[LINUX/BASE] Fixed mmap usage and (re)-implemented most parts of memory_posix.cc #2230
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Gliniak
reviewed
Oct 2, 2023
| flags |= MAP_FIXED_NOREPLACE; | ||
| } | ||
| void* result = mmap(base_address, length, prot, flags, -1, 0); | ||
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| if (result == MAP_FAILED) { |
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I would personally reverse this statement to prevent nesting.
aka.
if (result != MAP_FAILED) {
return result;
}
<remaining code without else>
src/xenia/base/memory_posix.cc
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| if (result == MAP_FAILED) { | ||
| // If the address is within this range, the mmap failed because we have | ||
| // already mapped this memory. | ||
| size_t region_begin = (size_t)base_address; |
src/xenia/base/memory_posix.cc
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| size_t region_end = (size_t)base_address + length; | ||
| for (const auto mapped_range : mapped_file_ranges) { | ||
| // Check if the allocation is within this range... | ||
| if (region_begin >= mapped_range.region_begin && |
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Maybe same thing as above. Reverse this condition and check for less nesting.
When it is outside of region then just return nullptr
src/xenia/base/memory_posix.cc
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| int flags = MAP_SHARED; | ||
| if (base_address != nullptr) { | ||
| flags = flags | MAP_FIXED_NOREPLACE; |
src/xenia/base/memory_posix.cc
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| if (result == MAP_FAILED) { | ||
| return nullptr; | ||
| }else { |
src/xenia/base/memory_posix.cc
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| @@ -96,6 +127,15 @@ void* AllocFixed(void* base_address, size_t length, | |||
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| bool DeallocFixed(void* base_address, size_t length, | |||
| DeallocationType deallocation_type) { | |||
| size_t region_begin = (size_t)base_address; | |||
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So I did implement some of these recommendations. I also added a mutex to avoid race conditions in multi-threaded scenarios. |
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RodoMa92
reviewed
Jan 18, 2024
| return munmap(base_address, length) == 0; | ||
| default: | ||
| assert_unhandled_case(deallocation_type); | ||
| } |
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In a release build the compiler here complained that there is no return value for all control paths. Just add a return false at the end of the function just to make it happy for now.
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As the title says. Previously the MapFileView function did not take into account the handle argument, as it used the MAP_ANONYMOUS and the MAP_PRIVATE flags.
Additionally, AllocFixed used mmap and DeallocFixed used munmap always, with the MAP_FIXED flag. This was not ideal for several reasons:
For more information regarding mmap, see:
https://man7.org/linux/man-pages/man2/mmap.2.html