Add ABI check for shims

Resolves #1631

Author: Nym Seddon

src/machine.rs

@@ -353,12 +353,12 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
     fn find_mir_or_eval_fn(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         instance: ty::Instance<'tcx>,
-        _abi: Abi,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
-        ecx.find_mir_or_eval_fn(instance, args, ret, unwind)
+        ecx.find_mir_or_eval_fn(instance, abi, args, ret, unwind)
     }
 
     #[inline(always)]

src/shims/mod.rs

@@ -16,6 +16,7 @@ pub mod tls;
 use log::trace;
 
 use rustc_middle::{mir, ty};
+use rustc_target::spec::abi::Abi;
 
 use crate::*;
 use helpers::check_arg_count;
@@ -25,6 +26,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     fn find_mir_or_eval_fn(
         &mut self,
         instance: ty::Instance<'tcx>,
+        abi: Abi,
         args: &[OpTy<'tcx, Tag>],
         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
         unwind: Option<mir::BasicBlock>,
@@ -40,6 +42,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
         }
 
+        if abi != Abi::C {
+            throw_ub_format!("calling a function with ABI {:?} using ABI {:?}", Abi::C, abi)
+        }
+
         // Try to see if we can do something about foreign items.
         if this.tcx.is_foreign_item(instance.def_id()) {
             // An external function call that does not have a MIR body. We either find MIR elsewhere
@@ -72,8 +78,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             return Ok(false);
         }
 
-        let req_align = this
-            .force_bits(this.read_scalar(align_op)?.check_init()?, this.pointer_size())?;
+        let req_align =
+            this.force_bits(this.read_scalar(align_op)?.check_init()?, this.pointer_size())?;
 
         // Stop if the alignment is not a power of two.
         if !req_align.is_power_of_two() {