minimal ptrace setup

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Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>

review comments

fix possible hang

Author: nia-e

Cargo.lock

@@ -40,6 +40,11 @@ libc = "0.2"
 libffi = "4.0.0"
 libloading = "0.8"
 
+[target.'cfg(target_os = "linux")'.dependencies]
+nix = { version = "0.30.1", features = ["mman", "ptrace", "signal"] }
+ipc-channel = "0.19.0"
+serde = { version = "1.0.219", features = ["derive"] }
+
 [dev-dependencies]
 ui_test = "0.29.1"
 colored = "2"

Cargo.toml

@@ -419,6 +419,11 @@ to Miri failing to detect cases of undefined behavior in a program.
   Finally, the flag is **unsound** in the sense that Miri stops tracking details such as
   initialization and provenance on memory shared with native code, so it is easily possible to write
   code that has UB which is missed by Miri.
+* `-Zmiri-force-old-native-lib-mode` disables the WIP improved native code access tracking. If for
+  whatever reason enabling native calls leads to odd behaviours or causes Miri to panic, disabling
+  the tracer *might* fix this. This will likely be removed once the tracer has been adequately
+  battle-tested. Note that this flag is only meaningful on Linux systems; other Unixes (currently)
+  exclusively use the old native-lib code.
 * `-Zmiri-measureme=<name>` enables `measureme` profiling for the interpreted program.
    This can be used to find which parts of your program are executing slowly under Miri.
    The profile is written out to a file inside a directory called `<name>`, and can be processed

README.md

@@ -266,6 +266,18 @@ impl IsolatedAlloc {
             alloc::dealloc(ptr, layout);
         }
     }
+
+    /// Returns a vector of page addresses managed by the allocator.
+    pub fn pages(&self) -> Vec<usize> {
+        let mut pages: Vec<_> =
+            self.page_ptrs.clone().into_iter().map(|p| p.expose_provenance()).collect();
+        for (ptr, size) in &self.huge_ptrs {
+            for i in 0..size / self.page_size {
+                pages.push(ptr.expose_provenance().strict_add(i * self.page_size));
+            }
+        }
+        pages
+    }
 }
 
 #[cfg(test)]

src/alloc/isolated_alloc.rs

@@ -227,10 +227,11 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
         } else {
             let return_code = miri::eval_entry(tcx, entry_def_id, entry_type, &config, None)
                 .unwrap_or_else(|| {
+                    #[cfg(target_os = "linux")]
+                    miri::register_retcode_sv(rustc_driver::EXIT_FAILURE);
                     tcx.dcx().abort_if_errors();
                     rustc_driver::EXIT_FAILURE
                 });
-
             std::process::exit(return_code);
         }
 
@@ -722,6 +723,8 @@ fn main() {
             } else {
                 show_error!("-Zmiri-native-lib `{}` does not exist", filename);
             }
+        } else if arg == "-Zmiri-force-old-native-lib-mode" {
+            miri_config.force_old_native_lib = true;
         } else if let Some(param) = arg.strip_prefix("-Zmiri-num-cpus=") {
             let num_cpus = param
                 .parse::<u32>()
@@ -792,6 +795,16 @@ fn main() {
 
     debug!("rustc arguments: {:?}", rustc_args);
     debug!("crate arguments: {:?}", miri_config.args);
+    #[cfg(target_os = "linux")]
+    if !miri_config.native_lib.is_empty() && !miri_config.force_old_native_lib {
+        // FIXME: This should display a diagnostic / warning on error
+        // SAFETY: If any other threads exist at this point (namely for the ctrlc
+        // handler), they will not interact with anything on the main rustc/Miri
+        // thread in an async-signal-unsafe way such as by accessing shared
+        // semaphores, etc.; the handler only calls `sleep()` and `exit()`, which
+        // are async-signal-safe, as is accessing atomics
+        let _ = unsafe { miri::init_sv() };
+    }
     run_compiler_and_exit(
         &rustc_args,
         &mut MiriCompilerCalls::new(miri_config, many_seeds, genmc_config),