svm: implement the process remap features

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4JMM0
CVE: NA

--------

This feature is to use debug the process memory.
Signed-off-by: NLijun Fang <fanglijun3@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/char/svm.c

@@ -36,12 +36,14 @@
 #define SVM_DEVICE_NAME "svm"
 #define ASID_SHIFT		48
 
+#define SVM_IOCTL_REMAP_PROC		0xfff4
 #define SVM_IOCTL_LOAD_FLAG			0xfffa
 #define SVM_IOCTL_PROCESS_BIND		0xffff
 
 #define CORE_SID		0
 
 #define SVM_IOCTL_RELEASE_PHYS32	0xfff3
+#define SVM_REMAP_MEM_LEN_MAX		(16 * 1024 * 1024)
 #define MMAP_PHY32_MAX (16 * 1024 * 1024)
 
 static int probe_index;
@@ -96,11 +98,21 @@ struct svm_process {
 	struct iommu_sva	*sva;
 };
 
+struct svm_proc_mem {
+	u32 dev_id;
+	u32 len;
+	u64 pid;
+	u64 vaddr;
+	u64 buf;
+};
+
 static char *svm_cmd_to_string(unsigned int cmd)
 {
 	switch (cmd) {
 	case SVM_IOCTL_PROCESS_BIND:
 		return "bind";
+	case SVM_IOCTL_REMAP_PROC:
+		return "remap proc";
 	case SVM_IOCTL_LOAD_FLAG:
 		return "load flag";
 	case SVM_IOCTL_RELEASE_PHYS32:
@@ -497,6 +509,151 @@ static int svm_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static long svm_remap_get_phys(struct mm_struct *mm, struct vm_area_struct *vma,
+			       unsigned long addr, unsigned long *phys,
+			       unsigned long *page_size, unsigned long *offset)
+{
+	long err = -EINVAL;
+	pgd_t *pgd = NULL;
+	p4d_t *p4d = NULL;
+	pud_t *pud = NULL;
+	pte_t *pte = NULL;
+
+	if (mm == NULL || vma == NULL || phys == NULL ||
+	    page_size == NULL || offset == NULL)
+		return err;
+
+	pgd = pgd_offset(mm, addr);
+	if (pgd_none_or_clear_bad(pgd))
+		return err;
+
+	p4d = p4d_offset(pgd, addr);
+	if (p4d_none_or_clear_bad(p4d))
+		return err;
+
+	pud = pud_offset(p4d, addr);
+	if (pud_none_or_clear_bad(pud))
+		return err;
+
+	pte = svm_get_pte(vma, pud, addr, page_size, offset);
+	if (pte && pte_present(*pte)) {
+		*phys = PFN_PHYS(pte_pfn(*pte));
+		return 0;
+	}
+
+	return err;
+}
+
+static long svm_remap_proc(unsigned long __user *arg)
+{
+	long ret = -EINVAL;
+	struct svm_proc_mem pmem;
+	struct task_struct *ptask = NULL;
+	struct mm_struct *pmm = NULL, *mm = current->mm;
+	struct vm_area_struct *pvma = NULL, *vma = NULL;
+	unsigned long end, vaddr, phys, buf, offset, pagesize;
+
+	if (!acpi_disabled)
+		return -EPERM;
+
+	if (arg == NULL) {
+		pr_err("arg is invalid.\n");
+		return ret;
+	}
+
+	ret = copy_from_user(&pmem, (void __user *)arg, sizeof(pmem));
+	if (ret) {
+		pr_err("failed to copy args from user space.\n");
+		return -EFAULT;
+	}
+
+	if (pmem.buf & (PAGE_SIZE - 1)) {
+		pr_err("address is not aligned with page size, addr:%pK.\n",
+		       (void *)pmem.buf);
+		return -EINVAL;
+	}
+
+	rcu_read_lock();
+	if (pmem.pid) {
+		ptask = find_task_by_vpid(pmem.pid);
+		if (!ptask) {
+			rcu_read_unlock();
+			pr_err("No task for this pid\n");
+			return -EINVAL;
+		}
+	} else {
+		ptask = current;
+	}
+
+	get_task_struct(ptask);
+	rcu_read_unlock();
+	pmm = ptask->mm;
+
+	down_read(&mm->mmap_lock);
+	down_read(&pmm->mmap_lock);
+
+	pvma = find_vma(pmm, pmem.vaddr);
+	if (pvma == NULL) {
+		ret = -ESRCH;
+		goto err;
+	}
+
+	vma = find_vma(mm, pmem.buf);
+	if (vma == NULL) {
+		ret = -ESRCH;
+		goto err;
+	}
+
+	if (pmem.len > SVM_REMAP_MEM_LEN_MAX) {
+		ret = -EINVAL;
+		pr_err("too large length of memory.\n");
+		goto err;
+	}
+	vaddr = pmem.vaddr;
+	end = vaddr + pmem.len;
+	buf = pmem.buf;
+	vma->vm_flags |= VM_SHARED;
+	if (end > pvma->vm_end || end < vaddr) {
+		ret = -EINVAL;
+		pr_err("memory length is out of range, vaddr:%pK, len:%u.\n",
+		       (void *)vaddr, pmem.len);
+		goto err;
+	}
+
+	do {
+		ret = svm_remap_get_phys(pmm, pvma, vaddr,
+					 &phys, &pagesize, &offset);
+		if (ret) {
+			ret = -EINVAL;
+			goto err;
+		}
+
+		vaddr += pagesize - offset;
+
+		do {
+			if (remap_pfn_range(vma, buf, phys >> PAGE_SHIFT,
+				PAGE_SIZE,
+				__pgprot(vma->vm_page_prot.pgprot |
+					 PTE_DIRTY))) {
+
+				ret = -ESRCH;
+				goto err;
+			}
+
+			offset += PAGE_SIZE;
+			buf += PAGE_SIZE;
+			phys += PAGE_SIZE;
+		} while (offset < pagesize);
+
+	} while (vaddr < end);
+
+err:
+	up_read(&pmm->mmap_lock);
+	up_read(&mm->mmap_lock);
+	put_task_struct(ptask);
+	return ret;
+}
+
 static int svm_proc_load_flag(int __user *arg)
 {
 	static atomic_t l2buf_load_flag = ATOMIC_INIT(0);
@@ -711,6 +868,9 @@ static long svm_ioctl(struct file *file, unsigned int cmd,
 			return -EFAULT;
 		}
 		break;
+	case SVM_IOCTL_REMAP_PROC:
+		err = svm_remap_proc((unsigned long __user *)arg);
+		break;
 	case SVM_IOCTL_LOAD_FLAG:
 		err = svm_proc_load_flag((int __user *)arg);
 		break;