ilp32 -march=rv32i asm.S -DSKIP_MULTICORE -o bin/$crate.o
+ar crs bin/riscv32i-unknown-none-elf.a bin/$crate.o
+
+riscv64-unknown-elf-gcc -ggdb3 -c -mabi=lp64 -march=rv64imac asm.S -o bin/$crate.o
+ar crs bin/riscv64imac-unknown-none-elf.a bin/$crate.o
+ar crs bin/riscv64gc-unknown-none-elf.a bin/$crate.o
+
+rm bin/$crate.o

build.rs

@@ -6,6 +6,18 @@ use std::path::PathBuf;
 
 fn main() {
     let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
+    let target = env::var("TARGET").unwrap();
+    let name = env::var("CARGO_PKG_NAME").unwrap();
+
+    if target.starts_with("riscv") {
+        fs::copy(
+            format!("bin/{}.a", target),
+            out_dir.join(format!("lib{}.a", name)),
+        ).unwrap();
+
+        println!("cargo:rustc-link-lib=static={}", name);
+        println!("cargo:rustc-link-search={}", out_dir.display());
+    }
 
     // Put the linker script somewhere the linker can find it
     fs::File::create(out_dir.join("memory.x"))

src/main.rs

@@ -12,6 +12,7 @@ mod macros;
 mod mem;
 mod processtable;
 mod syscalls;
+mod timer;
 
 pub use irq::sys_interrupt_claim;
 
@@ -39,6 +40,8 @@ fn xous_main() -> ! {
     }
 
     let uart = debug::DEFAULT_UART;
+    sys_interrupt_claim(0, timer::irq).unwrap();
+    timer::time_init();
 
     // Enable "RX_EMPTY" interrupt
     uart.enable_rx();
@@ -50,10 +53,19 @@ fn xous_main() -> ! {
     let mut mm = MemoryManager::new();
 
     println!("Creating process table...");
-    let mut _pt = ProcessTable::new(&mut mm);
+    ProcessTable::new(mm, kmain);
+    panic!("fell off main");
+}
 
+fn kmain(mm: MemoryManager, pt: ProcessTable) -> ! {
     println!("Entering main loop");
+    let mut last_time = timer::get_time();
     loop {
+        let new_time = timer::get_time();
+        if new_time >= last_time + 1000 {
+            last_time = new_time;
+            println!("Uptime: {} ms", new_time);
+        }
         // unsafe { vexriscv::asm::wfi() };
     }
 }

src/mem.rs

@@ -25,8 +25,8 @@ const IO_PAGE_COUNT: usize = IO_SIZE;
 const LCD_PAGE_COUNT: usize = LCD_SIZE / PAGE_SIZE;
 
 pub struct MemoryManager {
-    flash: [XousPid; FLASH_PAGE_COUNT],
     ram: [XousPid; RAM_PAGE_COUNT],
+    flash: [XousPid; FLASH_PAGE_COUNT],
     io: [XousPid; IO_PAGE_COUNT],
     lcd: [XousPid; LCD_PAGE_COUNT],
 }
@@ -241,22 +241,25 @@ impl MemoryManager {
     }
 
     /// Create an identity mapping, copying the kernel to itself
-    pub fn create_identity(&mut self, process: &Process, pid: XousPid) -> Result<(), XousError> {
+    pub fn create_identity(&mut self, process: &Process) -> Result<(), XousError> {
         let root_page = (process.satp & ((1 << 22) - 1)) << 9;
         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);
-        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
-                // );
+
+        let 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() {
+                // mm.claim_page(region & !0xfff, 1)
+                // .expect("Unable to claim region for PID 1");
                 self.map_page(
                     pt,
-                    flash_idx * PAGE_SIZE + FLASH_START,
-                    flash_idx * PAGE_SIZE + FLASH_START,
+                    region,
+                    region,
                 )?;
                 print!("Entries mapped: >");
                 let mut i = 0;
@@ -270,6 +273,18 @@ impl MemoryManager {
                 println!("");
             }
         }
+        // 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
+                // );
+        //     }
+        // }
+
+        // for (idx, page) in flash_orig.iter().enumerate() {
         Ok(())
     }
 

src/processtable.rs

@@ -1,7 +1,7 @@
 use crate::definitions::{MemoryAddress, XousError, XousPid};
 use crate::mem::MemoryManager;
 use crate::{filled_array, print, println};
-use vexriscv::register::{satp, mstatus};
+use vexriscv::register::{mstatus, satp};
 
 const MAX_PROCESS_COUNT: usize = 256;
 
@@ -26,8 +26,16 @@ pub struct ProcessTable {
     processes: [Process; MAX_PROCESS_COUNT],
 }
 
+extern "Rust" {
+    fn start_kmain(
+        kmain: extern "Rust" fn(MemoryManager, ProcessTable) -> !,
+        mm: MemoryManager,
+        pt: ProcessTable,
+    ) -> !;
+}
+
 impl ProcessTable {
-    pub fn new(mm: &mut MemoryManager) -> Self {
+    pub fn new(mut mm: MemoryManager, kmain: fn(MemoryManager, ProcessTable) -> !) -> ! {
         let mut pt = ProcessTable {
             processes: filled_array![Process { satp: 0 }; 256],
         };
@@ -36,7 +44,7 @@ impl ProcessTable {
         // for "PID 1"
         let root_page = mm.alloc_page(1).unwrap().get();
         pt.processes[1].satp = (root_page >> 9) | (1 << 22);
-        mm.create_identity(&pt.processes[1], 1)
+        mm.create_identity(&pt.processes[1])
             .expect("Unable to create identity mapping");
         println!("PID 1: {:?} root page @ {:08x}", pt.processes[1], root_page);
         println!("Enabling MMU...");
@@ -51,7 +59,7 @@ impl ProcessTable {
             // Switch to Supervisor mode
             mstatus::set_mpp(mstatus::MPP::Supervisor);
         };
-        println!("MMU enabled");
-        pt
+        println!("MMU enabled, jumping to kmain");
+        unsafe { start_kmain(kmain, mm, pt) }
     }
 }

src/timer.rs

@@ -0,0 +1,43 @@
+static mut TIME_MS: u32 = 0;
+
+pub fn irq(_irq_number: usize) {
+    let timer_base = 0xE0002800 as *mut u8;
+    unsafe {
+        TIME_MS = TIME_MS + 1;
+        timer_base.add(0x3c).write_volatile(1);
+    };
+}
+
+pub fn get_time() -> u32 {
+    unsafe { TIME_MS }
+}
+
+pub fn time_init() {
+    let timer_base = 0xE0002800 as *mut u8;
+    let period = 12_000_000 / 1000; // 12 MHz, 1 ms timer
+    unsafe {
+        // Disable, so we can update it
+        timer_base.add(0x20).write_volatile(0);
+
+        // Update "reload" register
+        timer_base.add(0x10).write_volatile((period >> 24) as u8);
+        timer_base.add(0x14).write_volatile((period >> 16) as u8);
+        timer_base.add(0x18).write_volatile((period >> 8) as u8);
+        timer_base.add(0x1c).write_volatile((period >> 0) as u8);
+
+        // Update "load" register
+        timer_base.add(0x00).write_volatile((period >> 24) as u8);
+        timer_base.add(0x04).write_volatile((period >> 16) as u8);
+        timer_base.add(0x08).write_volatile((period >> 8) as u8);
+        timer_base.add(0x0c).write_volatile((period >> 0) as u8);
+
+        // Enable ISR
+        timer_base.add(0x40).write_volatile(1);
+
+        // Set "pending" as well to clear it
+        timer_base.add(0x38).write_volatile(1);
+
+        // Finally, enable it
+        timer_base.add(0x20).write_volatile(1);
+    }
+}