On Tue, Feb 02, 2021 at 10:55:36AM -0800, Dave Hansen wrote: > On 2/1/21 5:37 PM, ira.weiny@xxxxxxxxx wrote: > > kmap is inefficient and we are trying to reduce the usage in the kernel. > > There is no readily apparent reason why the initp_page page needs to be > > allocated and kmap'ed() but sigstruct needs to be page aligned and token > > 512 byte aligned. > > Hi Ira, > > It's a *relatively* recent guaranteed, but: > > https://www.kernel.org/doc/Documentation/core-api/memory-allocation.rst > > says: > > > The address of a chunk allocated with `kmalloc` is aligned to at least > > ARCH_KMALLOC_MINALIGN bytes. For sizes which are a power of two, the > > alignment is also guaranteed to be at least the respective size. > > So, if you allocate a page with kmalloc(), you get an aligned page. Yay! And this what we do sgx_ioc_enclave_create() anyway, as I stated in my earlier response. Better to use the same pattern everywhere consitently when it makes sense. /Jarkko
