Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 377 insertions, 0 deletions

diff --git a/mozglue/baseprofiler/lul/LulMain.h b/mozglue/baseprofiler/lul/LulMain.h
new file mode 100644
index 0000000000..b0cb7f4f1e
--- /dev/null
+++ b/mozglue/baseprofiler/lul/LulMain.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef LulMain_h
+#define LulMain_h
+
+#include "PlatformMacros.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/MemoryReporting.h"
+
+// LUL: A Lightweight Unwind Library.
+// This file provides the end-user (external) interface for LUL.
+
+// Some comments about naming in the implementation.  These are safe
+// to ignore if you are merely using LUL, but are important if you
+// hack on its internals.
+//
+// Debuginfo readers in general have tended to use the word "address"
+// to mean several different things.  This sometimes makes them
+// difficult to understand and maintain.  LUL tries hard to avoid
+// using the word "address" and instead uses the following more
+// precise terms:
+//
+// * SVMA ("Stated Virtual Memory Address"): this is an address of a
+//   symbol (etc) as it is stated in the symbol table, or other
+//   metadata, of an object.  Such values are typically small and
+//   start from zero or thereabouts, unless the object has been
+//   prelinked.
+//
+// * AVMA ("Actual Virtual Memory Address"): this is the address of a
+//   symbol (etc) in a running process, that is, once the associated
+//   object has been mapped into a process.  Such values are typically
+//   much larger than SVMAs, since objects can get mapped arbitrarily
+//   far along the address space.
+//
+// * "Bias": the difference between AVMA and SVMA for a given symbol
+//   (specifically, AVMA - SVMA).  The bias is always an integral
+//   number of pages.  Once we know the bias for a given object's
+//   text section (for example), we can compute the AVMAs of all of
+//   its text symbols by adding the bias to their SVMAs.
+//
+// * "Image address": typically, to read debuginfo from an object we
+//   will temporarily mmap in the file so as to read symbol tables
+//   etc.  Addresses in this temporary mapping are called "Image
+//   addresses".  Note that the temporary mapping is entirely
+//   unrelated to the mappings of the file that the dynamic linker
+//   must perform merely in order to get the program to run.  Hence
+//   image addresses are unrelated to either SVMAs or AVMAs.
+
+namespace lul {
+
+// A machine word plus validity tag.
+class TaggedUWord {
+ public:
+  // RUNS IN NO-MALLOC CONTEXT
+  // Construct a valid one.
+  explicit TaggedUWord(uintptr_t w) : mValue(w), mValid(true) {}
+
+  // RUNS IN NO-MALLOC CONTEXT
+  // Construct an invalid one.
+  TaggedUWord() : mValue(0), mValid(false) {}
+
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord operator+(TaggedUWord rhs) const {
+    return (Valid() && rhs.Valid()) ? TaggedUWord(Value() + rhs.Value())
+                                    : TaggedUWord();
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord operator-(TaggedUWord rhs) const {
+    return (Valid() && rhs.Valid()) ? TaggedUWord(Value() - rhs.Value())
+                                    : TaggedUWord();
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord operator&(TaggedUWord rhs) const {
+    return (Valid() && rhs.Valid()) ? TaggedUWord(Value() & rhs.Value())
+                                    : TaggedUWord();
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord operator|(TaggedUWord rhs) const {
+    return (Valid() && rhs.Valid()) ? TaggedUWord(Value() | rhs.Value())
+                                    : TaggedUWord();
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord CmpGEs(TaggedUWord rhs) const {
+    if (Valid() && rhs.Valid()) {
+      intptr_t s1 = (intptr_t)Value();
+      intptr_t s2 = (intptr_t)rhs.Value();
+      return TaggedUWord(s1 >= s2 ? 1 : 0);
+    }
+    return TaggedUWord();
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord operator<<(TaggedUWord rhs) const {
+    if (Valid() && rhs.Valid()) {
+      uintptr_t shift = rhs.Value();
+      if (shift < 8 * sizeof(uintptr_t)) return TaggedUWord(Value() << shift);
+    }
+    return TaggedUWord();
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  // Is equal?  Note: non-validity on either side gives non-equality.
+  bool operator==(TaggedUWord other) const {
+    return (mValid && other.Valid()) ? (mValue == other.Value()) : false;
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  // Is it word-aligned?
+  bool IsAligned() const {
+    return mValid && (mValue & (sizeof(uintptr_t) - 1)) == 0;
+  }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  uintptr_t Value() const { return mValue; }
+
+  // RUNS IN NO-MALLOC CONTEXT
+  bool Valid() const { return mValid; }
+
+ private:
+  uintptr_t mValue;
+  bool mValid;
+};
+
+// The registers, with validity tags, that will be unwound.
+
+struct UnwindRegs {
+#if defined(GP_ARCH_arm)
+  TaggedUWord r7;
+  TaggedUWord r11;
+  TaggedUWord r12;
+  TaggedUWord r13;
+  TaggedUWord r14;
+  TaggedUWord r15;
+#elif defined(GP_ARCH_arm64)
+  TaggedUWord x29;
+  TaggedUWord x30;
+  TaggedUWord sp;
+  TaggedUWord pc;
+#elif defined(GP_ARCH_amd64) || defined(GP_ARCH_x86)
+  TaggedUWord xbp;
+  TaggedUWord xsp;
+  TaggedUWord xip;
+#elif defined(GP_ARCH_mips64)
+  TaggedUWord sp;
+  TaggedUWord fp;
+  TaggedUWord pc;
+#else
+#  error "Unknown plat"
+#endif
+};
+
+// The maximum number of bytes in a stack snapshot.  This value can be increased
+// if necessary, but testing showed that 160k is enough to obtain good
+// backtraces on x86_64 Linux.  Most backtraces fit comfortably into 4-8k of
+// stack space, but we do have some very deep stacks occasionally.  Please see
+// the comments in DoNativeBacktrace as to why it's OK to have this value be so
+// large.
+static const size_t N_STACK_BYTES = 160 * 1024;
+
+// The stack chunk image that will be unwound.
+struct StackImage {
+  // [start_avma, +len) specify the address range in the buffer.
+  // Obviously we require 0 <= len <= N_STACK_BYTES.
+  uintptr_t mStartAvma;
+  size_t mLen;
+  uint8_t mContents[N_STACK_BYTES];
+};
+
+// Statistics collection for the unwinder.
+template <typename T>
+class LULStats {
+ public:
+  LULStats() : mContext(0), mCFI(0), mFP(0) {}
+
+  template <typename S>
+  explicit LULStats(const LULStats<S>& aOther)
+      : mContext(aOther.mContext), mCFI(aOther.mCFI), mFP(aOther.mFP) {}
+
+  template <typename S>
+  LULStats<T>& operator=(const LULStats<S>& aOther) {
+    mContext = aOther.mContext;
+    mCFI = aOther.mCFI;
+    mFP = aOther.mFP;
+    return *this;
+  }
+
+  template <typename S>
+  uint32_t operator-(const LULStats<S>& aOther) {
+    return (mContext - aOther.mContext) + (mCFI - aOther.mCFI) +
+           (mFP - aOther.mFP);
+  }
+
+  T mContext;  // Number of context frames
+  T mCFI;      // Number of CFI/EXIDX frames
+  T mFP;       // Number of frame-pointer recovered frames
+};
+
+// The core unwinder library class.  Just one of these is needed, and
+// it can be shared by multiple unwinder threads.
+//
+// The library operates in one of two modes.
+//
+// * Admin mode.  The library is this state after creation.  In Admin
+//   mode, no unwinding may be performed.  It is however allowable to
+//   perform administrative tasks -- primarily, loading of unwind info
+//   -- in this mode.  In particular, it is safe for the library to
+//   perform dynamic memory allocation in this mode.  Safe in the
+//   sense that there is no risk of deadlock against unwinding threads
+//   that might -- because of where they have been sampled -- hold the
+//   system's malloc lock.
+//
+// * Unwind mode.  In this mode, calls to ::Unwind may be made, but
+//   nothing else.  ::Unwind guarantees not to make any dynamic memory
+//   requests, so as to guarantee that the calling thread won't
+//   deadlock in the case where it already holds the system's malloc lock.
+//
+// The library is created in Admin mode.  After debuginfo is loaded,
+// the caller must switch it into Unwind mode by calling
+// ::EnableUnwinding.  There is no way to switch it back to Admin mode
+// after that.  To safely switch back to Admin mode would require the
+// caller (or other external agent) to guarantee that there are no
+// pending ::Unwind calls.
+
+class PriMap;
+class SegArray;
+class UniqueStringUniverse;
+
+class LUL {
+ public:
+  // Create; supply a logging sink.  Sets the object in Admin mode.
+  explicit LUL(void (*aLog)(const char*));
+
+  // Destroy.  Caller is responsible for ensuring that no other
+  // threads are in Unwind calls.  All resources are freed and all
+  // registered unwinder threads are deregistered.  Can be called
+  // either in Admin or Unwind mode.
+  ~LUL();
+
+  // Notify the library that unwinding is now allowed and so
+  // admin-mode calls are no longer allowed.  The object is initially
+  // created in admin mode.  The only possible transition is
+  // admin->unwinding, therefore.
+  void EnableUnwinding();
+
+  // Notify of a new r-x mapping, and load the associated unwind info.
+  // The filename is strdup'd and used for debug printing.  If
+  // aMappedImage is NULL, this function will mmap/munmap the file
+  // itself, so as to be able to read the unwind info.  If
+  // aMappedImage is non-NULL then it is assumed to point to a
+  // called-supplied and caller-managed mapped image of the file.
+  // May only be called in Admin mode.
+  void NotifyAfterMap(uintptr_t aRXavma, size_t aSize, const char* aFileName,
+                      const void* aMappedImage);
+
+  // In rare cases we know an executable area exists but don't know
+  // what the associated file is.  This call notifies LUL of such
+  // areas.  This is important for correct functioning of stack
+  // scanning and of the x86-{linux,android} special-case
+  // __kernel_syscall function handling.
+  // This must be called only after the code area in
+  // question really has been mapped.
+  // May only be called in Admin mode.
+  void NotifyExecutableArea(uintptr_t aRXavma, size_t aSize);
+
+  // Notify that a mapped area has been unmapped; discard any
+  // associated unwind info.  Acquires mRWlock for writing.  Note that
+  // to avoid segfaulting the stack-scan unwinder, which inspects code
+  // areas, this must be called before the code area in question is
+  // really unmapped.  Note that, unlike NotifyAfterMap(), this
+  // function takes the start and end addresses of the range to be
+  // unmapped, rather than a start and a length parameter.  This is so
+  // as to make it possible to notify an unmap for the entire address
+  // space using a single call.
+  // May only be called in Admin mode.
+  void NotifyBeforeUnmap(uintptr_t aAvmaMin, uintptr_t aAvmaMax);
+
+  // Apply NotifyBeforeUnmap to the entire address space.  This causes
+  // LUL to discard all unwind and executable-area information for the
+  // entire address space.
+  // May only be called in Admin mode.
+  void NotifyBeforeUnmapAll() { NotifyBeforeUnmap(0, UINTPTR_MAX); }
+
+  // Returns the number of mappings currently registered.
+  // May only be called in Admin mode.
+  size_t CountMappings();
+
+  // Unwind |aStackImg| starting with the context in |aStartRegs|.
+  // Write the number of frames recovered in *aFramesUsed.  Put
+  // the PC values in aFramePCs[0 .. *aFramesUsed-1] and
+  // the SP values in aFrameSPs[0 .. *aFramesUsed-1].
+  // |aFramesAvail| is the size of the two output arrays and hence the
+  // largest possible value of *aFramesUsed.  PC values are always
+  // valid, and the unwind will stop when the PC becomes invalid, but
+  // the SP values might be invalid, in which case the value zero will
+  // be written in the relevant frameSPs[] slot.
+  //
+  // This function assumes that the SP values increase as it unwinds
+  // away from the innermost frame -- that is, that the stack grows
+  // down.  It monitors SP values as it unwinds to check they
+  // decrease, so as to avoid looping on corrupted stacks.
+  //
+  // May only be called in Unwind mode.  Multiple threads may unwind
+  // at once.  LUL user is responsible for ensuring that no thread makes
+  // any Admin calls whilst in Unwind mode.
+  // MOZ_CRASHes if the calling thread is not registered for unwinding.
+  //
+  // The calling thread must previously have been registered via a call to
+  // RegisterSampledThread.
+  void Unwind(/*OUT*/ uintptr_t* aFramePCs,
+              /*OUT*/ uintptr_t* aFrameSPs,
+              /*OUT*/ size_t* aFramesUsed,
+              /*OUT*/ size_t* aFramePointerFramesAcquired, size_t aFramesAvail,
+              UnwindRegs* aStartRegs, StackImage* aStackImg);
+
+  // The logging sink.  Call to send debug strings to the caller-
+  // specified destination.  Can only be called by the Admin thread.
+  void (*mLog)(const char*);
+
+  // Statistics relating to unwinding.  These have to be atomic since
+  // unwinding can occur on different threads simultaneously.
+  LULStats<mozilla::Atomic<uint32_t>> mStats;
+
+  // Possibly show the statistics.  This may not be called from any
+  // registered sampling thread, since it involves I/O.
+  void MaybeShowStats();
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf) const;
+
+ private:
+  // The statistics counters at the point where they were last printed.
+  LULStats<uint32_t> mStatsPrevious;
+
+  // Are we in admin mode?  Initially |true| but changes to |false|
+  // once unwinding begins.
+  bool mAdminMode;
+
+  // The thread ID associated with admin mode.  This is the only thread
+  // that is allowed do perform non-Unwind calls on this object.  Conversely,
+  // no registered Unwinding thread may be the admin thread.  This is so
+  // as to clearly partition the one thread that may do dynamic memory
+  // allocation from the threads that are being sampled, since the latter
+  // absolutely may not do dynamic memory allocation.
+  int mAdminThreadId;
+
+  // The top level mapping from code address ranges to postprocessed
+  // unwind info.  Basically a sorted array of (addr, len, info)
+  // records.  This field is updated by NotifyAfterMap and NotifyBeforeUnmap.
+  PriMap* mPriMap;
+
+  // An auxiliary structure that records which address ranges are
+  // mapped r-x, for the benefit of the stack scanner.
+  SegArray* mSegArray;
+
+  // A UniqueStringUniverse that holds all the strdup'd strings created
+  // whilst reading unwind information.  This is included so as to make
+  // it possible to free them in ~LUL.
+  UniqueStringUniverse* mUSU;
+};
+
+// Run unit tests on an initialised, loaded-up LUL instance, and print
+// summary results on |aLUL|'s logging sink.  Also return the number
+// of tests run in *aNTests and the number that passed in
+// *aNTestsPassed.
+void RunLulUnitTests(/*OUT*/ int* aNTests, /*OUT*/ int* aNTestsPassed,
+                     LUL* aLUL);
+
+}  // namespace lul
+
+#endif  // LulMain_h