Implement asm functions

.gitignore

@@ -1,2 +1,5 @@
 Cargo.lock
 target/
+bin/*.after
+bin/*.before
+bin/*.o

asm.S

@@ -0,0 +1,55 @@
+#include "asm.h"
+
+.section .text.__ebreak
+.global __ebreak
+__ebreak:
+    ebreak
+    ret
+
+.section .text.__wfi
+.global __wfi
+__wfi:
+    wfi
+    ret
+
+.section .text.__sfence_vma_all
+.global __sfence_vma_all
+__sfence_vma_all:
+    sfence.vma
+    ret
+
+.section .text.__sfence_vma
+.global __sfence_vma
+__sfence_vma:
+    sfence.vma a0, a1
+    ret
+
+
+// M-mode registers
+REG_READ(mcause, 0x342)
+REG_READ(mcycle, 0xB00)
+REG_READ(mepc, 0x341)
+REG_READ(mie, 0x304)
+REG_SET_CLEAR(mie, 0x304)
+REG_READ(minstret, 0xB02)
+REG_READ(mip, 0x344)
+REG_READ(misa, 0x301)
+REG_READ(mstatus, 0x300)
+REG_SET_CLEAR(mstatus, 0x300)
+REG_READ_WRITE(mtvec, 0x305)
+REG_READ(mvendorid, 0xF11)
+
+// S-mode registers
+REG_READ_WRITE(satp, 0x180)
+REG_READ(scause, 0x142)
+REG_READ_WRITE(sepc, 0x141)
+REG_READ(sie, 0x104)
+REG_SET_CLEAR(sie, 0x104)
+REG_READ(sip, 0x144)
+REG_READ_WRITE(sscratch, 0x140)
+REG_READ(sstatus, 0x100)
+REG_SET_CLEAR(sstatus, 0x100)
+REG_READ(stval, 0x143)
+REG_READ_WRITE(stvec, 0x105)
+
+REG_READ(time, 0xC01)

asm.h

@@ -0,0 +1,37 @@
+#ifndef __ASM_H
+#define __ASM_H
+
+#define REG_READ(name, offset) \
+.section .text.__read_ ## name; \
+.global __read_ ## name; \
+__read_ ## name: \
+    csrrs a0, offset, x0; \
+    ret
+
+#define REG_WRITE(name, offset) \
+.section .text.__write_ ## name; \
+.global __write_ ## name; \
+__write_ ## name: \
+    csrrw x0, offset, a0; \
+    ret
+
+#define REG_SET(name, offset) \
+.section .text.__set_ ## name; \
+.global __set_ ## name; \
+__set_ ## name: \
+    csrrs x0, offset, a0; \
+    ret
+
+#define REG_CLEAR(name, offset) \
+.section .text.__clear_ ## name; \
+.global __clear_ ## name; \
+__clear_ ## name: \
+    csrrc x0, offset, a0; \
+    ret
+
+
+#define REG_READ_WRITE(name, offset) REG_READ(name, offset); REG_WRITE(name, offset)
+#define REG_SET_CLEAR(name, offset) REG_SET(name, offset); REG_CLEAR(name, offset)
+
+#endif /* __ASM_H */
+

asm32.S

@@ -0,0 +1,5 @@
+#include "asm.h"
+
+REG_READ(mcycleh, 0xB80)
+REG_READ(minstreth, 0xB82)
+REG_READ(timeh, 0xC81)

assemble.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+crate=riscv
+
+# remove existing blobs because otherwise this will append object files to the old blobs
+rm -f bin/*.a
+
+riscv64-unknown-elf-gcc -c -mabi=ilp32 -march=rv32imac asm.S -o bin/$crate.o
+riscv64-unknown-elf-gcc -c -mabi=ilp32 -march=rv32imac asm32.S -o bin/$crate-32.o
+ar crs bin/riscv32imac-unknown-none-elf.a bin/$crate.o bin/$crate-32.o
+cp bin/riscv32imac-unknown-none-elf.a bin/riscv32imc-unknown-none-elf.a
+
+rm bin/$crate.o
+rm bin/$crate-32.o

build.rs

@@ -1,7 +1,20 @@
-use std::env;
+use std::path::PathBuf;
+use std::{env, fs};
 
 fn main() {
     let target = env::var("TARGET").unwrap();
+    let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
+    let name = env::var("CARGO_PKG_NAME").unwrap();
+
+    if target.starts_with("riscv") && env::var_os("CARGO_FEATURE_INLINE_ASM").is_none() {
+        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());
+    }
 
     if target.starts_with("riscv32") {
         println!("cargo:rustc-cfg=riscv");

check-blobs.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# Checks that the blobs are up to date with the committed assembly files
+
+set -euxo pipefail
+
+for lib in $(ls bin/*.a); do
+    filename=$(basename $lib)
+    riscv64-unknown-elf-objdump -Cd $lib > bin/${filename%.a}.before
+done
+
+./assemble.sh
+
+for lib in $(ls bin/*.a); do
+    filename=$(basename $lib)
+    riscv64-unknown-elf-objdump -Cd $lib > bin/${filename%.a}.after
+done
+
+for cksum in $(ls bin/*.after); do
+    diff -u $cksum ${cksum%.after}.before
+done