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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2026 Richard Qin */
/*
* Memory Management System Calls
*
* Implements: brk, mmap (anonymous only), munmap, mprotect.
*
* Reference: docs/specs/syscall.md §7.2
*/
#include <lume/types.h>
#include <lume/task.h>
#include <lume/vmm.h>
#include <lume/errno.h>
#include <lume/mman.h>
#include <lume/config.h>
#include <lume/klog.h>
/* Page alignment helpers */
static inline uint64 page_align_up(uint64 x)
{
return (x + kPageSize - 1) & ~(kPageSize - 1);
}
static inline uint64 page_align_down(uint64 x)
{
return x & ~(kPageSize - 1);
}
/* ======================================================================
* sys_brk
* ====================================================================== */
int64 sys_brk(uint64 new_brk, uint64, uint64, uint64, uint64, uint64)
{
VmSpace* mm = current_task()->mm;
if (!mm)
return -ENOMEM; /* kernel threads have no user address space */
if (new_brk == 0) {
return static_cast<int64>(mm->brk_end);
}
if (mm->brk_start == 0) {
uint64 init_brk = page_align_up(new_brk);
mm->brk_start = init_brk;
mm->brk_end = init_brk;
}
if (new_brk < mm->brk_start) {
return -EINVAL;
}
uint64 new_end = page_align_up(new_brk);
if (new_end > mm->brk_end) {
uint64 grow = new_end - mm->brk_end;
int ret = vmm_map_user(mm, mm->brk_end, grow, VM_READ | VM_WRITE);
if (ret < 0) {
return ret;
}
} else if (new_end < mm->brk_end) {
uint64 shrink = mm->brk_end - new_end;
int ret = vmm_unmap_user(mm, new_end, shrink);
if (ret < 0) {
return ret;
}
}
mm->brk_end = new_end;
return static_cast<int64>(new_brk);
}
/* ======================================================================
* sys_mmap
* ====================================================================== */
int64 sys_mmap(uint64 addr, uint64 length, uint64 prot,
uint64 flags, uint64 fd, uint64 offset)
{
printk("[mmap] addr=%llx len=%llx prot=%llx flags=%llx fd=%lld off=%llx\n",
addr, length, prot, flags, static_cast<int64>(fd), offset);
if (length == 0) return -EINVAL;
length = page_align_up(length);
if (offset % kPageSize != 0) return -EINVAL;
if ((flags & MAP_PRIVATE) && (flags & MAP_SHARED)) return -EINVAL;
if (!(flags & MAP_PRIVATE) && !(flags & MAP_SHARED)) return -EINVAL;
VmSpace* mm = current_task()->mm;
if (!mm) return -ENOMEM;
/* Phase 2: only anonymous private mappings */
if (!(flags & MAP_ANONYMOUS)) {
printk("[mmap] REJECTED: file-backed mmap not implemented\n");
return -ENOSYS; /* File-backed mmap is Phase 3 */
}
if (flags & MAP_SHARED)
return -ENOSYS; /* Shared mappings are Phase 3 */
(void)fd;
/* Convert POSIX prot → MI permission flags */
uint64 vm_perm = 0;
if (prot & PROT_READ) vm_perm |= VM_READ;
if (prot & PROT_WRITE) vm_perm |= VM_WRITE;
if (prot & PROT_EXEC) vm_perm |= VM_EXEC;
vm_perm |= VM_USER;
uint64 va = addr;
if (flags & MAP_FIXED) {
if (va % kPageSize != 0) return -EINVAL;
} else if (va != 0) {
va = page_align_down(va);
}
if (va == 0) {
va = mm_find_free_va(mm, length, kPageSize);
if (!va) return -ENOMEM;
}
if (flags & MAP_FIXED) {
int ret = vmm_unmap_user(mm, va, length);
if (ret < 0) return ret;
}
int ret = vmm_map_user(mm, va, length, vm_perm);
if (ret < 0 && !(flags & MAP_FIXED) && addr != 0) {
uint64 fallback = mm_find_free_va(mm, length, kPageSize);
if (!fallback) return ret;
ret = vmm_map_user(mm, fallback, length, vm_perm);
if (ret < 0) return ret;
va = fallback;
} else if (ret < 0) {
return ret;
}
return static_cast<int64>(va);
}
/* ======================================================================
* sys_munmap
* ====================================================================== */
int64 sys_munmap(uint64 addr, uint64 length, uint64, uint64, uint64, uint64)
{
if (length == 0) return -EINVAL;
if (addr % kPageSize != 0) return -EINVAL;
length = page_align_up(length);
VmSpace* mm = current_task()->mm;
if (!mm) return -EINVAL;
return vmm_unmap_user(mm, addr, length);
}
/* ======================================================================
* sys_mprotect — Phase 2 stub
* ====================================================================== */
int64 sys_mprotect(uint64 addr, uint64 len, uint64 prot,
uint64, uint64, uint64)
{
if (len == 0) return -EINVAL;
if (addr % kPageSize != 0) return -EINVAL;
VmSpace* mm = current_task()->mm;
if (!mm) return -ENOMEM;
uint64 vm_perm = 0;
if (prot & PROT_READ) vm_perm |= VM_READ;
if (prot & PROT_WRITE) vm_perm |= VM_WRITE;
if (prot & PROT_EXEC) vm_perm |= VM_EXEC;
return vmm_protect_user(mm, addr, len, vm_perm);
}
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