CBMC: Prove AArch64 mlk_poly_reduce_native based on HOL-Light spec

Signed-off-by: Matthias J. Kannwischer <matthias@kannwischer.eu>

Author: mkannwischer

dev/aarch64_clean/src/arith_native_aarch64.h

@@ -62,7 +62,14 @@ __contract__(
 );
 
 #define mlk_poly_reduce_asm MLK_NAMESPACE(poly_reduce_asm)
-void mlk_poly_reduce_asm(int16_t *);
+void mlk_poly_reduce_asm(int16_t *p)
+/* This must be kept in sync with the HOL-Light specification
+ * in proofs/hol_light/arm/proofs/mlkem_poly_reduce.ml */
+__contract__(
+  requires(memory_no_alias(p, sizeof(int16_t) * MLKEM_N))
+  assigns(memory_slice(p, sizeof(int16_t) * MLKEM_N))
+  ensures(array_bound(p, 0, MLKEM_N, 0, MLKEM_Q))
+);
 
 #define mlk_poly_tomont_asm MLK_NAMESPACE(poly_tomont_asm)
 void mlk_poly_tomont_asm(int16_t *p)

dev/aarch64_opt/src/arith_native_aarch64.h

@@ -62,7 +62,14 @@ __contract__(
 );
 
 #define mlk_poly_reduce_asm MLK_NAMESPACE(poly_reduce_asm)
-void mlk_poly_reduce_asm(int16_t *);
+void mlk_poly_reduce_asm(int16_t *p)
+/* This must be kept in sync with the HOL-Light specification
+ * in proofs/hol_light/arm/proofs/mlkem_poly_reduce.ml */
+__contract__(
+  requires(memory_no_alias(p, sizeof(int16_t) * MLKEM_N))
+  assigns(memory_slice(p, sizeof(int16_t) * MLKEM_N))
+  ensures(array_bound(p, 0, MLKEM_N, 0, MLKEM_Q))
+);
 
 #define mlk_poly_tomont_asm MLK_NAMESPACE(poly_tomont_asm)
 void mlk_poly_tomont_asm(int16_t *p)

mlkem/native/aarch64/src/arith_native_aarch64.h

@@ -62,7 +62,14 @@ __contract__(
 );
 
 #define mlk_poly_reduce_asm MLK_NAMESPACE(poly_reduce_asm)
-void mlk_poly_reduce_asm(int16_t *);
+void mlk_poly_reduce_asm(int16_t *p)
+/* This must be kept in sync with the HOL-Light specification
+ * in proofs/hol_light/arm/proofs/mlkem_poly_reduce.ml */
+__contract__(
+  requires(memory_no_alias(p, sizeof(int16_t) * MLKEM_N))
+  assigns(memory_slice(p, sizeof(int16_t) * MLKEM_N))
+  ensures(array_bound(p, 0, MLKEM_N, 0, MLKEM_Q))
+);
 
 #define mlk_poly_tomont_asm MLK_NAMESPACE(poly_tomont_asm)
 void mlk_poly_tomont_asm(int16_t *p)

proofs/cbmc/poly_reduce_native_aarch64/Makefile

@@ -0,0 +1,57 @@
+# Copyright (c) The mlkem-native project authors
+# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
+
+include ../Makefile_params.common
+
+HARNESS_ENTRY = harness
+HARNESS_FILE = poly_reduce_native_aarch64_harness
+
+# This should be a unique identifier for this proof, and will appear on the
+# Litani dashboard. It can be human-readable and contain spaces if you wish.
+PROOF_UID = poly_reduce_native_aarch64
+
+# We need to set MLK_CHECK_APIS as otherwise mlkem/native/api.h won't be
+# included, which contains the CBMC specifications.
+DEFINES += -DMLK_CONFIG_USE_NATIVE_BACKEND_ARITH -DMLK_CONFIG_ARITH_BACKEND_FILE="\"$(SRCDIR)/mlkem/native/aarch64/meta.h\"" -DMLK_CHECK_APIS
+INCLUDES +=
+
+REMOVE_FUNCTION_BODY +=
+UNWINDSET +=
+
+PROOF_SOURCES += $(PROOFDIR)/$(HARNESS_FILE).c
+PROJECT_SOURCES += $(SRCDIR)/mlkem/poly.c
+
+CHECK_FUNCTION_CONTRACTS=mlk_poly_reduce_native
+USE_FUNCTION_CONTRACTS=mlk_poly_reduce_asm
+APPLY_LOOP_CONTRACTS=on
+USE_DYNAMIC_FRAMES=1
+
+# Disable any setting of EXTERNAL_SAT_SOLVER, and choose SMT backend instead
+EXTERNAL_SAT_SOLVER=
+CBMCFLAGS=--smt2
+
+FUNCTION_NAME = poly_reduce_native_aarch64
+
+# If this proof is found to consume huge amounts of RAM, you can set the
+# EXPENSIVE variable. With new enough versions of the proof tools, this will
+# restrict the number of EXPENSIVE CBMC jobs running at once. See the
+# documentation in Makefile.common under the "Job Pools" heading for details.
+# EXPENSIVE = true
+
+# This function is large enough to need...
+CBMC_OBJECT_BITS = 8
+
+# If you require access to a file-local ("static") function or object to conduct
+# your proof, set the following (and do not include the original source file
+# ("mlkem/poly.c") in PROJECT_SOURCES).
+# REWRITTEN_SOURCES = $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i
+# include ../Makefile.common
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_SOURCE = $(SRCDIR)/mlkem/poly.c
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_FUNCTIONS = foo bar
+# $(PROOFDIR)/<__SOURCE_FILE_BASENAME__>.i_OBJECTS = baz
+# Care is required with variables on the left-hand side: REWRITTEN_SOURCES must
+# be set before including Makefile.common, but any use of variables on the
+# left-hand side requires those variables to be defined. Hence, _SOURCE,
+# _FUNCTIONS, _OBJECTS is set after including Makefile.common.
+
+include ../Makefile.common

proofs/cbmc/poly_reduce_native_aarch64/poly_reduce_native_aarch64_harness.c

@@ -0,0 +1,15 @@
+// Copyright (c) The mlkem-native project authors
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: MIT-0
+
+#include <stdint.h>
+#include "cbmc.h"
+#include "params.h"
+
+void mlk_poly_reduce_native(int16_t p[MLKEM_N]);
+
+void harness(void)
+{
+  int16_t *r;
+  mlk_poly_reduce_native(r);
+}

proofs/hol_light/arm/proofs/mlkem_poly_reduce.ml

@@ -118,6 +118,9 @@ let overall_lemma = prove
   REWRITE_TAC[MATCH_MP lemma_rem (CONGBOUND_RULE `barred x`)] THEN
   BITBLAST_TAC);;
 
+(* NOTE: This must be kept in sync with the CBMC specification
+ * in mlkem/native/aarch64/src/arith_native_aarch64.h *)
+
 let MLKEM_POLY_REDUCE_CORRECT = prove
  (`!a x pc.
         nonoverlapping (word pc,0x124) (a,512)