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Kernel: Pass "shared" flag to Region constructor

Browse source 
Before this change, we would sometimes map a region into the address
space with !is_shared(), and then moments later call set_shared(true).

I found this very confusing while debugging, so this patch makes us pass
the initial shared flag to the Region constructor, ensuring that it's in
the correct state by the time we first map the region.
This commit is contained in:
Andreas Kling 2021-01-02 16:38:05 +01:00
parent 1898aa8cd4
commit 5dae85afe7
10 changed files with 21 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

3
Kernel/Devices/BXVGADevice.cpp
View file

@ -191,7 +191,8 @@ KResultOr<Region*> BXVGADevice::mmap(Process& process, FileDescription&, Virtual
vmobject.release_nonnull(),
0,
"BXVGA Framebuffer",
prot);
prot,
shared);
if (!region)
return KResult(-ENOMEM);
dbg() << "BXVGADevice: mmap with size " << region->size() << " at " << region->vaddr();

3
Kernel/Devices/MBVGADevice.cpp
View file

@ -67,7 +67,8 @@ KResultOr<Region*> MBVGADevice::mmap(Process& process, FileDescription&, Virtual
vmobject.release_nonnull(),
0,
"MBVGA Framebuffer",
prot);
prot,
shared);
if (!region)
return KResult(-ENOMEM);
dbg() << "MBVGADevice: mmap with size " << region->size() << " at " << region->vaddr();

2
Kernel/FileSystem/InodeFile.cpp
View file

@ -79,7 +79,7 @@ KResultOr<Region*> InodeFile::mmap(Process& process, FileDescription& descriptio
vmobject = PrivateInodeVMObject::create_with_inode(inode());
if (!vmobject)
return KResult(-ENOMEM);
auto* region = process.allocate_region_with_vmobject(preferred_vaddr, size, *vmobject, offset, description.absolute_path(), prot);
auto* region = process.allocate_region_with_vmobject(preferred_vaddr, size, *vmobject, offset, description.absolute_path(), prot, shared);
if (!region)
return KResult(-ENOMEM);
return region;

8
Kernel/Process.cpp
View file

@ -163,7 +163,7 @@ Region* Process::allocate_region(VirtualAddress vaddr, size_t size, const String
return allocate_region(range, name, prot, strategy);
}
Region* Process::allocate_region_with_vmobject(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot)
Region* Process::allocate_region_with_vmobject(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool shared)
{
ASSERT(range.is_valid());
size_t end_in_vmobject = offset_in_vmobject + range.size();
@ -180,18 +180,18 @@ Region* Process::allocate_region_with_vmobject(const Range& range, NonnullRefPtr
return nullptr;
}
offset_in_vmobject &= PAGE_MASK;
auto& region = add_region(Region::create_user_accessible(this, range, move(vmobject), offset_in_vmobject, name, prot_to_region_access_flags(prot)));
auto& region = add_region(Region::create_user_accessible(this, range, move(vmobject), offset_in_vmobject, name, prot_to_region_access_flags(prot), true, shared));
if (!region.map(page_directory()))
return nullptr;
return &region;
}
Region* Process::allocate_region_with_vmobject(VirtualAddress vaddr, size_t size, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot)
Region* Process::allocate_region_with_vmobject(VirtualAddress vaddr, size_t size, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool shared)
{
auto range = allocate_range(vaddr, size);
if (!range.is_valid())
return nullptr;
return allocate_region_with_vmobject(range, move(vmobject), offset_in_vmobject, name, prot);
return allocate_region_with_vmobject(range, move(vmobject), offset_in_vmobject, name, prot, shared);
}
bool Process::deallocate_region(Region& region)

4
Kernel/Process.h
View file

@ -437,9 +437,9 @@ public:
return m_euid == 0;
}
Region* allocate_region_with_vmobject(VirtualAddress, size_t, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String& name, int prot);
Region* allocate_region_with_vmobject(VirtualAddress, size_t, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String& name, int prot, bool shared);
Region* allocate_region(VirtualAddress, size_t, const String& name, int prot = PROT_READ | PROT_WRITE, AllocationStrategy strategy = AllocationStrategy::Reserve);
Region* allocate_region_with_vmobject(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String& name, int prot);
Region* allocate_region_with_vmobject(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String& name, int prot, bool shared);
Region* allocate_region(const Range&, const String& name, int prot = PROT_READ | PROT_WRITE, AllocationStrategy strategy = AllocationStrategy::Reserve);
bool deallocate_region(Region& region);

3
Kernel/SharedBuffer.cpp
View file

@ -89,11 +89,10 @@ void* SharedBuffer::ref_for_process_and_get_address(Process& process)
for (auto& ref : m_refs) {
if (ref.pid == process.pid()) {
if (!ref.region) {
auto* region = process.allocate_region_with_vmobject(VirtualAddress(), size(), m_vmobject, 0, "SharedBuffer", PROT_READ | (m_writable ? PROT_WRITE : 0));
auto* region = process.allocate_region_with_vmobject(VirtualAddress(), size(), m_vmobject, 0, "SharedBuffer", PROT_READ | (m_writable ? PROT_WRITE : 0), true);
if (!region)
return (void*)-ENOMEM;
ref.region = region;
region->set_shared(true);
}
ref.count++;
m_total_refs++;

3
Kernel/Syscalls/execve.cpp
View file

@ -238,12 +238,11 @@ KResultOr<Process::LoadResult> Process::load_elf_object(FileDescription& object_
prot |= PROT_WRITE;
if (program_header.is_executable())
prot |= PROT_EXEC;
auto* region = allocate_region_with_vmobject(program_header.vaddr().offset(load_offset), program_header.size_in_memory(), *vmobject, program_header.offset(), elf_name, prot);
auto* region = allocate_region_with_vmobject(program_header.vaddr().offset(load_offset), program_header.size_in_memory(), *vmobject, program_header.offset(), elf_name, prot, true);
if (!region) {
ph_load_result = KResult(-ENOMEM);
return IterationDecision::Break;
}
region->set_shared(true);
if (program_header.offset() == 0)
load_base_address = (FlatPtr)region->vaddr().as_ptr();
return IterationDecision::Continue;

2
Kernel/Syscalls/mmap.cpp
View file

@ -438,7 +438,7 @@ void* Process::sys$mremap(Userspace<const Syscall::SC_mremap_params*> user_param
deallocate_region(*old_region);
auto new_vmobject = PrivateInodeVMObject::create_with_inode(inode);
auto* new_region = allocate_region_with_vmobject(range.base(), range.size(), new_vmobject, 0, old_name, old_prot);
auto* new_region = allocate_region_with_vmobject(range.base(), range.size(), new_vmobject, 0, old_name, old_prot, false);
new_region->set_mmap(true);
if (!new_region)

9
Kernel/VM/Region.cpp
View file

@ -40,13 +40,14 @@
namespace Kernel {
Region::Region(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, u8 access, bool cacheable, bool kernel)
Region::Region(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, u8 access, bool cacheable, bool kernel, bool shared)
: PurgeablePageRanges(vmobject)
, m_range(range)
, m_offset_in_vmobject(offset_in_vmobject)
, m_vmobject(move(vmobject))
, m_name(name)
, m_access(access)
, m_shared(shared)
, m_cacheable(cacheable)
, m_kernel(kernel)
{
@ -236,9 +237,9 @@ size_t Region::amount_shared() const
return bytes;
}
NonnullOwnPtr<Region> Region::create_user_accessible(Process* owner, const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable)
NonnullOwnPtr<Region> Region::create_user_accessible(Process* owner, const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable, bool shared)
{
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable, false);
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable, false, shared);
if (owner)
region->m_owner = owner->make_weak_ptr();
region->m_user_accessible = true;
@ -247,7 +248,7 @@ NonnullOwnPtr<Region> Region::create_user_accessible(Process* owner, const Range
NonnullOwnPtr<Region> Region::create_kernel_only(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable)
{
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable, true);
auto region = make<Region>(range, move(vmobject), offset_in_vmobject, name, access, cacheable, true, false);
region->m_user_accessible = false;
return region;
}

4
Kernel/VM/Region.h
View file

@ -61,7 +61,7 @@ public:
ZeroedOnFork,
};
static NonnullOwnPtr<Region> create_user_accessible(Process*, const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
static NonnullOwnPtr<Region> create_user_accessible(Process*, const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true, bool shared = false);
static NonnullOwnPtr<Region> create_kernel_only(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
~Region();
@ -182,7 +182,7 @@ public:
Region* m_prev { nullptr };
// NOTE: These are public so we can make<> them.
Region(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String&, u8 access, bool cacheable, bool kernel);
Region(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String&, u8 access, bool cacheable, bool kernel, bool shared);
void set_inherit_mode(InheritMode inherit_mode) { m_inherit_mode = inherit_mode; }