[PATCH for v24 v3 4/4] x86/sgx: Add @count to &sgx_enclave_add_pages

[Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>]

Add a single @count output variable to write the number of bytes
processed instead of encoding @count into three values and overwriting
input variable with those encodings.

This also more identical API to the comparable POSIX APIs (files and
sockets mainly).

Cc: Mark Shanahan <mark.shanahan@xxxxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
 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 f08008bef943..ab9e48cd294b 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.
- *
  * If ENCLS opcode fails, that effectively means that EPC has been invalidated.
  * When this happens the enclave is destroyed and -EIO is returned to the
  * caller.
@@ -510,6 +505,7 @@ 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))
@@ -538,7 +534,7 @@ 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;
@@ -547,15 +543,14 @@ 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