x86/sgx: Export sgx_encl_page_alloc()

Move sgx_encl_page_alloc() to encl.c and export it so that it can be
used in the implementation for support of adding pages to initialized
enclaves, which requires to allocate new enclave pages.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/57ae71b4ea17998467670232e12d6617b95c6811.1652137848.git.reinette.chatre@intel.com

Author: jarkkojs

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

@@ -887,6 +887,38 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,
 	return ret;
 }
 
+struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
+					  unsigned long offset,
+					  u64 secinfo_flags)
+{
+	struct sgx_encl_page *encl_page;
+	unsigned long prot;
+
+	encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL);
+	if (!encl_page)
+		return ERR_PTR(-ENOMEM);
+
+	encl_page->desc = encl->base + offset;
+	encl_page->encl = encl;
+
+	prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ)  |
+	       _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) |
+	       _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC);
+
+	/*
+	 * TCS pages must always RW set for CPU access while the SECINFO
+	 * permissions are *always* zero - the CPU ignores the user provided
+	 * values and silently overwrites them with zero permissions.
+	 */
+	if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS)
+		prot |= PROT_READ | PROT_WRITE;
+
+	/* Calculate maximum of the VM flags for the page. */
+	encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0);
+
+	return encl_page;
+}
+
 /**
  * sgx_zap_enclave_ptes() - remove PTEs mapping the address from enclave
  * @encl: the enclave

arch/x86/kernel/cpu/sgx/encl.h

@@ -112,6 +112,9 @@ int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,
 void sgx_encl_put_backing(struct sgx_backing *backing);
 int sgx_encl_test_and_clear_young(struct mm_struct *mm,
 				  struct sgx_encl_page *page);
+struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
+					  unsigned long offset,
+					  u64 secinfo_flags);
 void sgx_zap_enclave_ptes(struct sgx_encl *encl, unsigned long addr);
 struct sgx_epc_page *sgx_alloc_va_page(void);
 unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page);

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

@@ -169,38 +169,6 @@ static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg)
 	return ret;
 }
 
-static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
-						 unsigned long offset,
-						 u64 secinfo_flags)
-{
-	struct sgx_encl_page *encl_page;
-	unsigned long prot;
-
-	encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL);
-	if (!encl_page)
-		return ERR_PTR(-ENOMEM);
-
-	encl_page->desc = encl->base + offset;
-	encl_page->encl = encl;
-
-	prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ)  |
-	       _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) |
-	       _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC);
-
-	/*
-	 * TCS pages must always RW set for CPU access while the SECINFO
-	 * permissions are *always* zero - the CPU ignores the user provided
-	 * values and silently overwrites them with zero permissions.
-	 */
-	if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS)
-		prot |= PROT_READ | PROT_WRITE;
-
-	/* Calculate maximum of the VM flags for the page. */
-	encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0);
-
-	return encl_page;
-}
-
 static int sgx_validate_secinfo(struct sgx_secinfo *secinfo)
 {
 	u64 perm = secinfo->flags & SGX_SECINFO_PERMISSION_MASK;