Fix mmap clashing with temporary map addr. Add riscv toolchains in travis CI

.travis.yml

@@ -73,6 +73,26 @@ install:
       sudo apt install libfuse-dev;
     fi
 
+  - if [ $ARCH = riscv32 ]; then
+    if [ $TRAVIS_OS_NAME = linux ]; then
+    sudo apt update;
+    sudo apt install linux-headers-$(uname -r);
+    wget https://musl.cc/riscv32-linux-musl-cross.tgz;
+    tar -xvf riscv32-linux-musl-cross.tgz;
+    export PATH=$PATH:$PWD/riscv32-linux-musl-cross/bin;
+    fi;
+    fi
+  - if [ $ARCH = riscv64 ]; then
+    if [ $TRAVIS_OS_NAME = linux ]; then
+    sudo apt update;
+    sudo apt install linux-headers-$(uname -r);
+    wget https://musl.cc/riscv64-linux-musl-cross.tgz;
+    tar -xvf riscv64-linux-musl-cross.tgz;
+    export PATH=$PATH:$PWD/riscv64-linux-musl-cross/bin;
+    fi;
+    fi
+
+
 before_script:
   - rustup component add rust-src
   - (test -x $HOME/.cargo/bin/cargo-xbuild || cargo install cargo-xbuild)

crate/memory/src/paging/ext.rs

@@ -3,6 +3,9 @@
 use super::*;
 
 pub trait PageTableExt: PageTable {
+    // Take some special care here.
+    // TEMP_PAGE_ADDR mapping might be overwritten in the `f` below.
+    // So this should be really high in kernel space when necessary.
     const TEMP_PAGE_ADDR: VirtAddr = 0xcafeb000;
 
     fn with_temporary_map<T, D>(&mut self, target: PhysAddr, f: impl FnOnce(&mut Self, &mut D) -> T) -> T {

kernel/src/arch/x86_64/paging.rs

@@ -11,6 +11,7 @@ use x86_64::structures::paging::{
     frame::PhysFrame as Frame,
     FrameAllocator, FrameDeallocator
 };
+use crate::consts::KERNEL_OFFSET;
 use log::*;
 
 pub trait PageExt {
@@ -69,7 +70,9 @@ impl PageTable for ActivePageTable {
     }
 }
 
-impl PageTableExt for ActivePageTable {}
+impl PageTableExt for ActivePageTable {
+    const TEMP_PAGE_ADDR: usize = KERNEL_OFFSET | 0xcafeb000;
+}
 
 impl ActivePageTable {
     pub unsafe fn new() -> Self {