[llvm-commits] [compiler-rt] r171107 - in /compiler-rt/trunk/lib/asan: asan_allocator2.cc asan_rtl.cc tests/asan_test.cc

Tue Jul 16 06:42:45 PDT 2013

----- Original Message -----
> 
> Hi Hal,
> 
> 
> Values of SHADOW_GRANULARITY other than 8 are currently completely
> untested,
> so it's no surprise that some of the changes broke with
> SHADOW_GRANULARITY != 8.
> 
> 
> If we want to revive other values, we also need to set up testing for
> them.
> I am very curious, why are you using larger granularity?
> Larger granularity gives us more compact shadow (which is good) but
> it also increases the minimal
> possible redzone (which is not that good). Transition from
> granularity=8 to any larger one
> makes instrumentation of 64-bit loads more expensive (not good at
> all).

Unfortunately, the system that I'm targeting (the BG/Q CNK) has only a very limited virtual memory subsystem implementation. Specifically, it does not support mapping uncommitted pages. As a result, I need to make the shadow region as small as I can (because all of that memory is actually unavailable to the application). Luckily, the system also has 32-byte aligned stacks (and mallocs), and so I can use 32-byte granularity.

> 
> 
> As for the patches you propose, may I ask you to send them using
> http://llvm.org/docs/Phabricator.html ?

Okay (but I assume that means that the basic premise behind what I've proposed makes sense, and you'd like me to spend the time to create some test cases (which I think that I can do using the flexible mapping options), etc.).

 -Hal

> 
> 
> Thanks,
> 
> 
> --kcc
> 
> 
> 
> 
> 
> On Sat, Jul 6, 2013 at 3:14 AM, Hal Finkel < hfinkel at anl.gov > wrote:
> 
> 
> 
> ----- Original Message -----
> > Author: kcc
> > Date: Wed Dec 26 04:41:24 2012
> > New Revision: 171107
> > 
> > URL: http://llvm.org/viewvc/llvm-project?rev=171107&view=rev
> > Log:
> > [asan] asan_allocator2: implement adaptive redzones. Now with
> > asan_allocator2 allocations <= 48 bytes have 16 byte redzone,
> > allocations of 48-96 bytes -- have 32 bytes redzone, etc (max
> > redzone is 2048). If ASAN_OPTIONS=redzone=n is set, it changes the
> > minimal redzone size
> 
> I'm seeing a small problem with this in the case where
> SHADOW_GRANULARITY is greater than 8. If I set it to 32 then, for
> small allocations, the CHECK(IsAligned(needed_size, min_alignment));
> in Allocate fails.
> 
> Would it make sense to replace:
> u32 rz_log =
> 
> user_requested_size <= 64 - 16 ? 0 :
> 
> user_requested_size <= 128 - 32 ? 1 :
> 
> user_requested_size <= 512 - 64 ? 2 :
> ...
> 
> with something like:
> u32 rz_log =
> SHADOW_GRANULARITY <= 8 && user_requested_size <= 64 - 16 ? 0 :
> SHADOW_GRANULARITY <= 16 && user_requested_size <= 128 - 32 ? 1 :
> SHADOW_GRANULARITY <= 32 && user_requested_size <= 512 - 64 ? 2 :
> ...
> ?
> 
> -Hal
> 
> 
> 
> > 
> > Modified:
> > compiler-rt/trunk/lib/asan/asan_allocator2.cc
> > compiler-rt/trunk/lib/asan/asan_rtl.cc
> > compiler-rt/trunk/lib/asan/tests/asan_test.cc
> > 
> > Modified: compiler-rt/trunk/lib/asan/asan_allocator2.cc
> > URL:
> > http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator2.cc?rev=171107&r1=171106&r2=171107&view=diff
> > ==============================================================================
> > --- compiler-rt/trunk/lib/asan/asan_allocator2.cc (original)
> > +++ compiler-rt/trunk/lib/asan/asan_allocator2.cc Wed Dec 26
> > 04:41:24
> > 2012
> > @@ -99,11 +99,39 @@
> > // CHUNK_ALLOCATED: the chunk is allocated and not yet freed.
> > // CHUNK_QUARANTINE: the chunk was freed and put into quarantine
> > zone.
> > enum {
> > - CHUNK_AVAILABLE = 1,
> > + CHUNK_AVAILABLE = 0, // 0 is the default value even if we didn't
> > set it.
> > CHUNK_ALLOCATED = 2,
> > CHUNK_QUARANTINE = 3
> > };
> > 
> > +// Valid redzone sizes are 16, 32, 64, ... 2048, so we encode them
> > in 3 bits.
> > +// We use adaptive redzones: for larger allocation larger redzones
> > are used.
> > +static u32 RZLog2Size(u32 rz_log) {
> > + CHECK_LT(rz_log, 8);
> > + return 16 << rz_log;
> > +}
> > +
> > +static u32 RZSize2Log(u32 rz_size) {
> > + CHECK_GE(rz_size, 16);
> > + CHECK_LE(rz_size, 2048);
> > + CHECK(IsPowerOfTwo(rz_size));
> > + u32 res = __builtin_ctz(rz_size) - 4;
> > + CHECK_EQ(rz_size, RZLog2Size(res));
> > + return res;
> > +}
> > +
> > +static uptr ComputeRZLog(uptr user_requested_size) {
> > + u32 rz_log =
> > + user_requested_size <= 64 - 16 ? 0 :
> > + user_requested_size <= 128 - 32 ? 1 :
> > + user_requested_size <= 512 - 64 ? 2 :
> > + user_requested_size <= 4096 - 128 ? 3 :
> > + user_requested_size <= (1 << 14) - 256 ? 4 :
> > + user_requested_size <= (1 << 15) - 512 ? 5 :
> > + user_requested_size <= (1 << 16) - 1024 ? 6 : 7;
> > + return Max(rz_log, RZSize2Log(flags()->redzone));
> > +}
> > +
> > // The memory chunk allocated from the underlying allocator looks
> > like this:
> > // L L L L L L H H U U U U U U R R
> > // L -- left redzone words (0 or more bytes)
> > @@ -130,6 +158,7 @@
> > u32 free_tid : 24;
> > u32 from_memalign : 1;
> > u32 alloc_type : 2;
> > + u32 rz_log : 3;
> > // 2-nd 8 bytes
> > // This field is used for small sizes. For large sizes it is equal
> > to
> > // SizeClassMap::kMaxSize and the actual size is stored in the
> > @@ -149,11 +178,6 @@
> > COMPILER_CHECK(kChunkHeaderSize == 16);
> > COMPILER_CHECK(kChunkHeader2Size <= 16);
> > 
> > -static uptr ComputeRZSize(uptr user_requested_size) {
> > - // FIXME: implement adaptive redzones.
> > - return flags()->redzone;
> > -}
> > -
> > struct AsanChunk: ChunkBase {
> > uptr Beg() { return reinterpret_cast<uptr>(this) +
> > kChunkHeaderSize; }
> > uptr UsedSize() {
> > @@ -164,21 +188,22 @@
> > void *AllocBeg() {
> > if (from_memalign)
> > return allocator.GetBlockBegin(reinterpret_cast<void
> > *>(this));
> > - return reinterpret_cast<void*>(Beg() - ComputeRZSize(0));
> > + return reinterpret_cast<void*>(Beg() - RZLog2Size(rz_log));
> > }
> > // We store the alloc/free stack traces in the chunk itself.
> > u32 *AllocStackBeg() {
> > - return (u32*)(Beg() - ComputeRZSize(UsedSize()));
> > + return (u32*)(Beg() - RZLog2Size(rz_log));
> > }
> > uptr AllocStackSize() {
> > - return (ComputeRZSize(UsedSize()) - kChunkHeaderSize) /
> > sizeof(u32);
> > + CHECK_LE(RZLog2Size(rz_log), kChunkHeaderSize);
> > + return (RZLog2Size(rz_log) - kChunkHeaderSize) / sizeof(u32);
> > }
> > u32 *FreeStackBeg() {
> > return (u32*)(Beg() + kChunkHeader2Size);
> > }
> > uptr FreeStackSize() {
> > uptr available = Max(RoundUpTo(UsedSize(), SHADOW_GRANULARITY),
> > - ComputeRZSize(UsedSize()));
> > + (uptr)RZLog2Size(rz_log));
> > return (available - kChunkHeader2Size) / sizeof(u32);
> > }
> > };
> > @@ -246,10 +271,8 @@
> > PoisonShadow(m->Beg(),
> > RoundUpTo(m->UsedSize(), SHADOW_GRANULARITY),
> > kAsanHeapLeftRedzoneMagic);
> > - uptr alloc_beg = m->Beg() - ComputeRZSize(m->UsedSize());
> > - void *p = reinterpret_cast<void *>(alloc_beg);
> > + void *p = reinterpret_cast<void *>(m->AllocBeg());
> > if (m->from_memalign) {
> > - p = allocator.GetBlockBegin(p);
> > uptr *memalign_magic = reinterpret_cast<uptr *>(p);
> > CHECK_EQ(memalign_magic[0], kMemalignMagic);
> > CHECK_EQ(memalign_magic[1], reinterpret_cast<uptr>(m));
> > @@ -302,7 +325,8 @@
> > return 0; // 0 bytes with large alignment requested. Just
> > return 0.
> > }
> > CHECK(IsPowerOfTwo(alignment));
> > - uptr rz_size = ComputeRZSize(size);
> > + uptr rz_log = ComputeRZLog(size);
> > + uptr rz_size = RZLog2Size(rz_log);
> > uptr rounded_size = RoundUpTo(size, rz_size);
> > uptr needed_size = rounded_size + rz_size;
> > if (alignment > rz_size)
> > @@ -336,6 +360,7 @@
> > AsanChunk *m = reinterpret_cast<AsanChunk *>(chunk_beg);
> > m->chunk_state = CHUNK_ALLOCATED;
> > m->alloc_type = alloc_type;
> > + m->rz_log = rz_log;
> > u32 alloc_tid = t ? t->tid() : 0;
> > m->alloc_tid = alloc_tid;
> > CHECK_EQ(alloc_tid, m->alloc_tid); // Does alloc_tid fit into the
> > bitfield?
> > @@ -354,7 +379,9 @@
> > } else {
> > CHECK(!allocator.FromPrimary(allocated));
> > m->user_requested_size = SizeClassMap::kMaxSize;
> > - *reinterpret_cast<uptr *>(allocator.GetMetaData(allocated)) =
> > size;
> > + uptr *meta = reinterpret_cast<uptr
> > *>(allocator.GetMetaData(allocated));
> > + meta[0] = size;
> > + meta[1] = chunk_beg;
> > }
> > 
> > if (flags()->use_stack_depot) {
> > @@ -465,17 +492,34 @@
> > }
> > 
> > static AsanChunk *GetAsanChunkByAddr(uptr p) {
> > - uptr alloc_beg = reinterpret_cast<uptr>(
> > - allocator.GetBlockBegin(reinterpret_cast<void *>(p)));
> > + void *ptr = reinterpret_cast<void *>(p);
> > + uptr alloc_beg =
> > reinterpret_cast<uptr>(allocator.GetBlockBegin(ptr));
> > if (!alloc_beg) return 0;
> > uptr *memalign_magic = reinterpret_cast<uptr *>(alloc_beg);
> > if (memalign_magic[0] == kMemalignMagic) {
> > - AsanChunk *m = reinterpret_cast<AsanChunk
> > *>(memalign_magic[1]);
> > - CHECK(m->from_memalign);
> > - return m;
> > + AsanChunk *m = reinterpret_cast<AsanChunk *>(memalign_magic[1]);
> > + CHECK(m->from_memalign);
> > + return m;
> > + }
> > + if (!allocator.FromPrimary(ptr)) {
> > + uptr *meta = reinterpret_cast<uptr *>(
> > + allocator.GetMetaData(reinterpret_cast<void *>(alloc_beg)));
> > + AsanChunk *m = reinterpret_cast<AsanChunk *>(meta[1]);
> > + return m;
> > + }
> > + uptr actual_size = allocator.GetActuallyAllocatedSize(ptr);
> > + CHECK_LE(actual_size, SizeClassMap::kMaxSize);
> > + // We know the actually allocted size, but we don't know the
> > redzone size.
> > + // Just try all possible redzone sizes.
> > + for (u32 rz_log = 0; rz_log < 8; rz_log++) {
> > + u32 rz_size = RZLog2Size(rz_log);
> > + uptr max_possible_size = actual_size - rz_size;
> > + if (ComputeRZLog(max_possible_size) != rz_log)
> > + continue;
> > + return reinterpret_cast<AsanChunk *>(
> > + alloc_beg + rz_size - kChunkHeaderSize);
> > }
> > - uptr chunk_beg = alloc_beg + ComputeRZSize(0) - kChunkHeaderSize;
> > - return reinterpret_cast<AsanChunk *>(chunk_beg);
> > + return 0;
> > }
> > 
> > static uptr AllocationSize(uptr p) {
> > @@ -489,14 +533,19 @@
> > // We have an address between two chunks, and we want to report
> > just
> > one.
> > AsanChunk *ChooseChunk(uptr addr,
> > AsanChunk *left_chunk, AsanChunk
> > *right_chunk) {
> > - // Prefer an allocated chunk or a chunk from quarantine.
> > - if (left_chunk->chunk_state == CHUNK_AVAILABLE &&
> > - right_chunk->chunk_state != CHUNK_AVAILABLE)
> > - return right_chunk;
> > - if (right_chunk->chunk_state == CHUNK_AVAILABLE &&
> > - left_chunk->chunk_state != CHUNK_AVAILABLE)
> > - return left_chunk;
> > - // Choose based on offset.
> > + // Prefer an allocated chunk over freed chunk and freed chunk
> > + // over available chunk.
> > + if (left_chunk->chunk_state != right_chunk->chunk_state) {
> > + if (left_chunk->chunk_state == CHUNK_ALLOCATED)
> > + return left_chunk;
> > + if (right_chunk->chunk_state == CHUNK_ALLOCATED)
> > + return right_chunk;
> > + if (left_chunk->chunk_state == CHUNK_QUARANTINE)
> > + return left_chunk;
> > + if (right_chunk->chunk_state == CHUNK_QUARANTINE)
> > + return right_chunk;
> > + }
> > + // Same chunk_state: choose based on offset.
> > uptr l_offset = 0, r_offset = 0;
> > CHECK(AsanChunkView(left_chunk).AddrIsAtRight(addr, 1,
> > &l_offset));
> > CHECK(AsanChunkView(right_chunk).AddrIsAtLeft(addr, 1,
> > &r_offset));
> > 
> > Modified: compiler-rt/trunk/lib/asan/asan_rtl.cc
> > URL:
> > http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_rtl.cc?rev=171107&r1=171106&r2=171107&view=diff
> > ==============================================================================
> > --- compiler-rt/trunk/lib/asan/asan_rtl.cc (original)
> > +++ compiler-rt/trunk/lib/asan/asan_rtl.cc Wed Dec 26 04:41:24 2012
> > @@ -117,7 +117,7 @@
> > f->quarantine_size = (ASAN_LOW_MEMORY) ? 1UL << 26 : 1UL << 28;
> > f->symbolize = false;
> > f->verbosity = 0;
> > - f->redzone = (ASAN_LOW_MEMORY) ? 64 : 128;
> > + f->redzone = ASAN_ALLOCATOR_VERSION == 2 ? 16 : (ASAN_LOW_MEMORY)
> > ? 64 : 128;
> > f->debug = false;
> > f->report_globals = 1;
> > f->check_initialization_order = true;
> > 
> > Modified: compiler-rt/trunk/lib/asan/tests/asan_test.cc
> > URL:
> > http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/tests/asan_test.cc?rev=171107&r1=171106&r2=171107&view=diff
> > ==============================================================================
> > --- compiler-rt/trunk/lib/asan/tests/asan_test.cc (original)
> > +++ compiler-rt/trunk/lib/asan/tests/asan_test.cc Wed Dec 26
> > 04:41:24
> > 2012
> > @@ -479,7 +479,6 @@
> > 
> > #ifndef __APPLE__
> > void MemalignRun(size_t align, size_t size, int idx) {
> > - fprintf(stderr, "align %ld\n", align);
> > char *p = (char *)memalign(align, size);
> > Ident(p)[idx] = 0;
> > free(p);
> > @@ -899,8 +898,11 @@
> > LeftOOBWriteMessage(1));
> > EXPECT_DEATH(memset((char*)array - 5, 0, 6),
> > LeftOOBWriteMessage(5));
> > - EXPECT_DEATH(memset(array - 5, element, size + 5 * sizeof(T)),
> > - LeftOOBWriteMessage(5 * sizeof(T)));
> > + if (length >= 100) {
> > + // Large OOB, we find it only if the redzone is large enough.
> > + EXPECT_DEATH(memset(array - 5, element, size + 5 * sizeof(T)),
> > + LeftOOBWriteMessage(5 * sizeof(T)));
> > + }
> > // whole interval is to the left
> > EXPECT_DEATH(memset(array - 2, 0, sizeof(T)),
> > LeftOOBWriteMessage(2 * sizeof(T)));
> > 
> > 
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > 
> 
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
> 
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory