From f66d410f3ba767efb91c6b9545d373267cd975f2 Mon Sep 17 00:00:00 2001 From: Philip Chimento Date: Sat, 7 Sep 2019 20:43:40 +0200 Subject: [PATCH] ensure proper running on 64-bit and 32-bit BE platforms See: https://salsa.debian.org/gnome-team/mozjs60/blob/debian/master/debian/patches/jsproperty-endian.patch Signed-off-by: Philip Chimento Signed-off-by: Adam Duskett --- js/src/gc/Marking-inl.h | 16 ++++++++++++++++ js/src/gc/RelocationOverlay.h | 13 ++++++++++++- js/src/jsfriendapi.h | 8 ++++++++ js/src/vm/StringType.h | 13 +++++++++++++ 4 files changed, 49 insertions(+), 1 deletion(-) diff --git a/js/src/gc/Marking-inl.h b/js/src/gc/Marking-inl.h index 6d2a4c7..c773c21 100644 --- a/js/src/gc/Marking-inl.h +++ b/js/src/gc/Marking-inl.h @@ -82,12 +82,28 @@ inline void RelocationOverlay::forwardTo(Cell* cell) { MOZ_ASSERT(!isForwarded()); // The location of magic_ is important because it must never be valid to see // the value Relocated there in a GC thing that has not been moved. +#if MOZ_LITTLE_ENDIAN || JS_BITS_PER_WORD == 32 + // On 32-bit, the magic_ aliases with whatever comes after the first + // pointer; on little-endian 64-bit, the magic_ aliases with the + // 32 most significant bits of the pointer, which are the second half. static_assert(offsetof(RelocationOverlay, magic_) == offsetof(JSObject, group_) + sizeof(uint32_t), "RelocationOverlay::magic_ is in the wrong location"); static_assert(offsetof(RelocationOverlay, magic_) == offsetof(js::Shape, base_) + sizeof(uint32_t), "RelocationOverlay::magic_ is in the wrong location"); +#elif JS_BITS_PER_WORD == 64 + // On big-endian 64-bit, the magic_ aliases with the 32 most + // significant bits of the pointer, but now that's the first half. + static_assert(offsetof(RelocationOverlay, magic_) == + offsetof(JSObject, group_), + "RelocationOverlay::magic_ is in the wrong location"); + static_assert(offsetof(RelocationOverlay, magic_) == + offsetof(js::Shape, base_), + "RelocationOverlay::magic_ is in the wrong location"); +#else +# error "Unknown endianness or word size" +#endif static_assert( offsetof(RelocationOverlay, magic_) == offsetof(JSString, d.u1.length), "RelocationOverlay::magic_ is in the wrong location"); diff --git a/js/src/gc/RelocationOverlay.h b/js/src/gc/RelocationOverlay.h index a568843..399a541 100644 --- a/js/src/gc/RelocationOverlay.h +++ b/js/src/gc/RelocationOverlay.h @@ -33,14 +33,25 @@ class RelocationOverlay { /* See comment in js/public/HeapAPI.h. */ static const uint32_t Relocated = js::gc::Relocated; +#if MOZ_LITTLE_ENDIAN || JS_BITS_PER_WORD == 32 /* - * Keep the low 32 bits untouched. Use them to distinguish strings from + * Keep the first 32 bits untouched. Use them to distinguish strings from * objects in the nursery. */ uint32_t preserve_; /* Set to Relocated when moved. */ uint32_t magic_; +#elif JS_BITS_PER_WORD == 64 + /* + * On big-endian, we need to reorder to keep preserve_ lined up with the + * low 32 bits of the aligned group_ pointer in JSObject. + */ + uint32_t magic_; + uint32_t preserve_; +#else +# error "Unknown endianness or word size" +#endif /* The location |this| was moved to. */ Cell* newLocation_; diff --git a/js/src/jsfriendapi.h b/js/src/jsfriendapi.h index 4b8d18a..70ce0a1 100644 --- a/js/src/jsfriendapi.h +++ b/js/src/jsfriendapi.h @@ -9,6 +9,7 @@ #include "mozilla/Atomics.h" #include "mozilla/Casting.h" +#include "mozilla/EndianUtils.h" #include "mozilla/Maybe.h" #include "mozilla/MemoryReporting.h" #include "mozilla/UniquePtr.h" @@ -609,8 +610,15 @@ struct String { static const uint32_t LATIN1_CHARS_BIT = JS_BIT(6); static const uint32_t EXTERNAL_FLAGS = LINEAR_BIT | NON_ATOM_BIT | JS_BIT(5); static const uint32_t TYPE_FLAGS_MASK = JS_BIT(6) - 1; +#if MOZ_LITTLE_ENDIAN || JS_BITS_PER_WORD == 32 uint32_t flags; uint32_t length; +#elif JS_BITS_PER_WORD == 64 + uint32_t length; + uint32_t flags; +#else +# error "Unknown endianness or word size" +#endif union { const JS::Latin1Char* nonInlineCharsLatin1; const char16_t* nonInlineCharsTwoByte; diff --git a/js/src/vm/StringType.h b/js/src/vm/StringType.h index cde3427..c3400db 100644 --- a/js/src/vm/StringType.h +++ b/js/src/vm/StringType.h @@ -7,6 +7,7 @@ #ifndef vm_StringType_h #define vm_StringType_h +#include "mozilla/EndianUtils.h" #include "mozilla/MemoryReporting.h" #include "mozilla/PodOperations.h" #include "mozilla/Range.h" @@ -168,8 +169,20 @@ class JSString : public js::gc::Cell { struct Data { union { struct { +#if MOZ_LITTLE_ENDIAN || JS_BITS_PER_WORD == 32 uint32_t flags; /* JSString */ uint32_t length; /* JSString */ +#elif JS_BITS_PER_WORD == 64 + /* + * On big-endian, we need to reorder to keep flags lined up + * with the low 32 bits of the aligned group_ pointer in + * JSObject. + */ + uint32_t length; /* JSString */ + uint32_t flags; /* JSString */ +#else +# error "Unknown endianness or word size" +#endif }; uintptr_t flattenData; /* JSRope (temporary while flattening) */ } u1; -- 2.23.0