Commit ee56a283 authored by Kristen Carlson Accardi's avatar Kristen Carlson Accardi Committed by Borislav Petkov
Browse files

x86/sgx: Improve comments for sgx_encl_lookup/alloc_backing() 



Modify the comments for sgx_encl_lookup_backing() and for
sgx_encl_alloc_backing() to indicate that they take a reference
which must be dropped with a call to sgx_encl_put_backing().
Make sgx_encl_lookup_backing() static for now, and change the
name of sgx_encl_get_backing() to __sgx_encl_get_backing() to
make it more clear that sgx_encl_get_backing() is an internal
function.

Signed-off-by: default avatarKristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/all/YtUs3MKLzFg+rqEV@zn.tnic/
parent 568035b0

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

+14 −7
Original line number Diff line number Diff line
@@ -12,6 +12,9 @@ 
#include "encls.h"

#include "sgx.h"



static int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,

			    struct sgx_backing *backing);



#define PCMDS_PER_PAGE (PAGE_SIZE / sizeof(struct sgx_pcmd))

/*

 * 32 PCMD entries share a PCMD page. PCMD_FIRST_MASK is used to
@@ -914,7 +917,7 @@ static struct page *sgx_encl_get_backing_page(struct sgx_encl *encl, 
}



/**

 * sgx_encl_get_backing() - Pin the backing storage

 * __sgx_encl_get_backing() - Pin the backing storage

 * @encl:	an enclave pointer

 * @page_index:	enclave page index

 * @backing:	data for accessing backing storage for the page
@@ -926,7 +929,7 @@ static struct page *sgx_encl_get_backing_page(struct sgx_encl *encl, 
 *   0 on success,

 *   -errno otherwise.

 */

static int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,

static int __sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index,

			 struct sgx_backing *backing)

{

	pgoff_t page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index);
@@ -1001,7 +1004,7 @@ static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl) 
}



/**

 * sgx_encl_alloc_backing() - allocate a new backing storage page

 * sgx_encl_alloc_backing() - create a new backing storage page

 * @encl:	an enclave pointer

 * @page_index:	enclave page index

 * @backing:	data for accessing backing storage for the page
@@ -1009,7 +1012,9 @@ static struct mem_cgroup *sgx_encl_get_mem_cgroup(struct sgx_encl *encl) 
 * When called from ksgxd, sets the active memcg from one of the

 * mms in the enclave's mm_list prior to any backing page allocation,

 * in order to ensure that shmem page allocations are charged to the

 * enclave.

 * enclave.  Create a backing page for loading data back into an EPC page with

 * ELDU.  This function takes a reference on a new backing page which

 * must be dropped with a corresponding call to sgx_encl_put_backing().

 *

 * Return:

 *   0 on success,
@@ -1022,7 +1027,7 @@ int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index, 
	struct mem_cgroup *memcg = set_active_memcg(encl_memcg);

	int ret;



	ret = sgx_encl_get_backing(encl, page_index, backing);

	ret = __sgx_encl_get_backing(encl, page_index, backing);



	set_active_memcg(memcg);

	mem_cgroup_put(encl_memcg);
@@ -1040,15 +1045,17 @@ int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index, 
 * It is the caller's responsibility to ensure that it is appropriate to use

 * sgx_encl_lookup_backing() rather than sgx_encl_alloc_backing(). If lookup is

 * not used correctly, this will cause an allocation which is not accounted for.

 * This function takes a reference on an existing backing page which must be

 * dropped with a corresponding call to sgx_encl_put_backing().

 *

 * Return:

 *   0 on success,

 *   -errno otherwise.

 */

int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,

static int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,

			   struct sgx_backing *backing)

{

	return sgx_encl_get_backing(encl, page_index, backing);

	return __sgx_encl_get_backing(encl, page_index, backing);

}



/**

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

+0 −2
Original line number Diff line number Diff line
@@ -107,8 +107,6 @@ bool current_is_ksgxd(void); 
void sgx_encl_release(struct kref *ref);

int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm);

const cpumask_t *sgx_encl_cpumask(struct sgx_encl *encl);

int sgx_encl_lookup_backing(struct sgx_encl *encl, unsigned long page_index,

			    struct sgx_backing *backing);

int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index,

			   struct sgx_backing *backing);

void sgx_encl_put_backing(struct sgx_backing *backing);