On 8/25/2020 12:19 PM, Dave Hansen wrote:
On 8/25/20 11:43 AM, Yu, Yu-cheng wrote:
arch_prctl(ARCH_X86_CET_MMAP_SHSTK, u64 *args)
Allocate a new shadow stack.
The parameter 'args' is a pointer to a user buffer.
*args = desired size
*(args + 1) = MAP_32BIT or MAP_POPULATE
On returning, *args is the allocated shadow stack address.
This is hideous. Would this be better as a new syscall?
Could you point out why this is hideous, so that I can modify the
arch_prctl?
Passing values in memory is hideous when we don't have to. A syscall
would let you have separate arguments for size and flags and would also
let you have a nice return value instead of needing to do that in memory
too.
That is a good justification.
I think this is more arch-specific. Even if it becomes a new syscall,
we still need to pass the same parameters.
Right, but without the copying in and out of memory.
Linux-api is already on the Cc list. Do we need to add more people to
get some agreements for the syscall?
