Auto merge of rust-lang#2140 - V0ldek:page_size, r=RalfJung

Update GetSystemInfo to work with `page_size` (rust-lang#2136)

- Change logic in GetSystemInfo shim to take into account the two possible layouts of `SYSTEM_INFO`, the first-field-is-union used by [winapi::um::sysinfoapi::SYSTEM_INFO](https://docs.rs/winapi/latest/winapi/um/sysinfoapi/struct.SYSTEM_INFO.html), and first-two-fields-are-inlined-union used by [num_cpus](https://github.com/seanmonstar/num_cpus/blob/5f1b03332000b4c4274b5bd35fac516049ff1c6b/src/lib.rs#L206).
- Fill out the `dwPageSize` field with the `PAGE_SIZE` constant of `4096`.

Closes rust-lang#2136

Author: bors

src/machine.rs

@@ -178,9 +178,11 @@ pub struct AllocExtra {
 pub struct PrimitiveLayouts<'tcx> {
     pub unit: TyAndLayout<'tcx>,
     pub i8: TyAndLayout<'tcx>,
+    pub i16: TyAndLayout<'tcx>,
     pub i32: TyAndLayout<'tcx>,
     pub isize: TyAndLayout<'tcx>,
     pub u8: TyAndLayout<'tcx>,
+    pub u16: TyAndLayout<'tcx>,
     pub u32: TyAndLayout<'tcx>,
     pub usize: TyAndLayout<'tcx>,
     pub bool: TyAndLayout<'tcx>,
@@ -194,9 +196,11 @@ impl<'mir, 'tcx: 'mir> PrimitiveLayouts<'tcx> {
         Ok(Self {
             unit: layout_cx.layout_of(tcx.mk_unit())?,
             i8: layout_cx.layout_of(tcx.types.i8)?,
+            i16: layout_cx.layout_of(tcx.types.i16)?,
             i32: layout_cx.layout_of(tcx.types.i32)?,
             isize: layout_cx.layout_of(tcx.types.isize)?,
             u8: layout_cx.layout_of(tcx.types.u8)?,
+            u16: layout_cx.layout_of(tcx.types.u16)?,
             u32: layout_cx.layout_of(tcx.types.u32)?,
             usize: layout_cx.layout_of(tcx.types.usize)?,
             bool: layout_cx.layout_of(tcx.types.bool)?,

src/shims/windows/foreign_items.rs

@@ -8,6 +8,7 @@ use rustc_target::spec::abi::Abi;
 use crate::*;
 use shims::foreign_items::EmulateByNameResult;
 use shims::windows::sync::EvalContextExt as _;
+use smallvec::SmallVec;
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
@@ -119,10 +120,56 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     system_info.ptr,
                     iter::repeat(0u8).take(system_info.layout.size.bytes() as usize),
                 )?;
+                // Set selected fields.
+                let word_layout = this.machine.layouts.u16;
+                let dword_layout = this.machine.layouts.u32;
+                let usize_layout = this.machine.layouts.usize;
+
+                // Using `mplace_field` is error-prone, see: https://github.com/rust-lang/miri/issues/2136.
+                // Pointer fields have different sizes on different targets.
+                // To avoid all these issue we calculate the offsets ourselves.
+                let field_sizes = [
+                    word_layout.size,  // 0,  wProcessorArchitecture      : WORD
+                    word_layout.size,  // 1,  wReserved                   : WORD
+                    dword_layout.size, // 2,  dwPageSize                  : DWORD
+                    usize_layout.size, // 3,  lpMinimumApplicationAddress : LPVOID
+                    usize_layout.size, // 4,  lpMaximumApplicationAddress : LPVOID
+                    usize_layout.size, // 5,  dwActiveProcessorMask       : DWORD_PTR
+                    dword_layout.size, // 6,  dwNumberOfProcessors        : DWORD
+                    dword_layout.size, // 7,  dwProcessorType             : DWORD
+                    dword_layout.size, // 8,  dwAllocationGranularity     : DWORD
+                    word_layout.size,  // 9,  wProcessorLevel             : WORD
+                    word_layout.size,  // 10, wProcessorRevision          : WORD
+                ];
+                let field_offsets: SmallVec<[Size; 11]> = field_sizes
+                    .iter()
+                    .copied()
+                    .scan(Size::ZERO, |a, x| {
+                        let res = Some(*a);
+                        *a += x;
+                        res
+                    })
+                    .collect();
+
+                // Set page size.
+                let page_size = system_info.offset(
+                    field_offsets[2],
+                    MemPlaceMeta::None,
+                    dword_layout,
+                    &this.tcx,
+                )?;
+                this.write_scalar(
+                    Scalar::from_int(PAGE_SIZE, dword_layout.size),
+                    &page_size.into(),
+                )?;
                 // Set number of processors.
-                let dword_size = Size::from_bytes(4);
-                let num_cpus = this.mplace_field(&system_info, 6)?;
-                this.write_scalar(Scalar::from_int(NUM_CPUS, dword_size), &num_cpus.into())?;
+                let num_cpus = system_info.offset(
+                    field_offsets[6],
+                    MemPlaceMeta::None,
+                    dword_layout,
+                    &this.tcx,
+                )?;
+                this.write_scalar(Scalar::from_int(NUM_CPUS, dword_layout.size), &num_cpus.into())?;
             }
 
             // Thread-local storage

test-cargo-miri/Cargo.lock

@@ -22,6 +22,7 @@ rand = { version = "0.8", features = ["small_rng"] }
 getrandom_1 = { package = "getrandom", version = "0.1" }
 getrandom_2 = { package = "getrandom", version = "0.2" }
 serde_derive = "1.0" # not actually used, but exercises some unique code path (`--extern` .so file)
+page_size = "0.4.1"
 
 [lib]
 test = false # test that this is respected (will show in the output)

test-cargo-miri/Cargo.toml

@@ -5,7 +5,7 @@ test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
 
 imported main
 
-running 7 tests
-..i....
-test result: ok. 6 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
+running 8 tests
+..i.....
+test result: ok. 7 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
 

test-cargo-miri/test.cross-target.stdout.ref

@@ -5,9 +5,9 @@ test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
 
 imported main
 
-running 7 tests
-..i....
-test result: ok. 6 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
+running 8 tests
+..i.....
+test result: ok. 7 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
 
 
 running 4 tests

test-cargo-miri/test.default.stdout.ref

@@ -8,5 +8,5 @@ imported main
 running 1 test
 test simple1 ... ok
 
-test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 6 filtered out
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 7 filtered out
 

test-cargo-miri/test.filter.cross-target.stdout.ref

@@ -8,7 +8,7 @@ imported main
 running 1 test
 test simple1 ... ok
 
-test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 6 filtered out
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 7 filtered out
 
 
 running 0 tests

test-cargo-miri/test.filter.stdout.ref

@@ -1,12 +1,13 @@
 
-running 7 tests
+running 8 tests
 test cargo_env ... ok
 test do_panic - should panic ... ok
 test does_not_work_on_miri ... ignored
 test entropy_rng ... ok
 test fail_index_check - should panic ... ok
+test page_size ... ok
 test simple1 ... ok
 test simple2 ... ok
 
-test result: ok. 6 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
+test result: ok. 7 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
 

test-cargo-miri/test.test-target.stdout.ref

@@ -1,4 +1,4 @@
-use rand::{SeedableRng, Rng, rngs::SmallRng};
+use rand::{rngs::SmallRng, Rng, SeedableRng};
 
 // Having more than 1 test does seem to make a difference
 // (i.e., this calls ptr::swap which having just one test does not).
@@ -49,14 +49,27 @@ fn cargo_env() {
 }
 
 #[test]
-#[should_panic(expected="Explicit panic")]
-fn do_panic() { // In large, friendly letters :)
+#[should_panic(expected = "Explicit panic")]
+fn do_panic() // In large, friendly letters :)
+{
     panic!("Explicit panic from test!");
 }
 
 #[test]
 #[allow(unconditional_panic)]
-#[should_panic(expected="the len is 0 but the index is 42")]
+#[should_panic(expected = "the len is 0 but the index is 42")]
 fn fail_index_check() {
     [][42]
 }
+
+#[test]
+fn page_size() {
+    let page_size = page_size::get();
+
+    // In particular, this checks that it is not 0.
+    assert!(
+        page_size.next_power_of_two() == page_size,
+        "page size not a power of two: {}",
+        page_size
+    );
+}