On Fri, Jun 21, 2019 at 12:08:51AM +0300, Jarkko Sakkinen wrote: > On Wed, Jun 19, 2019 at 03:23:51PM -0700, Sean Christopherson wrote: > > SGX enclaves have an associated Enclave Linear Range (ELRANGE) that is > > tracked and enforced by the CPU using a base+mask approach, similar to > > how hardware range registers such as the variable MTRRs. As a result, > > the ELRANGE must be naturally sized and aligned. > > > > To reduce boilerplate code that would be needed in every userspace > > enclave loader, the SGX driver naturally aligns the mmap() address and > > also requires the range to be naturally sized. Unfortunately, SGX fails > > to grant a waiver to the MAP_FIXED case, e.g. incorrectly rejects mmap() > > if userspace is attempting to map a small slice of an existing enclave. > > > > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > --- > > arch/x86/kernel/cpu/sgx/driver/main.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/kernel/cpu/sgx/driver/main.c b/arch/x86/kernel/cpu/sgx/driver/main.c > > index 07aa5f91b2dd..29384cdd0842 100644 > > --- a/arch/x86/kernel/cpu/sgx/driver/main.c > > +++ b/arch/x86/kernel/cpu/sgx/driver/main.c > > @@ -115,7 +115,13 @@ static unsigned long sgx_get_unmapped_area(struct file *file, > > unsigned long pgoff, > > unsigned long flags) > > { > > - if (len < 2 * PAGE_SIZE || len & (len - 1) || flags & MAP_PRIVATE) > > + if (flags & MAP_PRIVATE) > > + return -EINVAL; > > + > > + if (flags & MAP_FIXED) > > + return addr; > > + > > + if (len < 2 * PAGE_SIZE || len & (len - 1)) > > return -EINVAL; > > Why the last check is needed given that mmap() no longer does not > associate with the layout of the enclave? I'd just wipe it away. In any case, I squashed this one. /Jarkko