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Merge pull request #4639 from randombit/jack/cleanup-build-h

Remove most toggles from build.h

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/src/lib/utils/mem_pool/mem_pool.cpp

/*
* (C) 2018,2019 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/mem_pool.h>

#include <botan/mem_ops.h>
#include <algorithm>

#if defined(BOTAN_HAS_VALGRIND) || defined(BOTAN_ENABLE_DEBUG_ASSERTS)
   /**
    * @brief Prohibits access to unused memory pages in Botan's memory pool
    *
    * If BOTAN_MEM_POOL_USE_MMU_PROTECTIONS is defined, the Memory_Pool
    * class used for mlock'ed memory will use OS calls to set page
    * permissions so as to prohibit access to pages on the free list, then
    * enable read/write access when the page is set to be used. This will
    * turn (some) use after free bugs into a crash.
    *
    * The additional syscalls have a substantial performance impact, which
    * is why this option is not enabled by default. It is used when built for
    * running in valgrind or debug assertions are enabled.
    */
   #define BOTAN_MEM_POOL_USE_MMU_PROTECTIONS
#endif

#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS) && defined(BOTAN_HAS_OS_UTILS)
   #include <botan/internal/os_utils.h>
#endif

namespace Botan {

/*
* Memory pool theory of operation
*
* This allocator is not useful for general purpose but works well within the
* context of allocating cryptographic keys. It makes several assumptions which
* don't work for implementing malloc but simplify and speed up the implementation:
*
* - There is some set of pages, which cannot be expanded later. These are pages
*   which were allocated, mlocked and passed to the Memory_Pool constructor.
*
* - The allocator is allowed to return null anytime it feels like not servicing
*   a request, in which case the request will be sent to calloc instead. In
*   particular, requests which are too small or too large are rejected.
*
* - Most allocations are powers of 2, the remainder are usually a multiple of 8
*
* - Free requests include the size of the allocation, so there is no need to
*   track this within the pool.
*
* - Alignment is important to the caller. For this allocator, any allocation of
*   size N is aligned evenly at N bytes.
*
* Initially each page is in the free page list. Each page is used for just one
* size of allocation, with requests bucketed into a small number of common
* sizes. If the allocation would be too big or too small it is rejected by the pool.
*
* The free list is maintained by a bitmap, one per page/Bucket. Since each
* Bucket only maintains objects of a single size, each bit set or clear
* indicates the status of one object.
*
* An allocation walks the list of buckets and asks each in turn if there is
* space. If a Bucket does not have any space, it sets a boolean flag m_is_full
* so that it does not need to rescan when asked again. The flag is cleared on
* first free from that bucket. If no bucket has space, but there are some free
* pages left, a free page is claimed as a new Bucket for that size. In this case
* it is pushed to the front of the list so it is first in line to service new
* requests.
*
* A deallocation also walks the list of buckets for the size and asks each
* Bucket in turn if it recognizes the pointer. When a Bucket becomes empty as a
* result of a deallocation, it is recycled back into the free pool. When this
* happens, the Buckets page goes to the end of the free list. All pages on the
* free list are marked in the MMU as noaccess, so anything touching them will
* immediately crash. They are only marked R/W once placed into a new bucket.
* Making the free list FIFO maximizes the time between the last free of a bucket
* and that page being writable again, maximizing chances of crashing after a
* use-after-free.
*
* Future work
* -------------
*
* The allocator is protected by a global lock. It would be good to break this
* up, since almost all of the work can actually be done in parallel especially
* when allocating objects of different sizes (which can't possibly share a
* bucket).
*
* It may be worthwhile to optimize deallocation by storing the Buckets in order
* (by pointer value) which would allow binary search to find the owning bucket.
*
* A useful addition would be to randomize the allocations. Memory_Pool would be
* changed to receive also a RandomNumberGenerator& object (presumably the system
* RNG, or maybe a ChaCha_RNG seeded with system RNG). Then the bucket to use and
* the offset within the bucket would be chosen randomly, instead of using first fit.
*
* Right now we don't make any provision for threading, so if two threads both
* allocate 32 byte values one after the other, the two allocations will likely
* share a cache line. Ensuring that distinct threads will (tend to) use distinct
* buckets would reduce this.
*
* Supporting a realloc-style API may be useful.
*/

namespace {

size_t choose_bucket(size_t n) {
   const size_t MINIMUM_ALLOCATION = 16;
   const size_t MAXIMUM_ALLOCATION = 256;

   if(n < MINIMUM_ALLOCATION || n > MAXIMUM_ALLOCATION) {
      return 0;
   }

   // Need to tune these

   const size_t buckets[] = {
      16,
      24,
      32,
      48,
      64,
      80,
      96,
      112,
      128,
      160,
      192,
      256,
      0,
   };

   for(size_t i = 0; buckets[i]; ++i) {
      if(n <= buckets[i]) {
         return buckets[i];
      }
   }

   return 0;
}

inline bool ptr_in_pool(const void* pool_ptr, size_t poolsize, const void* buf_ptr, size_t bufsize) {
   const uintptr_t pool = reinterpret_cast<uintptr_t>(pool_ptr);
   const uintptr_t buf = reinterpret_cast<uintptr_t>(buf_ptr);
   return (buf >= pool) && (buf + bufsize <= pool + poolsize);
}

// return index of first set bit
template <typename T>
size_t find_set_bit(T b) {
   size_t s = 8 * sizeof(T) / 2;
   size_t bit = 0;

   // In this context we don't need to be const-time
   while(s > 0) {
      const T mask = (static_cast<T>(1) << s) - 1;
      if((b & mask) == 0) {
         bit += s;
         b >>= s;
      }
      s /= 2;
   }

   return bit;
}

class BitMap final {
   public:
      explicit BitMap(size_t bits) : m_len(bits) {
         m_bits.resize((bits + BITMASK_BITS - 1) / BITMASK_BITS);
         // MSVC warns if the cast isn't there, clang-tidy warns that the cast is pointless
         m_main_mask = static_cast<bitmask_type>(~0);  // NOLINT(bugprone-misplaced-widening-cast)
         m_last_mask = m_main_mask;

         if(bits % BITMASK_BITS != 0) {
            m_last_mask = (static_cast<bitmask_type>(1) << (bits % BITMASK_BITS)) - 1;
         }
      }

      bool find_free(size_t* bit);

      void free(size_t bit) {
         BOTAN_ASSERT_NOMSG(bit <= m_len);
         const size_t w = bit / BITMASK_BITS;
         BOTAN_ASSERT_NOMSG(w < m_bits.size());
         const bitmask_type mask = static_cast<bitmask_type>(1) << (bit % BITMASK_BITS);
         m_bits[w] = m_bits[w] & (~mask);
      }

      bool empty() const {
         for(auto bitset : m_bits) {
            if(bitset != 0) {
               return false;
            }
         }

         return true;
      }

   private:
#if defined(BOTAN_ENABLE_DEBUG_ASSERTS)
      using bitmask_type = uint8_t;
#else
      using bitmask_type = word;
#endif

      static const size_t BITMASK_BITS = sizeof(bitmask_type) * 8;

      size_t m_len;
      bitmask_type m_main_mask;
      bitmask_type m_last_mask;
      std::vector<bitmask_type> m_bits;
};

bool BitMap::find_free(size_t* bit) {
   for(size_t i = 0; i != m_bits.size(); ++i) {
      const bitmask_type mask = (i == m_bits.size() - 1) ? m_last_mask : m_main_mask;
      if((m_bits[i] & mask) != mask) {
         const size_t free_bit = find_set_bit(~m_bits[i]);
         const bitmask_type bmask = static_cast<bitmask_type>(1) << (free_bit % BITMASK_BITS);
         BOTAN_ASSERT_NOMSG((m_bits[i] & bmask) == 0);
         m_bits[i] |= bmask;
         *bit = BITMASK_BITS * i + free_bit;
         return true;
      }
   }

   return false;
}

}  // namespace

class Bucket final {
   public:
      Bucket(uint8_t* mem, size_t mem_size, size_t item_size) :
            m_item_size(item_size),
            m_page_size(mem_size),
            m_range(mem),
            m_bitmap(mem_size / item_size),
            m_is_full(false) {}

      uint8_t* alloc() {
         if(m_is_full) {
            // I know I am full
            return nullptr;
         }

         size_t offset;
         if(!m_bitmap.find_free(&offset)) {
            // I just found out I am full
            m_is_full = true;
            return nullptr;
         }

         BOTAN_ASSERT(offset * m_item_size < m_page_size, "Offset is in range");
         return m_range + m_item_size * offset;
      }

      bool free(void* p) {
         if(!in_this_bucket(p)) {
            return false;
         }

         /*
         Zero also any trailing bytes, which should not have been written to,
         but maybe the user was bad and wrote past the end.
         */
         std::memset(p, 0, m_item_size);

         const size_t offset = (reinterpret_cast<uintptr_t>(p) - reinterpret_cast<uintptr_t>(m_range)) / m_item_size;

         m_bitmap.free(offset);
         m_is_full = false;

         return true;
      }

      bool in_this_bucket(void* p) const { return ptr_in_pool(m_range, m_page_size, p, m_item_size); }

      bool empty() const { return m_bitmap.empty(); }

      uint8_t* ptr() const { return m_range; }

   private:
      size_t m_item_size;
      size_t m_page_size;
      uint8_t* m_range;
      BitMap m_bitmap;
      bool m_is_full;
};

Memory_Pool::Memory_Pool(const std::vector<void*>& pages, size_t page_size) : m_page_size(page_size) {
   m_min_page_ptr = ~static_cast<uintptr_t>(0);
   m_max_page_ptr = 0;

   for(auto page : pages) {
      const uintptr_t p = reinterpret_cast<uintptr_t>(page);

      m_min_page_ptr = std::min(p, m_min_page_ptr);
      m_max_page_ptr = std::max(p, m_max_page_ptr);

      clear_bytes(page, m_page_size);
#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
      OS::page_prohibit_access(page);
#endif
      m_free_pages.push_back(static_cast<uint8_t*>(page));
   }

   /*
   Right now this points to the start of the last page, adjust it to instead
   point to the first byte of the following page
   */
   m_max_page_ptr += page_size;
}

Memory_Pool::~Memory_Pool()  // NOLINT(*-use-equals-default)
{
#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
   for(size_t i = 0; i != m_free_pages.size(); ++i) {
      OS::page_allow_access(m_free_pages[i]);
   }
#endif
}

void* Memory_Pool::allocate(size_t n) {
   if(n > m_page_size) {
      return nullptr;
   }

   const size_t n_bucket = choose_bucket(n);

   if(n_bucket > 0) {
      lock_guard_type<mutex_type> lock(m_mutex);

      std::deque<Bucket>& buckets = m_buckets_for[n_bucket];

      /*
      It would be optimal to pick the bucket with the most usage,
      since a bucket with say 1 item allocated out of it has a high
      chance of becoming later freed and then the whole page can be
      recycled.
      */
      for(auto& bucket : buckets) {
         if(uint8_t* p = bucket.alloc()) {
            return p;
         }

         // If the bucket is full, maybe move it to the end of the list?
         // Otoh bucket search should be very fast
      }

      if(!m_free_pages.empty()) {
         uint8_t* ptr = m_free_pages[0];
         m_free_pages.pop_front();
#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
         OS::page_allow_access(ptr);
#endif
         buckets.push_front(Bucket(ptr, m_page_size, n_bucket));
         void* p = buckets[0].alloc();
         BOTAN_ASSERT_NOMSG(p != nullptr);
         return p;
      }
   }

   // out of room
   return nullptr;
}

bool Memory_Pool::deallocate(void* p, size_t len) noexcept {
   // Do a fast range check first, before taking the lock
   const uintptr_t p_val = reinterpret_cast<uintptr_t>(p);
   if(p_val < m_min_page_ptr || p_val > m_max_page_ptr) {
      return false;
   }

   const size_t n_bucket = choose_bucket(len);

   if(n_bucket != 0) {
      try {
         lock_guard_type<mutex_type> lock(m_mutex);

         std::deque<Bucket>& buckets = m_buckets_for[n_bucket];

         for(size_t i = 0; i != buckets.size(); ++i) {
            Bucket& bucket = buckets[i];
            if(bucket.free(p)) {
               if(bucket.empty()) {
#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
                  OS::page_prohibit_access(bucket.ptr());
#endif
                  m_free_pages.push_back(bucket.ptr());

                  if(i != buckets.size() - 1) {
                     std::swap(buckets.back(), buckets[i]);
                  }
                  buckets.pop_back();
               }
               return true;
            }
         }
      } catch(...) {
         /*
         * The only exception throws that can occur in the above code are from
         * either the STL or BOTAN_ASSERT failures. In either case, such an
         * error indicates a logic error or data corruption in the memory
         * allocator such that it is no longer safe to continue executing.
         *
         * Since this function is noexcept, simply letting the exception escape
         * is sufficient for terminate to be called. However in this scenario
         * it is implementation defined if any stack unwinding is performed.
         * Since stack unwinding could cause further memory deallocations this
         * could result in further corruption in this allocator state. To prevent
         * this, call terminate directly.
         */
         std::terminate();
      }
   }

   return false;
}

}  // namespace Botan

1	/*
2	* (C) 2018,2019 Jack Lloyd
3	*
4	* Botan is released under the Simplified BSD License (see license.txt)
5	*/
6
7	#include <botan/internal/mem_pool.h>
8
9	#include <botan/mem_ops.h>
10	#include <algorithm>
11
12	#if defined(BOTAN_HAS_VALGRIND) \|\| defined(BOTAN_ENABLE_DEBUG_ASSERTS)
13	/**
14	* @brief Prohibits access to unused memory pages in Botan's memory pool
15	*
16	* If BOTAN_MEM_POOL_USE_MMU_PROTECTIONS is defined, the Memory_Pool
17	* class used for mlock'ed memory will use OS calls to set page
18	* permissions so as to prohibit access to pages on the free list, then
19	* enable read/write access when the page is set to be used. This will
20	* turn (some) use after free bugs into a crash.
21	*
22	* The additional syscalls have a substantial performance impact, which
23	* is why this option is not enabled by default. It is used when built for
24	* running in valgrind or debug assertions are enabled.
25	*/
26	#define BOTAN_MEM_POOL_USE_MMU_PROTECTIONS
27	#endif
28
29	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS) && defined(BOTAN_HAS_OS_UTILS)
30	#include <botan/internal/os_utils.h>
31	#endif
32
33	namespace Botan {
34
35	/*
36	* Memory pool theory of operation
37	*
38	* This allocator is not useful for general purpose but works well within the
39	* context of allocating cryptographic keys. It makes several assumptions which
40	* don't work for implementing malloc but simplify and speed up the implementation:
41	*
42	* - There is some set of pages, which cannot be expanded later. These are pages
43	* which were allocated, mlocked and passed to the Memory_Pool constructor.
44	*
45	* - The allocator is allowed to return null anytime it feels like not servicing
46	* a request, in which case the request will be sent to calloc instead. In
47	* particular, requests which are too small or too large are rejected.
48	*
49	* - Most allocations are powers of 2, the remainder are usually a multiple of 8
50	*
51	* - Free requests include the size of the allocation, so there is no need to
52	* track this within the pool.
53	*
54	* - Alignment is important to the caller. For this allocator, any allocation of
55	* size N is aligned evenly at N bytes.
56	*
57	* Initially each page is in the free page list. Each page is used for just one
58	* size of allocation, with requests bucketed into a small number of common
59	* sizes. If the allocation would be too big or too small it is rejected by the pool.
60	*
61	* The free list is maintained by a bitmap, one per page/Bucket. Since each
62	* Bucket only maintains objects of a single size, each bit set or clear
63	* indicates the status of one object.
64	*
65	* An allocation walks the list of buckets and asks each in turn if there is
66	* space. If a Bucket does not have any space, it sets a boolean flag m_is_full
67	* so that it does not need to rescan when asked again. The flag is cleared on
68	* first free from that bucket. If no bucket has space, but there are some free
69	* pages left, a free page is claimed as a new Bucket for that size. In this case
70	* it is pushed to the front of the list so it is first in line to service new
71	* requests.
72	*
73	* A deallocation also walks the list of buckets for the size and asks each
74	* Bucket in turn if it recognizes the pointer. When a Bucket becomes empty as a
75	* result of a deallocation, it is recycled back into the free pool. When this
76	* happens, the Buckets page goes to the end of the free list. All pages on the
77	* free list are marked in the MMU as noaccess, so anything touching them will
78	* immediately crash. They are only marked R/W once placed into a new bucket.
79	* Making the free list FIFO maximizes the time between the last free of a bucket
80	* and that page being writable again, maximizing chances of crashing after a
81	* use-after-free.
82	*
83	* Future work
84	* -------------
85	*
86	* The allocator is protected by a global lock. It would be good to break this
87	* up, since almost all of the work can actually be done in parallel especially
88	* when allocating objects of different sizes (which can't possibly share a
89	* bucket).
90	*
91	* It may be worthwhile to optimize deallocation by storing the Buckets in order
92	* (by pointer value) which would allow binary search to find the owning bucket.
93	*
94	* A useful addition would be to randomize the allocations. Memory_Pool would be
95	* changed to receive also a RandomNumberGenerator& object (presumably the system
96	* RNG, or maybe a ChaCha_RNG seeded with system RNG). Then the bucket to use and
97	* the offset within the bucket would be chosen randomly, instead of using first fit.
98	*
99	* Right now we don't make any provision for threading, so if two threads both
100	* allocate 32 byte values one after the other, the two allocations will likely
101	* share a cache line. Ensuring that distinct threads will (tend to) use distinct
102	* buckets would reduce this.
103	*
104	* Supporting a realloc-style API may be useful.
105	*/
106
107	namespace {
108
109	size_t choose_bucket(size_t n) {	295,844,491✔
110	const size_t MINIMUM_ALLOCATION = 16;	295,844,491✔
111	const size_t MAXIMUM_ALLOCATION = 256;	295,844,491✔
112
113	if(n < MINIMUM_ALLOCATION \|\| n > MAXIMUM_ALLOCATION) {	295,844,491✔
114	return 0;
115	}
116
117	// Need to tune these
118
119	const size_t buckets[] = {	263,741,185✔
120	16,
121	24,
122	32,
123	48,
124	64,
125	80,
126	96,
127	112,
128	128,
129	160,
130	192,
131	256,
132	0,
133	};
134
135	for(size_t i = 0; buckets[i]; ++i) {	1,410,911,170✔
136	if(n <= buckets[i]) {	1,410,911,170✔
137	return buckets[i];	263,741,185✔
138	}
139	}
140
141	return 0;
142	}
143
144	inline bool ptr_in_pool(const void* pool_ptr, size_t poolsize, const void* buf_ptr, size_t bufsize) {	430,239,308✔
145	const uintptr_t pool = reinterpret_cast<uintptr_t>(pool_ptr);	430,239,308✔
146	const uintptr_t buf = reinterpret_cast<uintptr_t>(buf_ptr);	430,239,308✔
147	return (buf >= pool) && (buf + bufsize <= pool + poolsize);	290,609,378✔
148	}
149
150	// return index of first set bit
151	template <typename T>
152	size_t find_set_bit(T b) {	131,799,450✔
153	size_t s = 8 * sizeof(T) / 2;	131,799,450✔
154	size_t bit = 0;	131,799,450✔
155
156	// In this context we don't need to be const-time
157	while(s > 0) {	922,596,150✔
158	const T mask = (static_cast<T>(1) << s) - 1;	790,796,700✔
159	if((b & mask) == 0) {	790,796,700✔
160	bit += s;	283,078,300✔
161	b >>= s;	283,078,300✔
162	}
163	s /= 2;	790,796,700✔
164	}
165
166	return bit;
167	}
168
169	class BitMap final {	80,293✔
170	public:
171	explicit BitMap(size_t bits) : m_len(bits) {	10,113,705✔
172	m_bits.resize((bits + BITMASK_BITS - 1) / BITMASK_BITS);	10,113,705✔
173	// MSVC warns if the cast isn't there, clang-tidy warns that the cast is pointless
174	m_main_mask = static_cast<bitmask_type>(~0); // NOLINT(bugprone-misplaced-widening-cast)	10,113,705✔
175	m_last_mask = m_main_mask;	10,113,705✔
176
177	if(bits % BITMASK_BITS != 0) {	10,113,705✔
178	m_last_mask = (static_cast<bitmask_type>(1) << (bits % BITMASK_BITS)) - 1;	6,394,181✔
179	}
180	}	10,113,705✔
181
182	bool find_free(size_t* bit);
183
184	void free(size_t bit) {	131,700,095✔
185	BOTAN_ASSERT_NOMSG(bit <= m_len);	131,700,095✔
186	const size_t w = bit / BITMASK_BITS;	131,700,095✔
187	BOTAN_ASSERT_NOMSG(w < m_bits.size());	131,700,095✔
188	const bitmask_type mask = static_cast<bitmask_type>(1) << (bit % BITMASK_BITS);	131,700,095✔
189	m_bits[w] = m_bits[w] & (~mask);	131,700,095✔
190	}	131,700,095✔
191
192	bool empty() const {	131,700,095✔
193	for(auto bitset : m_bits) {	156,395,808✔
194	if(bitset != 0) {	146,283,801✔
195	return false;
196	}
197	}
198
199	return true;
200	}
201
202	private:
203	#if defined(BOTAN_ENABLE_DEBUG_ASSERTS)
204	using bitmask_type = uint8_t;
205	#else
206	using bitmask_type = word;
207	#endif
208
209	static const size_t BITMASK_BITS = sizeof(bitmask_type) * 8;
210
211	size_t m_len;
212	bitmask_type m_main_mask;
213	bitmask_type m_last_mask;
214	std::vector<bitmask_type> m_bits;
215	};
216
217	bool BitMap::find_free(size_t* bit) {	139,423,234✔
218	for(size_t i = 0; i != m_bits.size(); ++i) {	161,953,988✔
219	const bitmask_type mask = (i == m_bits.size() - 1) ? m_last_mask : m_main_mask;	154,330,204✔
220	if((m_bits[i] & mask) != mask) {	154,330,204✔
221	const size_t free_bit = find_set_bit(~m_bits[i]);	131,799,450✔
222	const bitmask_type bmask = static_cast<bitmask_type>(1) << (free_bit % BITMASK_BITS);	131,799,450✔
223	BOTAN_ASSERT_NOMSG((m_bits[i] & bmask) == 0);	131,799,450✔
224	m_bits[i] \|= bmask;	131,799,450✔
225	bit = BITMASK_BITS i + free_bit;	131,799,450✔
226	return true;	131,799,450✔
227	}
228	}
229
230	return false;
231	}
232
233	} // namespace
234
235	class Bucket final {	18,586,349✔
236	public:
237	Bucket(uint8_t* mem, size_t mem_size, size_t item_size) :	10,113,705✔
238	m_item_size(item_size),	10,113,705✔
239	m_page_size(mem_size),	10,113,705✔
240	m_range(mem),	10,113,705✔
241	m_bitmap(mem_size / item_size),	10,113,705✔
242	m_is_full(false) {}	10,113,705✔
243
244	uint8_t* alloc() {	418,677,986✔
245	if(m_is_full) {	418,677,986✔
246	// I know I am full
247	return nullptr;
248	}
249
250	size_t offset;	139,423,234✔
251	if(!m_bitmap.find_free(&offset)) {	139,423,234✔
252	// I just found out I am full
253	m_is_full = true;	7,623,784✔
254	return nullptr;	7,623,784✔
255	}
256
257	BOTAN_ASSERT(offset * m_item_size < m_page_size, "Offset is in range");	131,799,450✔
258	return m_range + m_item_size * offset;	131,799,450✔
259	}
260
261	bool free(void* p) {	430,239,308✔
262	if(!in_this_bucket(p)) {	992,178,711✔
263	return false;
264	}
265
266	/*
267	Zero also any trailing bytes, which should not have been written to,
268	but maybe the user was bad and wrote past the end.
269	*/
270	std::memset(p, 0, m_item_size);	131,700,095✔
271
272	const size_t offset = (reinterpret_cast<uintptr_t>(p) - reinterpret_cast<uintptr_t>(m_range)) / m_item_size;	131,700,095✔
273
274	m_bitmap.free(offset);	131,700,095✔
275	m_is_full = false;	131,700,095✔
276
277	return true;	131,700,095✔
278	}
279
280	bool in_this_bucket(void* p) const { return ptr_in_pool(m_range, m_page_size, p, m_item_size); }	561,939,403✔
281
282	bool empty() const { return m_bitmap.empty(); }	263,400,190✔
283
284	uint8_t* ptr() const { return m_range; }	10,112,007✔
285
286	private:
287	size_t m_item_size;
288	size_t m_page_size;
289	uint8_t* m_range;
290	BitMap m_bitmap;
291	bool m_is_full;
292	};
293
294	Memory_Pool::Memory_Pool(const std::vector<void*>& pages, size_t page_size) : m_page_size(page_size) {	9,736✔
295	m_min_page_ptr = ~static_cast<uintptr_t>(0);	9,736✔
296	m_max_page_ptr = 0;	9,736✔
297
298	for(auto page : pages) {	1,131,944✔
299	const uintptr_t p = reinterpret_cast<uintptr_t>(page);	1,122,208✔
300
301	m_min_page_ptr = std::min(p, m_min_page_ptr);	1,122,208✔
302	m_max_page_ptr = std::max(p, m_max_page_ptr);	1,122,208✔
303
304	clear_bytes(page, m_page_size);	1,122,208✔
305	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
306	OS::page_prohibit_access(page);
307	#endif
308	m_free_pages.push_back(static_cast<uint8_t*>(page));	1,122,208✔
309	}
310
311	/*
312	Right now this points to the start of the last page, adjust it to instead
313	point to the first byte of the following page
314	*/
315	m_max_page_ptr += page_size;	9,736✔
316	}	9,736✔
317
318	Memory_Pool::~Memory_Pool() // NOLINT(*-use-equals-default)	9,736✔
319	{
320	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
321	for(size_t i = 0; i != m_free_pages.size(); ++i) {
322	OS::page_allow_access(m_free_pages[i]);
323	}
324	#endif
325	}	9,736✔
326
327	void* Memory_Pool::allocate(size_t n) {	164,219,657✔
328	if(n > m_page_size) {	164,219,657✔
329	return nullptr;
330	}
331
332	const size_t n_bucket = choose_bucket(n);	164,144,396✔
333
334	if(n_bucket > 0) {	164,144,396✔
335	lock_guard_type<mutex_type> lock(m_mutex);	132,041,090✔
336
337	std::deque<Bucket>& buckets = m_buckets_for[n_bucket];	132,041,090✔
338
339	/*
340	It would be optimal to pick the bucket with the most usage,
341	since a bucket with say 1 item allocated out of it has a high
342	chance of becoming later freed and then the whole page can be
343	recycled.
344	*/
345	for(auto& bucket : buckets) {	705,798,162✔
346	if(uint8_t* p = bucket.alloc()) {	408,564,281✔
347	return p;	121,685,745✔
348	}
349
350	// If the bucket is full, maybe move it to the end of the list?
351	// Otoh bucket search should be very fast
352	}
353
354	if(!m_free_pages.empty()) {	10,355,345✔
355	uint8_t* ptr = m_free_pages[0];	10,113,705✔
356	m_free_pages.pop_front();	10,113,705✔
357	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
358	OS::page_allow_access(ptr);
359	#endif
360	buckets.push_front(Bucket(ptr, m_page_size, n_bucket));	10,113,705✔
361	void* p = buckets[0].alloc();	10,113,705✔
362	BOTAN_ASSERT_NOMSG(p != nullptr);	10,113,705✔
363	return p;
364	}
365	}	132,041,090✔
366
367	// out of room
368	return nullptr;
369	}
370
371	bool Memory_Pool::deallocate(void* p, size_t len) noexcept {	163,962,504✔
372	// Do a fast range check first, before taking the lock
373	const uintptr_t p_val = reinterpret_cast<uintptr_t>(p);	163,962,504✔
374	if(p_val < m_min_page_ptr \|\| p_val > m_max_page_ptr) {	163,962,504✔
375	return false;
376	}
377
378	const size_t n_bucket = choose_bucket(len);	131,700,095✔
379
380	if(n_bucket != 0) {	131,700,095✔
381	try {	131,700,095✔
382	lock_guard_type<mutex_type> lock(m_mutex);	131,700,095✔
383
384	std::deque<Bucket>& buckets = m_buckets_for[n_bucket];	131,700,095✔
385
386	for(size_t i = 0; i != buckets.size(); ++i) {	430,239,308✔
387	Bucket& bucket = buckets[i];	430,239,308✔
388	if(bucket.free(p)) {	430,239,308✔
389	if(bucket.empty()) {	263,400,190✔
390	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
391	OS::page_prohibit_access(bucket.ptr());
392	#endif
393	m_free_pages.push_back(bucket.ptr());	10,112,007✔
394
395	if(i != buckets.size() - 1) {	10,112,007✔
396	std::swap(buckets.back(), buckets[i]);	93,721✔
397	}
398	buckets.pop_back();	10,112,007✔
399	}
400	return true;	131,700,095✔
401	}
402	}
403	} catch(...) {	131,700,095✔
404	/*
405	* The only exception throws that can occur in the above code are from
406	* either the STL or BOTAN_ASSERT failures. In either case, such an
407	* error indicates a logic error or data corruption in the memory
408	* allocator such that it is no longer safe to continue executing.
409	*
410	* Since this function is noexcept, simply letting the exception escape
411	* is sufficient for terminate to be called. However in this scenario
412	* it is implementation defined if any stack unwinding is performed.
413	* Since stack unwinding could cause further memory deallocations this
414	* could result in further corruption in this allocator state. To prevent
415	* this, call terminate directly.
416	*/
417	std::terminate();	×
418	}
419	}
420
421	return false;
422	}
423
424	} // namespace Botan

randombit / botan / 13190843806

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