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rustc_codegen_llvm: Add a new 'pc' option to branch-protection
Add a new 'pc' option to -Z branch-protection for aarch64 that enables the use of PC as a diversifier in PAC branch protection code. When the pauth-lr target feature is enabled in combination with -Z branch-protection=pac-ret,pc, the new 9.5-a instructions (pacibsppc, retaasppc, etc) will be generated.
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12 files changed

+97
-17
lines changed

12 files changed

+97
-17
lines changed

‎compiler/rustc_codegen_llvm/src/attributes.rs

+4-1
Original file line numberDiff line numberDiff line change
@@ -424,7 +424,10 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
424424
if bti {
425425
to_add.push(llvm::CreateAttrString(cx.llcx, "branch-target-enforcement"));
426426
}
427-
if let Some(PacRet { leaf, key }) = pac_ret {
427+
if let Some(PacRet { leaf, pc, key }) = pac_ret {
428+
if pc {
429+
to_add.push(llvm::CreateAttrString(cx.llcx, "branch-protection-pauth-lr"));
430+
}
428431
to_add.push(llvm::CreateAttrStringValue(
429432
cx.llcx,
430433
"sign-return-address",

‎compiler/rustc_codegen_llvm/src/context.rs

+7-1
Original file line numberDiff line numberDiff line change
@@ -302,7 +302,13 @@ pub(crate) unsafe fn create_module<'ll>(
302302
"sign-return-address",
303303
pac_ret.is_some().into(),
304304
);
305-
let pac_opts = pac_ret.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
305+
let pac_opts = pac_ret.unwrap_or(PacRet { leaf: false, pc: false, key: PAuthKey::A });
306+
llvm::add_module_flag_u32(
307+
llmod,
308+
llvm::ModuleFlagMergeBehavior::Min,
309+
"branch-protection-pauth-lr",
310+
pac_opts.pc.into(),
311+
);
306312
llvm::add_module_flag_u32(
307313
llmod,
308314
llvm::ModuleFlagMergeBehavior::Min,

‎compiler/rustc_interface/src/tests.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -764,7 +764,7 @@ fn test_unstable_options_tracking_hash() {
764764
branch_protection,
765765
Some(BranchProtection {
766766
bti: true,
767-
pac_ret: Some(PacRet { leaf: true, key: PAuthKey::B })
767+
pac_ret: Some(PacRet { leaf: true, pc: true, key: PAuthKey::B })
768768
})
769769
);
770770
tracked!(codegen_backend, Some("abc".to_string()));

‎compiler/rustc_session/src/config.rs

+1
Original file line numberDiff line numberDiff line change
@@ -1319,6 +1319,7 @@ pub enum PAuthKey {
13191319
#[derive(Clone, Copy, Hash, Debug, PartialEq)]
13201320
pub struct PacRet {
13211321
pub leaf: bool,
1322+
pub pc: bool,
13221323
pub key: PAuthKey,
13231324
}
13241325

‎compiler/rustc_session/src/options.rs

+6-3
Original file line numberDiff line numberDiff line change
@@ -442,8 +442,7 @@ mod desc {
442442
pub(crate) const parse_polonius: &str = "either no value or `legacy` (the default), or `next`";
443443
pub(crate) const parse_stack_protector: &str =
444444
"one of (`none` (default), `basic`, `strong`, or `all`)";
445-
pub(crate) const parse_branch_protection: &str =
446-
"a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf`";
445+
pub(crate) const parse_branch_protection: &str = "a `,` separated combination of `bti`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf`";
447446
pub(crate) const parse_proc_macro_execution_strategy: &str =
448447
"one of supported execution strategies (`same-thread`, or `cross-thread`)";
449448
pub(crate) const parse_remap_path_scope: &str =
@@ -1396,7 +1395,7 @@ mod parse {
13961395
match opt {
13971396
"bti" => slot.bti = true,
13981397
"pac-ret" if slot.pac_ret.is_none() => {
1399-
slot.pac_ret = Some(PacRet { leaf: false, key: PAuthKey::A })
1398+
slot.pac_ret = Some(PacRet { leaf: false, pc: false, key: PAuthKey::A })
14001399
}
14011400
"leaf" => match slot.pac_ret.as_mut() {
14021401
Some(pac) => pac.leaf = true,
@@ -1406,6 +1405,10 @@ mod parse {
14061405
Some(pac) => pac.key = PAuthKey::B,
14071406
_ => return false,
14081407
},
1408+
"pc" => match slot.pac_ret.as_mut() {
1409+
Some(pac) => pac.pc = true,
1410+
_ => return false,
1411+
},
14091412
_ => return false,
14101413
};
14111414
}

‎src/doc/unstable-book/src/compiler-flags/branch-protection.md

+2-1
Original file line numberDiff line numberDiff line change
@@ -9,11 +9,12 @@ This option is only accepted when targeting AArch64 architectures.
99
It takes some combination of the following values, separated by a `,`.
1010

1111
- `pac-ret` - Enable pointer authentication for non-leaf functions.
12+
- `pc` - Use PC as a diversifier using PAuthLR instructions
1213
- `leaf` - Enable pointer authentication for all functions, including leaf functions.
1314
- `b-key` - Sign return addresses with key B, instead of the default key A.
1415
- `bti` - Enable branch target identification.
1516

16-
`leaf` and `b-key` are only valid if `pac-ret` was previously specified.
17+
`leaf`, `b-key` and `pc` are only valid if `pac-ret` was previously specified.
1718
For example, `-Z branch-protection=bti,pac-ret,leaf` is valid, but
1819
`-Z branch-protection=bti,leaf,pac-ret` is not.
1920

‎tests/assembly/aarch64-pointer-auth.rs

+13-4
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,13 @@
11
// Test that PAC instructions are emitted when branch-protection is specified.
22

3+
//@ revisions: PACRET PAUTHLR_NOP PAUTHLR
34
//@ assembly-output: emit-asm
4-
//@ compile-flags: --target aarch64-unknown-linux-gnu
5-
//@ compile-flags: -Z branch-protection=pac-ret,leaf
65
//@ needs-llvm-components: aarch64
6+
//@ compile-flags: --target aarch64-unknown-linux-gnu
7+
//@ [PACRET] compile-flags: -Z branch-protection=pac-ret,leaf
8+
//@ [PAUTHLR_NOP] compile-flags: -Z branch-protection=pac-ret,pc,leaf
9+
//@ [PAUTHLR] compile-flags: -C target-feature=+pauth-lr -Z branch-protection=pac-ret,pc,leaf
10+
//@ min-llvm-version: 19
711

812
#![feature(no_core, lang_items)]
913
#![no_std]
@@ -13,8 +17,13 @@
1317
#[lang = "sized"]
1418
trait Sized {}
1519

16-
// CHECK: hint #25
17-
// CHECK: hint #29
20+
// PACRET: hint #25
21+
// PACRET: hint #29
22+
// PAUTHLR_NOP: hint #25
23+
// PAUTHLR_NOP: hint #39
24+
// PAUTHLR_NOP: hint #29
25+
// PAUTHLR: paciasppc
26+
// PAUTHLR: autiasppc
1827
#[no_mangle]
1928
pub fn test() -> u8 {
2029
42

‎tests/codegen/branch-protection.rs

+41-1
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,15 @@
11
// Test that the correct module flags are emitted with different branch protection flags.
22

3-
//@ revisions: BTI PACRET LEAF BKEY NONE
3+
//@ revisions: BTI PACRET LEAF BKEY PAUTHLR PAUTHLR_BKEY PAUTHLR_LEAF PAUTHLR_BTI NONE
44
//@ needs-llvm-components: aarch64
55
//@ [BTI] compile-flags: -Z branch-protection=bti
66
//@ [PACRET] compile-flags: -Z branch-protection=pac-ret
77
//@ [LEAF] compile-flags: -Z branch-protection=pac-ret,leaf
88
//@ [BKEY] compile-flags: -Z branch-protection=pac-ret,b-key
9+
//@ [PAUTHLR] compile-flags: -Z branch-protection=pac-ret,pc
10+
//@ [PAUTHLR_BKEY] compile-flags: -Z branch-protection=pac-ret,pc,b-key
11+
//@ [PAUTHLR_LEAF] compile-flags: -Z branch-protection=pac-ret,pc,leaf
12+
//@ [PAUTHLR_BTI] compile-flags: -Z branch-protection=bti,pac-ret,pc
913
//@ compile-flags: --target aarch64-unknown-linux-gnu
1014
//@ min-llvm-version: 19
1115

@@ -24,30 +28,66 @@ pub fn test() {}
2428
// BTI: attributes [[ATTR]] = {{.*}} "branch-target-enforcement"
2529
// BTI: !"branch-target-enforcement", i32 1
2630
// BTI: !"sign-return-address", i32 0
31+
// BTI: !"branch-protection-pauth-lr", i32 0
2732
// BTI: !"sign-return-address-all", i32 0
2833
// BTI: !"sign-return-address-with-bkey", i32 0
2934

3035
// PACRET: attributes [[ATTR]] = {{.*}} "sign-return-address"="non-leaf"
3136
// PACRET-SAME: "sign-return-address-key"="a_key"
3237
// PACRET: !"branch-target-enforcement", i32 0
3338
// PACRET: !"sign-return-address", i32 1
39+
// PACRET: !"branch-protection-pauth-lr", i32 0
3440
// PACRET: !"sign-return-address-all", i32 0
3541
// PACRET: !"sign-return-address-with-bkey", i32 0
3642

3743
// LEAF: attributes [[ATTR]] = {{.*}} "sign-return-address"="all"
3844
// LEAF-SAME: "sign-return-address-key"="a_key"
3945
// LEAF: !"branch-target-enforcement", i32 0
4046
// LEAF: !"sign-return-address", i32 1
47+
// LEAF: !"branch-protection-pauth-lr", i32 0
4148
// LEAF: !"sign-return-address-all", i32 1
4249
// LEAF: !"sign-return-address-with-bkey", i32 0
4350

4451
// BKEY: attributes [[ATTR]] = {{.*}} "sign-return-address"="non-leaf"
4552
// BKEY-SAME: "sign-return-address-key"="b_key"
4653
// BKEY: !"branch-target-enforcement", i32 0
4754
// BKEY: !"sign-return-address", i32 1
55+
// BKEY: !"branch-protection-pauth-lr", i32 0
4856
// BKEY: !"sign-return-address-all", i32 0
4957
// BKEY: !"sign-return-address-with-bkey", i32 1
5058

59+
// PAUTHLR: attributes [[ATTR]] = {{.*}} "sign-return-address"="non-leaf"
60+
// PAUTHLR-SAME: "sign-return-address-key"="a_key"
61+
// PAUTHLR: !"branch-target-enforcement", i32 0
62+
// PAUTHLR: !"sign-return-address", i32 1
63+
// PAUTHLR: !"branch-protection-pauth-lr", i32 1
64+
// PAUTHLR: !"sign-return-address-all", i32 0
65+
// PAUTHLR: !"sign-return-address-with-bkey", i32 0
66+
67+
// PAUTHLR_BKEY: attributes [[ATTR]] = {{.*}} "sign-return-address"="non-leaf"
68+
// PAUTHLR_BKEY-SAME: "sign-return-address-key"="b_key"
69+
// PAUTHLR_BKEY: !"branch-target-enforcement", i32 0
70+
// PAUTHLR_BKEY: !"sign-return-address", i32 1
71+
// PAUTHLR_BKEY: !"branch-protection-pauth-lr", i32 1
72+
// PAUTHLR_BKEY: !"sign-return-address-all", i32 0
73+
// PAUTHLR_BKEY: !"sign-return-address-with-bkey", i32 1
74+
75+
// PAUTHLR_LEAF: attributes [[ATTR]] = {{.*}} "sign-return-address"="all"
76+
// PAUTHLR_LEAF-SAME: "sign-return-address-key"="a_key"
77+
// PAUTHLR_LEAF: !"branch-target-enforcement", i32 0
78+
// PAUTHLR_LEAF: !"sign-return-address", i32 1
79+
// PAUTHLR_LEAF: !"branch-protection-pauth-lr", i32 1
80+
// PAUTHLR_LEAF: !"sign-return-address-all", i32 1
81+
// PAUTHLR_LEAF: !"sign-return-address-with-bkey", i32 0
82+
83+
// PAUTHLR_BTI: attributes [[ATTR]] = {{.*}} "sign-return-address"="non-leaf"
84+
// PAUTHLR_BTI-SAME: "sign-return-address-key"="a_key"
85+
// PAUTHLR_BTI: !"branch-target-enforcement", i32 1
86+
// PAUTHLR_BTI: !"sign-return-address", i32 1
87+
// PAUTHLR_BTI: !"branch-protection-pauth-lr", i32 1
88+
// PAUTHLR_BTI: !"sign-return-address-all", i32 0
89+
// PAUTHLR_BTI: !"sign-return-address-with-bkey", i32 0
90+
5191
// NONE-NOT: branch-target-enforcement
5292
// NONE-NOT: sign-return-address
5393
// NONE-NOT: sign-return-address-all

‎tests/run-make/pointer-auth-link-with-c/rmake.rs

+13-1
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
// `-Z branch protection` is an unstable compiler feature which adds pointer-authentication
22
// code (PAC), a useful hashing measure for verifying that pointers have not been modified.
33
// This test checks that compilation and execution is successful when this feature is activated,
4-
// with some of its possible extra arguments (bti, pac-ret, leaf).
4+
// with some of its possible extra arguments (bti, pac-ret, pc, leaf, b-key).
55
// See https://github.com/rust-lang/rust/pull/88354
66

77
//@ only-aarch64
@@ -25,4 +25,16 @@ fn main() {
2525
llvm_ar().obj_to_ar().output_input("libtest.a", &obj_file).run();
2626
rustc().arg("-Zbranch-protection=bti,pac-ret,leaf").input("test.rs").run();
2727
run("test");
28+
29+
// FIXME: +pc was only recently added to LLVM
30+
// cc().arg("-v")
31+
// .arg("-c")
32+
// .out_exe("test")
33+
// .input("test.c")
34+
// .arg("-mbranch-protection=bti+pac-ret+pc+leaf")
35+
// .run();
36+
// let obj_file = if is_msvc() { "test.obj" } else { "test" };
37+
// llvm_ar().obj_to_ar().output_input("libtest.a", &obj_file).run();
38+
// rustc().arg("-Zbranch-protection=bti,pac-ret,pc,leaf").input("test.rs").run();
39+
// run("test");
2840
}

‎tests/ui/invalid-compile-flags/branch-protection-missing-pac-ret.BADFLAGS.stderr

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,2 +1,2 @@
1-
error: incorrect value `leaf` for unstable option `branch-protection` - a `,` separated combination of `bti`, `b-key`, `pac-ret`, or `leaf` was expected
1+
error: incorrect value `leaf` for unstable option `branch-protection` - a `,` separated combination of `bti`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf` was expected
22

‎tests/ui/invalid-compile-flags/branch-protection-missing-pac-ret.BADFLAGSPC.stderr

+2
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,2 @@
1+
error: incorrect value `pc` for unstable option `branch-protection` - a `,` separated combination of `bti`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf` was expected
2+

‎tests/ui/invalid-compile-flags/branch-protection-missing-pac-ret.rs

+6-3
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,10 @@
1-
//@ revisions: BADFLAGS BADTARGET
1+
//@ revisions: BADFLAGS BADFLAGSPC BADTARGET
22
//@ [BADFLAGS] compile-flags: --target=aarch64-unknown-linux-gnu -Zbranch-protection=leaf
33
//@ [BADFLAGS] check-fail
44
//@ [BADFLAGS] needs-llvm-components: aarch64
5+
//@ [BADFLAGSPC] compile-flags: --target=aarch64-unknown-linux-gnu -Zbranch-protection=pc
6+
//@ [BADFLAGSPC] check-fail
7+
//@ [BADFLAGSPC] needs-llvm-components: aarch64
58
//@ [BADTARGET] compile-flags: --target=x86_64-unknown-linux-gnu -Zbranch-protection=bti
69
//@ [BADTARGET] check-fail
710
//@ [BADTARGET] needs-llvm-components: x86
@@ -10,5 +13,5 @@
1013
#![feature(no_core, lang_items)]
1114
#![no_core]
1215

13-
#[lang="sized"]
14-
trait Sized { }
16+
#[lang = "sized"]
17+
trait Sized {}

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