From a7a5b5ce485512e659fd4f8a1edb2cda3021517f Mon Sep 17 00:00:00 2001 From: Zheng Xu Date: Thu, 1 Sep 2016 16:58:30 +0800 Subject: [PATCH] Bug 1143022 - Manually mmap on arm64 to ensure high 17 bits are clear. r=ehoogeveen There might be 48-bit VA on arm64 depending on kernel configuration. Manually mmap heap memory to align with the assumption made by JS engine. Change-Id: I2853e284b92aecf609e00bb82718e5df535bbba2 --- js/src/gc/Memory.cpp | 37 ++++++++++++++++++++++++++++++- js/src/jsapi-tests/testGCAllocator.cpp | 40 +++++++++++++++++++++++++++------- 2 files changed, 68 insertions(+), 9 deletions(-) diff --git a/js/src/gc/Memory.cpp b/js/src/gc/Memory.cpp index 8db2c68e..db2063d 100644 --- a/js/src/gc/Memory.cpp +++ b/js/src/gc/Memory.cpp @@ -379,7 +379,7 @@ static inline void* MapMemoryAt(void* desired, size_t length, int prot = PROT_READ | PROT_WRITE, int flags = MAP_PRIVATE | MAP_ANON, int fd = -1, off_t offset = 0) { -#if defined(__ia64__) || (defined(__sparc64__) && defined(__NetBSD__)) +#if defined(__ia64__) || (defined(__sparc64__) && defined(__NetBSD__)) || defined(__aarch64__) MOZ_ASSERT(0xffff800000000000ULL & (uintptr_t(desired) + length - 1) == 0); #endif void* region = mmap(desired, length, prot, flags, fd, offset); @@ -429,6 +429,41 @@ MapMemory(size_t length, int prot = PROT_READ | PROT_WRITE, return nullptr; } return region; +#elif defined(__aarch64__) + /* + * There might be similar virtual address issue on arm64 which depends on + * hardware and kernel configurations. But the work around is slightly + * different due to the different mmap behavior. + * + * TODO: Merge with the above code block if this implementation works for + * ia64 and sparc64. + */ + const uintptr_t start = UINT64_C(0x0000070000000000); + const uintptr_t end = UINT64_C(0x0000800000000000); + const uintptr_t step = ChunkSize; + /* + * Optimization options if there are too many retries in practice: + * 1. Examine /proc/self/maps to find an available address. This file is + * not always available, however. In addition, even if we examine + * /proc/self/maps, we may still need to retry several times due to + * racing with other threads. + * 2. Use a global/static variable with lock to track the addresses we have + * allocated or tried. + */ + uintptr_t hint; + void* region = MAP_FAILED; + for (hint = start; region == MAP_FAILED && hint + length <= end; hint += step) { + region = mmap((void*)hint, length, prot, flags, fd, offset); + if (region != MAP_FAILED) { + if ((uintptr_t(region) + (length - 1)) & 0xffff800000000000) { + if (munmap(region, length)) { + MOZ_ASSERT(errno == ENOMEM); + } + region = MAP_FAILED; + } + } + } + return region == MAP_FAILED ? nullptr : region; #else void* region = MozTaggedAnonymousMmap(nullptr, length, prot, flags, fd, offset, "js-gc-heap"); if (region == MAP_FAILED) diff --git a/js/src/jsapi-tests/testGCAllocator.cpp b/js/src/jsapi-tests/testGCAllocator.cpp index 2d36d2f..9bf1692 100644 --- a/js/src/jsapi-tests/testGCAllocator.cpp +++ b/js/src/jsapi-tests/testGCAllocator.cpp @@ -257,7 +257,7 @@ unmapPages(void* p, size_t size) void* mapMemoryAt(void* desired, size_t length) { -#if defined(__ia64__) || (defined(__sparc64__) && defined(__NetBSD__)) +#if defined(__ia64__) || (defined(__sparc64__) && defined(__NetBSD__)) || defined(__aarch64__) MOZ_RELEASE_ASSERT(0xffff800000000000ULL & (uintptr_t(desired) + length - 1) == 0); #endif void* region = mmap(desired, length, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); @@ -274,21 +274,45 @@ mapMemoryAt(void* desired, size_t length) void* mapMemory(size_t length) { - void* hint = nullptr; + int prot = PROT_READ | PROT_WRITE; + int flags = MAP_PRIVATE | MAP_ANON; + int fd = -1; + off_t offset = 0; + // The test code must be aligned with the implementation in gc/Memory.cpp. #if defined(__ia64__) || (defined(__sparc64__) && defined(__NetBSD__)) - hint = (void*)0x0000070000000000ULL; -#endif - void* region = mmap(hint, length, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); + void* region = mmap((void*)0x0000070000000000, length, prot, flags, fd, offset); if (region == MAP_FAILED) return nullptr; -#if defined(__ia64__) || (defined(__sparc64__) && defined(__NetBSD__)) - if ((uintptr_t(region) + (length - 1)) & 0xffff800000000000ULL) { + if ((uintptr_t(region) + (length - 1)) & 0xffff800000000000) { if (munmap(region, length)) MOZ_RELEASE_ASSERT(errno == ENOMEM); return nullptr; } -#endif return region; +#elif defined(__aarch64__) + const uintptr_t start = UINT64_C(0x0000070000000000); + const uintptr_t end = UINT64_C(0x0000800000000000); + const uintptr_t step = js::gc::ChunkSize; + uintptr_t hint; + void* region = MAP_FAILED; + for (hint = start; region == MAP_FAILED && hint + length <= end; hint += step) { + region = mmap((void*)hint, length, prot, flags, fd, offset); + if (region != MAP_FAILED) { + if ((uintptr_t(region) + (length - 1)) & 0xffff800000000000) { + if (munmap(region, length)) { + MOZ_RELEASE_ASSERT(errno == ENOMEM); + } + region = MAP_FAILED; + } + } + } + return region == MAP_FAILED ? nullptr : region; +#else + void* region = mmap(nullptr, length, prot, flags, fd, offset); + if (region == MAP_FAILED) + return nullptr; + return region; +#endif } void -- 1.9.1