5123321399

Committed 30 May 2023 04:06PM UTC coverage: 92.213% (+0.004%) from 92.209%

Build # 5123321399

Build Type

Pull #3558

github

Committed by

web-flow

Commit Message

Merge dd72f7389 into 057bcbc35

Pull Request Pull Request #3558: Add braces around all if/else statements

Run Details

75602 of 81986 relevant lines covered (92.21%)

11859779.3 hits per line

Source File
Press 'n' to go to next uncovered line, 'b' for previous

99.17

/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_MEM_POOL_USE_MMU_PROTECTIONS)
   #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;

      enum { BITMASK_BITS = 8 };
#else
      using bitmask_type = word;

      enum { BITMASK_BITS = BOTAN_MP_WORD_BITS };
#endif

      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_MEM_POOL_USE_MMU_PROTECTIONS)
13	#include <botan/internal/os_utils.h>
14	#endif
15
16	namespace Botan {
17
18	/*
19	* Memory pool theory of operation
20	*
21	* This allocator is not useful for general purpose but works well within the
22	* context of allocating cryptographic keys. It makes several assumptions which
23	* don't work for implementing malloc but simplify and speed up the implementation:
24	*
25	* - There is some set of pages, which cannot be expanded later. These are pages
26	* which were allocated, mlocked and passed to the Memory_Pool constructor.
27	*
28	* - The allocator is allowed to return null anytime it feels like not servicing
29	* a request, in which case the request will be sent to calloc instead. In
30	* particular, requests which are too small or too large are rejected.
31	*
32	* - Most allocations are powers of 2, the remainder are usually a multiple of 8
33	*
34	* - Free requests include the size of the allocation, so there is no need to
35	* track this within the pool.
36	*
37	* - Alignment is important to the caller. For this allocator, any allocation of
38	* size N is aligned evenly at N bytes.
39	*
40	* Initially each page is in the free page list. Each page is used for just one
41	* size of allocation, with requests bucketed into a small number of common
42	* sizes. If the allocation would be too big or too small it is rejected by the pool.
43	*
44	* The free list is maintained by a bitmap, one per page/Bucket. Since each
45	* Bucket only maintains objects of a single size, each bit set or clear
46	* indicates the status of one object.
47	*
48	* An allocation walks the list of buckets and asks each in turn if there is
49	* space. If a Bucket does not have any space, it sets a boolean flag m_is_full
50	* so that it does not need to rescan when asked again. The flag is cleared on
51	* first free from that bucket. If no bucket has space, but there are some free
52	* pages left, a free page is claimed as a new Bucket for that size. In this case
53	* it is pushed to the front of the list so it is first in line to service new
54	* requests.
55	*
56	* A deallocation also walks the list of buckets for the size and asks each
57	* Bucket in turn if it recognizes the pointer. When a Bucket becomes empty as a
58	* result of a deallocation, it is recycled back into the free pool. When this
59	* happens, the Buckets page goes to the end of the free list. All pages on the
60	* free list are marked in the MMU as noaccess, so anything touching them will
61	* immediately crash. They are only marked R/W once placed into a new bucket.
62	* Making the free list FIFO maximizes the time between the last free of a bucket
63	* and that page being writable again, maximizing chances of crashing after a
64	* use-after-free.
65	*
66	* Future work
67	* -------------
68	*
69	* The allocator is protected by a global lock. It would be good to break this
70	* up, since almost all of the work can actually be done in parallel especially
71	* when allocating objects of different sizes (which can't possibly share a
72	* bucket).
73	*
74	* It may be worthwhile to optimize deallocation by storing the Buckets in order
75	* (by pointer value) which would allow binary search to find the owning bucket.
76	*
77	* A useful addition would be to randomize the allocations. Memory_Pool would be
78	* changed to receive also a RandomNumberGenerator& object (presumably the system
79	* RNG, or maybe a ChaCha_RNG seeded with system RNG). Then the bucket to use and
80	* the offset within the bucket would be chosen randomly, instead of using first fit.
81	*
82	* Right now we don't make any provision for threading, so if two threads both
83	* allocate 32 byte values one after the other, the two allocations will likely
84	* share a cache line. Ensuring that distinct threads will (tend to) use distinct
85	* buckets would reduce this.
86	*
87	* Supporting a realloc-style API may be useful.
88	*/
89
90	namespace {
91
92	size_t choose_bucket(size_t n) {	216,132,551✔
93	const size_t MINIMUM_ALLOCATION = 16;	216,132,551✔
94	const size_t MAXIMUM_ALLOCATION = 256;	216,132,551✔
95
96	if(n < MINIMUM_ALLOCATION \|\| n > MAXIMUM_ALLOCATION) {	216,132,551✔
97	return 0;
98	}
99
100	// Need to tune these
101
102	const size_t buckets[] = {	200,470,481✔
103	16,
104	24,
105	32,
106	48,
107	64,
108	80,
109	96,
110	112,
111	128,
112	160,
113	192,
114	256,
115	0,
116	};
117
118	for(size_t i = 0; buckets[i]; ++i) {	1,116,038,050✔
119	if(n <= buckets[i]) {	1,116,038,050✔
120	return buckets[i];	200,470,481✔
121	}
122	}
123
124	return 0;
125	}
126
127	inline bool ptr_in_pool(const void* pool_ptr, size_t poolsize, const void* buf_ptr, size_t bufsize) {	99,144,957✔
128	const uintptr_t pool = reinterpret_cast<uintptr_t>(pool_ptr);	99,144,957✔
129	const uintptr_t buf = reinterpret_cast<uintptr_t>(buf_ptr);	99,144,957✔
130	return (buf >= pool) && (buf + bufsize <= pool + poolsize);	85,130,707✔
131	}
132
133	// return index of first set bit
134	template <typename T>
135	size_t find_set_bit(T b) {	75,033,735✔
136	size_t s = 8 * sizeof(T) / 2;
137	size_t bit = 0;
138
139	// In this context we don't need to be const-time
140	while(s > 0) {	525,236,145✔
141	const T mask = (static_cast<T>(1) << s) - 1;	450,202,410✔
142	if((b & mask) == 0) {	450,202,410✔
143	bit += s;	141,395,644✔
144	b >>= s;	141,395,644✔
145	}
146	s /= 2;	450,202,410✔
147	}
148
149	return bit;
150	}
151
152	class BitMap final {	37,096,930✔
153	public:
154	explicit BitMap(size_t bits) : m_len(bits) {	7,365,932✔
155	m_bits.resize((bits + BITMASK_BITS - 1) / BITMASK_BITS);	7,365,932✔
156	// MSVC warns if the cast isn't there, clang-tidy warns that the cast is pointless
157	m_main_mask = static_cast<bitmask_type>(~0); // NOLINT(bugprone-misplaced-widening-cast)	7,365,932✔
158	m_last_mask = m_main_mask;	7,365,932✔
159
160	if(bits % BITMASK_BITS != 0) {	7,365,932✔
161	m_last_mask = (static_cast<bitmask_type>(1) << (bits % BITMASK_BITS)) - 1;	4,165,275✔
162	}
163	}	7,365,932✔
164
165	bool find_free(size_t* bit);
166
167	void free(size_t bit) {	75,030,772✔
168	BOTAN_ASSERT_NOMSG(bit <= m_len);	75,030,772✔
169	const size_t w = bit / BITMASK_BITS;	75,030,772✔
170	BOTAN_ASSERT_NOMSG(w < m_bits.size());	75,030,772✔
171	const bitmask_type mask = static_cast<bitmask_type>(1) << (bit % BITMASK_BITS);	75,030,772✔
172	m_bits[w] = m_bits[w] & (~mask);	75,030,772✔
173	}	75,030,772✔
174
175	bool empty() const {	75,030,772✔
176	for(auto bitset : m_bits) {	89,072,151✔
177	if(bitset != 0) {	81,708,260✔
178	return false;
179	}
180	}
181
182	return true;
183	}
184
185	private:
186	#if defined(BOTAN_ENABLE_DEBUG_ASSERTS)
187	using bitmask_type = uint8_t;
188
189	enum { BITMASK_BITS = 8 };
190	#else
191	using bitmask_type = word;
192
193	enum { BITMASK_BITS = BOTAN_MP_WORD_BITS };
194	#endif
195
196	size_t m_len;
197	bitmask_type m_main_mask;
198	bitmask_type m_last_mask;
199	std::vector<bitmask_type> m_bits;
200	};
201
202	bool BitMap::find_free(size_t* bit) {	77,100,459✔
203	for(size_t i = 0; i != m_bits.size(); ++i) {	79,664,352✔
204	const bitmask_type mask = (i == m_bits.size() - 1) ? m_last_mask : m_main_mask;	77,597,628✔
205	if((m_bits[i] & mask) != mask) {	77,597,628✔
206	const size_t free_bit = find_set_bit(~m_bits[i]);	75,033,735✔
207	const bitmask_type bmask = static_cast<bitmask_type>(1) << (free_bit % BITMASK_BITS);	75,033,735✔
208	BOTAN_ASSERT_NOMSG((m_bits[i] & bmask) == 0);	75,033,735✔
209	m_bits[i] \|= bmask;	75,033,735✔
210	bit = BITMASK_BITS i + free_bit;	75,033,735✔
211	return true;	75,033,735✔
212	}
213	}
214
215	return false;
216	}
217
218	} // namespace
219
220	class Bucket final {	19,733,282✔
221	public:
222	Bucket(uint8_t* mem, size_t mem_size, size_t item_size) :	7,365,932✔
223	m_item_size(item_size),	7,365,932✔
224	m_page_size(mem_size),	7,365,932✔
225	m_range(mem),	7,365,932✔
226	m_bitmap(mem_size / item_size),	7,365,932✔
227	m_is_full(false) {}	7,365,932✔
228
229	uint8_t* alloc() {	204,251,000✔
230	if(m_is_full) {	204,251,000✔
231	// I know I am full
232	return nullptr;
233	}
234
235	size_t offset;	77,100,459✔
236	if(!m_bitmap.find_free(&offset)) {	77,100,459✔
237	// I just found out I am full
238	m_is_full = true;	2,066,724✔
239	return nullptr;	2,066,724✔
240	}
241
242	BOTAN_ASSERT(offset * m_item_size < m_page_size, "Offset is in range");	75,033,735✔
243	return m_range + m_item_size * offset;	75,033,735✔
244	}
245
246	bool free(void* p) {	99,144,957✔
247	if(!in_this_bucket(p)) {	273,320,686✔
248	return false;
249	}
250
251	/*
252	Zero also any trailing bytes, which should not have been written to,
253	but maybe the user was bad and wrote past the end.
254	*/
255	std::memset(p, 0, m_item_size);	75,030,772✔
256
257	const size_t offset = (reinterpret_cast<uintptr_t>(p) - reinterpret_cast<uintptr_t>(m_range)) / m_item_size;	75,030,772✔
258
259	m_bitmap.free(offset);	75,030,772✔
260	m_is_full = false;	75,030,772✔
261
262	return true;	75,030,772✔
263	}
264
265	bool in_this_bucket(void* p) const { return ptr_in_pool(m_range, m_page_size, p, m_item_size); }	174,175,729✔
266
267	bool empty() const { return m_bitmap.empty(); }	150,061,544✔
268
269	uint8_t* ptr() const { return m_range; }	7,363,891✔
270
271	private:
272	size_t m_item_size;
273	size_t m_page_size;
274	uint8_t* m_range;
275	BitMap m_bitmap;
276	bool m_is_full;
277	};
278
279	Memory_Pool::Memory_Pool(const std::vector<void*>& pages, size_t page_size) : m_page_size(page_size) {	9,583✔
280	m_min_page_ptr = ~static_cast<uintptr_t>(0);	9,583✔
281	m_max_page_ptr = 0;	9,583✔
282
283	for(auto page : pages) {	150,911✔
284	const uintptr_t p = reinterpret_cast<uintptr_t>(page);	141,328✔
285
286	m_min_page_ptr = std::min(p, m_min_page_ptr);	141,328✔
287	m_max_page_ptr = std::max(p, m_max_page_ptr);	141,328✔
288
289	clear_bytes(page, m_page_size);	141,328✔
290	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
291	OS::page_prohibit_access(page);
292	#endif
293	m_free_pages.push_back(static_cast<uint8_t*>(page));	141,328✔
294	}
295
296	/*
297	Right now this points to the start of the last page, adjust it to instead
298	point to the first byte of the following page
299	*/
300	m_max_page_ptr += page_size;	9,583✔
301	}	9,583✔
302
303	Memory_Pool::~Memory_Pool() // NOLINT(*-use-equals-default)	9,583✔
304	{
305	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
306	for(size_t i = 0; i != m_free_pages.size(); ++i) {
307	OS::page_allow_access(m_free_pages[i]);
308	}
309	#endif
310	}	9,583✔
311
312	void* Memory_Pool::allocate(size_t n) {	141,135,877✔
313	if(n > m_page_size) {	141,135,877✔
314	return nullptr;
315	}
316
317	const size_t n_bucket = choose_bucket(n);	141,101,779✔
318
319	if(n_bucket > 0) {	141,101,779✔
320	lock_guard_type<mutex_type> lock(m_mutex);	125,439,709✔
321
322	std::deque<Bucket>& buckets = m_buckets_for[n_bucket];	125,439,709✔
323
324	/*
325	It would be optimal to pick the bucket with the most usage,
326	since a bucket with say 1 item allocated out of it has a high
327	chance of becoming later freed and then the whole page can be
328	recycled.
329	*/
330	for(auto& bucket : buckets) {	383,874,239✔
331	if(uint8_t* p = bucket.alloc()) {	196,885,068✔
332	return p;	67,667,803✔
333	}
334
335	// If the bucket is full, maybe move it to the end of the list?
336	// Otoh bucket search should be very fast
337	}
338
339	if(!m_free_pages.empty()) {	57,771,906✔
340	uint8_t* ptr = m_free_pages[0];	7,365,932✔
341	m_free_pages.pop_front();	7,365,932✔
342	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
343	OS::page_allow_access(ptr);
344	#endif
345	buckets.push_front(Bucket(ptr, m_page_size, n_bucket));	7,365,932✔
346	void* p = buckets[0].alloc();	7,365,932✔
347	BOTAN_ASSERT_NOMSG(p != nullptr);	7,365,932✔
348	return p;
349	}
350	}	125,439,709✔
351
352	// out of room
353	return nullptr;
354	}
355
356	bool Memory_Pool::deallocate(void* p, size_t len) noexcept {	141,085,482✔
357	// Do a fast range check first, before taking the lock
358	const uintptr_t p_val = reinterpret_cast<uintptr_t>(p);	141,085,482✔
359	if(p_val < m_min_page_ptr \|\| p_val > m_max_page_ptr) {	141,085,482✔
360	return false;
361	}
362
363	const size_t n_bucket = choose_bucket(len);	75,030,772✔
364
365	if(n_bucket != 0) {	75,030,772✔
366	try {	75,030,772✔
367	lock_guard_type<mutex_type> lock(m_mutex);	75,030,772✔
368
369	std::deque<Bucket>& buckets = m_buckets_for[n_bucket];	75,030,772✔
370
371	for(size_t i = 0; i != buckets.size(); ++i) {	99,144,957✔
372	Bucket& bucket = buckets[i];	99,144,957✔
373	if(bucket.free(p)) {	99,144,957✔
374	if(bucket.empty()) {	150,061,544✔
375	#if defined(BOTAN_MEM_POOL_USE_MMU_PROTECTIONS)
376	OS::page_prohibit_access(bucket.ptr());
377	#endif
378	m_free_pages.push_back(bucket.ptr());	7,363,891✔
379
380	if(i != buckets.size() - 1) {	7,363,891✔
381	std::swap(buckets.back(), buckets[i]);	104,197✔
382	}
383	buckets.pop_back();	7,363,891✔
384	}
385	return true;	75,030,772✔
386	}
387	}
388	} catch(...) {	75,030,772✔
389	/*
390	* The only exception throws that can occur in the above code are from
391	* either the STL or BOTAN_ASSERT failures. In either case, such an
392	* error indicates a logic error or data corruption in the memory
393	* allocator such that it is no longer safe to continue executing.
394	*
395	* Since this function is noexcept, simply letting the exception escape
396	* is sufficient for terminate to be called. However in this scenario
397	* it is implementation defined if any stack unwinding is performed.
398	* Since stack unwinding could cause further memory deallocations this
399	* could result in further corruption in this allocator state. To prevent
400	* this, call terminate directly.
401	*/
402	std::terminate();	×
403	}
404	}
405
406	return false;
407	}
408
409	} // namespace Botan

randombit / botan / 5123321399

Source File Press 'n' to go to next uncovered line, 'b' for previous

Source File
Press 'n' to go to next uncovered line, 'b' for previous