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Merge pull request #4642 from randombit/jack/target-info-header

Add internal target_info.h header

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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 <botan/internal/target_info.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 <botan/internal/target_info.h>
11	#include <algorithm>
12
13	#if defined(BOTAN_HAS_VALGRIND) \|\| defined(BOTAN_ENABLE_DEBUG_ASSERTS)
14	/**
15	* @brief Prohibits access to unused memory pages in Botan's memory pool
16	*
17	* If BOTAN_MEM_POOL_USE_MMU_PROTECTIONS is defined, the Memory_Pool
18	* class used for mlock'ed memory will use OS calls to set page
19	* permissions so as to prohibit access to pages on the free list, then
20	* enable read/write access when the page is set to be used. This will
21	* turn (some) use after free bugs into a crash.
22	*
23	* The additional syscalls have a substantial performance impact, which
24	* is why this option is not enabled by default. It is used when built for
25	* running in valgrind or debug assertions are enabled.
26	*/
27	#define BOTAN_MEM_POOL_USE_MMU_PROTECTIONS
28	#endif
29
30	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS) && defined(BOTAN_HAS_OS_UTILS)
31	#include <botan/internal/os_utils.h>
32	#endif
33
34	namespace Botan {
35
36	/*
37	* Memory pool theory of operation
38	*
39	* This allocator is not useful for general purpose but works well within the
40	* context of allocating cryptographic keys. It makes several assumptions which
41	* don't work for implementing malloc but simplify and speed up the implementation:
42	*
43	* - There is some set of pages, which cannot be expanded later. These are pages
44	* which were allocated, mlocked and passed to the Memory_Pool constructor.
45	*
46	* - The allocator is allowed to return null anytime it feels like not servicing
47	* a request, in which case the request will be sent to calloc instead. In
48	* particular, requests which are too small or too large are rejected.
49	*
50	* - Most allocations are powers of 2, the remainder are usually a multiple of 8
51	*
52	* - Free requests include the size of the allocation, so there is no need to
53	* track this within the pool.
54	*
55	* - Alignment is important to the caller. For this allocator, any allocation of
56	* size N is aligned evenly at N bytes.
57	*
58	* Initially each page is in the free page list. Each page is used for just one
59	* size of allocation, with requests bucketed into a small number of common
60	* sizes. If the allocation would be too big or too small it is rejected by the pool.
61	*
62	* The free list is maintained by a bitmap, one per page/Bucket. Since each
63	* Bucket only maintains objects of a single size, each bit set or clear
64	* indicates the status of one object.
65	*
66	* An allocation walks the list of buckets and asks each in turn if there is
67	* space. If a Bucket does not have any space, it sets a boolean flag m_is_full
68	* so that it does not need to rescan when asked again. The flag is cleared on
69	* first free from that bucket. If no bucket has space, but there are some free
70	* pages left, a free page is claimed as a new Bucket for that size. In this case
71	* it is pushed to the front of the list so it is first in line to service new
72	* requests.
73	*
74	* A deallocation also walks the list of buckets for the size and asks each
75	* Bucket in turn if it recognizes the pointer. When a Bucket becomes empty as a
76	* result of a deallocation, it is recycled back into the free pool. When this
77	* happens, the Buckets page goes to the end of the free list. All pages on the
78	* free list are marked in the MMU as noaccess, so anything touching them will
79	* immediately crash. They are only marked R/W once placed into a new bucket.
80	* Making the free list FIFO maximizes the time between the last free of a bucket
81	* and that page being writable again, maximizing chances of crashing after a
82	* use-after-free.
83	*
84	* Future work
85	* -------------
86	*
87	* The allocator is protected by a global lock. It would be good to break this
88	* up, since almost all of the work can actually be done in parallel especially
89	* when allocating objects of different sizes (which can't possibly share a
90	* bucket).
91	*
92	* It may be worthwhile to optimize deallocation by storing the Buckets in order
93	* (by pointer value) which would allow binary search to find the owning bucket.
94	*
95	* A useful addition would be to randomize the allocations. Memory_Pool would be
96	* changed to receive also a RandomNumberGenerator& object (presumably the system
97	* RNG, or maybe a ChaCha_RNG seeded with system RNG). Then the bucket to use and
98	* the offset within the bucket would be chosen randomly, instead of using first fit.
99	*
100	* Right now we don't make any provision for threading, so if two threads both
101	* allocate 32 byte values one after the other, the two allocations will likely
102	* share a cache line. Ensuring that distinct threads will (tend to) use distinct
103	* buckets would reduce this.
104	*
105	* Supporting a realloc-style API may be useful.
106	*/
107
108	namespace {
109
110	size_t choose_bucket(size_t n) {	290,225,326✔
111	const size_t MINIMUM_ALLOCATION = 16;	290,225,326✔
112	const size_t MAXIMUM_ALLOCATION = 256;	290,225,326✔
113
114	if(n < MINIMUM_ALLOCATION \|\| n > MAXIMUM_ALLOCATION) {	290,225,326✔
115	return 0;
116	}
117
118	// Need to tune these
119
120	const size_t buckets[] = {	259,788,954✔
121	16,
122	24,
123	32,
124	48,
125	64,
126	80,
127	96,
128	112,
129	128,
130	160,
131	192,
132	256,
133	0,
134	};
135
136	for(size_t i = 0; buckets[i]; ++i) {	1,368,771,978✔
137	if(n <= buckets[i]) {	1,368,771,978✔
138	return buckets[i];	259,788,954✔
139	}
140	}
141
142	return 0;
143	}
144
145	inline bool ptr_in_pool(const void* pool_ptr, size_t poolsize, const void* buf_ptr, size_t bufsize) {	423,343,657✔
146	const uintptr_t pool = reinterpret_cast<uintptr_t>(pool_ptr);	423,343,657✔
147	const uintptr_t buf = reinterpret_cast<uintptr_t>(buf_ptr);	423,343,657✔
148	return (buf >= pool) && (buf + bufsize <= pool + poolsize);	279,070,794✔
149	}
150
151	// return index of first set bit
152	template <typename T>
153	size_t find_set_bit(T b) {	129,821,877✔
154	size_t s = 8 * sizeof(T) / 2;	129,821,877✔
155	size_t bit = 0;	129,821,877✔
156
157	// In this context we don't need to be const-time
158	while(s > 0) {	908,753,139✔
159	const T mask = (static_cast<T>(1) << s) - 1;	778,931,262✔
160	if((b & mask) == 0) {	778,931,262✔
161	bit += s;	293,718,647✔
162	b >>= s;	293,718,647✔
163	}
164	s /= 2;	778,931,262✔
165	}
166
167	return bit;
168	}
169
170	class BitMap final {	75,016✔
171	public:
172	explicit BitMap(size_t bits) : m_len(bits) {	10,286,437✔
173	m_bits.resize((bits + BITMASK_BITS - 1) / BITMASK_BITS);	10,286,437✔
174	// MSVC warns if the cast isn't there, clang-tidy warns that the cast is pointless
175	m_main_mask = static_cast<bitmask_type>(~0); // NOLINT(bugprone-misplaced-widening-cast)	10,286,437✔
176	m_last_mask = m_main_mask;	10,286,437✔
177
178	if(bits % BITMASK_BITS != 0) {	10,286,437✔
179	m_last_mask = (static_cast<bitmask_type>(1) << (bits % BITMASK_BITS)) - 1;	6,058,177✔
180	}
181	}	10,286,437✔
182
183	bool find_free(size_t* bit);
184
185	void free(size_t bit) {	129,729,634✔
186	BOTAN_ASSERT_NOMSG(bit <= m_len);	129,729,634✔
187	const size_t w = bit / BITMASK_BITS;	129,729,634✔
188	BOTAN_ASSERT_NOMSG(w < m_bits.size());	129,729,634✔
189	const bitmask_type mask = static_cast<bitmask_type>(1) << (bit % BITMASK_BITS);	129,729,634✔
190	m_bits[w] = m_bits[w] & (~mask);	129,729,634✔
191	}	129,729,634✔
192
193	bool empty() const {	129,729,634✔
194	for(auto bitset : m_bits) {	156,180,951✔
195	if(bitset != 0) {	145,896,151✔
196	return false;
197	}
198	}
199
200	return true;
201	}
202
203	private:
204	#if defined(BOTAN_ENABLE_DEBUG_ASSERTS)
205	using bitmask_type = uint8_t;
206	#else
207	using bitmask_type = word;
208	#endif
209
210	static const size_t BITMASK_BITS = sizeof(bitmask_type) * 8;
211
212	size_t m_len;
213	bitmask_type m_main_mask;
214	bitmask_type m_last_mask;
215	std::vector<bitmask_type> m_bits;
216	};
217
218	bool BitMap::find_free(size_t* bit) {	137,508,930✔
219	for(size_t i = 0; i != m_bits.size(); ++i) {	160,115,024✔
220	const bitmask_type mask = (i == m_bits.size() - 1) ? m_last_mask : m_main_mask;	152,427,971✔
221	if((m_bits[i] & mask) != mask) {	152,427,971✔
222	const size_t free_bit = find_set_bit(~m_bits[i]);	129,821,877✔
223	const bitmask_type bmask = static_cast<bitmask_type>(1) << (free_bit % BITMASK_BITS);	129,821,877✔
224	BOTAN_ASSERT_NOMSG((m_bits[i] & bmask) == 0);	129,821,877✔
225	m_bits[i] \|= bmask;	129,821,877✔
226	bit = BITMASK_BITS i + free_bit;	129,821,877✔
227	return true;	129,821,877✔
228	}
229	}
230
231	return false;
232	}
233
234	} // namespace
235
236	class Bucket final {	18,897,734✔
237	public:
238	Bucket(uint8_t* mem, size_t mem_size, size_t item_size) :	10,286,437✔
239	m_item_size(item_size),	10,286,437✔
240	m_page_size(mem_size),	10,286,437✔
241	m_range(mem),	10,286,437✔
242	m_bitmap(mem_size / item_size),	10,286,437✔
243	m_is_full(false) {}	10,286,437✔
244
245	uint8_t* alloc() {	411,063,966✔
246	if(m_is_full) {	411,063,966✔
247	// I know I am full
248	return nullptr;
249	}
250
251	size_t offset;	137,508,930✔
252	if(!m_bitmap.find_free(&offset)) {	137,508,930✔
253	// I just found out I am full
254	m_is_full = true;	7,687,053✔
255	return nullptr;	7,687,053✔
256	}
257
258	BOTAN_ASSERT(offset * m_item_size < m_page_size, "Offset is in range");	129,821,877✔
259	return m_range + m_item_size * offset;	129,821,877✔
260	}
261
262	bool free(void* p) {	423,343,657✔
263	if(!in_this_bucket(p)) {	976,416,948✔
264	return false;
265	}
266
267	/*
268	Zero also any trailing bytes, which should not have been written to,
269	but maybe the user was bad and wrote past the end.
270	*/
271	std::memset(p, 0, m_item_size);	129,729,634✔
272
273	const size_t offset = (reinterpret_cast<uintptr_t>(p) - reinterpret_cast<uintptr_t>(m_range)) / m_item_size;	129,729,634✔
274
275	m_bitmap.free(offset);	129,729,634✔
276	m_is_full = false;	129,729,634✔
277
278	return true;	129,729,634✔
279	}
280
281	bool in_this_bucket(void* p) const { return ptr_in_pool(m_range, m_page_size, p, m_item_size); }	553,073,291✔
282
283	bool empty() const { return m_bitmap.empty(); }	259,459,268✔
284
285	uint8_t* ptr() const { return m_range; }	10,284,800✔
286
287	private:
288	size_t m_item_size;
289	size_t m_page_size;
290	uint8_t* m_range;
291	BitMap m_bitmap;
292	bool m_is_full;
293	};
294
295	Memory_Pool::Memory_Pool(const std::vector<void*>& pages, size_t page_size) : m_page_size(page_size) {	9,736✔
296	m_min_page_ptr = ~static_cast<uintptr_t>(0);	9,736✔
297	m_max_page_ptr = 0;	9,736✔
298
299	for(auto page : pages) {	1,131,944✔
300	const uintptr_t p = reinterpret_cast<uintptr_t>(page);	1,122,208✔
301
302	m_min_page_ptr = std::min(p, m_min_page_ptr);	1,122,208✔
303	m_max_page_ptr = std::max(p, m_max_page_ptr);	1,122,208✔
304
305	clear_bytes(page, m_page_size);	1,122,208✔
306	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
307	OS::page_prohibit_access(page);
308	#endif
309	m_free_pages.push_back(static_cast<uint8_t*>(page));	1,122,208✔
310	}
311
312	/*
313	Right now this points to the start of the last page, adjust it to instead
314	point to the first byte of the following page
315	*/
316	m_max_page_ptr += page_size;	9,736✔
317	}	9,736✔
318
319	Memory_Pool::~Memory_Pool() // NOLINT(*-use-equals-default)	9,736✔
320	{
321	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
322	for(size_t i = 0; i != m_free_pages.size(); ++i) {
323	OS::page_allow_access(m_free_pages[i]);
324	}
325	#endif
326	}	9,736✔
327
328	void* Memory_Pool::allocate(size_t n) {	160,571,031✔
329	if(n > m_page_size) {	160,571,031✔
330	return nullptr;
331	}
332
333	const size_t n_bucket = choose_bucket(n);	160,495,692✔
334
335	if(n_bucket > 0) {	160,495,692✔
336	lock_guard_type<mutex_type> lock(m_mutex);	130,059,320✔
337
338	std::deque<Bucket>& buckets = m_buckets_for[n_bucket];	130,059,320✔
339
340	/*
341	It would be optimal to pick the bucket with the most usage,
342	since a bucket with say 1 item allocated out of it has a high
343	chance of becoming later freed and then the whole page can be
344	recycled.
345	*/
346	for(auto& bucket : buckets) {	692,543,498✔
347	if(uint8_t* p = bucket.alloc()) {	400,777,529✔
348	return p;	119,535,440✔
349	}
350
351	// If the bucket is full, maybe move it to the end of the list?
352	// Otoh bucket search should be very fast
353	}
354
355	if(!m_free_pages.empty()) {	10,523,880✔
356	uint8_t* ptr = m_free_pages[0];	10,286,437✔
357	m_free_pages.pop_front();	10,286,437✔
358	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
359	OS::page_allow_access(ptr);
360	#endif
361	buckets.push_front(Bucket(ptr, m_page_size, n_bucket));	10,286,437✔
362	void* p = buckets[0].alloc();	10,286,437✔
363	BOTAN_ASSERT_NOMSG(p != nullptr);	10,286,437✔
364	return p;
365	}
366	}	130,059,320✔
367
368	// out of room
369	return nullptr;
370	}
371
372	bool Memory_Pool::deallocate(void* p, size_t len) noexcept {	160,327,076✔
373	// Do a fast range check first, before taking the lock
374	const uintptr_t p_val = reinterpret_cast<uintptr_t>(p);	160,327,076✔
375	if(p_val < m_min_page_ptr \|\| p_val > m_max_page_ptr) {	160,327,076✔
376	return false;
377	}
378
379	const size_t n_bucket = choose_bucket(len);	129,729,634✔
380
381	if(n_bucket != 0) {	129,729,634✔
382	try {	129,729,634✔
383	lock_guard_type<mutex_type> lock(m_mutex);	129,729,634✔
384
385	std::deque<Bucket>& buckets = m_buckets_for[n_bucket];	129,729,634✔
386
387	for(size_t i = 0; i != buckets.size(); ++i) {	423,343,657✔
388	Bucket& bucket = buckets[i];	423,343,657✔
389	if(bucket.free(p)) {	423,343,657✔
390	if(bucket.empty()) {	259,459,268✔
391	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
392	OS::page_prohibit_access(bucket.ptr());
393	#endif
394	m_free_pages.push_back(bucket.ptr());	10,284,800✔
395
396	if(i != buckets.size() - 1) {	10,284,800✔
397	std::swap(buckets.back(), buckets[i]);	87,531✔
398	}
399	buckets.pop_back();	10,284,800✔
400	}
401	return true;	129,729,634✔
402	}
403	}
404	} catch(...) {	129,729,634✔
405	/*
406	* The only exception throws that can occur in the above code are from
407	* either the STL or BOTAN_ASSERT failures. In either case, such an
408	* error indicates a logic error or data corruption in the memory
409	* allocator such that it is no longer safe to continue executing.
410	*
411	* Since this function is noexcept, simply letting the exception escape
412	* is sufficient for terminate to be called. However in this scenario
413	* it is implementation defined if any stack unwinding is performed.
414	* Since stack unwinding could cause further memory deallocations this
415	* could result in further corruption in this allocator state. To prevent
416	* this, call terminate directly.
417	*/
418	std::terminate();	×
419	}
420	}
421
422	return false;
423	}
424
425	} // namespace Botan

randombit / botan / 13210394651

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