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Strong error testing on buddy allocator

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This commit is contained in:
Baptiste Wicht 2018-03-28 15:23:21 +02:00
parent 2b5344319f
commit e1871c01bb
1 changed files with 72 additions and 24 deletions
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96
kernel/include/buddy_allocator.hpp
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@ -65,39 +65,45 @@ public:
}
}
/*!
* \brief Compute the actual memory that will be reserved to
* allocate for this number of pages.
*/
size_t necessary_size(size_t pages){
if(pages <= max_block){
auto l = level(pages);
return level_size(l) * Unit;
} else if(pages <= max_block * static_bitmap::bits_per_word){
auto l = word_level(pages);
return word_level_size(l) * Unit;
} else {
//TODO Complete allocation for bigger blocks
return 0;
}
}
/*!
* \brief Allocate memory for the given amount of pages
*/
size_t allocate(size_t pages){
if(pages > max_block){
if(pages > max_block * static_bitmap::bits_per_word){
logging::logf(logging::log_level::ERROR, "buddy: Impossible to allocate more than 33M block:%u\n", pages);
//TODO Implement larger allocation
return 0;
} else {
// Select a level for which a whole word can hold the necessary pages
auto l = word_level(pages);
auto index = bitmaps[l].set_word();
auto address = block_start(l, index);
if(pages <= max_block){
// 1. In the easy case, at most one block of the highest
// level will be used
if(address + level_size(l) >= last_address){
logging::logf(logging::log_level::ERROR, "buddy: Address too high level:%u index:%u address:%h\n", l, index, address);
return 0;
}
//Mark all bits of the word as used
for(size_t b = 0; b < static_bitmap::bits_per_word; ++b){
mark_used(l, index + b);
}
return address;
}
} else {
auto l = level(pages);
auto index = bitmaps[l].set_bit();
if(index == static_bitmap::npos){
logging::logf(logging::log_level::ERROR, "buddy: There is no free bit pages:%u level:%u index:%u address:%h\n", pages, l, index);
return 0;
}
auto address = block_start(l, index);
if(address + level_size(l) >= last_address){
if(address + level_size(l) * Unit >= last_address){
logging::logf(logging::log_level::ERROR, "buddy: Address too high pages:%u level:%u index:%u address:%h\n", pages, l, index, address);
return 0;
}
@ -105,6 +111,41 @@ public:
mark_used(l, index);
return address;
} else if(pages <= max_block * static_bitmap::bits_per_word){
// 2. In the more complex case, several contiguous
// bits are used to form a bigger block, only
// within a single word
// Select a level for which a whole word can hold the necessary pages
auto l = word_level(pages);
auto index = bitmaps[l].set_word();
if(index == static_bitmap::npos){
logging::logf(logging::log_level::ERROR, "buddy: There is no free word pages:%u level:%u index:%u address:%h\n", pages, l, index);
return 0;
}
auto address = block_start(l, index);
if(address + word_level_size(l) * Unit >= last_address){
logging::logf(logging::log_level::ERROR, "buddy: Address too high level:%u index:%u address:%h\n", l, index, address);
return 0;
}
//Mark all bits of the word as used
for(size_t b = 0; b < static_bitmap::bits_per_word; ++b){
mark_used(l, index + b);
}
return address;
} else {
// 3 In the most complex case, several contiguous
// words are needed to form a bigger block
logging::logf(logging::log_level::ERROR, "buddy: Impossible to allocate more than 33M block:%u\n", pages);
//TODO Implement larger allocation
return 0;
}
}
@ -142,6 +183,13 @@ public:
return pow(2, level);
}
/*!
* \brief The size of the given level
*/
static size_t word_level_size(size_t level){
return static_bitmap::bits_per_word * pow(2, level);
}
private:
/*!
* \brief Returns the level to use for the given amount of pages