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Support basic mmap'ing of a file!

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All right, we can now mmap() a file and it gets magically paged in from fs
in response to an NP page fault. This is really cool :^)

I need to refactor this to support sharing of read-only file-backed pages,
but it's cool to just have something working.
This commit is contained in:
Andreas Kling 2018-11-08 12:59:16 +01:00
parent fdbd9f1e27
commit 3c8064a787
8 changed files with 141 additions and 14 deletions
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54
Kernel/Process.cpp
View file

@ -106,6 +106,28 @@ Region* Process::allocate_region(LinearAddress laddr, size_t size, String&& name
return m_regions.last().ptr();
}
Region* Process::allocate_file_backed_region(LinearAddress laddr, size_t size, RetainPtr<VirtualFileSystem::Node>&& vnode, String&& name, bool is_readable, bool is_writable)
{
ASSERT(!vnode->isCharacterDevice());
// FIXME: This needs sanity checks. What if this overlaps existing regions?
if (laddr.is_null()) {
laddr = m_nextRegion;
m_nextRegion = m_nextRegion.offset(size).offset(PAGE_SIZE);
}
laddr.mask(0xfffff000);
unsigned page_count = ceilDiv(size, PAGE_SIZE);
Vector<RetainPtr<PhysicalPage>> physical_pages;
physical_pages.resize(page_count); // Start out with no physical pages!
m_regions.append(adopt(*new Region(laddr, size, move(physical_pages), move(name), is_readable, is_writable)));
m_regions.last()->m_vnode = move(vnode);
MM.mapRegion(*this, *m_regions.last());
return m_regions.last().ptr();
}
bool Process::deallocate_region(Region& region)
{
InterruptDisabler disabler;
@ -141,19 +163,41 @@ int Process::sys$set_mmap_name(void* addr, size_t size, const char* name)
void* Process::sys$mmap(const Syscall::SC_mmap_params* params)
{
VALIDATE_USER_READ_WITH_RETURN_TYPE(params, sizeof(Syscall::SC_mmap_params), void*);
InterruptDisabler disabler;
void* addr = (void*)params->addr;
size_t size = params->size;
int prot = params->prot;
int flags = params->flags;
int fd = params->fd;
Unix::off_t offset = params->offset;
// FIXME: Implement mapping at a client-preferred address. Most of the support is already in plcae.
if (size == 0)
return (void*)-EINVAL;
if ((dword)addr & ~PAGE_MASK || size & ~PAGE_MASK)
return (void*)-EINVAL;
if (flags & MAP_ANONYMOUS) {
InterruptDisabler disabler;
// FIXME: Implement mapping at a client-specified address. Most of the support is already in plcae.
ASSERT(addr == nullptr);
auto* region = allocate_region(LinearAddress(), size, "mmap", prot & PROT_READ, prot & PROT_WRITE);
if (!region)
return (void*)-ENOMEM;
return region->linearAddress.asPtr();
}
if (offset & ~PAGE_MASK)
return (void*)-EINVAL;
auto* descriptor = file_descriptor(fd);
if (!descriptor)
return (void*)-EBADF;
if (descriptor->vnode()->isCharacterDevice())
return (void*)-ENODEV;
// FIXME: If PROT_EXEC, check that the underlying file system isn't mounted noexec.
auto region_name = descriptor->absolute_path();
InterruptDisabler disabler;
// FIXME: Implement mapping at a client-specified address. Most of the support is already in plcae.
ASSERT(addr == nullptr);
auto* region = allocate_region(LinearAddress(), size, "mmap");
auto* region = allocate_file_backed_region(LinearAddress(), size, descriptor->vnode(), move(region_name), prot & PROT_READ, prot & PROT_WRITE);
if (!region)
return (void*)-1;
return (void*)region->linearAddress.get();
return (void*)-ENOMEM;
return region->linearAddress.asPtr();
}
int Process::sys$munmap(void* addr, size_t size)