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Kernel: Make Region single-owner instead of ref-counted

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This simplifies the ownership model and makes Region easier to reason
about. Userspace Regions are now primarily kept by Process::m_regions.

Kernel Regions are kept in various OwnPtr<Regions>'s.

Regions now only ever get unmapped when they are destroyed.
This commit is contained in:
Andreas Kling 2019-09-27 14:19:07 +02:00
parent 7a7f6a24e9
commit 7f9a33dba1
9 changed files with 44 additions and 41 deletions
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21
Kernel/Process.cpp
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@ -152,7 +152,6 @@ bool Process::deallocate_region(Region& region)
InterruptDisabler disabler;
for (int i = 0; i < m_regions.size(); ++i) {
if (&m_regions[i] == &region) {
MM.unmap_region(region);
m_regions.remove(i);
return true;
}
@ -305,12 +304,11 @@ Process* Process::fork(RegisterDump& regs)
#ifdef FORK_DEBUG
dbg() << "fork: cloning Region{" << &region << "} '" << region.name() << "' @ " << region.vaddr();
#endif
auto cloned_region = region.clone();
child->m_regions.append(move(cloned_region));
child->m_regions.append(region.clone());
MM.map_region(*child, child->m_regions.last());
if (&region == m_master_tls_region)
child->m_master_tls_region = child->m_regions.last();
child->m_master_tls_region = &child->m_regions.last();
}
for (auto gid : m_gids)
@ -401,10 +399,14 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
ASSERT(description->inode());
auto vmo = InodeVMObject::create_with_inode(*description->inode());
RefPtr<Region> region = allocate_region_with_vmo(VirtualAddress(), metadata.size, vmo, 0, description->absolute_path(), PROT_READ);
auto* region = allocate_region_with_vmo(VirtualAddress(), metadata.size, vmo, 0, description->absolute_path(), PROT_READ);
ASSERT(region);
RefPtr<Region> master_tls_region;
// NOTE: We yank this out of 'm_regions' since we're about to manipulate the vector
// and we don't want it getting lost.
auto executable_region = m_regions.take_last();
Region* master_tls_region { nullptr };
size_t master_tls_size = 0;
size_t master_tls_alignment = 0;
@ -412,7 +414,7 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
{
// Okay, here comes the sleight of hand, pay close attention..
auto old_regions = move(m_regions);
m_regions.append(*region);
m_regions.append(move(executable_region));
loader = make<ELFLoader>(region->vaddr().as_ptr());
loader->map_section_hook = [&](VirtualAddress vaddr, size_t size, size_t alignment, size_t offset_in_image, bool is_readable, bool is_writable, bool is_executable, const String& name) {
ASSERT(size);
@ -451,6 +453,7 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
// FIXME: RAII this somehow instead.
ASSERT(&current->process() == this);
MM.enter_process_paging_scope(*this);
executable_region = m_regions.take_first();
m_regions = move(old_regions);
kprintf("do_exec: Failure loading %s\n", path.characters());
return -ENOEXEC;
@ -464,7 +467,7 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
m_executable = description->custody();
// Copy of the master TLS region that we will clone for new threads
m_master_tls_region = master_tls_region.ptr();
m_master_tls_region = master_tls_region;
if (metadata.is_setuid())
m_euid = metadata.uid;
@ -823,7 +826,7 @@ void create_signal_trampolines()
InterruptDisabler disabler;
// NOTE: We leak this region.
auto* trampoline_region = MM.allocate_user_accessible_kernel_region(PAGE_SIZE, "Signal trampolines").leak_ref();
auto* trampoline_region = MM.allocate_user_accessible_kernel_region(PAGE_SIZE, "Signal trampolines").leak_ptr();
g_return_to_ring3_from_signal_trampoline = trampoline_region->vaddr();
u8* trampoline = (u8*)asm_signal_trampoline;