Thread (12 messages) 12 messages, 6 authors, 2020-09-02

Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack

From: Florian Weimer <hidden>
Date: 2020-08-26 16:52:38
Also in: linux-arch, linux-doc, linux-mm, lkml

Possibly related (same subject, not in this thread)

* Dave Martin:
On Tue, Aug 25, 2020 at 04:34:27PM -0700, Yu, Yu-cheng wrote:
quoted
On 8/25/2020 4:20 PM, Dave Hansen wrote:
quoted
On 8/25/20 2:04 PM, Yu, Yu-cheng wrote:
quoted
quoted
quoted
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?
What kind of agreement are you looking for?  I'd suggest just coding it
up and posting the patches.  Adding syscalls really is really pretty
straightforward and isn't much code at all.
Sure, I will do that.
Alternatively, would a regular prctl() work here?
Is this something appliation code has to call, or just the dynamic
loader?

prctl in glibc is a variadic function, so if there's a mismatch between
the kernel/userspace syscall convention and the userspace calling
convention (for variadic functions) for specific types, it can't be made
to work in a generic way.

The loader can use inline assembly for system calls and does not have
this issue, but applications would be implcated by it.

Thanks,
Florian
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