Improve FWU documentation
- Clarify the documentation of the 'FWU_SMC_IMAGE_COPY' SMC in the
Firmware Update guide. Also extend the list of pre-conditions to
include the additional input validation implemented by previous
patches.
- Improve documentation of bl1_plat_mem_check() in the porting
guide. It now specifies that the generic FWU code protects
bl1_plat_mem_check() from integer overflows resulting from
the addition of the base address and size passed in arguments.
Change-Id: I07b47a3778df7b9c089529b2dd2135707640a91c
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/docs/porting-guide.md b/docs/porting-guide.md
index a74966c..e8486f1 100644
--- a/docs/porting-guide.md
+++ b/docs/porting-guide.md
@@ -1121,10 +1121,15 @@
unsigned int flags
Return : int
-BL1 calls this function while handling FWU copy and authenticate SMCs. The
-platform must ensure that the provided `mem_base` and `mem_size` are mapped into
-BL1, and that this memory corresponds to either a secure or non-secure memory
-region as indicated by the security state of the `flags` argument.
+BL1 calls this function while handling FWU related SMCs, more specifically when
+copying or authenticating an image. Its responsibility is to ensure that the
+region of memory identified by `mem_base` and `mem_size` is mapped in BL1, and
+that this memory corresponds to either a secure or non-secure memory region as
+indicated by the security state of the `flags` argument.
+
+This function can safely assume that the value resulting from the addition of
+`mem_base` and `mem_size` fits into a `uintptr_t` type variable and does not
+overflow.
This function must return 0 on success, a non-null error code otherwise.