blake2: fix build + warnings on no_std targets

Many of the warnings were occurring because the parallel backend requires x86 SIMD intrinsics (AVX2 or SSE41) and therefore the parallel code is dead on other targets. This commit feature gates all such code, ensuring that everything will build warning-free on other targets, and that users who attempt to use the parallel APIs on unsupported targets get compile errors rather than warnings.
RustCrypto · Aug 29, 2021 · 2f45194 · 2f45194
1 parent f2caf71
commit 2f45194
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diff --git a/.github/workflows/blake2.yml b/.github/workflows/blake2.yml
@@ -17,30 +17,28 @@ env:
   RUSTFLAGS: "-Dwarnings"
 
 jobs:
-  # TODO(tarcieri): re-enable these when failures are addressed:
-  # <https://github.com/RustCrypto/hashes/pull/228/checks?check_run_id=1831937705>
-#  build:
-#    runs-on: ubuntu-latest
-#    strategy:
-#      matrix:
-#        rust:
-#          - 1.41.0 # MSRV
-#          - stable
-#        target:
-#          - thumbv7em-none-eabi
-#          - wasm32-unknown-unknown
-#    steps:
-#      - uses: actions/checkout@v1
-#      - uses: actions-rs/toolchain@v1
-#        with:
-#          profile: minimal
-#          toolchain: ${{ matrix.rust }}
-#          target: ${{ matrix.target }}
-#          override: true
-#      - run: cargo build --target ${{ matrix.target }} --release --no-default-features
-#      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features blake2b
-#      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features blake2s
-#      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features blake2b,blake2s
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - 1.41.0 # MSRV
+          - stable
+        target:
+          - thumbv7em-none-eabi
+          - wasm32-unknown-unknown
+    steps:
+      - uses: actions/checkout@v1
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          target: ${{ matrix.target }}
+          override: true
+      - run: cargo build --target ${{ matrix.target }} --release --no-default-features
+      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features blake2b
+      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features blake2s
+      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features blake2b,blake2s
 
   test:
     runs-on: ubuntu-latest

diff --git a/blake2/Cargo.toml b/blake2/Cargo.toml
@@ -17,7 +17,7 @@ arrayvec = { version = "0.5", default-features = false }
 crypto-mac = "0.8"
 digest = "0.9"
 opaque-debug = "0.3"
-subtle = ">=2, <2.5"
+subtle = { version = ">=2, <2.5", default-features = false }
 
 [dev-dependencies]
 crypto-mac = { version = "0.8", features = ["dev"] }
@@ -39,3 +39,7 @@ blake2s = []
 # performance. This feature disables some inlining, improving the performance
 # of the portable implementation in that specific case.
 uninline_portable = []
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
diff --git a/blake2/src/blake2b.rs b/blake2/src/blake2b.rs
@@ -24,9 +24,12 @@
 //! ```
 
 pub(crate) mod backend;
-pub mod many;
 pub(crate) mod state;
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+#[cfg_attr(docsrs, doc(cfg(any(target_arch = "x86", target_arch = "x86_64"))))]
+pub mod many;
+
 mod hash;
 mod params;
 #[cfg(test)]
@@ -280,10 +283,10 @@ pub(crate) fn paint_test_input(buf: &mut [u8]) {
 
 // This module is pub for internal benchmarks only. Please don't use it.
 #[doc(hidden)]
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub mod benchmarks {
-    use crate::blake2bp;
-
     use super::*;
+    use crate::blake2bp;
 
     pub fn force_portable(params: &mut Params) {
         params.implementation = backend::Implementation::portable();

diff --git a/blake2/src/blake2b/backend.rs b/blake2/src/blake2b/backend.rs
@@ -13,9 +13,6 @@ use core::cmp;
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub const MAX_DEGREE: usize = 4;
 
-#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
-pub const MAX_DEGREE: usize = 1;
-
 /// Variants other than Portable are unreachable in no_std, unless CPU features
 /// are explicitly enabled for the build with e.g. RUSTFLAGS="-C target-feature=avx2".
 /// This might change in the future if is_x86_feature_detected moves into libcore.
@@ -91,11 +88,10 @@ impl Implementation {
         None
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     pub fn degree(&self) -> usize {
         match self.0 {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Avx2 => avx2::DEGREE,
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Sse41 => sse41::DEGREE,
             Platform::Portable => 1,
         }
@@ -123,19 +119,19 @@ impl Implementation {
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     pub fn compress2_loop(&self, jobs: &mut [Job<'_, '_>; 2], finalize: Finalize, stride: Stride) {
         match self.0 {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Avx2 | Platform::Sse41 => unsafe {
                 sse41::compress2_loop(jobs, finalize, stride)
             },
             _ => panic!("unsupported"),
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     pub fn compress4_loop(&self, jobs: &mut [Job<'_, '_>; 4], finalize: Finalize, stride: Stride) {
         match self.0 {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Avx2 => unsafe { avx2::compress4_loop(jobs, finalize, stride) },
             _ => panic!("unsupported"),
         }
@@ -196,14 +192,16 @@ impl LastNode {
 
 #[derive(Clone, Copy, Debug)]
 pub enum Stride {
-    Serial,   // BLAKE2b/BLAKE2s
+    Serial, // BLAKE2b/BLAKE2s
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     Parallel, // BLAKE2bp/BLAKE2sp
 }
 
 impl Stride {
     pub fn padded_blockbytes(&self) -> usize {
         match self {
             Stride::Serial => BLOCKBYTES,
+            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Stride::Parallel => crate::blake2bp::DEGREE * BLOCKBYTES,
         }
     }
@@ -217,6 +215,7 @@ pub(crate) fn count_high(count: Count) -> Word {
     (count >> (8 * size_of::<Word>())) as Word
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub(crate) fn assemble_count(low: Word, high: Word) -> Count {
     low as Count + ((high as Count) << (8 * size_of::<Word>()))
 }

diff --git a/blake2/src/blake2b/test.rs b/blake2/src/blake2b/test.rs
@@ -1,4 +1,6 @@
 use super::*;
+
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 use crate::blake2bp;
 
 const EMPTY_HASH: &str = "786a02f742015903c6c6fd852552d272912f4740e15847618a86e217f71f5419\
@@ -120,6 +122,7 @@ fn test_all_parameters() {
     );
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 fn test_all_parameters_blake2bp() {
     let mut params = crate::blake2bp::Params::new();
@@ -183,18 +186,21 @@ fn test_long_inner_hash_length_panics() {
     Params::new().inner_hash_length(OUTBYTES + 1);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2bp_short_hash_length_panics() {
     blake2bp::Params::new().hash_length(0);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2bp_long_hash_length_panics() {
     blake2bp::Params::new().hash_length(OUTBYTES + 1);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2bp_long_key_panics() {

diff --git a/blake2/src/blake2bp.rs b/blake2/src/blake2bp.rs
@@ -27,9 +27,6 @@ use crate::blake2b::{
 };
 use core::{cmp, fmt, mem::size_of};
 
-#[cfg(feature = "std")]
-use std;
-
 pub(crate) const DEGREE: usize = 4;
 
 /// Compute the BLAKE2bp hash of a slice of bytes all at once, using default

diff --git a/blake2/src/blake2s.rs b/blake2/src/blake2s.rs
@@ -23,17 +23,19 @@
 //! ```
 
 pub(crate) mod backend;
-pub mod many;
 pub(crate) mod state;
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+#[cfg_attr(docsrs, doc(cfg(any(target_arch = "x86", target_arch = "x86_64"))))]
+pub mod many;
+
 mod hash;
 mod params;
 #[cfg(test)]
 mod test;
 
 pub use self::{hash::Hash, params::Params, state::State};
 
-use crate::blake2sp;
 use core::{fmt, mem::size_of};
 use crypto_mac::{InvalidKeyLength, Mac, NewMac};
 use digest::{
@@ -270,8 +272,10 @@ pub(crate) fn paint_test_input(buf: &mut [u8]) {
 
 // This module is pub for internal benchmarks only. Please don't use it.
 #[doc(hidden)]
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub mod benchmarks {
     use super::*;
+    use crate::blake2sp;
 
     pub fn force_portable(params: &mut Params) {
         params.implementation = backend::Implementation::portable();

diff --git a/blake2/src/blake2s/backend.rs b/blake2/src/blake2s/backend.rs
@@ -13,9 +13,6 @@ use core::cmp;
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub const MAX_DEGREE: usize = 8;
 
-#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
-pub const MAX_DEGREE: usize = 1;
-
 /// Variants other than Portable are unreachable in no_std, unless CPU features
 /// are explicitly enabled for the build with e.g. RUSTFLAGS="-C target-feature=avx2".
 /// This might change in the future if is_x86_feature_detected moves into libcore.
@@ -91,11 +88,10 @@ impl Implementation {
         None
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     pub fn degree(&self) -> usize {
         match self.0 {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Avx2 => avx2::DEGREE,
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Sse41 => sse41::DEGREE,
             Platform::Portable => 1,
         }
@@ -121,19 +117,19 @@ impl Implementation {
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     pub fn compress4_loop(&self, jobs: &mut [Job<'_, '_>; 4], finalize: Finalize, stride: Stride) {
         match self.0 {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Avx2 | Platform::Sse41 => unsafe {
                 sse41::compress4_loop(jobs, finalize, stride)
             },
             _ => panic!("unsupported"),
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     pub fn compress8_loop(&self, jobs: &mut [Job<'_, '_>; 8], finalize: Finalize, stride: Stride) {
         match self.0 {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Platform::Avx2 => unsafe { avx2::compress8_loop(jobs, finalize, stride) },
             _ => panic!("unsupported"),
         }
@@ -194,14 +190,16 @@ impl LastNode {
 
 #[derive(Clone, Copy, Debug)]
 pub enum Stride {
-    Serial,   // BLAKE2b/BLAKE2s
+    Serial, // BLAKE2b/BLAKE2s
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     Parallel, // BLAKE2bp/BLAKE2sp
 }
 
 impl Stride {
     pub fn padded_blockbytes(&self) -> usize {
         match self {
             Stride::Serial => BLOCKBYTES,
+            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
             Stride::Parallel => crate::blake2sp::DEGREE * BLOCKBYTES,
         }
     }
@@ -215,6 +213,7 @@ pub(crate) fn count_high(count: Count) -> Word {
     (count >> (8 * size_of::<Word>())) as Word
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub(crate) fn assemble_count(low: Word, high: Word) -> Count {
     low as Count + ((high as Count) << (8 * size_of::<Word>()))
 }

diff --git a/blake2/src/blake2s/test.rs b/blake2/src/blake2s/test.rs
@@ -1,5 +1,8 @@
 use super::*;
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+use crate::blake2sp;
+
 const EMPTY_HASH: &str = "69217a3079908094e11121d042354a7c1f55b6482ca1a51e1b250dfd1ed0eef9";
 const ABC_HASH: &str = "508c5e8c327c14e2e1a72ba34eeb452f37458b209ed63a294d999b4c86675982";
 const ONE_BLOCK_HASH: &str = "ae09db7cd54f42b490ef09b6bc541af688e4959bb8c53f359a6f56e38ab454a3";
@@ -115,6 +118,7 @@ fn test_all_parameters() {
     );
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 fn test_all_parameters_blake2sp() {
     let mut params = blake2sp::Params::new();
@@ -178,29 +182,34 @@ fn test_long_inner_hash_length_panics() {
     Params::new().inner_hash_length(OUTBYTES + 1);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2sp_short_hash_length_panics() {
     blake2sp::Params::new().hash_length(0);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2sp_long_hash_length_panics() {
     blake2sp::Params::new().hash_length(OUTBYTES + 1);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2sp_long_key_panics() {
     blake2sp::Params::new().key(&[0; KEYBYTES + 1]);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 fn test_blake2sp_max_offset_ok() {
     Params::new().node_offset((1 << 48) - 1);
 }
 
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 #[test]
 #[should_panic]
 fn test_blake2sp_offset_too_large_panics() {

diff --git a/blake2/src/blake2sp.rs b/blake2/src/blake2sp.rs
@@ -27,9 +27,6 @@ use crate::blake2s::{
 };
 use core::{cmp, fmt, mem::size_of};
 
-#[cfg(feature = "std")]
-use std;
-
 pub(crate) const DEGREE: usize = 8;
 
 /// Compute the BLAKE2sp hash of a slice of bytes all at once, using default