Turn down SelSan implementation.

PiperOrigin-RevId: 817685013
Change-Id: I42561354407f69846a19dfb5b08eba8fbcb86ab5

Author: ckennelly

tcmalloc/BUILD

@@ -76,7 +76,6 @@ tcmalloc_deps = [
     "@com_google_absl//absl/base:dynamic_annotations",
     "@com_google_absl//absl/debugging:stacktrace",
     "@com_google_absl//absl/debugging:symbolize",
-    "//tcmalloc/selsan",
     "@com_google_absl//absl/memory",
     "@com_google_absl//absl/status",
     "@com_google_absl//absl/status:statusor",
@@ -330,7 +329,6 @@ create_tcmalloc_libraries(
         "//tcmalloc/internal:system_allocator",
         "//tcmalloc/internal:timeseries_tracker",
         "//tcmalloc/internal:util",
-        "//tcmalloc/selsan",
         "@com_google_absl//absl/algorithm:container",
         "@com_google_absl//absl/base",
         "@com_google_absl//absl/base:core_headers",

tcmalloc/central_freelist.cc

@@ -32,7 +32,6 @@
 #include "tcmalloc/page_allocator_interface.h"
 #include "tcmalloc/pagemap.h"
 #include "tcmalloc/pages.h"
-#include "tcmalloc/selsan/selsan.h"
 #include "tcmalloc/span.h"
 #include "tcmalloc/static_vars.h"
 
@@ -45,9 +44,6 @@ static MemoryTag MemoryTagFromSizeClass(size_t size_class) {
   if (IsExpandedSizeClass(size_class)) {
     return MemoryTag::kCold;
   }
-  if (selsan::IsEnabled()) {
-    return MemoryTag::kSelSan;
-  }
   if (!tc_globals.numa_topology().numa_aware()) {
     return MemoryTag::kNormal;
   }

tcmalloc/central_freelist.h

@@ -37,7 +37,6 @@
 #include "tcmalloc/internal/logging.h"
 #include "tcmalloc/internal/optimization.h"
 #include "tcmalloc/pages.h"
-#include "tcmalloc/selsan/selsan.h"
 #include "tcmalloc/span.h"
 #include "tcmalloc/span_stats.h"
 
@@ -322,9 +321,6 @@ inline void CentralFreeList<Forwarder>::Init(
   if (object_size_ == 0) {
     return;
   }
-  if (selsan::IsEnabled()) {
-    object_size_ = selsan::RoundUpObjectSize(object_size_);
-  }
   pages_per_span_ = forwarder_.class_to_pages(size_class);
   objects_per_span_ =
       pages_per_span_.in_bytes() / (object_size_ ? object_size_ : 1);
@@ -462,12 +458,6 @@ inline void CentralFreeList<Forwarder>::InsertRange(absl::Span<void*> batch) {
   TC_CHECK(!batch.empty());
   TC_CHECK_LE(batch.size(), kMaxObjectsToMove);
 
-  if (selsan::IsEnabled()) {
-    for (auto& ptr : batch) {
-      ptr = selsan::ResetTag(ptr, object_size_);
-    }
-  }
-
   Span* spans[kMaxObjectsToMove];
   // First, map objects to spans and prefetch spans outside of our mutex
   // (to reduce critical section size and cache misses).
@@ -522,26 +512,7 @@ void CentralFreeList<Forwarder>::DeallocateSpans(absl::Span<Span*> spans) {
       completed_spans_[LifetimeBucketNum(lifetime)].LossyAdd(1);
     }
   }
-  if (ABSL_PREDICT_TRUE(!selsan::IsEnabled())) {
-    return forwarder_.DeallocateSpans(objects_per_span_, spans);
-  }
-  Span* selsan_spans[kMaxObjectsToMove];
-  size_t selsan_count = 0;
-  size_t normal_count = 0;
-  for (Span* span : spans) {
-    if (IsSelSanMemory(span->start_address())) {
-      selsan_spans[selsan_count++] = span;
-    } else {
-      spans[normal_count++] = span;
-    }
-  }
-
-  if (normal_count) {
-    forwarder_.DeallocateSpans(objects_per_span_, {spans.data(), normal_count});
-  }
-  if (selsan_count) {
-    forwarder_.DeallocateSpans(objects_per_span_, {selsan_spans, selsan_count});
-  }
+  return forwarder_.DeallocateSpans(objects_per_span_, spans);
 }
 
 template <class Forwarder>

tcmalloc/global_stats.cc

@@ -46,7 +46,6 @@
 #include "tcmalloc/pagemap.h"
 #include "tcmalloc/pages.h"
 #include "tcmalloc/parameters.h"
-#include "tcmalloc/selsan/selsan.h"
 #include "tcmalloc/span.h"
 #include "tcmalloc/span_stats.h"
 #include "tcmalloc/stack_trace_table.h"
@@ -500,11 +499,7 @@ void DumpStats(Printer& out, int level) {
     }
     tc_globals.page_allocator().Print(out, MemoryTag::kSampled, pageflags);
     tc_globals.page_allocator().Print(out, MemoryTag::kCold, pageflags);
-    if (selsan::IsEnabled()) {
-      tc_globals.page_allocator().Print(out, MemoryTag::kSelSan, pageflags);
-    }
     tc_globals.guardedpage_allocator().Print(out);
-    selsan::PrintTextStats(out);
 
     out.printf("------------------------------------------------\n");
     out.printf("Configured limits and related statistics\n");
@@ -729,10 +724,6 @@ void DumpStatsInPbtxt(Printer& out, int level) {
   tc_globals.page_allocator().PrintInPbtxt(region, MemoryTag::kSampled,
                                            pageflags);
   tc_globals.page_allocator().PrintInPbtxt(region, MemoryTag::kCold, pageflags);
-  if (selsan::IsEnabled()) {
-    tc_globals.page_allocator().PrintInPbtxt(region, MemoryTag::kSelSan,
-                                             pageflags);
-  }
   // We do not collect tracking information in pbtxt.
 
   size_t soft_limit_bytes =
@@ -772,7 +763,6 @@ void DumpStatsInPbtxt(Printer& out, int level) {
     auto gwp_asan = region.CreateSubRegion("gwp_asan");
     tc_globals.guardedpage_allocator().PrintInPbtxt(gwp_asan);
   }
-  selsan::PrintPbtxtStats(region);
 
   region.PrintI64("memory_release_failures",
                   tc_globals.system_allocator().release_errors());

tcmalloc/internal/config.h

@@ -133,13 +133,6 @@ inline constexpr int kAddressBits = 48;
 inline constexpr int kAddressBits = 8 * sizeof(void*);
 #endif
 
-#ifdef TCMALLOC_INTERNAL_SELSAN
-// TODO(b/404529382): add tcmalloc test suite and remove maybe_unused annotation
-[[maybe_unused]] inline constexpr bool kSelSanPresent = true;
-#else
-inline constexpr bool kSelSanPresent = false;
-#endif
-
 #if defined(ABSL_HAVE_ADDRESS_SANITIZER) || \
     defined(ABSL_HAVE_MEMORY_SANITIZER) || defined(ABSL_HAVE_THREAD_SANITIZER)
 inline constexpr bool kSanitizerPresent = true;
@@ -148,9 +141,8 @@ inline constexpr bool kSanitizerPresent = false;
 #endif
 
 // Sanitizers constrain the memory layout which causes problems with the
-// enlarged tags required to represent NUMA partitions and for SelSan.
+// enlarged tags required to represent NUMA partitions.
 #if defined(ABSL_HAVE_MEMORY_SANITIZER) || defined(ABSL_HAVE_THREAD_SANITIZER)
-static_assert(!kSelSanPresent, "MSan/TSan are incompatible with SelSan.");
 inline constexpr bool kSanitizerAddressSpace = true;
 #else
 inline constexpr bool kSanitizerAddressSpace = false;

tcmalloc/internal/memory_tag.cc

@@ -29,8 +29,6 @@ absl::string_view MemoryTagToLabel(MemoryTag tag) {
       return "NORMAL_P1";
     case MemoryTag::kSampled:
       return "SAMPLED";
-    case MemoryTag::kSelSan:
-      return "SELSAN";
     case MemoryTag::kCold:
       return "COLD";
     case MemoryTag::kMetadata:

tcmalloc/internal/memory_tag.h

@@ -38,10 +38,6 @@ enum class MemoryTag : uint8_t {
   kCold = 0x2,
   // Metadata
   kMetadata = 0x3,
-  // SelSan sampled spans, kept separately because we need to quickly
-  // distinguish them from the rest during delete and they also consume
-  // shadow memory. 0xfe is an arbitrary value that shouldn't be used.
-  kSelSan = kSelSanPresent ? 0x1 : 0xfe,
 };
 
 inline constexpr uintptr_t kTagShift = std::min(kAddressBits - 4, 42);
@@ -67,20 +63,6 @@ inline bool IsNormalMemory(const void* ptr) {
   return res;
 }
 
-inline bool IsSelSanMemory(const void* ptr) {
-  // This is a faster way to check for SelSan memory provided we already know
-  // it's not a normal memory, and assuming it's not kMetadata (both assumptions
-  // are checked by the assert below). A straightforward comparison with kSelSan
-  // leads to extraction/check of 2 bits (these use 2 8-byte immediates);
-  // this check can be done with a single BT instruction.
-  // kSelSanPresent part allows to optimize away branches in non SelSan build.
-  bool res =
-      kSelSanPresent && (static_cast<uintptr_t>(GetMemoryTag(ptr)) &
-                         static_cast<uintptr_t>(MemoryTag::kSelSan)) != 0;
-  TC_ASSERT_EQ(res, GetMemoryTag(ptr) == MemoryTag::kSelSan);
-  return res;
-}
-
 absl::string_view MemoryTagToLabel(MemoryTag tag);
 
 }  // namespace tcmalloc::tcmalloc_internal

tcmalloc/internal/parameter_accessors.h

@@ -53,8 +53,6 @@ ABSL_ATTRIBUTE_WEAK size_t TCMalloc_Internal_GetStats(char* buffer,
                                                       size_t buffer_length);
 ABSL_ATTRIBUTE_WEAK void TCMalloc_Internal_SetGuardedSamplingInterval(
     int64_t v);
-ABSL_ATTRIBUTE_WEAK int TCMalloc_Internal_GetSelSanPercent();
-ABSL_ATTRIBUTE_WEAK void TCMalloc_Internal_SetSelSanPercent(int v);
 ABSL_ATTRIBUTE_WEAK void TCMalloc_Internal_SetHeapSizeHardLimit(uint64_t v);
 ABSL_ATTRIBUTE_WEAK void TCMalloc_Internal_SetHPAASubrelease(bool v);
 ABSL_ATTRIBUTE_WEAK void TCMalloc_Internal_SetReleasePartialAllocPagesEnabled(

tcmalloc/internal/system_allocator.h

@@ -185,7 +185,6 @@ class SystemAllocator {
   absl::once_flag rnd_flag_;
 
   uintptr_t next_sampled_addr_ ABSL_GUARDED_BY(spinlock_) = 0;
-  uintptr_t next_selsan_addr_ ABSL_GUARDED_BY(spinlock_) = 0;
   std::array<uintptr_t, kNumaPartitions> next_normal_addr_
       ABSL_GUARDED_BY(spinlock_) = {0};
   uintptr_t next_cold_addr_ ABSL_GUARDED_BY(spinlock_) = 0;
@@ -206,7 +205,6 @@ class SystemAllocator {
   std::array<AddressRegion*, kNumaPartitions> normal_region_
       ABSL_GUARDED_BY(spinlock_){{nullptr}};
   AddressRegion* sampled_region_ ABSL_GUARDED_BY(spinlock_){nullptr};
-  AddressRegion* selsan_region_ ABSL_GUARDED_BY(spinlock_){nullptr};
   AddressRegion* cold_region_ ABSL_GUARDED_BY(spinlock_){nullptr};
   AddressRegion* metadata_region_ ABSL_GUARDED_BY(spinlock_){nullptr};
 
@@ -330,7 +328,6 @@ template <typename Topology>
 void SystemAllocator<Topology>::DiscardMappedRegions() {
   std::fill(normal_region_.begin(), normal_region_.end(), nullptr);
   sampled_region_ = nullptr;
-  selsan_region_ = nullptr;
   cold_region_ = nullptr;
   metadata_region_ = nullptr;
 }
@@ -458,8 +455,6 @@ std::pair<void*, size_t> SystemAllocator<Topology>::AllocateFromRegion(
             return &normal_region_[1];
           case MemoryTag::kSampled:
             return &sampled_region_;
-          case MemoryTag::kSelSan:
-            return &selsan_region_;
           case MemoryTag::kCold:
             return &cold_region_;
           case MemoryTag::kMetadata:
@@ -512,8 +507,6 @@ void* SystemAllocator<Topology>::MmapAlignedLocked(size_t size,
         switch (tag) {
           case MemoryTag::kSampled:
             return &next_sampled_addr_;
-          case MemoryTag::kSelSan:
-            return &next_selsan_addr_;
           case MemoryTag::kNormalP0:
             numa_partition = 0;
             return &next_normal_addr_[0];
@@ -736,11 +729,6 @@ AddressRegionFactory::UsageHint SystemAllocator<Topology>::TagToHint(
         return UsageHint::kNormalNumaAwareS1;
       }
       return UsageHint::kNormal;
-    case MemoryTag::kSelSan:
-      if (topology_.numa_aware()) {
-        return UsageHint::kNormalNumaAwareS0;
-      }
-      return UsageHint::kNormal;
     case MemoryTag::kSampled:
       return UsageHint::kInfrequentAllocation;
     case MemoryTag::kCold:

tcmalloc/malloc_extension.cc

@@ -43,8 +43,7 @@
      defined(ABSL_HAVE_THREAD_SANITIZER) ||    \
      defined(ABSL_HAVE_HWADDRESS_SANITIZER) || \
      defined(ABSL_HAVE_DATAFLOW_SANITIZER) ||  \
-     defined(ABSL_HAVE_LEAK_SANITIZER)) &&     \
-    !defined(TCMALLOC_INTERNAL_SELSAN)
+     defined(ABSL_HAVE_LEAK_SANITIZER))
 #define TCMALLOC_UNDER_SANITIZERS 1
 static constexpr size_t kTerabyte = (size_t)(1ULL << 40);