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

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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: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/all/YtUs3MKLzFg+rqEV@zn.tnic/
This commit is contained in:
Kristen Carlson Accardi 2022-08-12 11:18:03 -07:00 committed by Borislav Petkov
parent 568035b01c
commit ee56a28398
2 changed files with 14 additions and 9 deletions
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21
arch/x86/kernel/cpu/sgx/encl.c
View File

@ -12,6 +12,9 @@
#include "encls.h" #include "encls.h"
#include "sgx.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)) #define PCMDS_PER_PAGE (PAGE_SIZE / sizeof(struct sgx_pcmd))
/* /*
* 32 PCMD entries share a PCMD page. PCMD_FIRST_MASK is used to * 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 * @encl: an enclave pointer
* @page_index: enclave page index * @page_index: enclave page index
* @backing: data for accessing backing storage for the page * @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, * 0 on success,
* -errno otherwise. * -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) struct sgx_backing *backing)
{ {
pgoff_t page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index); 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 * @encl: an enclave pointer
* @page_index: enclave page index * @page_index: enclave page index
* @backing: data for accessing backing storage for the page * @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 * 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, * 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 * 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: * Return:
* 0 on success, * 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); struct mem_cgroup *memcg = set_active_memcg(encl_memcg);
int ret; int ret;
ret = sgx_encl_get_backing(encl, page_index, backing); ret = __sgx_encl_get_backing(encl, page_index, backing);
set_active_memcg(memcg); set_active_memcg(memcg);
mem_cgroup_put(encl_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 * 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 * 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. * 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: * Return:
* 0 on success, * 0 on success,
* -errno otherwise. * -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) struct sgx_backing *backing)
{ {
return sgx_encl_get_backing(encl, page_index, backing); return __sgx_encl_get_backing(encl, page_index, backing);
} }
/** /**

2
arch/x86/kernel/cpu/sgx/encl.h
View File

@ -107,8 +107,6 @@ bool current_is_ksgxd(void);
void sgx_encl_release(struct kref *ref); void sgx_encl_release(struct kref *ref);
int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm); int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm);
const cpumask_t *sgx_encl_cpumask(struct sgx_encl *encl); 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, int sgx_encl_alloc_backing(struct sgx_encl *encl, unsigned long page_index,
struct sgx_backing *backing); struct sgx_backing *backing);
void sgx_encl_put_backing(struct sgx_backing *backing); void sgx_encl_put_backing(struct sgx_backing *backing);