feat(syscall/mincore):实现了mincore系统调用 (#1258)

kaleidoscope416 · fslongjin · web-flow · commit be0c86d7ed77 · 2025-09-24T23:12:07.000+08:00
* feat(syscall/mincore):实现了mincore系统调用

* 往usebuffer直接写入，在get_page处改为拿一次锁

* 更改原先测试

* 完成can_do_mincore

* fmt

* fix(mm): 完善mincore系统调用实现

- 添加大页支持，在遇到大页时按4K粒度填充
- 修复地址对齐检查，将assert改为返回EINVAL错误
- 严格验证用户缓冲区映射与写权限
- 修复VMA查找和排序逻辑，确保地址连续性判断正确
- 添加覆盖完整性校验
- 重写mincore测试用例，增加边界条件和文件映射测试

Signed-off-by: longjin &lt;longjin@DragonOS.org&gt;

---------

Signed-off-by: longjin &lt;longjin@DragonOS.org&gt;
Co-authored-by: longjin &lt;longjin@DragonOS.org&gt;
diff --git a/kernel/src/mm/mincore.rs b/kernel/src/mm/mincore.rs
@@ -0,0 +1,124 @@
+use crate::arch::MMArch;
+use crate::{
+    arch::mm::PageMapper,
+    mm::{ucontext::LockedVMA, MemoryManagementArch, VirtAddr},
+};
+use system_error::SystemError;
+
+impl LockedVMA {
+    pub fn do_mincore(
+        &self,
+        mapper: &PageMapper,
+        vec: &mut [u8],
+        start_addr: VirtAddr,
+        end_addr: VirtAddr,
+        offset: usize,
+    ) -> Result<(), SystemError> {
+        let total_pages = (end_addr - start_addr) >> MMArch::PAGE_SHIFT;
+        if vec.len() < total_pages + offset {
+            return Err(SystemError::EINVAL);
+        }
+
+        if !self.can_do_mincore() {
+            let pages = (end_addr - start_addr) >> MMArch::PAGE_SHIFT;
+            vec[offset..offset + pages].fill(0);
+            return Ok(());
+        }
+        // 支持多级页表遍历；在遇到大页时按4K粒度填充
+        self.mincore_walk_page_range(mapper, start_addr, end_addr, 3, vec, offset);
+        Ok(())
+    }
+
+    fn mincore_walk_page_range(
+        &self,
+        mapper: &PageMapper,
+        start_addr: VirtAddr,
+        end_addr: VirtAddr,
+        level: usize,
+        vec: &mut [u8],
+        vec_offset: usize,
+    ) -> usize {
+        let mut page_count = 0;
+        let mut start = start_addr;
+        while start < end_addr {
+            let entry_size = MMArch::PAGE_SIZE << (level * MMArch::PAGE_ENTRY_SHIFT);
+            let next = core::cmp::min(end_addr, start + entry_size);
+            if let Some(entry) = mapper.get_entry(start, level) {
+                // 大页处理：当上层条目标记为大页时，按子页数量批量填充
+                if level > 0 && entry.flags().has_flag(MMArch::ENTRY_FLAG_HUGE_PAGE) {
+                    let sub_pages = (next - start) >> MMArch::PAGE_SHIFT;
+                    let val = if entry.present() { 1 } else { 0 };
+                    vec[vec_offset + page_count..vec_offset + page_count + sub_pages].fill(val);
+                    page_count += sub_pages;
+                } else if level > 0 {
+                    let sub_pages = self.mincore_walk_page_range(
+                        mapper,
+                        start,
+                        next,
+                        level - 1,
+                        vec,
+                        vec_offset + page_count,
+                    );
+                    page_count += sub_pages;
+                } else {
+                    vec[vec_offset + page_count] = if entry.present() { 1 } else { 0 };
+                    page_count += 1;
+                }
+            } else {
+                let unmapped_pages =
+                    self.mincore_unmapped_range(start, next, vec, vec_offset + page_count);
+                page_count += unmapped_pages;
+            }
+            start = next;
+        }
+        page_count
+    }
+
+    fn mincore_unmapped_range(
+        &self,
+        start_addr: VirtAddr,
+        end_addr: VirtAddr,
+        vec: &mut [u8],
+        vec_offset: usize,
+    ) -> usize {
+        let nr = (end_addr - start_addr) >> MMArch::PAGE_SHIFT;
+        if self.is_anonymous() {
+            vec[vec_offset..vec_offset + nr].fill(0);
+        } else {
+            let guard = self.lock_irqsave();
+            let pgoff = ((start_addr - guard.region().start()) >> MMArch::PAGE_SHIFT)
+                + guard.file_page_offset().unwrap();
+            if guard.vm_file().is_none() {
+                vec[vec_offset..vec_offset + nr].fill(0);
+                return nr;
+            }
+            let page_cache = guard.vm_file().unwrap().inode().page_cache();
+            match page_cache {
+                Some(page_cache) => {
+                    let cache_guard = page_cache.lock_irqsave();
+                    for i in 0..nr {
+                        if cache_guard.get_page(pgoff + i).is_some() {
+                            vec[vec_offset + i] = 1;
+                        } else {
+                            vec[vec_offset + i] = 0;
+                        }
+                    }
+                }
+                None => {
+                    vec[vec_offset..vec_offset + nr].fill(0);
+                }
+            }
+        }
+        nr
+    }
+
+    pub fn can_do_mincore(&self) -> bool {
+        //todo: 没有实现vm_ops,这里只能找到匿名映射和文件映射。对于设备映射和其他特殊映射（对应linux中vm_ops有值，但不是文件映射的vma），返回false
+        if self.is_accessible() {
+            return true;
+        } else {
+            //todo: 若文件不是当前用户所有，需要当前用户对文件有写权限,否则返回false
+            return true;
+        }
+    }
+}
diff --git a/kernel/src/mm/mod.rs b/kernel/src/mm/mod.rs
@@ -27,6 +27,7 @@ pub mod init;
 pub mod kernel_mapper;
 pub mod madvise;
 pub mod memblock;
+pub mod mincore;
 pub mod mmio_buddy;
 pub mod no_init;
 pub mod page;
diff --git a/kernel/src/mm/syscall/sys_mincore.rs b/kernel/src/mm/syscall/sys_mincore.rs
@@ -1,8 +1,15 @@
 use crate::arch::interrupt::TrapFrame;
 use crate::arch::syscall::nr::SYS_MINCORE;
+use crate::arch::MMArch;
+use crate::libs::align::page_align_up;
+use crate::mm::allocator::page_frame::{PageFrameCount, VirtPageFrame};
+use crate::mm::ucontext::AddressSpace;
+use crate::mm::{verify_area, MemoryManagementArch};
 use crate::syscall::table::{FormattedSyscallParam, Syscall};
+use crate::syscall::user_access::UserBufferWriter;
 use system_error::SystemError;
 
+use crate::mm::VirtAddr;
 use alloc::vec::Vec;
 
 pub struct SysMincoreHandle;
@@ -14,9 +21,39 @@ impl Syscall for SysMincoreHandle {
 
     /// ## mincore系统调用
     ///
-    /// todo: 参考 https://code.dragonos.org.cn/xref/linux-6.6.21/mm/mincore.c#232 实现mincore
-    fn handle(&self, _args: &[usize], _frame: &mut TrapFrame) -> Result<usize, SystemError> {
-        return Err(SystemError::ENOSYS);
+    /// ## 参数
+    ///
+    /// - `start_vaddr`：起始地址(已经对齐到页)
+    /// - `len`：需要遍历的长度
+    /// - `vec`：用户空间的vec指针
+    fn handle(&self, args: &[usize], _frame: &mut TrapFrame) -> Result<usize, SystemError> {
+        let start_vaddr = VirtAddr::new(Self::start_vaddr(args));
+        let len = Self::len(args);
+        let vec = Self::vec(args);
+        // 未对齐返回 EINVAL，而不是触发 panic
+        if !start_vaddr.check_aligned(MMArch::PAGE_SIZE) {
+            return Err(SystemError::EINVAL);
+        }
+
+        if verify_area(start_vaddr, len).is_err() {
+            return Err(SystemError::ENOMEM);
+        }
+        if len == 0 {
+            return Err(SystemError::EINVAL);
+        }
+        let len = page_align_up(len);
+        let current_address_space = AddressSpace::current()?;
+        let start_frame = VirtPageFrame::new(start_vaddr);
+        let page_count = len >> MMArch::PAGE_SHIFT;
+
+        // 严格验证 vec 映射与写权限，失败返回 EFAULT
+        let mut writer = UserBufferWriter::new_checked(vec as *mut u8, page_count, true)?;
+        let buf: &mut [u8] = writer.buffer(0)?;
+        let page_count = PageFrameCount::new(page_count);
+        current_address_space
+            .read()
+            .mincore(start_frame, page_count, buf)?;
+        return Ok(0);
     }
 
     /// Formats the syscall arguments for display/debugging purposes.
diff --git a/kernel/src/mm/ucontext.rs b/kernel/src/mm/ucontext.rs
@@ -398,7 +398,7 @@ impl InnerAddressSpace {
         drop(fd_table_guard);
 
         // offset需要4K对齐
-        if !offset & (MMArch::PAGE_SIZE - 1) == 0 {
+        if (offset & (MMArch::PAGE_SIZE - 1)) != 0 {
             return Err(SystemError::EINVAL);
         }
         let pgoff = offset >> MMArch::PAGE_SHIFT;
@@ -435,7 +435,10 @@ impl InnerAddressSpace {
         // todo!(impl mmap for other file)
         // https://github.com/DragonOS-Community/DragonOS/pull/912#discussion_r1765334272
         let file = file.unwrap();
-        let _ = file.inode().mmap(start_vaddr.data(), len, offset);
+        // 传入实际映射后的起始虚拟地址，而非用户传入的 hint
+        let _ = file
+            .inode()
+            .mmap(start_page.virt_address().data(), len, offset);
         return Ok(start_page);
     }
 
@@ -704,6 +707,45 @@ impl InnerAddressSpace {
         return Ok(());
     }
 
+    pub fn mincore(
+        &self,
+        start_page: VirtPageFrame,
+        page_count: PageFrameCount,
+        vec: &mut [u8],
+    ) -> Result<(), SystemError> {
+        let mapper = &self.user_mapper.utable;
+
+        if self.mappings.contains(start_page.virt_address()).is_none() {
+            return Err(SystemError::ENOMEM);
+        }
+
+        let mut last_vaddr = start_page.virt_address();
+        let region = VirtRegion::new(start_page.virt_address(), page_count.bytes());
+        let mut vmas = self.mappings.conflicts(region).collect::<Vec<_>>();
+        // 为保证与地址连续性的判断正确，这里按起始地址升序遍历
+        vmas.sort_by_key(|v| v.lock_irqsave().region().start().data());
+        let mut offset = 0;
+        for v in vmas {
+            let region = *v.lock_irqsave().region();
+            // 保证相邻的两个vma连续
+            if region.start() != last_vaddr && last_vaddr != start_page.virt_address() {
+                return Err(SystemError::ENOMEM);
+            }
+            let start_vaddr = last_vaddr;
+            let end_vaddr = core::cmp::min(region.end(), start_vaddr + page_count.bytes());
+            v.do_mincore(mapper, vec, start_vaddr, end_vaddr, offset)?;
+            let page_count_this_vma = (end_vaddr - start_vaddr) >> MMArch::PAGE_SHIFT;
+            offset += page_count_this_vma;
+            last_vaddr = end_vaddr;
+        }
+
+        // 校验覆盖完整性：若末尾未覆盖到请求范围，则返回 ENOMEM
+        if last_vaddr != region.end() {
+            return Err(SystemError::ENOMEM);
+        }
+
+        return Ok(());
+    }
     pub fn madvise(
         &mut self,
         start_page: VirtPageFrame,
@@ -974,9 +1016,10 @@ impl UserMappings {
             if guard.region.contains(vaddr) {
                 return Some(v.clone());
             }
-            if guard.region.start >= vaddr
-                && if let Some(ref nearest) = nearest {
-                    guard.region.start < nearest.lock_irqsave().region.start
+            // 选择起始地址不大于 vaddr 的 VMA 中，起始地址最大的一个
+            if guard.region.start <= vaddr
+                && if let Some(ref current) = nearest {
+                    guard.region.start > current.lock_irqsave().region.start
                 } else {
                     true
                 }
diff --git a/user/apps/c_unitest/test_mincore.c b/user/apps/c_unitest/test_mincore.c
