Bug 531915 - part 6 - optionally use fdlibm's sin, cos, and tan in jsmath r=tjr,arai

Adds a new preference javascript.options.use_fdlibm_for_sin_cos_tan (default
false) and uses fdlibm for Math.sin, Math.cos, and Math.tan conditioned on it.

Differential Revision: https://phabricator.services.mozilla.com/D119426

browser/components/resistfingerprinting/test/browser/browser.ini

@@ -20,6 +20,7 @@ https_first_disabled = true
 skip-if =
   (os == "mac") #Bug 1570812
   os == 'linux' && bits == 64 && !debug # Bug 1570812
+[browser_math.js]
 [browser_navigator.js]
 https_first_disabled = true
 skip-if =

browser/components/resistfingerprinting/test/browser/browser_math.js

@@ -0,0 +1,107 @@
+/**
+ * Bug 531915 - A test for verifying that the JS Math fingerprint is constant
+ *              when using fdlibm for Math.sin, Math.cos, and Math.tan.
+ */
+
+async function test_math(rfp_pref, fdlibm_pref) {
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["javascript.options.use_fdlibm_for_sin_cos_tan", fdlibm_pref],
+      ["privacy.resistFingerprinting", rfp_pref],
+    ],
+  });
+
+  let tab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    TEST_PATH + "file_dummy.html"
+  );
+
+  await SpecialPowers.spawn(tab.linkedBrowser, [], async function() {
+    // override is to check strict equality like we would do in a JS ref test.
+    function strictly_is(a, b) {
+      ok(a === b);
+    }
+
+    //
+    // Tests adapted from https://github.com/arkenfox/TZP/blob/5e3f5ff2c64b4edc7beecd8308aa4f7a3efb49e3/tests/math.html#L158-L319
+    //
+    strictly_is(Math.cos(1e251), -0.37419577499634155);
+    strictly_is(Math.cos(1e140), -0.7854805190645291);
+    strictly_is(Math.cos(1e12), 0.7914463018528902);
+    strictly_is(Math.cos(1e130), -0.767224894221913);
+    strictly_is(Math.cos(1e272), -0.7415825695514536);
+    strictly_is(Math.cos(1), 0.5403023058681398);
+    strictly_is(Math.cos(1e284), 0.7086865671674247);
+    strictly_is(Math.cos(1e75), -0.7482651726250321);
+    strictly_is(Math.cos(Math.PI), -1);
+    strictly_is(Math.cos(-1e308), -0.8913089376870335);
+    strictly_is(Math.cos(13 * Math.E), -0.7108118501064332);
+    strictly_is(Math.cos(57 * Math.E), -0.536911695749024);
+    strictly_is(Math.cos(21 * Math.LN2), -0.4067775970251724);
+    strictly_is(Math.cos(51 * Math.LN2), -0.7017203400855446);
+    strictly_is(Math.cos(21 * Math.LOG2E), 0.4362848063618998);
+    strictly_is(Math.cos(25 * Math.SQRT2), -0.6982689820462377);
+    strictly_is(Math.cos(50 * Math.SQRT1_2), -0.6982689820462377);
+    strictly_is(Math.cos(21 * Math.SQRT1_2), -0.6534063185820198);
+    strictly_is(Math.cos(17 * Math.LOG10E), 0.4537557425982784);
+    strictly_is(Math.cos(2 * Math.LOG10E), 0.6459044007438142);
+
+    strictly_is(Math.sin(1e251), -0.9273497301314576);
+    strictly_is(Math.sin(1e140), -0.6188863822787813);
+    strictly_is(Math.sin(1e12), -0.6112387023768895);
+    strictly_is(Math.sin(1e130), 0.6413781736901984);
+    strictly_is(Math.sin(1e272), 0.6708616046081811);
+    strictly_is(Math.sin(1), 0.8414709848078965);
+    strictly_is(Math.sin(1e284), -0.7055234578073583);
+    strictly_is(Math.sin(1e75), 0.66339975236386);
+    strictly_is(Math.sin(Math.PI), 1.2246467991473532e-16);
+    strictly_is(Math.sin(39 * Math.E), -0.7181630308570678);
+    strictly_is(Math.sin(35 * Math.LN2), -0.765996413898051);
+    strictly_is(Math.sin(110 * Math.LOG2E), 0.9989410140273757);
+    strictly_is(Math.sin(7 * Math.LOG10E), 0.10135692924965616);
+    strictly_is(Math.sin(35 * Math.SQRT1_2), -0.3746357547858202);
+    strictly_is(Math.sin(21 * Math.SQRT2), -0.9892668187780497);
+
+    strictly_is(Math.tan(1e251), 2.478247463217681);
+    strictly_is(Math.tan(1e140), 0.7879079967710036);
+    strictly_is(Math.tan(1e12), -0.7723059681318761);
+    strictly_is(Math.tan(1e130), -0.8359715365344825);
+    strictly_is(Math.tan(1e272), -0.904635076595654);
+    strictly_is(Math.tan(1), 1.5574077246549023);
+    strictly_is(Math.tan(1e284), -0.9955366596368418);
+    strictly_is(Math.tan(1e75), -0.8865837628611647);
+    strictly_is(Math.tan(-1e308), 0.5086861259107568);
+    strictly_is(Math.tan(Math.PI), -1.2246467991473532e-16);
+    strictly_is(Math.tan(6 * Math.E), 0.6866761546452431);
+    strictly_is(Math.tan(6 * Math.LN2), 1.6182817135715877);
+    strictly_is(Math.tan(10 * Math.LOG2E), -3.3537128705376014);
+    strictly_is(Math.tan(17 * Math.SQRT2), -1.9222955461799982);
+    strictly_is(Math.tan(34 * Math.SQRT1_2), -1.9222955461799982);
+    strictly_is(Math.tan(10 * Math.LOG10E), 2.5824856130712432);
+
+    //
+    // Tests adapted from https://github.com/fingerprintjs/fingerprintjs/blob/7096a5589af495f1f46067963e13ad27d887d185/src/sources/math.ts#L32-L64
+    //
+    strictly_is(Math.acos(0.123124234234234242), 1.4473588658278522);
+    strictly_is(Math.acosh(1e308), 709.889355822726);
+    strictly_is(Math.asin(0.123124234234234242), 0.12343746096704435);
+    strictly_is(Math.asinh(1), 0.881373587019543);
+    strictly_is(Math.atanh(0.5), 0.5493061443340548);
+    strictly_is(Math.atan(0.5), 0.4636476090008061);
+    strictly_is(Math.sin(-1e300), 0.8178819121159085);
+    strictly_is(Math.sinh(1), 1.1752011936438014);
+    strictly_is(Math.cos(10.000000000123), -0.8390715290095377);
+    strictly_is(Math.cosh(1), 1.5430806348152437);
+    strictly_is(Math.tan(-1e300), -1.4214488238747245);
+    strictly_is(Math.tanh(1), 0.7615941559557649);
+    strictly_is(Math.exp(1), 2.718281828459045);
+    strictly_is(Math.expm1(1), 1.718281828459045);
+    strictly_is(Math.log1p(10), 2.3978952727983707);
+  });
+
+  BrowserTestUtils.removeTab(tab);
+}
+
+add_task(test_math.bind(null, false, true));
+add_task(test_math.bind(null, true, false));
+add_task(test_math.bind(null, true, true));

js/public/CompileOptions.h

@@ -167,6 +167,8 @@ class JS_PUBLIC_API TransitiveCompileOptions {
   uint32_t introductionOffset = 0;
   bool hasIntroductionInfo = false;
 
+  bool useFdlibmForSinCosTan = false;
+
  protected:
   TransitiveCompileOptions() = default;
 

js/src/jit-test/tests/basic/fdlibm-for-sin-cos-tan-argument.js

@@ -0,0 +1,7 @@
+// |jit-test| --use-fdlibm-for-sin-cos-tan
+// Test that fdlibm is being used for sin, cos, and tan.
+
+// Tests adapted from https://github.com/arkenfox/TZP/blob/master/tests/math.html#L158-L319
+assertEq(Math.cos(1e284), 0.7086865671674247);
+assertEq(Math.sin(7*Math.LOG10E), 0.10135692924965616);
+assertEq(Math.tan(6*Math.E), 0.6866761546452431);

js/src/jsapi.cpp

@@ -2329,6 +2329,7 @@ void JS::TransitiveCompileOptions::copyPODTransitiveOptions(
   classStaticBlocks = rhs.classStaticBlocks;
   useStencilXDR = rhs.useStencilXDR;
   useOffThreadParseGlobal = rhs.useOffThreadParseGlobal;
+  useFdlibmForSinCosTan = rhs.useFdlibmForSinCosTan;
 };
 
 void JS::ReadOnlyCompileOptions::copyPODNonTransitiveOptions(
@@ -2417,6 +2418,8 @@ JS::CompileOptions::CompileOptions(JSContext* cx) : ReadOnlyCompileOptions() {
   useStencilXDR = !UseOffThreadParseGlobal();
   useOffThreadParseGlobal = UseOffThreadParseGlobal();
 
+  useFdlibmForSinCosTan = math_use_fdlibm_for_sin_cos_tan();
+
   sourcePragmas_ = cx->options().sourcePragmas();
 
   // Certain modes of operation force strict-mode in general.

js/src/jsapi.h

@@ -64,6 +64,16 @@
 
 /************************************************************************/
 
+namespace JS {
+/**
+ * Tell JS engine whether to use fdlibm for Math.sin, Math.cos, and Math.tan.
+ * Using fdlibm ensures that we don't expose a math fingerprint.
+ */
+extern JS_PUBLIC_API void SetUseFdlibmForSinCosTan(bool value);
+}  // namespace JS
+
+/************************************************************************/
+
 struct JSFunctionSpec;
 struct JSPropertySpec;
 

js/src/jsmath.cpp

@@ -52,6 +52,12 @@ using mozilla::NumberEqualsInt32;
 using mozilla::PositiveInfinity;
 using mozilla::WrappingMultiply;
 
+static mozilla::Atomic<bool, mozilla::Relaxed> sUseFdlibmForSinCosTan;
+
+JS_PUBLIC_API void JS::SetUseFdlibmForSinCosTan(bool value) {
+  sUseFdlibmForSinCosTan = value;
+}
+
 template <UnaryMathFunctionType F>
 static bool math_function(JSContext* cx, HandleValue val,
                           MutableHandleValue res) {
@@ -206,13 +212,25 @@ bool js::math_clz32(JSContext* cx, unsigned argc, Value* vp) {
   return true;
 }
 
-double js::math_cos_impl(double x) {
+bool js::math_use_fdlibm_for_sin_cos_tan() { return sUseFdlibmForSinCosTan; }
+
+double js::math_cos_fdlibm_impl(double x) {
+  MOZ_ASSERT(sUseFdlibmForSinCosTan);
+  AutoUnsafeCallWithABI unsafe;
+  return fdlibm::cos(x);
+}
+
+double js::math_cos_native_impl(double x) {
+  MOZ_ASSERT(!sUseFdlibmForSinCosTan);
   AutoUnsafeCallWithABI unsafe;
   return cos(x);
 }
 
 bool js::math_cos(JSContext* cx, unsigned argc, Value* vp) {
-  return math_function<math_cos_impl>(cx, argc, vp);
+  if (sUseFdlibmForSinCosTan) {
+    return math_function<math_cos_fdlibm_impl>(cx, argc, vp);
+  }
+  return math_function<math_cos_native_impl>(cx, argc, vp);
 }
 
 double js::math_exp_impl(double x) {
@@ -582,18 +600,31 @@ js::math_round(JSContext* cx, unsigned argc, Value* vp) {
   return math_round_handle(cx, args[0], args.rval());
 }
 
-double js::math_sin_impl(double x) {
+double js::math_sin_fdlibm_impl(double x) {
+  MOZ_ASSERT(sUseFdlibmForSinCosTan);
+  AutoUnsafeCallWithABI unsafe;
+  return fdlibm::sin(x);
+}
+
+double js::math_sin_native_impl(double x) {
+  MOZ_ASSERT(!sUseFdlibmForSinCosTan);
   AutoUnsafeCallWithABI unsafe(UnsafeABIStrictness::AllowPendingExceptions);
   return sin(x);
 }
 
 bool js::math_sin_handle(JSContext* cx, HandleValue val,
                          MutableHandleValue res) {
-  return math_function<math_sin_impl>(cx, val, res);
+  if (sUseFdlibmForSinCosTan) {
+    return math_function<math_sin_fdlibm_impl>(cx, val, res);
+  }
+  return math_function<math_sin_native_impl>(cx, val, res);
 }
 
 bool js::math_sin(JSContext* cx, unsigned argc, Value* vp) {
-  return math_function<math_sin_impl>(cx, argc, vp);
+  if (sUseFdlibmForSinCosTan) {
+    return math_function<math_sin_fdlibm_impl>(cx, argc, vp);
+  }
+  return math_function<math_sin_native_impl>(cx, argc, vp);
 }
 
 double js::math_sqrt_impl(double x) {
@@ -610,13 +641,23 @@ bool js::math_sqrt(JSContext* cx, unsigned argc, Value* vp) {
   return math_function<math_sqrt_impl>(cx, argc, vp);
 }
 
-double js::math_tan_impl(double x) {
+double js::math_tan_fdlibm_impl(double x) {
+  MOZ_ASSERT(sUseFdlibmForSinCosTan);
+  AutoUnsafeCallWithABI unsafe;
+  return fdlibm::tan(x);
+}
+
+double js::math_tan_native_impl(double x) {
+  MOZ_ASSERT(!sUseFdlibmForSinCosTan);
   AutoUnsafeCallWithABI unsafe;
   return tan(x);
 }
 
 bool js::math_tan(JSContext* cx, unsigned argc, Value* vp) {
-  return math_function<math_tan_impl>(cx, argc, vp);
+  if (sUseFdlibmForSinCosTan) {
+    return math_function<math_tan_fdlibm_impl>(cx, argc, vp);
+  }
+  return math_function<math_tan_native_impl>(cx, argc, vp);
 }
 
 double js::math_log10_impl(double x) {
@@ -885,13 +926,22 @@ UnaryMathFunctionType js::GetUnaryMathFunctionPtr(UnaryMathFunction fun) {
     case UnaryMathFunction::Log:
       return math_log_impl;
     case UnaryMathFunction::Sin:
-      return math_sin_impl;
+      if (sUseFdlibmForSinCosTan) {
+        return math_sin_fdlibm_impl;
+      }
+      return math_sin_native_impl;
     case UnaryMathFunction::Cos:
-      return math_cos_impl;
+      if (sUseFdlibmForSinCosTan) {
+        return math_cos_fdlibm_impl;
+      }
+      return math_cos_native_impl;
     case UnaryMathFunction::Exp:
       return math_exp_impl;
     case UnaryMathFunction::Tan:
-      return math_tan_impl;
+      if (sUseFdlibmForSinCosTan) {
+        return math_tan_fdlibm_impl;
+      }
+      return math_tan_native_impl;
     case UnaryMathFunction::ATan:
       return math_atan_impl;
     case UnaryMathFunction::ASin:

js/src/jsmath.h

@@ -109,16 +109,20 @@ extern double math_log_impl(double x);
 extern bool math_log_handle(JSContext* cx, HandleValue val,
                             MutableHandleValue res);
 
+extern bool math_use_fdlibm_for_sin_cos_tan();
+
 extern bool math_sin(JSContext* cx, unsigned argc, js::Value* vp);
 
-extern double math_sin_impl(double x);
+extern double math_sin_fdlibm_impl(double x);
+extern double math_sin_native_impl(double x);
 
 extern bool math_sin_handle(JSContext* cx, HandleValue val,
                             MutableHandleValue res);
 
 extern bool math_cos(JSContext* cx, unsigned argc, js::Value* vp);
 
-extern double math_cos_impl(double x);
+extern double math_cos_fdlibm_impl(double x);
+extern double math_cos_native_impl(double x);
 
 extern bool math_exp(JSContext* cx, unsigned argc, js::Value* vp);
 
@@ -126,7 +130,8 @@ extern double math_exp_impl(double x);
 
 extern bool math_tan(JSContext* cx, unsigned argc, js::Value* vp);
 
-extern double math_tan_impl(double x);
+extern double math_tan_fdlibm_impl(double x);
+extern double math_tan_native_impl(double x);
 
 extern bool math_log10(JSContext* cx, unsigned argc, js::Value* vp);
 

js/src/shell/js.cpp

@@ -638,6 +638,8 @@ bool shell::compileOnly = false;
 bool shell::disableOOMFunctions = false;
 bool shell::defaultToSameCompartment = true;
 
+bool shell::useFdlibmForSinCosTan = false;
+
 #ifdef DEBUG
 bool shell::dumpEntrainedVariables = false;
 bool shell::OOM_printAllocationCount = false;
@@ -11274,6 +11276,7 @@ static bool SetContextOptions(JSContext* cx, const OptionParser& op) {
   enableTopLevelAwait = op.getBoolOption("enable-top-level-await");
   enableClassStaticBlocks = op.getBoolOption("enable-class-static-blocks");
   useOffThreadParseGlobal = op.getBoolOption("off-thread-parse-global");
+  useFdlibmForSinCosTan = op.getBoolOption("use-fdlibm-for-sin-cos-tan");
 
   JS::ContextOptionsRef(cx)
       .setAsmJS(enableAsmJS)
@@ -11307,6 +11310,7 @@ static bool SetContextOptions(JSContext* cx, const OptionParser& op) {
       .setClassStaticBlocks(enableClassStaticBlocks);
 
   JS::SetUseOffThreadParseGlobal(useOffThreadParseGlobal);
+  JS::SetUseFdlibmForSinCosTan(useFdlibmForSinCosTan);
 
   // Check --fast-warmup first because it sets default warm-up thresholds. These
   // thresholds can then be overridden below by --ion-eager and other flags.
@@ -12490,7 +12494,9 @@ int main(int argc, char** argv) {
       !op.addBoolOption('\0', "reprl", "Enable REPRL mode for fuzzing") ||
 #endif
       !op.addStringOption('\0', "telemetry-dir", "[directory]",
-                          "Output telemetry results in a directory")) {
+                          "Output telemetry results in a directory") ||
+      !op.addBoolOption('\0', "use-fdlibm-for-sin-cos-tan",
+                        "Use fdlibm for Math.sin, Math.cos, and Math.tan")) {
     return EXIT_FAILURE;
   }
 

js/src/shell/jsshell.h

@@ -157,6 +157,8 @@ extern bool dumpEntrainedVariables;
 extern bool OOM_printAllocationCount;
 #endif
 
+extern bool useFdlibmForSinCosTan;
+
 extern UniqueChars processWideModuleLoadPath;
 
 // Alias the global dstName to namespaceObj.srcName. For example, if dstName is

js/src/wasm/WasmBuiltins.cpp

@@ -1427,10 +1427,12 @@ bool wasm::NeedsBuiltinThunk(SymbolicAddress sym) {
 // Each JS builtin can have several overloads. These must all be enumerated in
 // PopulateTypedNatives() so they can be included in the process-wide thunk set.
 
+#define FOR_EACH_SIN_COS_TAN_NATIVE(_) \
+  _(math_sin, MathSin)                 \
+  _(math_tan, MathTan)                 \
+  _(math_cos, MathCos)
+
 #define FOR_EACH_UNARY_NATIVE(_) \
-  _(math_sin, MathSin)           \
-  _(math_tan, MathTan)           \
-  _(math_cos, MathCos)           \
   _(math_exp, MathExp)           \
   _(math_log, MathLog)           \
   _(math_asin, MathASin)         \
@@ -1455,6 +1457,14 @@ bool wasm::NeedsBuiltinThunk(SymbolicAddress sym) {
   _(ecmaHypot, MathHypot)         \
   _(ecmaPow, MathPow)
 
+#define DEFINE_SIN_COS_TAN_FLOAT_WRAPPER(func, _)  \
+  static float func##_impl_f32(float x) {          \
+    if (math_use_fdlibm_for_sin_cos_tan()) {       \
+      return float(func##_fdlibm_impl(double(x))); \
+    }                                              \
+    return float(func##_native_impl(double(x)));   \
+  }
+
 #define DEFINE_UNARY_FLOAT_WRAPPER(func, _) \
   static float func##_impl_f32(float x) {   \
     return float(func##_impl(double(x)));   \
@@ -1465,6 +1475,7 @@ bool wasm::NeedsBuiltinThunk(SymbolicAddress sym) {
     return float(func(double(x), double(y))); \
   }
 
+FOR_EACH_SIN_COS_TAN_NATIVE(DEFINE_SIN_COS_TAN_FLOAT_WRAPPER)
 FOR_EACH_UNARY_NATIVE(DEFINE_UNARY_FLOAT_WRAPPER)
 FOR_EACH_BINARY_NATIVE(DEFINE_BINARY_FLOAT_WRAPPER)
 
@@ -1496,6 +1507,14 @@ static bool PopulateTypedNatives(TypedNativeToFuncPtrMap* typedNatives) {
                             FuncCast(funcName, abiType)))                  \
     return false;
 
+#define ADD_SIN_COS_TAN_OVERLOADS(funcName, native)                  \
+  if (math_use_fdlibm_for_sin_cos_tan()) {                           \
+    ADD_OVERLOAD(funcName##_fdlibm_impl, native, Args_Double_Double) \
+  } else {                                                           \
+    ADD_OVERLOAD(funcName##_native_impl, native, Args_Double_Double) \
+  }                                                                  \
+  ADD_OVERLOAD(funcName##_impl_f32, native, Args_Float32_Float32)
+
 #define ADD_UNARY_OVERLOADS(funcName, native)               \
   ADD_OVERLOAD(funcName##_impl, native, Args_Double_Double) \
   ADD_OVERLOAD(funcName##_impl_f32, native, Args_Float32_Float32)
@@ -1504,6 +1523,7 @@ static bool PopulateTypedNatives(TypedNativeToFuncPtrMap* typedNatives) {
   ADD_OVERLOAD(funcName, native, Args_Double_DoubleDouble) \
   ADD_OVERLOAD(funcName##_f32, native, Args_Float32_Float32Float32)
 
+  FOR_EACH_SIN_COS_TAN_NATIVE(ADD_SIN_COS_TAN_OVERLOADS)
   FOR_EACH_UNARY_NATIVE(ADD_UNARY_OVERLOADS)
   FOR_EACH_BINARY_NATIVE(ADD_BINARY_OVERLOADS)
 

js/xpconnect/src/XPCJSContext.cpp

@@ -1048,6 +1048,10 @@ static void ReloadPrefsCallback(const char* pref, void* aXpccx) {
       .setErgnomicBrandChecks(ergnomicBrandChecksEnabled)
       .setTopLevelAwait(topLevelAwaitEnabled);
 
+  JS::SetUseFdlibmForSinCosTan(
+      Preferences::GetBool(JS_OPTIONS_DOT_STR "use_fdlibm_for_sin_cos_tan") ||
+      Preferences::GetBool("privacy.resistFingerprinting"));
+
   nsCOMPtr<nsIXULRuntime> xr = do_GetService("@mozilla.org/xre/runtime;1");
   if (xr) {
     bool safeMode = false;

modules/libpref/init/StaticPrefList.yaml

@@ -6150,6 +6150,14 @@
   mirror: always
   do_not_use_directly: true
 
+# Whether to use fdlibm for Math.sin, Math.cos, and Math.tan. When
+# privacy.resistFingerprinting is true, this pref is ignored and fdlibm is used
+# anyway.
+- name: javascript.options.use_fdlibm_for_sin_cos_tan
+  type: bool
+  value: false
+  mirror: always
+
 #---------------------------------------------------------------------------
 # Prefs starting with "layers."
 #---------------------------------------------------------------------------

toolkit/components/resistfingerprinting/nsRFPService.cpp

@@ -33,6 +33,7 @@
 #include "mozilla/RefPtr.h"
 #include "mozilla/Services.h"
 #include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPrefs_javascript.h"
 #include "mozilla/StaticPrefs_privacy.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/TextEvents.h"
@@ -716,6 +717,12 @@ void nsRFPService::UpdateRFPPref() {
 
   bool privacyResistFingerprinting =
       StaticPrefs::privacy_resistFingerprinting();
+
+  // set fdlibm pref
+  JS::SetUseFdlibmForSinCosTan(
+      StaticPrefs::javascript_options_use_fdlibm_for_sin_cos_tan() ||
+      privacyResistFingerprinting);
+
   if (privacyResistFingerprinting) {
     PR_SetEnv("TZ=UTC");
   } else if (sInitialized) {