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Kernel/LibC: Implement MMAP_FIXED_NOREPLACE

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This is a handy thing from linux

Also fix MMAP_FIXED validation and error reporting
This commit is contained in:
Bananymous
2025-11-10 03:52:33 +02:00
parent 82c8eeb4be
commit f1d12c330e
4 changed files with 45 additions and 33 deletions
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1
kernel/include/kernel/Memory/MemoryRegion.h
View File

@@ -33,6 +33,7 @@ namespace Kernel
bool contains(vaddr_t address) const;
bool contains_fully(vaddr_t address, size_t size) const;
bool overlaps(vaddr_t address, size_t size) const;
bool is_contained_by(vaddr_t address, size_t size) const;
bool writable() const { return m_flags & PageTable::Flags::ReadWrite; }

5
kernel/kernel/Memory/MemoryRegion.cpp
View File

@@ -50,6 +50,11 @@ namespace Kernel
return true;
}
bool MemoryRegion::is_contained_by(vaddr_t address, size_t size) const
{
return address <= m_vaddr && m_vaddr + m_size <= address + size;
}
BAN::ErrorOr<void> MemoryRegion::mprotect(PageTable::flags_t new_page_flags)
{
if (m_flags == new_page_flags)

17
kernel/kernel/Process.cpp
View File

@@ -2221,28 +2221,33 @@ namespace Kernel
LockGuard _(m_process_lock);
AddressRange address_range { .start = 0x400000, .end = USERSPACE_END };
if (args.flags & MAP_FIXED)
if (args.flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))
{
const vaddr_t vaddr = reinterpret_cast<vaddr_t>(args.addr);
if (vaddr % PAGE_SIZE)
if (vaddr == 0 || vaddr % PAGE_SIZE)
return BAN::Error::from_errno(EINVAL);
if (!PageTable::is_valid_pointer(vaddr))
return BAN::Error::from_errno(ENOMEM);
if (!PageTable::is_valid_pointer(vaddr + args.len))
return BAN::Error::from_errno(ENOMEM);
address_range = {
.start = vaddr,
.end = vaddr + args.len,
};
for (size_t i = 0; i < m_mapped_regions.size(); i++)
if (args.flags & MAP_FIXED_NOREPLACE)
;
else for (size_t i = 0; i < m_mapped_regions.size(); i++)
{
if (!m_mapped_regions[i]->overlaps(vaddr, args.len))
continue;
if (!m_mapped_regions[i]->contains_fully(vaddr, args.len))
if (!m_mapped_regions[i]->is_contained_by(vaddr, args.len))
derrorln("VERY BROKEN MAP_FIXED UNMAP");
m_mapped_regions[i]->wait_not_pinned();
m_mapped_regions.remove(i--);
}
}
if (const vaddr_t vaddr = reinterpret_cast<vaddr_t>(args.addr); vaddr == 0)
else if (const vaddr_t vaddr = reinterpret_cast<vaddr_t>(args.addr); vaddr == 0)
;
else if (vaddr % PAGE_SIZE)
;