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From: yulei.kernel@gmail.com
To: akpm@linux-foundation.org, naoya.horiguchi@nec.com,
	viro@zeniv.linux.org.uk, pbonzini@redhat.com
Cc: linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, xiaoguangrong.eric@gmail.com,
	kernellwp@gmail.com, lihaiwei.kernel@gmail.com,
	Yulei Zhang <yuleixzhang@tencent.com>,
	Xiao Guangrong <gloryxiao@tencent.com>
Subject: [PATCH 09/35] dmemfs: support remote access
Date: Thu,  8 Oct 2020 15:53:59 +0800	[thread overview]
Message-ID: <0b749ec1fab63b2d8ee2354f576579fe23917c26.1602093760.git.yuleixzhang@tencent.com> (raw)
In-Reply-To: <cover.1602093760.git.yuleixzhang@tencent.com>
In-Reply-To: <cover.1602093760.git.yuleixzhang@tencent.com>

From: Yulei Zhang <yuleixzhang@tencent.com>

It is required by ptrace_writedata and ptrace_readdata to access
dmem memory remotely. The typical user is gdb, after this patch,
gdb is able to read & write memory owned by the attached process

Signed-off-by: Xiao Guangrong <gloryxiao@tencent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
---
 fs/dmemfs/inode.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/fs/dmemfs/inode.c b/fs/dmemfs/inode.c
index 8b0516d98ee7..4dacbf7e6844 100644
--- a/fs/dmemfs/inode.c
+++ b/fs/dmemfs/inode.c
@@ -367,6 +367,51 @@ static void radix_put_entry(void)
 	rcu_read_unlock();
 }
 
+static bool check_vma_access(struct vm_area_struct *vma, int write)
+{
+	vm_flags_t vm_flags = write ? VM_WRITE : VM_READ;
+
+	return !!(vm_flags & vma->vm_flags);
+}
+
+static int
+dmemfs_access_dmem(struct vm_area_struct *vma, unsigned long addr,
+		   void *buf, int len, int write)
+{
+	struct inode *inode = file_inode(vma->vm_file);
+	struct super_block *sb = inode->i_sb;
+	void *entry, *maddr;
+	int offset, pgoff;
+
+	if (!check_vma_access(vma, write))
+		return -EACCES;
+
+	pgoff = linear_page_index(vma, addr);
+	if (pgoff > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
+		return -EFAULT;
+
+	entry = radix_get_create_entry(vma, addr, inode, pgoff);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
+
+	offset = addr & (sb->s_blocksize - 1);
+	addr = dmem_entry_to_addr(inode, entry);
+
+	/*
+	 * it is not beyond vma's region as the vma should be aligned
+	 * to blocksize
+	 */
+	len = min(len, (int)(sb->s_blocksize - offset));
+	maddr = __va(addr);
+	if (write)
+		memcpy(maddr + offset, buf, len);
+	else
+		memcpy(buf, maddr + offset, len);
+	radix_put_entry();
+
+	return len;
+}
+
 static vm_fault_t dmemfs_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
@@ -403,6 +448,7 @@ static unsigned long dmemfs_pagesize(struct vm_area_struct *vma)
 static const struct vm_operations_struct dmemfs_vm_ops = {
 	.fault = dmemfs_fault,
 	.pagesize = dmemfs_pagesize,
+	.access = dmemfs_access_dmem,
 };
 
 int dmemfs_file_mmap(struct file *file, struct vm_area_struct *vma)
-- 
2.28.0


  parent reply	other threads:[~2020-10-08  7:54 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-08  7:53 [PATCH 00/35] Enhance memory utilization with DMEMFS yulei.kernel
2020-10-08  7:53 ` [PATCH 01/35] fs: introduce dmemfs module yulei.kernel
2020-11-10 20:04   ` Al Viro
2020-11-11  8:53     ` yulei zhang
2020-11-11 23:09       ` Al Viro
2020-11-12 10:03         ` yulei zhang
2020-10-08  7:53 ` [PATCH 02/35] mm: support direct memory reservation yulei.kernel
2020-10-08 20:27   ` Randy Dunlap
2020-10-08 20:34   ` Randy Dunlap
2020-10-08  7:53 ` [PATCH 03/35] dmem: implement dmem memory management yulei.kernel
2020-10-08  7:53 ` [PATCH 04/35] dmem: let pat recognize dmem yulei.kernel
2020-10-13  7:27   ` Paolo Bonzini
2020-10-13  9:53     ` yulei zhang
2020-10-08  7:53 ` [PATCH 05/35] dmemfs: support mmap yulei.kernel
2020-10-08  7:53 ` [PATCH 06/35] dmemfs: support truncating inode down yulei.kernel
2020-10-08  7:53 ` [PATCH 07/35] dmem: trace core functions yulei.kernel
2020-10-08  7:53 ` [PATCH 08/35] dmem: show some statistic in debugfs yulei.kernel
2020-10-08 20:23   ` Randy Dunlap
2020-10-09 11:49     ` yulei zhang
2020-10-08  7:53 ` yulei.kernel [this message]
2020-10-08  7:54 ` [PATCH 10/35] dmemfs: introduce max_alloc_try_dpages parameter yulei.kernel
2020-10-08  7:54 ` [PATCH 11/35] mm: export mempolicy interfaces to serve dmem allocator yulei.kernel
2020-10-08  7:54 ` [PATCH 12/35] dmem: introduce mempolicy support yulei.kernel
2020-10-08  7:54 ` [PATCH 13/35] mm, dmem: introduce PFN_DMEM and pfn_t_dmem yulei.kernel
2020-10-08  7:54 ` [PATCH 14/35] mm, dmem: dmem-pmd vs thp-pmd yulei.kernel
2020-10-08  7:54 ` [PATCH 15/35] mm: add pmd_special() check for pmd_trans_huge_lock() yulei.kernel
2020-10-08  7:54 ` [PATCH 16/35] dmemfs: introduce ->split() to dmemfs_vm_ops yulei.kernel
2020-10-08  7:54 ` [PATCH 17/35] mm, dmemfs: support unmap_page_range() for dmemfs pmd yulei.kernel
2020-10-08  7:54 ` [PATCH 18/35] mm: follow_pmd_mask() for dmem huge pmd yulei.kernel
2020-10-08  7:54 ` [PATCH 19/35] mm: gup_huge_pmd() " yulei.kernel
2020-10-08  7:54 ` [PATCH 20/35] mm: support dmem huge pmd for vmf_insert_pfn_pmd() yulei.kernel
2020-10-08  7:54 ` [PATCH 21/35] mm: support dmem huge pmd for follow_pfn() yulei.kernel
2020-10-08  7:54 ` [PATCH 22/35] kvm, x86: Distinguish dmemfs page from mmio page yulei.kernel
2020-10-09  0:58   ` Sean Christopherson
2020-10-09 10:28     ` Joao Martins
2020-10-09 11:42       ` yulei zhang
2020-10-08  7:54 ` [PATCH 23/35] kvm, x86: introduce VM_DMEM yulei.kernel
2020-10-08  7:54 ` [PATCH 24/35] dmemfs: support hugepage for dmemfs yulei.kernel
2020-10-08  7:54 ` [PATCH 25/35] mm, x86, dmem: fix estimation of reserved page for vaddr_get_pfn() yulei.kernel
2020-10-08  7:54 ` [PATCH 26/35] mm, dmem: introduce pud_special() yulei.kernel
2020-10-08  7:54 ` [PATCH 27/35] mm: add pud_special() to support dmem huge pud yulei.kernel
2020-10-08  7:54 ` [PATCH 28/35] mm, dmemfs: support huge_fault() for dmemfs yulei.kernel
2020-10-08  7:54 ` [PATCH 29/35] mm: add follow_pte_pud() yulei.kernel
2020-10-08  7:54 ` [PATCH 30/35] dmem: introduce dmem_bitmap_alloc() and dmem_bitmap_free() yulei.kernel
2020-10-08  7:54 ` [PATCH 31/35] dmem: introduce mce handler yulei.kernel
2020-10-08  7:54 ` [PATCH 32/35] mm, dmemfs: register and handle the dmem mce yulei.kernel
2020-10-08  7:54 ` [PATCH 33/35] kvm, x86: temporary disable record_steal_time for dmem yulei.kernel
2020-10-08  7:54 ` [PATCH 34/35] dmem: add dmem unit tests yulei.kernel
2020-10-08  7:54 ` [PATCH 35/35] Add documentation for dmemfs yulei.kernel
2020-10-09  1:26   ` Randy Dunlap
2020-10-08 19:01 ` [PATCH 00/35] Enhance memory utilization with DMEMFS Joao Martins
2020-10-09 11:39   ` yulei zhang
2020-10-09 11:53     ` Joao Martins
2020-10-10  8:15       ` yulei zhang
2020-10-12 10:59         ` Joao Martins
2020-10-14 22:25           ` Dan Williams
2020-10-19 13:37             ` Paolo Bonzini
2020-10-19 19:03               ` Joao Martins
2020-10-20 15:22                 ` yulei zhang
2020-10-12 11:57 ` Zengtao (B)
2020-10-13  2:45   ` yulei zhang

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