On 19 April 2017 at 11:33, Catalin Marinas [off-list ref] wrote:

On Tue, Apr 18, 2017 at 09:01:52PM +0100, Peter Maydell wrote:

quoted

quoted

That's affecting most architectures with a risk of ABI breakage. We
could do it on arm64 only, though I'm not yet clear on the ABI
implications (at a first look, there shouldn't be any).

Is there a reason why it isn't just straightforwardly a bug
(which we could fix) to make READ_IMPLIES_EXEC propagate to
child processes?

While I agree that it looks like a bug, if there are user programs
relying on such bug we call it "ABI".

Can there be any? Such a program would behave differently
depending on how the program that spawned it happened to
have been compiled, and for instance could break when
the OS happened to have its init binary updated even if
the kernel didn't change.

quoted

Behaviour shouldn't be variable across architectures either, I would
hope.

The behaviour has already been variable for a long time. Even on x86,
AFAICT x86_32 differs from x86_64 in this respect.

That also sounds like a bug to me.

Anyway, the patch should be posted to linux-arch for a cross-arch
discussion.

Agreed -- there may be something I'm missing, since it looks
like this behaviour of inheriting READ_IMPLIES_EXEC has always
been there.

thanks
-- PMM