[PATCH for v24 v2 4/4] x86/sgx: add @count to &sgx_enclave_add_pages

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

Add @count write the number of bytes added as there is not any good reason
to overwrite input parameters. Also, three parameters are unnecessarily
overwritten as the amount of change is the same for each of them.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 arch/x86/include/uapi/asm/sgx.h |  2 ++
 arch/x86/kernel/cpu/sgx/ioctl.c | 17 ++++++-----------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
index 88644b6ad849..e196cfd44b70 100644
--- a/arch/x86/include/uapi/asm/sgx.h
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -45,6 +45,7 @@ struct sgx_enclave_create  {
  * @length:	length of the data (multiple of the page size)
  * @secinfo:	address for the SECINFO data
  * @flags:	page control flags
+ * @count:	number of bytes added (multiple of the page size)
  */
 struct sgx_enclave_add_pages {
 	__u64	src;
@@ -52,6 +53,7 @@ struct sgx_enclave_add_pages {
 	__u64	length;
 	__u64	secinfo;
 	__u64	flags;
+	__u64	count;
 };
 
 /**
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index deca49bd4f58..e8697d145dfb 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -491,11 +491,6 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
  * permissions. In effect, this allows mmap() with PROT_NONE to be used to seek
  * an address range for the enclave that can be then populated into SECS.
  *
- * @arg->addr, @arg->src and @arg->length are adjusted to reflect the
- * remaining pages that need to be added to the enclave, e.g. userspace can
- * re-invoke SGX_IOC_ENCLAVE_ADD_PAGES using the same struct in response to an
- * ERESTARTSYS error.
- *
  * Return:
  *   0 on success,
  *   -EACCES if an executable source page is located in a noexec partition,
@@ -506,6 +501,7 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
 {
 	struct sgx_enclave_add_pages addp;
 	struct sgx_secinfo secinfo;
+	unsigned long c;
 	int ret;
 
 	if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED))
@@ -534,7 +530,7 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
 	if (sgx_validate_secinfo(&secinfo))
 		return -EINVAL;
 
-	for ( ; addp.length > 0; addp.length -= PAGE_SIZE) {
+	for (c = 0 ; c < addp.length; c += PAGE_SIZE) {
 		if (signal_pending(current)) {
 			ret = -ERESTARTSYS;
 			break;
@@ -543,15 +539,14 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
 		if (need_resched())
 			cond_resched();
 
-		ret = sgx_encl_add_page(encl, addp.src, addp.offset,
-					addp.length, &secinfo, addp.flags);
+		ret = sgx_encl_add_page(encl, addp.src + c, addp.offset + c,
+					addp.length - c, &secinfo, addp.flags);
 		if (ret)
 			break;
-
-		addp.offset += PAGE_SIZE;
-		addp.src += PAGE_SIZE;
 	}
 
+	addp.count = c;
+
 	if (copy_to_user(arg, &addp, sizeof(addp)))
 		return -EFAULT;
 
-- 
2.20.1