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Kernel+LibC: Add a very limited sys$mremap() implementation

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This syscall can currently only remap a shared file-backed mapping into
a private file-backed mapping.
This commit is contained in:
Andreas Kling 2020-12-29 02:11:47 +01:00
parent c1360ef22e
commit 30dbe9c78a
6 changed files with 71 additions and 1 deletions
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37
Kernel/Syscalls/mmap.cpp
View file

@ -28,6 +28,7 @@
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
#include <Kernel/VM/PageDirectory.h>
#include <Kernel/VM/PrivateInodeVMObject.h>
#include <Kernel/VM/PurgeableVMObject.h>
#include <Kernel/VM/Region.h>
#include <Kernel/VM/SharedInodeVMObject.h>
@ -422,6 +423,42 @@ int Process::sys$munmap(void* addr, size_t size)
return -EINVAL;
}
void* Process::sys$mremap(Userspace<const Syscall::SC_mremap_params*> user_params)
{
REQUIRE_PROMISE(stdio);
Syscall::SC_mremap_params params;
if (!copy_from_user(&params, user_params))
return (void*)-EFAULT;
auto* old_region = find_region_from_range(Range { VirtualAddress(params.old_address), params.old_size });
if (!old_region)
return (void*)-EINVAL;
if (!old_region->is_mmap())
return (void*)-EPERM;
if (old_region->vmobject().is_shared_inode() && params.flags & MAP_PRIVATE && !(params.flags & MAP_ANONYMOUS) && !(params.flags & MAP_PURGEABLE)) {
auto range = old_region->range();
auto old_name = old_region->name();
auto old_prot = region_access_flags_to_prot(old_region->access());
NonnullRefPtr inode = static_cast<SharedInodeVMObject&>(old_region->vmobject()).inode();
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);
new_region->set_mmap(true);
if (!new_region)
return (void*)-ENOMEM;
return new_region->vaddr().as_ptr();
}
dbgln("sys$mremap: Unimplemented remap request (flags={})", params.flags);
return (void*)-ENOTIMPL;
}
void* Process::sys$allocate_tls(size_t size)
{
REQUIRE_PROMISE(stdio);