32-bit fixes (#288)

* fix the new div2n1n_vartime on 32-bit - regression from #286

* remove unnecessary defensive programming

* reactivate 32-bit CI to check on #244

* 32-bit: centralize OS, ISA and env variable config

* enable assemble on x86 32-bit

.github/workflows/ci.yml

@@ -9,21 +9,24 @@ jobs:
       matrix:
         nim_version: [version-1-6] # [version-1-4, devel]
         target:
+          - os: linux
+            cpu: i386
+            TEST_LANG: c
+            BACKEND: NO_ASM
+          - os: linux
+            cpu: i386
+            TEST_LANG: c
+            BACKEND: ASM
+
           - os: linux
             cpu: amd64
             TEST_LANG: c
             BACKEND: NO_ASM
-
-          # 32-bit CI failing with https://github.com/mratsim/constantine/issues/244
-          # "E: Unable to correct problems, you have held broken packages.""
-          # - os: linux
-          #   cpu: i386
-          #   TEST_LANG: c
-          #   BACKEND: NO_ASM
           - os: linux
             cpu: amd64
             TEST_LANG: c
             BACKEND: ASM
+
           - os: windows
             cpu: amd64
             TEST_LANG: c
@@ -32,6 +35,7 @@ jobs:
             cpu: amd64
             TEST_LANG: c
             BACKEND: ASM
+
           - os: macos
             cpu: amd64
             TEST_LANG: c

benchmarks/bench_blueprint.nim

@@ -60,7 +60,7 @@ echo "  release: ", defined(release)
 echo "  danger: ", defined(danger)
 echo "  inline assembly: ", UseASM_X86_64
 
-when (sizeof(int) == 4) or defined(CTT_32):
+when CTT_32:
   echo "⚠️ Warning: using Constantine with 32-bit limbs"
 else:
   echo "Using Constantine with 64-bit limbs"

benchmarks/bench_evm_modexp_dos.nim

@@ -7,7 +7,8 @@ import
 
 proc report(op: string, elapsedNs: int64, elapsedCycles: int64, iters: int) =
   let ns = elapsedNs div iters
-  let cycles = elapsedCycles div iters
+  when SupportsGetTicks:
+    let cycles = elapsedCycles div iters
   let throughput = 1e9 / float64(ns)
   when SupportsGetTicks:
     echo &"{op:<70} {throughput:>15.3f} ops/s {ns:>16} ns/op {cycles:>12} CPU cycles (approx)"
@@ -17,12 +18,15 @@ proc report(op: string, elapsedNs: int64, elapsedCycles: int64, iters: int) =
 template bench(fnCall: untyped, ticks, ns: var int64): untyped =
   block:
     let startTime = getMonotime()
-    let startClock = getTicks()
+    when SupportsGetTicks:
+      let startClock = getTicks()
     fnCall
-    let stopClock = getTicks()
+    when SupportsGetTicks:
+      let stopClock = getTicks()
     let stopTime = getMonotime()
 
-    ticks += stopClock - startClock
+    when SupportsGetTicks:
+      ticks += stopClock - startClock
     ns += inNanoseconds(stopTime-startTime)
 
 func computeGasFee(inputs: openArray[byte]): tuple[eip128, eip2565: int] =
@@ -91,8 +95,8 @@ func computeGasFee(inputs: openArray[byte]): tuple[eip128, eip2565: int] =
     baseStop  = baseStart+baseByteLen-1
     expStart  = baseStop+1
     expStop   = expStart+exponentByteLen-1
-    modStart  = expStop+1
-    modStop   = modStart+modulusByteLen-1
+    # modStart  = expStop+1
+    # modStop   = modStart+modulusByteLen-1
 
   template exponent(): untyped =
     inputs.toOpenArray(expStart, expStop)

benchmarks/bench_fp_double_precision.nim

@@ -61,7 +61,7 @@ echo "  release: ", defined(release)
 echo "  danger: ", defined(danger)
 echo "  inline assembly: ", UseASM_X86_64
 
-when (sizeof(int) == 4) or defined(CTT_32):
+when CTT_32:
   echo "⚠️ Warning: using Constantine with 32-bit limbs"
 else:
   echo "Using Constantine with 64-bit limbs"

constantine/ethereum_evm_precompiles.nim

@@ -433,9 +433,6 @@ func eth_evm_modexp*(r: var openArray[byte], inputs: openArray[byte]): CttEVMSta
   if r.len != modulusByteLen:
     return cttEVM_InvalidOutputSize
 
-  if baseWordLen > modulusWordLen:
-    return cttEVM_InvalidInputSize
-
   # Special cases
   # ----------------------
   if paddedLengths.len + baseByteLen + exponentByteLen >= inputs.len:

constantine/math/arithmetic/finite_fields_double_precision.nim

@@ -136,7 +136,7 @@ func sum2xMod*(r: var FpDbl, a, b: FpDbl) =
 
     # Conditional reduction by 2ⁿp
     staticFor i, 0, N:
-      SecretBool(overflowed).ccopy(r.limbs2x[i+N], t[i])
+      overflowed.ccopy(r.limbs2x[i+N], t[i])
 
 func neg2xMod*(r: var FpDbl, a: FpDbl) =
   ## Double-precision modular substraction

constantine/platforms/abstractions.nim

@@ -17,28 +17,19 @@ import ./metering/tracer
 
 export primitives, tracer
 
-# ------------------------------------------------------------
-
-const CTT_ASM {.booldefine.} = true
-const UseASM_X86_32* = CTT_ASM and X86 and GCC_Compatible
-const UseASM_X86_64* = sizeof(pointer)*8 == 64 and UseASM_X86_32
-
-# We use Nim effect system to track vartime subroutines
-type VarTime*   = object
-
 # ############################################################
 #
 #                      Secret Words
 #
 # ############################################################
 
-when sizeof(int) == 8 and not defined(CTT_32):
+when CTT_32:
   type
-    BaseType* = uint64
+    BaseType* = uint32
       ## Physical BigInt for conversion in "normal integers"
 else:
   type
-    BaseType* = uint32
+    BaseType* = uint64
       ## Physical BigInt for conversion in "normal integers"
 
 type
@@ -131,12 +122,12 @@ debug: # Don't allow printing secret words by default
 
 type SignedSecretWord* = distinct SecretWord
 
-when sizeof(int) == 8 and not defined(CTT_32):
-  type
-    SignedBaseType* = int64
-else:
+when CTT_32:
   type
     SignedBaseType* = int32
+else:
+  type
+    SignedBaseType* = int64
 
 template fmap(x: SignedSecretWord, op: untyped, y: SignedSecretWord): SignedSecretWord =
   ## Unwrap x and y from their distinct type

constantine/platforms/config.nim

@@ -0,0 +1,31 @@
+# Constantine
+# Copyright (c) 2018-2019    Status Research & Development GmbH
+# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
+# Licensed and distributed under either of
+#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
+#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
+# at your option. This file may not be copied, modified, or distributed except according to those terms.
+
+# Compiler and CPU architecture configuration
+# ------------------------------------------------------------
+
+const GCC_Compatible* = defined(gcc) or defined(clang) or defined(llvm_gcc)
+const X86* = defined(amd64) or defined(i386)
+
+when sizeof(int) == 8 and GCC_Compatible:
+  type
+    uint128*{.importc: "unsigned __int128".} = object
+    int128*{.importc: "__int128".} = object
+
+# Env variable configuration
+# ------------------------------------------------------------
+
+const CTT_ASM {.booldefine.} = true
+const CTT_32* {.booldefine.} = bool(sizeof(pointer)*8 == 32)
+const UseASM_X86_32* = CTT_ASM and X86 and GCC_Compatible
+const UseASM_X86_64* = not(CTT_32) and UseASM_X86_32
+
+when UseASM_X86_64:
+  static: doAssert bool(sizeof(pointer)*8 == 64), "Only 32-bit and 64-bit platforms are supported"
+
+const UseAsmSyntaxIntel* {.booldefine.} = true

constantine/platforms/constant_time/ct_types.nim

@@ -33,10 +33,5 @@ type
   Carry* = Ct[uint8]  # distinct range[0'u8 .. 1]
   Borrow* = Ct[uint8] # distinct range[0'u8 .. 1]
 
-const GCC_Compatible* = defined(gcc) or defined(clang) or defined(llvm_gcc)
-const X86* = defined(amd64) or defined(i386)
-
-when sizeof(int) == 8 and GCC_Compatible:
-  type
-    uint128*{.importc: "unsigned __int128".} = object
-    int128*{.importc: "__int128".} = object
+  VarTime*   = object
+    ## For use with Nim effect system to track vartime subroutines

constantine/platforms/constant_time/multiplexers.nim

@@ -6,8 +6,9 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ./ct_types
-import ../isa/macro_assembler_x86
+import
+  ./ct_types,
+  ../config
 
 # ############################################################
 #

constantine/platforms/intrinsics/addcarry_subborrow.nim

@@ -6,7 +6,9 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../constant_time/ct_types
+import
+  ../config,
+  ../constant_time/ct_types
 
 # ############################################################
 #

constantine/platforms/intrinsics/bitops.nim

@@ -6,7 +6,7 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../constant_time/ct_types
+import ../config
 
 when GCC_Compatible:
   func builtin_clz(n: uint32): cint {.importc: "__builtin_clz", nodecl.}

constantine/platforms/intrinsics/extended_precision.nim

@@ -13,6 +13,7 @@
 # ############################################################
 
 import
+  ../config,
   ./addcarry_subborrow,
   ../constant_time/ct_types,
   ../constant_time/ct_routines

constantine/platforms/intrinsics/extended_precision_64bit_uint128.nim

@@ -6,7 +6,9 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import ../constant_time/ct_types
+import
+  ../config,
+  ../constant_time/ct_types
 
 # ############################################################
 #
@@ -86,7 +88,7 @@ func smul*(hi, lo: var Ct[uint64], a, b: Ct[uint64]) {.inline.} =
   ##
   ## Inputs are intentionally unsigned
   ## as we use their unchecked raw representation for cryptography
-  ## 
+  ##
   ## This is constant-time on most hardware
   ## See: https://www.bearssl.org/ctmul.html
   block:

constantine/platforms/intrinsics/extended_precision_vartime.nim

@@ -15,8 +15,8 @@
 
 import ../abstractions
 
-func div2n1n_nim_vartime[T: SomeUnsignedInt](q, r: var T, n_hi, n_lo, d: T) {.tags:[VarTime].}=
-  ## Division uint128 by uint64
+func div2n1n_nim_vartime[T: SomeUnsignedInt](q, r: var T, n_hi, n_lo, d: T) {.used, tags:[VarTime].}=
+  ## Division uint128 by uint64 or uint64 by uint32
   ## Warning ⚠️ :
   ##   - if n_hi == d, quotient does not fit in an uint64 and will throw SIGFPE
   ##   - if n_hi > d result is undefined
@@ -59,7 +59,7 @@ func div2n1n_nim_vartime[T: SomeUnsignedInt](q, r: var T, n_hi, n_lo, d: T) {.ta
   q = (q1 shl halfSize) or q2
   r = r2
 
-when sizeof(int) == 8 and defined(vcc):
+when not(CTT_32) and defined(vcc):
   func udiv128_vartime(highDividend, lowDividend, divisor: uint64, remainder: var uint64): uint64 {.importc:"_udiv128", header: "<intrin.h>", nodecl, tags:[VarTime].}
     ## Division 128 by 64, Microsoft only, 64-bit only,
     ## returns quotient as return value remainder as var parameter
@@ -74,7 +74,7 @@ when sizeof(int) == 8 and defined(vcc):
       ##   - if n_hi > d result is undefined
       q = udiv128_vartime(n_hi, n_lo, d, r)
 
-elif sizeof(int) == 8 and GCC_Compatible:
+elif not(CTT_32) and GCC_Compatible:
   type
     uint128{.importc: "unsigned __int128".} = object
 
@@ -108,15 +108,16 @@ func div2n1n_vartime*(q, r: var SecretWord, n_hi, n_lo, d: SecretWord) {.inline.
   ## To avoid issues, n_hi, n_lo, d should be normalized.
   ## i.e. shifted (== multiplied by the same power of 2)
   ## so that the most significant bit in d is set.
-  when sizeof(int) == 4:
+  when CTT_32:
     let dividend = (uint64(n_hi) shl 32) or uint64(n_lo)
     let divisor = uint64(d)
-    q = uint32(dividend div divisor)
-    r = uint32(dividend mod divisor)
-  when nimvm:
-    div2n1n_nim_vartime(BaseType q, BaseType r, BaseType n_hi, BaseType n_lo, BaseType d)
+    q = SecretWord(dividend div divisor)
+    r = SecretWord(dividend mod divisor)
   else:
-    when declared(div2n1n_128_vartime):
-      div2n1n_128_vartime(BaseType q, BaseType r, BaseType n_hi, BaseType n_lo, BaseType d)
-    else:
+    when nimvm:
       div2n1n_nim_vartime(BaseType q, BaseType r, BaseType n_hi, BaseType n_lo, BaseType d)
+    else:
+      when declared(div2n1n_128_vartime):
+        div2n1n_128_vartime(BaseType q, BaseType r, BaseType n_hi, BaseType n_lo, BaseType d)
+      else:
+        div2n1n_nim_vartime(BaseType q, BaseType r, BaseType n_hi, BaseType n_lo, BaseType d)

constantine/platforms/isa/macro_assembler_x86.nim

@@ -6,7 +6,7 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-const UseAsmSyntaxIntel* {.booldefine.} = true
+import ../config
 
 when UseAsmSyntaxIntel:
   # We need Intel syntax.

constantine/platforms/isa/macro_assembler_x86_att.nim

@@ -6,7 +6,9 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import std/[macros, strutils, sets, hashes, algorithm]
+import
+  std/[macros, strutils, sets, hashes, algorithm],
+  ../config
 
 # A compile-time inline assembler
 
@@ -39,15 +41,7 @@ type
     # Clobbered register
     ClobberedReg
 
-when sizeof(int) == 8 and not defined(CTT_32):
-  type
-    Register* = enum
-      rbx
-      rdx
-      r8
-      rax
-      xmm0
-else:
+when CTT_32:
   type
     Register* = enum
       rbx  = "ebx"
@@ -55,6 +49,14 @@ else:
       r8   = "r8d"
       rax  = "eax"
       xmm0
+else:
+  type
+    Register* = enum
+      rbx
+      rdx
+      r8
+      rax
+      xmm0
 
 type
   Constraint* = enum

constantine/platforms/isa/macro_assembler_x86_intel.nim

@@ -6,7 +6,9 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import std/[macros, strutils, sets, hashes, algorithm]
+import
+  std/[macros, strutils, sets, hashes, algorithm],
+  ../config
 
 # A compile-time inline assembler
 
@@ -39,15 +41,7 @@ type
     # Clobbered register
     ClobberedReg
 
-when sizeof(int) == 8 and not defined(CTT_32):
-  type
-    Register* = enum
-      rbx
-      rdx
-      r8
-      rax
-      xmm0
-else:
+when CTT_32:
   type
     Register* = enum
       rbx  = "ebx"
@@ -55,6 +49,14 @@ else:
       r8   = "r8d"
       rax  = "eax"
       xmm0
+else:
+  type
+    Register* = enum
+      rbx
+      rdx
+      r8
+      rax
+      xmm0
 
 type
   Constraint* = enum
@@ -464,14 +466,17 @@ func getStrOffset(a: Assembler_x86, op: Operand): string =
   if op.desc.rm in {Mem, MemOffsettable}:
     # Directly accessing memory
     if defined(gcc):
+      # https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#x86-Operand-Modifiers
+      # q: Print the DImode name of the register.
+      # k: Print the SImode name of the register.
       if a.wordBitWidth == 64:
         if op.offset == 0:
           return "%q" & op.desc.asmId
         return "%q" & op.desc.asmId & " + " & $(op.offset * a.wordSize)
       else:
         if op.offset == 0:
-          return "%d" & op.desc.asmId
-        return "%d" & op.desc.asmId & " + " & $(op.offset * a.wordSize)
+          return "%k" & op.desc.asmId
+        return "%k" & op.desc.asmId & " + " & $(op.offset * a.wordSize)
     elif defined(clang):
       if a.wordBitWidth == 64:
         if op.offset == 0:

constantine/platforms/primitives.nim

@@ -7,6 +7,7 @@
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
 import
+  ./config,
   constant_time/[
     ct_types,
     ct_routines,
@@ -23,6 +24,7 @@ import
   ./allocs
 
 export
+  config,
   ct_types,
   ct_routines,
   multiplexers,

tests/math_arbitrary_precision/t_bigints_mod.nim

@@ -4,7 +4,8 @@ import
   ../../constantine/math/[
     arithmetic,
     io/io_bigints],
-  ../../constantine/math_arbitrary_precision/arithmetic/limbs_divmod_vartime
+  ../../constantine/math_arbitrary_precision/arithmetic/limbs_divmod_vartime,
+  ../../constantine/platforms/abstractions
 
 let a = BigInt[64].fromUint(0xa0e5cb56a1c08396'u64)
 let M = BigInt[64].fromUint(0xae57180eceb0206f'u64)
@@ -14,9 +15,9 @@ var r, r2: BigInt[64]
 r.reduce(a, M)
 doAssert r2.limbs.reduce_vartime(a.limbs, M.limbs)
 
-let rU64 = 0xa0e5cb56a1c08396'u64 mod 0xae57180eceb0206f'u64
+let rBase = cast[BaseType](0xa0e5cb56a1c08396'u64) mod cast[BaseType](0xae57180eceb0206f'u64)
 # echo r.toHex()
 
-doAssert rU64 == a.limbs[0].uint64
+doAssert rBase == a.limbs[0].BaseType
 doAssert bool(a == r)
 echo "SUCCESS: t_bigints_mod.nim"

tests/t_ethereum_evm_modexp.nim

@@ -206,7 +206,7 @@ suite "EVM ModExp precompile (EIP-198)":
         0xa0]
     var r = newSeq[byte](1)
     let status = r.eth_evm_modexp(input)
-    doAssert status == cttEVM_Success
+    doAssert status == cttEVM_Success, "Failure status: " & $status
 
   test "Audit #6 - DOS Vector 1":
     let input = [