diff --git a/README.md b/README.md
index 81c4f5ffef..5803a88c0e 100644
--- a/README.md
+++ b/README.md
@@ -538,15 +538,23 @@ extern "Rust" {
fn miri_start_panic(payload: *mut u8) -> !;
/// Miri-provided extern function to get the internal unique identifier for the allocation that a pointer
- /// points to. This is only useful as an input to `miri_print_stacks`, and it is a separate call because
+ /// points to. If this pointer is invalid (not pointing to an allocation), interpretation will abort.
+ ///
+ /// This is only useful as an input to `miri_print_borrow_stacks`, and it is a separate call because
/// getting a pointer to an allocation at runtime can change the borrow stacks in the allocation.
+ /// This function should be considered unstable. It exists only to support `miri_print_borrow_stacks` and so
+ /// inherits all of its instability.
fn miri_get_alloc_id(ptr: *const ()) -> u64;
/// Miri-provided extern function to print (from the interpreter, not the program) the contents of all
- /// borrow stacks in an allocation. The format of what this emits is unstable and may change at any time.
- /// In particular, users should be aware that Miri will periodically attempt to garbage collect the
- /// contents of all stacks. Callers of this function may wish to pass `-Zmiri-tag-gc=0` to disable the GC.
- fn miri_print_stacks(alloc_id: u64);
+ /// borrow stacks in an allocation. The leftmost tag is the bottom of the stack.
+ /// The format of what this emits is unstable and may change at any time. In particular, users should be
+ /// aware that Miri will periodically attempt to garbage collect the contents of all stacks. Callers of
+ /// this function may wish to pass `-Zmiri-tag-gc=0` to disable the GC.
+ ///
+ /// This function is extremely unstable. At any time the format of its output may change, its signature may
+ /// change, or it may be removed entirely.
+ fn miri_print_borrow_stacks(alloc_id: u64);
/// Miri-provided extern function to print (from the interpreter, not the
/// program) the contents of a section of program memory, as bytes. Bytes
diff --git a/src/shims/foreign_items.rs b/src/shims/foreign_items.rs
index 9d0e47cd06..1b3205aabc 100644
--- a/src/shims/foreign_items.rs
+++ b/src/shims/foreign_items.rs
@@ -420,10 +420,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
"miri_get_alloc_id" => {
let [ptr] = this.check_shim(abi, Abi::Rust, link_name, args)?;
let ptr = this.read_pointer(ptr)?;
- let (alloc_id, _, _) = this.ptr_get_alloc_id(ptr)?;
+ let (alloc_id, _, _) = this.ptr_get_alloc_id(ptr).map_err(|_e| {
+ err_machine_stop!(TerminationInfo::Abort(
+ format!("pointer passed to miri_get_alloc_id must not be dangling, got {ptr:?}")
+ ))
+ })?;
this.write_scalar(Scalar::from_u64(alloc_id.0.get()), dest)?;
}
- "miri_print_stacks" => {
+ "miri_print_borrow_stacks" => {
let [id] = this.check_shim(abi, Abi::Rust, link_name, args)?;
let id = this.read_scalar(id)?.to_u64()?;
if let Some(id) = std::num::NonZeroU64::new(id) {
diff --git a/src/stacked_borrows/mod.rs b/src/stacked_borrows/mod.rs
index a2f003e6cc..cc27b71eb5 100644
--- a/src/stacked_borrows/mod.rs
+++ b/src/stacked_borrows/mod.rs
@@ -1154,6 +1154,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
let stacks = alloc_extra.stacked_borrows.as_ref().unwrap().borrow();
for (range, stack) in stacks.stacks.iter_all() {
print!("{range:?}: [");
+ if let Some(bottom) = stack.unknown_bottom() {
+ print!(" unknown-bottom(..{bottom:?})");
+ }
for i in 0..stack.len() {
let item = stack.get(i).unwrap();
print!(" {:?}{:?}", item.perm(), item.tag());
diff --git a/tests/pass/stacked-borrows/stack-printing.rs b/tests/pass/stacked-borrows/stack-printing.rs
index 8d96a2e1ca..3ca937ae13 100644
--- a/tests/pass/stacked-borrows/stack-printing.rs
+++ b/tests/pass/stacked-borrows/stack-printing.rs
@@ -1,3 +1,5 @@
+//@compile-flags: -Zmiri-permissive-provenance
+#![feature(strict_provenance)]
use std::{
alloc::{self, Layout},
mem::ManuallyDrop,
@@ -5,25 +7,40 @@ use std::{
extern "Rust" {
fn miri_get_alloc_id(ptr: *const u8) -> u64;
- fn miri_print_stacks(alloc_id: u64);
+ fn miri_print_borrow_stacks(alloc_id: u64);
+}
+
+fn get_alloc_id(ptr: *const u8) -> u64 {
+ unsafe { miri_get_alloc_id(ptr) }
+}
+
+fn print_borrow_stacks(alloc_id: u64) {
+ unsafe { miri_print_borrow_stacks(alloc_id) }
}
fn main() {
let ptr = unsafe { alloc::alloc(Layout::new::<u8>()) };
- let alloc_id = unsafe { miri_get_alloc_id(ptr) };
- unsafe { miri_print_stacks(alloc_id) };
+ let alloc_id = get_alloc_id(ptr);
+ print_borrow_stacks(alloc_id);
assert!(!ptr.is_null());
- unsafe { miri_print_stacks(alloc_id) };
+ print_borrow_stacks(alloc_id);
unsafe { *ptr = 42 };
- unsafe { miri_print_stacks(alloc_id) };
+ print_borrow_stacks(alloc_id);
let _b = unsafe { ManuallyDrop::new(Box::from_raw(ptr)) };
- unsafe { miri_print_stacks(alloc_id) };
+ print_borrow_stacks(alloc_id);
let _ptr = unsafe { &*ptr };
- unsafe { miri_print_stacks(alloc_id) };
+ print_borrow_stacks(alloc_id);
+
+ // Create an unknown bottom, and print it
+ let ptr = ptr as usize as *mut u8;
+ unsafe {
+ *ptr = 5;
+ }
+ print_borrow_stacks(alloc_id);
unsafe { alloc::dealloc(ptr, Layout::new::<u8>()) };
}
diff --git a/tests/pass/stacked-borrows/stack-printing.stdout b/tests/pass/stacked-borrows/stack-printing.stdout
index 660ee71e6f..8387330782 100644
--- a/tests/pass/stacked-borrows/stack-printing.stdout
+++ b/tests/pass/stacked-borrows/stack-printing.stdout
@@ -3,3 +3,4 @@
0..1: [ SharedReadWrite<TAG> ]
0..1: [ SharedReadWrite<TAG> Unique<TAG> Unique<TAG> Unique<TAG> Unique<TAG> Unique<TAG> ]
0..1: [ SharedReadWrite<TAG> Disabled<TAG> Disabled<TAG> Disabled<TAG> Disabled<TAG> Disabled<TAG> SharedReadOnly<TAG> ]
+0..1: [ unknown-bottom(..<TAG>) ]