x86/sgx: Return -ERESTARTSYS in sgx_ioc_enclave_add_pages()

Return -ERESTARTSYS instead of -EINTR in sgx_ioc_enclave_add_pages()
when interrupted before any pages have been processed. At this point
ioctl can be obviously safely restarted.
Reported-by: Haitao Huang <haitao.huang@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201118213932.63341-1-jarkko@kernel.org

arch/x86/kernel/cpu/sgx/ioctl.c

@@ -444,7 +444,7 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
 	for (c = 0 ; c < add_arg.length; c += PAGE_SIZE) {
 		if (signal_pending(current)) {
 			if (!c)
-				ret = -EINTR;
+				ret = -ERESTARTSYS;
 
 			break;
 		}