refactor(el3-spmc): add comments and cleanup code
No functional change intended.
Change-Id: I08300ec4cb2e11d26c4a108769919d0c474292ff
Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
diff --git a/services/std_svc/spm/el3_spmc/spmc_shared_mem.c b/services/std_svc/spm/el3_spmc/spmc_shared_mem.c
index 88cf2cd..5c3d580 100644
--- a/services/std_svc/spm/el3_spmc/spmc_shared_mem.c
+++ b/services/std_svc/spm/el3_spmc/spmc_shared_mem.c
@@ -777,16 +777,16 @@
static int spmc_shmem_check_obj(struct spmc_shmem_obj *obj,
uint32_t ffa_version)
{
- uint64_t total_page_count;
+ unsigned long long total_page_count;
const struct ffa_emad_v1_0 *first_emad;
const struct ffa_emad_v1_0 *end_emad;
size_t emad_size;
- uint32_t comp_mrd_offset = 0;
+ uint32_t comp_mrd_offset;
size_t header_emad_size;
size_t size;
size_t count;
size_t expected_size;
- struct ffa_comp_mrd *comp;
+ const struct ffa_comp_mrd *comp;
if (obj->desc_filled != obj->desc_size) {
ERROR("BUG: %s called on incomplete object (%zu != %zu)\n",
@@ -884,16 +884,18 @@
}
size -= comp_mrd_offset;
+ /* Check that there is enough space for the composite descriptor. */
if (size < sizeof(struct ffa_comp_mrd)) {
WARN("%s: invalid object, offset %u, total size %zu, no header space.\n",
__func__, comp_mrd_offset, obj->desc_size);
return FFA_ERROR_INVALID_PARAMETER;
}
- size -= sizeof(struct ffa_comp_mrd);
+ size -= sizeof(*comp);
count = size / sizeof(struct ffa_cons_mrd);
- comp = spmc_shmem_obj_get_comp_mrd(obj, ffa_version);
+ comp = (const struct ffa_comp_mrd *)
+ ((const uint8_t *)(&obj->desc) + comp_mrd_offset);
if (comp->address_range_count != count) {
WARN("%s: invalid object, desc count %u != %zu\n",
@@ -901,6 +903,7 @@
return FFA_ERROR_INVALID_PARAMETER;
}
+ /* Ensure that the expected and actual sizes are equal. */
expected_size = comp_mrd_offset + sizeof(*comp) +
count * sizeof(struct ffa_cons_mrd);
@@ -912,6 +915,10 @@
total_page_count = 0;
+ /*
+ * comp->address_range_count is 32-bit, so 'count' must fit in a
+ * uint32_t at this point.
+ */
for (size_t i = 0; i < count; i++) {
const struct ffa_cons_mrd *mrd = comp->address_range_array + i;
@@ -921,12 +928,17 @@
__func__, i, (unsigned long long)mrd->address);
}
+ /*
+ * No overflow possible: total_page_count can hold at
+ * least 2^64 - 1, but will be have at most 2^32 - 1.
+ * values added to it, each of which cannot exceed 2^32 - 1.
+ */
total_page_count += mrd->page_count;
}
+
if (comp->total_page_count != total_page_count) {
- WARN("%s: invalid object, desc total_page_count %u != %" PRIu64 "\n",
- __func__, comp->total_page_count,
- total_page_count);
+ WARN("%s: invalid object, desc total_page_count %u != %llu\n",
+ __func__, comp->total_page_count, total_page_count);
return FFA_ERROR_INVALID_PARAMETER;
}