nak: Add an instruction fuzzing tool

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24998>

src/nouveau/compiler/meson.build

@@ -90,6 +90,15 @@ _libnak = static_library(
   gnu_symbol_visibility : 'hidden',
 )
 
+if with_tools.contains('nouveau')
+  executable(
+    'nvfuzz',
+    files('nvfuzz.rs'),
+    rust_crate_type : 'bin',
+    install : true
+  )
+endif
+
 idep_nak = declare_dependency(
   include_directories : include_directories('.'),
   link_with : _libnak,

src/nouveau/compiler/nvfuzz.rs

@@ -0,0 +1,98 @@
+/*
+ * Copyright © 2022 Collabora, Ltd.
+ * SPDX-License-Identifier: MIT
+ */
+
+mod bitset;
+mod util;
+
+use crate::bitset::*;
+
+use std::fs;
+use std::io::Write;
+use std::ops::Range;
+use std::path::PathBuf;
+use std::process::Command;
+
+const TMP_FILE: &str = "/tmp/nvfuzz";
+const SM: &str = "SM75";
+
+fn find_cuda() -> std::io::Result<PathBuf> {
+    let paths = fs::read_dir("/usr/local")?;
+
+    for path in paths {
+        let mut path = path?.path();
+        let Some(fname) = path.file_name() else {
+            continue;
+        };
+
+        let Some(fname) = fname.to_str() else {
+            continue;
+        };
+
+        if !fname.starts_with("cuda-") {
+            continue;
+        }
+
+        path.push("bin");
+        path.push("nvdisasm");
+        if path.exists() {
+            return Ok(path)
+        }
+    }
+
+    Err(std::io::Error::new(
+        std::io::ErrorKind::NotFound,
+        "Failed to find nvdisasm",
+    ))
+}
+
+//fn write_tmpfile(data: &[u32]) -> std::io::Result<()> {
+//    let mut file = std::fs::File::create(TMP_FILE)?;
+//    for dw in data {
+//        file.write(dw.to_le_bytes())?;
+//    }
+//}
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    let range: Vec<&str> = args[1].split("..").collect();
+    let range: Range<usize> = Range {
+        start: range[0].parse().unwrap(),
+        end: range[1].parse().unwrap(),
+    };
+
+    let mut instr: [u32; 4] = [
+        u32::from_str_radix(&args[2], 16).unwrap(),
+        u32::from_str_radix(&args[3], 16).unwrap(),
+        u32::from_str_radix(&args[4], 16).unwrap(),
+        u32::from_str_radix(&args[5], 16).unwrap(),
+    ];
+
+    let cuda_path = find_cuda().expect("Failed to find CUDA");
+
+    for bits in 0..(1_u64 << range.len()) {
+        BitSetMutView::new(&mut instr).set_field(range.clone(), bits);
+
+        print!("With {:#x} in {}..{}:", bits, range.start, range.end);
+        for dw in instr {
+            print!(" {:#x}", dw);
+        }
+        print!("\n");
+
+        let mut data = Vec::new();
+        for dw in instr {
+            data.extend(dw.to_le_bytes());
+        }
+        std::fs::write(TMP_FILE, data).expect("Failed to write file");
+
+        let out = Command::new(cuda_path.as_path())
+            .arg("-b")
+            .arg(SM)
+            .arg(TMP_FILE)
+            .output()
+            .expect("failed to execute process");
+        std::io::stderr().write_all(&out.stderr).expect("IO error");
+        std::io::stdout().write_all(&out.stdout).expect("IO error");
+    }
+}