Start working on cache detection using Clementine Maurice's performance counter approach.

Add a new crate for that, getting out of cache_utils no_std / use_std mess.

Cargo.lock

@@ -112,6 +112,10 @@ dependencies = [
  "nix 0.28.0",
 ]
 
+[[package]]
+name = "cache_slice"
+version = "0.1.0"
+
 [[package]]
 name = "cache_utils"
 version = "0.1.0"

Cargo.toml

@@ -15,5 +15,6 @@ members = [
     "basic_timing_cache_channel",
     "turn_lock",
     "CacheObserver",
-    "dendrobates-t-azureus"
+    "dendrobates-t-azureus",
+    "cache_slice",
 ]

cache_slice/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "cache_slice"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

cache_slice/src/bin/rdmsr.rs

@@ -0,0 +1,24 @@
+use cache_slice::msr;
+use std::env;
+fn main() {
+    let mut args = env::args().into_iter();
+    args.next();
+    for arg in args {
+        match arg.parse::<u32>() {
+            Ok(msr) => {
+                match msr::read_msr_on_cpu(msr, 0) {
+                    Ok(result) => {
+                        println!("MSR {}: {:x}", msr, result);
+                    },
+                    Err(e) => {
+                        eprintln!("Error, failed to read MSR {}: {}", msr, e);
+                    }
+                }
+            },
+            Err(e) => {
+                eprintln!("Error: {}", e);
+                eprintln!("{} is not a valid MSR number", arg);
+            }
+        }
+    }
+}

cache_slice/src/lib.rs

@@ -0,0 +1,16 @@
+pub mod msr;
+
+pub fn add(left: u64, right: u64) -> u64 {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}

cache_slice/src/msr.rs

@@ -0,0 +1,42 @@
+use core::mem::size_of;
+use std::format;
+use std::fs::{File, OpenOptions};
+use std::os::unix::fs::FileExt;
+use std::io::{Result, Error, ErrorKind};
+
+pub fn write_msr_on_cpu(msr: u32, cpu: u8, value: u64) -> Result<()> {
+    let path = format!("/dev/cpu/{}/msr", cpu);
+    let file : File = OpenOptions::new().write(true).open(path).expect("Failed to open MSR, are you running as root ?");
+    match file.write_at(&value.to_ne_bytes(), msr as u64) {
+        Ok(size) => {
+            if size == size_of::<u64>() {
+                Ok(())
+            } else {
+                Err(Error::other("Failed to write complete value"))
+            }
+        },
+        Err(e) => Err(e)
+    }
+}
+
+pub fn read_msr_on_cpu(msr: u32, cpu: u8) -> Result<u64> {
+    let path = format!("/dev/cpu/{}/msr", cpu);
+    let file : File = OpenOptions::new().read(true).open(path).expect("Failed to open MSR, are you running as root ?");
+    let mut read_data = [0u8; size_of::<u64>()];
+    match file.read_at(&mut read_data, msr as u64) {
+        Ok(size) => {
+            if size == size_of::<u64>() {
+                Ok(u64::from_ne_bytes(read_data))
+            } else {
+                Err(Error::other("Failed to write complete value"))
+            }
+        },
+        Err(e) => Err(e)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    // TODO how can we test model specific register read / write ?
+}