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- Changed the separator from '+' to ','.
- Moved the branch protection options from -C to -Z.
- Additional test for incorrect branch-protection option.
- Remove LLVM < 12 code.
- Style fixes.

Co-authored-by: James McGregor <james.mcgregor2@arm.com>
This commit is contained in:
Jamie Cunliffe 2021-12-01 15:56:59 +00:00
parent 837cc1687f
commit 984ca4689d
12 changed files with 57 additions and 120 deletions
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54
compiler/rustc_codegen_llvm/src/attributes.rs
View File

@ -9,7 +9,7 @@ use rustc_hir::def_id::DefId;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::ty::{self, TyCtxt};
use rustc_session::config::{BranchProtection, OptLevel, PAuthKey};
use rustc_session::config::OptLevel;
use rustc_session::Session;
use rustc_target::spec::abi::Abi;
use rustc_target::spec::{FramePointer, SanitizerSet, StackProbeType, StackProtector};
@ -203,58 +203,6 @@ pub fn non_lazy_bind(sess: &Session, llfn: &'ll Value) {
}
}
pub fn set_branch_protection(sess: &Session, llfn: &'ll Value) {
// Setting PAC/BTI function attributes is only necessary for LLVM 11 and earlier.
// For LLVM 12 and greater, module-level metadata attributes are set in
// `compiler/rustc_codegen_llvm/src/context.rs`.
if llvm_util::get_version() >= (12, 0, 0) {
return;
}
let BranchProtection { bti, pac_ret: pac } = sess.opts.cg.branch_protection;
if bti {
llvm::AddFunctionAttrString(
llfn,
llvm::AttributePlace::Function,
cstr!("branch-target-enforcement"),
);
}
if let Some(pac_opts) = pac {
if pac_opts.leaf {
llvm::AddFunctionAttrStringValue(
llfn,
llvm::AttributePlace::Function,
cstr!("sign-return-address"),
cstr!("non-leaf"),
);
} else {
llvm::AddFunctionAttrStringValue(
llfn,
llvm::AttributePlace::Function,
cstr!("sign-return-address"),
cstr!("all"),
);
}
match pac_opts.key {
PAuthKey::A => llvm::AddFunctionAttrStringValue(
llfn,
llvm::AttributePlace::Function,
cstr!("sign-return-address-key"),
cstr!("a_key"),
),
PAuthKey::B => llvm::AddFunctionAttrStringValue(
llfn,
llvm::AttributePlace::Function,
cstr!("sign-return-address-key"),
cstr!("b_key"),
),
}
}
}
pub(crate) fn default_optimisation_attrs(sess: &Session, llfn: &'ll Value) {
match sess.opts.optimize {
OptLevel::Size => {

42
compiler/rustc_codegen_llvm/src/context.rs
View File

@ -21,7 +21,7 @@ use rustc_middle::ty::layout::{
};
use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
use rustc_middle::{bug, span_bug};
use rustc_session::config::{BranchProtection, CFGuard, CrateType, DebugInfo, PAuthKey};
use rustc_session::config::{BranchProtection, CFGuard, CrateType, DebugInfo, PAuthKey, PacRet};
use rustc_session::Session;
use rustc_span::source_map::Span;
use rustc_span::symbol::Symbol;
@ -243,7 +243,7 @@ pub unsafe fn create_module(
}
if sess.target.arch == "aarch64" {
let BranchProtection { bti, pac_ret: pac } = sess.opts.cg.branch_protection;
let BranchProtection { bti, pac_ret: pac } = sess.opts.debugging_opts.branch_protection;
llvm::LLVMRustAddModuleFlag(
llmod,
@ -251,27 +251,23 @@ pub unsafe fn create_module(
bti.into(),
);
if let Some(pac_opts) = pac {
llvm::LLVMRustAddModuleFlag(llmod, "sign-return-address\0".as_ptr().cast(), 1);
llvm::LLVMRustAddModuleFlag(
llmod,
"sign-return-address-all\0".as_ptr().cast(),
pac_opts.leaf.into(),
);
llvm::LLVMRustAddModuleFlag(
llmod,
"sign-return-address-with-bkey\0".as_ptr().cast(),
if pac_opts.key == PAuthKey::A { 0 } else { 1 },
);
} else {
llvm::LLVMRustAddModuleFlag(llmod, "sign-return-address\0".as_ptr().cast(), 0);
llvm::LLVMRustAddModuleFlag(llmod, "sign-return-address-all\0".as_ptr().cast(), 0);
llvm::LLVMRustAddModuleFlag(
llmod,
"sign-return-address-with-bkey\0".as_ptr().cast(),
0,
);
}
llvm::LLVMRustAddModuleFlag(
llmod,
"sign-return-address\0".as_ptr().cast(),
pac.is_some().into(),
);
let pac_opts = pac.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
llvm::LLVMRustAddModuleFlag(
llmod,
"sign-return-address-all\0".as_ptr().cast(),
pac_opts.leaf.into(),
);
let is_bkey = if pac_opts.key == PAuthKey::A { false } else { true };
llvm::LLVMRustAddModuleFlag(
llmod,
"sign-return-address-with-bkey\0".as_ptr().cast(),
is_bkey.into(),
);
}
llmod

4
compiler/rustc_codegen_llvm/src/declare.rs
View File

@ -45,10 +45,6 @@ fn declare_raw_fn(
llvm::Attribute::NoRedZone.apply_llfn(Function, llfn);
}
if cx.tcx.sess.target.arch == "aarch64" {
attributes::set_branch_protection(cx.tcx.sess, llfn);
}
attributes::default_optimisation_attrs(cx.tcx.sess, llfn);
attributes::non_lazy_bind(cx.sess(), llfn);

8
compiler/rustc_interface/src/tests.rs
View File

@ -567,10 +567,6 @@ fn test_codegen_options_tracking_hash() {
// Make sure that changing a [TRACKED] option changes the hash.
// This list is in alphabetical order.
tracked!(
branch_protection,
BranchProtection { bti: true, pac_ret: Some(PacRet { leaf: true, key: PAuthKey::B }) }
);
tracked!(code_model, Some(CodeModel::Large));
tracked!(control_flow_guard, CFGuard::Checks);
tracked!(debug_assertions, Some(true));
@ -723,6 +719,10 @@ fn test_debugging_options_tracking_hash() {
tracked!(asm_comments, true);
tracked!(assume_incomplete_release, true);
tracked!(binary_dep_depinfo, true);
tracked!(
branch_protection,
BranchProtection { bti: true, pac_ret: Some(PacRet { leaf: true, key: PAuthKey::B }) }
);
tracked!(chalk, true);
tracked!(codegen_backend, Some("abc".to_string()));
tracked!(crate_attr, vec!["abc".to_string()]);

9
compiler/rustc_session/src/options.rs
View File

@ -390,7 +390,7 @@ mod desc {
pub const parse_stack_protector: &str =
"one of (`none` (default), `basic`, `strong`, or `all`)";
pub const parse_branch_protection: &str =
"a `+` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf`";
"a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf`";
}
mod parse {
@ -935,7 +935,7 @@ mod parse {
crate fn parse_branch_protection(slot: &mut BranchProtection, v: Option<&str>) -> bool {
match v {
Some(s) => {
for opt in s.split('+') {
for opt in s.split(',') {
match opt {
"bti" => slot.bti = true,
"pac-ret" if slot.pac_ret.is_none() => {
@ -953,7 +953,6 @@ mod parse {
};
}
}
_ => return false,
}
true
@ -971,8 +970,6 @@ options! {
ar: String = (String::new(), parse_string, [UNTRACKED],
"this option is deprecated and does nothing"),
branch_protection: BranchProtection = (BranchProtection::default(), parse_branch_protection, [TRACKED],
"set options for branch target identification and pointer authentication on AArch64"),
code_model: Option<CodeModel> = (None, parse_code_model, [TRACKED],
"choose the code model to use (`rustc --print code-models` for details)"),
codegen_units: Option<usize> = (None, parse_opt_number, [UNTRACKED],
@ -1101,6 +1098,8 @@ options! {
(default: no)"),
borrowck: String = ("migrate".to_string(), parse_string, [UNTRACKED],
"select which borrowck is used (`mir` or `migrate`) (default: `migrate`)"),
branch_protection: BranchProtection = (BranchProtection::default(), parse_branch_protection, [TRACKED],
"set options for branch target identification and pointer authentication on AArch64"),
cgu_partitioning_strategy: Option<String> = (None, parse_opt_string, [TRACKED],
"the codegen unit partitioning strategy to use"),
chalk: bool = (false, parse_bool, [TRACKED],

23
src/doc/rustc/src/codegen-options/index.md
View File

@ -7,29 +7,6 @@ a version of this list for your exact compiler by running `rustc -C help`.
This option is deprecated and does nothing.
## branch-protection
This option lets you enable branch authentication instructions on AArch64.
This option is ignored for non-AArch64 architectures.
It takes some combination of the following values, separated by a `+`.
- `pac-ret` - Enable pointer authentication for non-leaf functions.
- `leaf` - Enable pointer authentication for all functions, including leaf functions.
- `b-key` - Sign return addresses with key B, instead of the default key A.
- `bti` - Enable branch target identification.
`leaf` and `b-key` are only valid if `pac-ret` was previously specified.
For example, `-C branch-protection=bti+pac-ret+leaf` is valid, but
`-C branch-protection=bti+leaf+pac-ret` is not.
Repeated values are ignored.
For example, `-C branch-protection=pac-ret+leaf+pac-ret` is equivalent to
`-C branch-protection=pac-ret+leaf`.
Rust's standard library does not ship with BTI or pointer authentication enabled by default. \
In Cargo projects the standard library can be recompiled with pointer authentication using the nightly
[build-std](https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#build-std) feature.
## code-model
This option lets you choose which code model to use. \

18
src/doc/unstable-book/src/compiler-flags/branch-protection.md Normal file
View File

@ -0,0 +1,18 @@
# `branch-protection`
This option lets you enable branch authentication instructions on AArch64.
This option is ignored for non-AArch64 architectures.
It takes some combination of the following values, separated by a `,`.
- `pac-ret` - Enable pointer authentication for non-leaf functions.
- `leaf` - Enable pointer authentication for all functions, including leaf functions.
- `b-key` - Sign return addresses with key B, instead of the default key A.
- `bti` - Enable branch target identification.
`leaf` and `b-key` are only valid if `pac-ret` was previously specified.
For example, `-Z branch-protection=bti,pac-ret,leaf` is valid, but
`-Z branch-protection=bti,leaf,pac-ret` is not.
Rust's standard library does not ship with BTI or pointer authentication enabled by default.
In Cargo projects the standard library can be recompiled with pointer authentication using the nightly
[build-std](https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#build-std) feature.

2
src/test/assembly/aarch64-pointer-auth.rs
View File

@ -3,7 +3,7 @@
// min-llvm-version: 10.0.1
// assembly-output: emit-asm
// compile-flags: --target aarch64-unknown-linux-gnu
// compile-flags: -C branch-protection=pac-ret+leaf
// compile-flags: -Z branch-protection=pac-ret,leaf
// needs-llvm-components: aarch64
#![feature(no_core, lang_items)]

8
src/test/codegen/branch-protection.rs
View File

@ -3,10 +3,10 @@
// revisions: bti pac-ret leaf b-key
// min-llvm-version: 12.0.0
// needs-llvm-components: aarch64
// [bti] compile-flags: -C branch-protection=bti
// [pac-ret] compile-flags: -C branch-protection=pac-ret
// [leaf] compile-flags: -C branch-protection=pac-ret+leaf
// [b-key] compile-flags: -C branch-protection=pac-ret+b-key
// [bti] compile-flags: -Z branch-protection=bti
// [pac-ret] compile-flags: -Z branch-protection=pac-ret
// [leaf] compile-flags: -Z branch-protection=pac-ret,leaf
// [b-key] compile-flags: -Z branch-protection=pac-ret,b-key
// compile-flags: --target aarch64-unknown-linux-gnu
#![crate_type = "lib"]

6
src/test/run-make-fulldeps/pointer-auth-link-with-c/Makefile
View File

@ -5,10 +5,10 @@
all:
$(COMPILE_OBJ) $(TMPDIR)/test.o test.c
$(AR) rcs $(TMPDIR)/libtest.a $(TMPDIR)/test.o
$(RUSTC) -C branch-protection=bti+pac-ret+leaf test.rs
$(RUSTC) -Z branch-protection=bti,pac-ret,leaf test.rs
$(call RUN,test)
$(COMPILE_OBJ) $(TMPDIR)/test.o test.c -mbranch-protection=bti+pac-ret+leaf
$(AR) rcs $(TMPDIR)/libtest.a $(TMPDIR)/test.o
$(RUSTC) -C branch-protection=bti+pac-ret+leaf test.rs
$(call RUN,test)
$(RUSTC) -Z branch-protection=bti,pac-ret,leaf test.rs
$(call RUN,test)

1
src/test/ui/invalid-compile-flags/branch-protection-missing-pac-ret.rs Normal file
View File

@ -0,0 +1 @@
// compile-flags: -Z branch-protection=leaf

2
src/test/ui/invalid-compile-flags/branch-protection-missing-pac-ret.stderr Normal file
View File

@ -0,0 +1,2 @@
error: incorrect value `leaf` for debugging option `branch-protection` - a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf` was expected