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Kernel: Protect processes' master TLS with a fine-grained spinlock

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This moves it out of the scope of the big process lock, and allows us
to wean some syscalls off it, starting with sys$allocate_tls.
This commit is contained in:
Idan Horowitz 2023-12-16 12:37:28 +02:00 • committed by Andreas Kling
parent cd56ec6e5c
commit 6a4b93b3e0
7 changed files with 91 additions and 86 deletions
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32
Kernel/Syscalls/fork.cpp
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@ -158,21 +158,27 @@ ErrorOr<FlatPtr> Process::sys$fork(RegisterState& regs)
#endif
TRY(address_space().with([&](auto& parent_space) {
return child->address_space().with([&](auto& child_space) -> ErrorOr<void> {
child_space->set_enforces_syscall_regions(parent_space->enforces_syscall_regions());
for (auto& region : parent_space->region_tree().regions()) {
dbgln_if(FORK_DEBUG, "fork: cloning Region '{}' @ {}", region.name(), region.vaddr());
auto region_clone = TRY(region.try_clone());
TRY(region_clone->map(child_space->page_directory(), Memory::ShouldFlushTLB::No));
TRY(child_space->region_tree().place_specifically(*region_clone, region.range()));
auto* child_region = region_clone.leak_ptr();
return m_master_tls.with([&](auto& parent_master_tls) -> ErrorOr<void> {
return child->address_space().with([&](auto& child_space) -> ErrorOr<void> {
child_space->set_enforces_syscall_regions(parent_space->enforces_syscall_regions());
for (auto& region : parent_space->region_tree().regions()) {
dbgln_if(FORK_DEBUG, "fork: cloning Region '{}' @ {}", region.name(), region.vaddr());
auto region_clone = TRY(region.try_clone());
TRY(region_clone->map(child_space->page_directory(), Memory::ShouldFlushTLB::No));
TRY(child_space->region_tree().place_specifically(*region_clone, region.range()));
auto* child_region = region_clone.leak_ptr();
if (&region == m_master_tls_region.unsafe_ptr()) {
child->m_master_tls_region = TRY(child_region->try_make_weak_ptr());
child->m_master_tls_size = m_master_tls_size;
child->m_master_tls_alignment = m_master_tls_alignment;
if (&region == parent_master_tls.region.unsafe_ptr()) {
TRY(child->m_master_tls.with([&](auto& child_master_tls) -> ErrorOr<void> {
child_master_tls.region = TRY(child_region->try_make_weak_ptr());
child_master_tls.size = parent_master_tls.size;
child_master_tls.alignment = parent_master_tls.alignment;
return {};
}));
}
}
}
return {};
});
return {};
});
}));