Auto merge of #1461 - RalfJung:rwlock-win, r=RalfJung

Implement rwlocks on Windows

Fixes #1059

Author: bors

src/helpers.rs

@@ -467,6 +467,37 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
         }
     }
+    
+    fn read_scalar_at_offset(
+        &self,
+        op: OpTy<'tcx, Tag>,
+        offset: u64,
+        layout: TyAndLayout<'tcx>,
+    ) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {
+        let this = self.eval_context_ref();
+        let op_place = this.deref_operand(op)?;
+        let offset = Size::from_bytes(offset);
+        // Ensure that the following read at an offset is within bounds
+        assert!(op_place.layout.size >= offset + layout.size);
+        let value_place = op_place.offset(offset, MemPlaceMeta::None, layout, this)?;
+        this.read_scalar(value_place.into())
+    }
+
+    fn write_scalar_at_offset(
+        &mut self,
+        op: OpTy<'tcx, Tag>,
+        offset: u64,
+        value: impl Into<ScalarMaybeUninit<Tag>>,
+        layout: TyAndLayout<'tcx>,
+    ) -> InterpResult<'tcx, ()> {
+        let this = self.eval_context_mut();
+        let op_place = this.deref_operand(op)?;
+        let offset = Size::from_bytes(offset);
+        // Ensure that the following read at an offset is within bounds
+        assert!(op_place.layout.size >= offset + layout.size);
+        let value_place = op_place.offset(offset, MemPlaceMeta::None, layout, this)?;
+        this.write_scalar(value, value_place.into())
+    }
 }
 
 /// Check that the number of args is what we expect.

src/shims/dlsym.rs

@@ -1,34 +1,24 @@
 use rustc_middle::mir;
 
 use crate::*;
-use helpers::check_arg_count;
+use shims::posix::dlsym as posix;
+use shims::windows::dlsym as windows;
 
 #[derive(Debug, Copy, Clone)]
+#[allow(non_camel_case_types)]
 pub enum Dlsym {
-    GetEntropy,
+    Posix(posix::Dlsym),
+    Windows(windows::Dlsym),
 }
 
 impl Dlsym {
     // Returns an error for unsupported symbols, and None if this symbol
     // should become a NULL pointer (pretend it does not exist).
     pub fn from_str(name: &[u8], target_os: &str) -> InterpResult<'static, Option<Dlsym>> {
-        use self::Dlsym::*;
-        let name = String::from_utf8_lossy(name);
+        let name = &*String::from_utf8_lossy(name);
         Ok(match target_os {
-            "linux" => match &*name {
-                "__pthread_get_minstack" => None,
-                _ => throw_unsup_format!("unsupported Linux dlsym: {}", name),
-            }
-            "macos" => match &*name {
-                "getentropy" => Some(GetEntropy),
-                _ => throw_unsup_format!("unsupported macOS dlsym: {}", name),
-            }
-            "windows" => match &*name {
-                "SetThreadStackGuarantee" => None,
-                "AcquireSRWLockExclusive" => None,
-                "GetSystemTimePreciseAsFileTime" => None,
-                _ => throw_unsup_format!("unsupported Windows dlsym: {}", name),
-            }
+            "linux" | "macos" => posix::Dlsym::from_str(name, target_os)?.map(Dlsym::Posix),
+            "windows" => windows::Dlsym::from_str(name)?.map(Dlsym::Windows),
             os => bug!("dlsym not implemented for target_os {}", os),
         })
     }
@@ -42,23 +32,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
     ) -> InterpResult<'tcx> {
-        use self::Dlsym::*;
-
         let this = self.eval_context_mut();
-        let (dest, ret) = ret.expect("we don't support any diverging dlsym");
-
         match dlsym {
-            GetEntropy => {
-                let &[ptr, len] = check_arg_count(args)?;
-                let ptr = this.read_scalar(ptr)?.not_undef()?;
-                let len = this.read_scalar(len)?.to_machine_usize(this)?;
-                this.gen_random(ptr, len)?;
-                this.write_null(dest)?;
-            }
+            Dlsym::Posix(dlsym) => posix::EvalContextExt::call_dlsym(this, dlsym, args, ret),
+            Dlsym::Windows(dlsym) => windows::EvalContextExt::call_dlsym(this, dlsym, args, ret),
         }
-
-        this.dump_place(*dest);
-        this.go_to_block(ret);
-        Ok(())
     }
 }

src/shims/foreign_items.rs

@@ -129,7 +129,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 // This matches calls to the foreign item `panic_impl`.
                 // The implementation is provided by the function with the `#[panic_handler]` attribute.
                 "panic_impl" => {
-                    this.check_panic_supported()?;
                     let panic_impl_id = tcx.lang_items().panic_impl().unwrap();
                     let panic_impl_instance = ty::Instance::mono(tcx, panic_impl_id);
                     return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));

src/shims/mod.rs

@@ -52,14 +52,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             return this.emulate_foreign_item(instance.def_id(), args, ret, unwind);
         }
 
-        // Better error message for panics on Windows.
-        let def_id = instance.def_id();
-        if Some(def_id) == this.tcx.lang_items().begin_panic_fn() ||
-            Some(def_id) == this.tcx.lang_items().panic_impl()
-        {
-            this.check_panic_supported()?;
-        }
-
         // Otherwise, load the MIR.
         Ok(Some(&*this.load_mir(instance.def, None)?))
     }

src/shims/panic.rs

@@ -34,14 +34,6 @@ pub struct CatchUnwindData<'tcx> {
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
-    /// Check if panicking is supported on this target, and give a good error otherwise.
-    fn check_panic_supported(&self) -> InterpResult<'tcx> {
-        match self.eval_context_ref().tcx.sess.target.target.target_os.as_str() {
-            "linux" | "macos" => Ok(()),
-            _ => throw_unsup_format!("panicking is not supported on this target"),
-        }
-    }
-
     /// Handles the special `miri_start_panic` intrinsic, which is called
     /// by libpanic_unwind to delegate the actual unwinding process to Miri.
     fn handle_miri_start_panic(

src/shims/posix/dlsym.rs

@@ -0,0 +1,39 @@
+use rustc_middle::mir;
+
+use crate::*;
+use shims::posix::linux::dlsym as linux;
+use shims::posix::macos::dlsym as macos;
+
+#[derive(Debug, Copy, Clone)]
+pub enum Dlsym {
+    Linux(linux::Dlsym),
+    MacOs(macos::Dlsym),
+}
+
+impl Dlsym {
+    // Returns an error for unsupported symbols, and None if this symbol
+    // should become a NULL pointer (pretend it does not exist).
+    pub fn from_str(name: &str, target_os: &str) -> InterpResult<'static, Option<Dlsym>> {
+        Ok(match target_os {
+            "linux" => linux::Dlsym::from_str(name)?.map(Dlsym::Linux),
+            "macos" => macos::Dlsym::from_str(name)?.map(Dlsym::MacOs),
+            _ => unreachable!(),
+        })
+    }
+}
+
+impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
+pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
+    fn call_dlsym(
+        &mut self,
+        dlsym: Dlsym,
+        args: &[OpTy<'tcx, Tag>],
+        ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
+    ) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+        match dlsym {
+            Dlsym::Linux(dlsym) => linux::EvalContextExt::call_dlsym(this, dlsym, args, ret),
+            Dlsym::MacOs(dlsym) => macos::EvalContextExt::call_dlsym(this, dlsym, args, ret),
+        }
+    }
+}

src/shims/posix/linux/dlsym.rs

@@ -0,0 +1,34 @@
+use rustc_middle::mir;
+
+use crate::*;
+
+#[derive(Debug, Copy, Clone)]
+pub enum Dlsym {
+}
+
+impl Dlsym {
+    // Returns an error for unsupported symbols, and None if this symbol
+    // should become a NULL pointer (pretend it does not exist).
+    pub fn from_str(name: &str) -> InterpResult<'static, Option<Dlsym>> {
+        Ok(match &*name {
+            "__pthread_get_minstack" => None,
+            _ => throw_unsup_format!("unsupported Linux dlsym: {}", name),
+        })
+    }
+}
+
+impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
+pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
+    fn call_dlsym(
+        &mut self,
+        dlsym: Dlsym,
+        _args: &[OpTy<'tcx, Tag>],
+        ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
+    ) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+        let (_dest, _ret) = ret.expect("we don't support any diverging dlsym");
+        assert!(this.tcx.sess.target.target.target_os == "linux");
+
+        match dlsym {}
+    }
+}

src/shims/posix/linux/mod.rs

@@ -1 +1,2 @@
 pub mod foreign_items;
+pub mod dlsym;

src/shims/posix/macos/dlsym.rs

@@ -0,0 +1,49 @@
+use rustc_middle::mir;
+
+use crate::*;
+use helpers::check_arg_count;
+
+#[derive(Debug, Copy, Clone)]
+#[allow(non_camel_case_types)]
+pub enum Dlsym {
+    getentropy,
+}
+
+impl Dlsym {
+    // Returns an error for unsupported symbols, and None if this symbol
+    // should become a NULL pointer (pretend it does not exist).
+    pub fn from_str(name: &str) -> InterpResult<'static, Option<Dlsym>> {
+        Ok(match name {
+            "getentropy" => Some(Dlsym::getentropy),
+            _ => throw_unsup_format!("unsupported macOS dlsym: {}", name),
+        })
+    }
+}
+
+impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
+pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
+    fn call_dlsym(
+        &mut self,
+        dlsym: Dlsym,
+        args: &[OpTy<'tcx, Tag>],
+        ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
+    ) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+        let (dest, ret) = ret.expect("we don't support any diverging dlsym");
+        assert!(this.tcx.sess.target.target.target_os == "macos");
+
+        match dlsym {
+            Dlsym::getentropy => {
+                let &[ptr, len] = check_arg_count(args)?;
+                let ptr = this.read_scalar(ptr)?.not_undef()?;
+                let len = this.read_scalar(len)?.to_machine_usize(this)?;
+                this.gen_random(ptr, len)?;
+                this.write_null(dest)?;
+            }
+        }
+
+        this.dump_place(*dest);
+        this.go_to_block(ret);
+        Ok(())
+    }
+}

src/shims/posix/macos/mod.rs

@@ -1 +1,2 @@
 pub mod foreign_items;
+pub mod dlsym;

src/shims/posix/mod.rs

@@ -1,4 +1,5 @@
 pub mod foreign_items;
+pub mod dlsym;
 
 mod fs;
 mod sync;