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Kernel: Hoist VM range allocation up to sys$mmap() itself

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Instead of letting each File subclass do range allocation in their
mmap() override, do it up front in sys$mmap().

This makes us honor alignment requests for file-backed memory mappings
and simplifies the code somwhat.
This commit is contained in:
Andreas Kling 2021-01-25 14:52:36 +01:00
parent adcc1c1eff
commit ab14b0ac64
13 changed files with 26 additions and 36 deletions
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20
Kernel/Syscalls/mmap.cpp
View file

@ -133,16 +133,13 @@ void* Process::sys$mmap(Userspace<const Syscall::SC_mmap_params*> user_params)
return (void*)-EINVAL;
Region* region = nullptr;
Optional<Range> range;
if (map_noreserve || map_anonymous) {
range = allocate_range(VirtualAddress(addr), size, alignment);
if (!range.value().is_valid())
return (void*)-ENOMEM;
}
auto range = allocate_range(VirtualAddress(addr), size, alignment);
if (!range.is_valid())
return (void*)-ENOMEM;
if (map_anonymous) {
auto strategy = map_noreserve ? AllocationStrategy::None : AllocationStrategy::Reserve;
auto region_or_error = allocate_region(range.value(), !name.is_null() ? name : "mmap", prot, strategy);
auto region_or_error = allocate_region(range, !name.is_null() ? name : "mmap", prot, strategy);
if (region_or_error.is_error() && (!map_fixed && addr != 0))
region_or_error = allocate_region(allocate_range({}, size), !name.is_null() ? name : "mmap", prot, strategy);
if (region_or_error.is_error())
@ -169,13 +166,8 @@ void* Process::sys$mmap(Userspace<const Syscall::SC_mmap_params*> user_params)
if (!validate_inode_mmap_prot(*this, prot, *description->inode(), map_shared))
return (void*)-EACCES;
}
auto region_or_error = description->mmap(*this, VirtualAddress(addr), static_cast<size_t>(offset), size, prot, map_shared);
if (region_or_error.is_error()) {
// Fail if MAP_FIXED or address is 0, retry otherwise
if (map_fixed || addr == 0)
return (void*)region_or_error.error().error();
region_or_error = description->mmap(*this, {}, static_cast<size_t>(offset), size, prot, map_shared);
}
auto region_or_error = description->mmap(*this, range, static_cast<size_t>(offset), prot, map_shared);
if (region_or_error.is_error())
return (void*)region_or_error.error().error();
region = region_or_error.value();