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refactor extern static handling

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This commit is contained in:
Ralf Jung 2024-01-24 09:37:00 +01:00
parent cf22ee0c0c
commit cba1fdbff3
4 changed files with 82 additions and 73 deletions
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5
src/tools/miri/ci/ci.sh
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@ -121,9 +121,8 @@ case $HOST_TARGET in
MIRI_TEST_TARGET=aarch64-apple-darwin run_tests
MIRI_TEST_TARGET=i686-pc-windows-gnu run_tests
# Some targets are only partially supported.
# FIXME: freeBSD disabled due to https://github.com/rust-lang/miri/issues/3276
#MIRI_TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal hello integer vec panic/panic concurrency/simple pthread-threadname libc-getentropy libc-getrandom libc-misc libc-fs atomic env align
#MIRI_TEST_TARGET=i686-unknown-freebsd run_tests_minimal hello integer vec panic/panic concurrency/simple pthread-threadname libc-getentropy libc-getrandom libc-misc libc-fs atomic env align
MIRI_TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal hello integer vec panic/panic concurrency/simple pthread-threadname libc-getentropy libc-getrandom libc-misc libc-fs atomic env align
MIRI_TEST_TARGET=i686-unknown-freebsd run_tests_minimal hello integer vec panic/panic concurrency/simple pthread-threadname libc-getentropy libc-getrandom libc-misc libc-fs atomic env align
MIRI_TEST_TARGET=aarch64-linux-android run_tests_minimal hello integer vec panic/panic
MIRI_TEST_TARGET=wasm32-wasi run_tests_minimal no_std integer strings wasm
MIRI_TEST_TARGET=wasm32-unknown-unknown run_tests_minimal no_std integer strings wasm

71
src/tools/miri/src/machine.rs
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@ -691,7 +691,7 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
Ok(())
}
fn add_extern_static(
pub(crate) fn add_extern_static(
this: &mut MiriInterpCx<'mir, 'tcx>,
name: &str,
ptr: Pointer<Option<Provenance>>,
@ -701,75 +701,6 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
this.machine.extern_statics.try_insert(Symbol::intern(name), ptr).unwrap();
}
fn alloc_extern_static(
this: &mut MiriInterpCx<'mir, 'tcx>,
name: &str,
val: ImmTy<'tcx, Provenance>,
) -> InterpResult<'tcx> {
let place = this.allocate(val.layout, MiriMemoryKind::ExternStatic.into())?;
this.write_immediate(*val, &place)?;
Self::add_extern_static(this, name, place.ptr());
Ok(())
}
/// Sets up the "extern statics" for this machine.
fn init_extern_statics(this: &mut MiriInterpCx<'mir, 'tcx>) -> InterpResult<'tcx> {
// "__rust_no_alloc_shim_is_unstable"
let val = ImmTy::from_int(0, this.machine.layouts.u8);
Self::alloc_extern_static(this, "__rust_no_alloc_shim_is_unstable", val)?;
match this.tcx.sess.target.os.as_ref() {
"linux" => {
// "environ"
Self::add_extern_static(
this,
"environ",
this.machine.env_vars.environ.as_ref().unwrap().ptr(),
);
// A couple zero-initialized pointer-sized extern statics.
// Most of them are for weak symbols, which we all set to null (indicating that the
// symbol is not supported, and triggering fallback code which ends up calling a
// syscall that we do support).
for name in &["__cxa_thread_atexit_impl", "getrandom", "statx", "__clock_gettime64"]
{
let val = ImmTy::from_int(0, this.machine.layouts.usize);
Self::alloc_extern_static(this, name, val)?;
}
}
"freebsd" => {
// "environ"
Self::add_extern_static(
this,
"environ",
this.machine.env_vars.environ.as_ref().unwrap().ptr(),
);
}
"android" => {
// "signal" -- just needs a non-zero pointer value (function does not even get called),
// but we arrange for this to be callable anyway (it will then do nothing).
let layout = this.machine.layouts.const_raw_ptr;
let ptr = this.fn_ptr(FnVal::Other(DynSym::from_str("signal")));
let val = ImmTy::from_scalar(Scalar::from_pointer(ptr, this), layout);
Self::alloc_extern_static(this, "signal", val)?;
// A couple zero-initialized pointer-sized extern statics.
// Most of them are for weak symbols, which we all set to null (indicating that the
// symbol is not supported, and triggering fallback code.)
for name in &["bsd_signal"] {
let val = ImmTy::from_int(0, this.machine.layouts.usize);
Self::alloc_extern_static(this, name, val)?;
}
}
"windows" => {
// "_tls_used"
// This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
let val = ImmTy::from_int(0, this.machine.layouts.u8);
Self::alloc_extern_static(this, "_tls_used", val)?;
}
_ => {} // No "extern statics" supported on this target
}
Ok(())
}
pub(crate) fn communicate(&self) -> bool {
self.isolated_op == IsolatedOp::Allow
}

78
src/tools/miri/src/shims/extern_static.rs Normal file
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@ -0,0 +1,78 @@
//! Provides the `extern static` that this platform expects.
use crate::*;
impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
fn alloc_extern_static(
this: &mut MiriInterpCx<'mir, 'tcx>,
name: &str,
val: ImmTy<'tcx, Provenance>,
) -> InterpResult<'tcx> {
let place = this.allocate(val.layout, MiriMemoryKind::ExternStatic.into())?;
this.write_immediate(*val, &place)?;
Self::add_extern_static(this, name, place.ptr());
Ok(())
}
/// Zero-initialized pointer-sized extern statics are pretty common.
/// Most of them are for weak symbols, which we all set to null (indicating that the
/// symbol is not supported, and triggering fallback code which ends up calling a
/// syscall that we do support).
fn null_ptr_extern_statics(
this: &mut MiriInterpCx<'mir, 'tcx>,
names: &[&str],
) -> InterpResult<'tcx> {
for name in names {
let val = ImmTy::from_int(0, this.machine.layouts.usize);
Self::alloc_extern_static(this, name, val)?;
}
Ok(())
}
/// Sets up the "extern statics" for this machine.
pub fn init_extern_statics(this: &mut MiriInterpCx<'mir, 'tcx>) -> InterpResult<'tcx> {
// "__rust_no_alloc_shim_is_unstable"
let val = ImmTy::from_int(0, this.machine.layouts.u8);
Self::alloc_extern_static(this, "__rust_no_alloc_shim_is_unstable", val)?;
match this.tcx.sess.target.os.as_ref() {
"linux" => {
Self::null_ptr_extern_statics(
this,
&["__cxa_thread_atexit_impl", "getrandom", "statx", "__clock_gettime64"],
)?;
// "environ"
Self::add_extern_static(
this,
"environ",
this.machine.env_vars.environ.as_ref().unwrap().ptr(),
);
}
"freebsd" => {
// "environ"
Self::add_extern_static(
this,
"environ",
this.machine.env_vars.environ.as_ref().unwrap().ptr(),
);
}
"android" => {
Self::null_ptr_extern_statics(this, &["bsd_signal"])?;
// "signal" -- just needs a non-zero pointer value (function does not even get called),
// but we arrange for this to call the `signal` function anyway.
let layout = this.machine.layouts.const_raw_ptr;
let ptr = this.fn_ptr(FnVal::Other(DynSym::from_str("signal")));
let val = ImmTy::from_scalar(Scalar::from_pointer(ptr, this), layout);
Self::alloc_extern_static(this, "signal", val)?;
}
"windows" => {
// "_tls_used"
// This is some obscure hack that is part of the Windows TLS story. It's a `u8`.
let val = ImmTy::from_int(0, this.machine.layouts.u8);
Self::alloc_extern_static(this, "_tls_used", val)?;
}
_ => {} // No "extern statics" supported on this target
}
Ok(())
}
}

1
src/tools/miri/src/shims/mod.rs
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@ -10,6 +10,7 @@ pub mod windows;
mod x86;
pub mod env;
pub mod extern_static;
pub mod os_str;
pub mod panic;
pub mod time;