From 903a79a1efff18fc7cc50db09a3fe5d768adc9a8 Mon 19 Mar 2018 09:58:06 +0100 From: Lars T Hansen Date: Fri, 23 Mar 2018 22:01:33 +0000 Subject: [PATCH] save and restore non-volatile x28 on ARM64 for generated unboxed object constructor Fixes: https://bugzilla.mozilla.org/show_bug.cgi?id=1375074 Upsream-status: Applied See: https://hg.mozilla.org/mozilla-central/rev/800abe66894d Signed-off-by: Lars T Hansen Signed-off-by: Adam Duskett --- js/src/vm/UnboxedObject.cpp | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) diff --git a/js/src/vm/UnboxedObject.cpp b/js/src/vm/UnboxedObject.cpp index 35ca20d7405f..1c20a1093d13 100644 --- a/js/src/vm/UnboxedObject.cpp +++ b/js/src/vm/UnboxedObject.cpp @@ -86,9 +86,16 @@ static const uintptr_t CLEAR_CONSTRUCTOR_CODE_TOKEN = 0x1; #endif #ifdef JS_CODEGEN_ARM64 - // ARM64 communicates stack address via sp, but uses a pseudo-sp for - // addressing. - masm.initStackPtr(); + // ARM64 communicates stack address via sp, but uses a pseudo-sp (PSP) for + // addressing. The register we use for PSP may however also be used by + // calling code, and it is nonvolatile, so save it. Do this as a special + // case first because the generic save/restore code needs the PSP to be + // initialized already. + MOZ_ASSERT(PseudoStackPointer64.Is(masm.GetStackPointer64())); + masm.Str(PseudoStackPointer64, vixl::MemOperand(sp, -16, vixl::PreIndex)); + + // Initialize the PSP from the SP. + masm.initStackPtr(); #endif MOZ_ASSERT(propertiesReg.volatile_()); @@ -239,7 +246,22 @@ static const uintptr_t CLEAR_CONSTRUCTOR_CODE_TOKEN = 0x1; if (ScratchDoubleReg.volatile_()) masm.pop(ScratchDoubleReg); masm.PopRegsInMask(savedNonVolatileRegisters); - masm.abiret(); +#ifdef JS_CODEGEN_ARM64 + // Now restore the value that was in the PSP register on entry, and return. + + // Obtain the correct SP from the PSP. + masm.Mov(sp, PseudoStackPointer64); + + // Restore the saved value of the PSP register, this value is whatever the + // caller had saved in it, not any actual SP value, and it must not be + // overwritten subsequently. + masm.Ldr(PseudoStackPointer64, vixl::MemOperand(sp, 16, vixl::PostIndex)); + + // Perform a plain Ret(), as abiret() will move SP <- PSP and that is wrong. + masm.Ret(vixl::lr); +#else + masm.abiret(); +#endif masm.bind(&failureStoreOther); -- 2.23.0