UPSTREAM: ARM: domains: add memory dependencies to get_domain/set_domain
We need to have memory dependencies on get_domain/set_domain to avoid
the compiler over-optimising these inline assembly instructions.
Loads/stores must not be reordered across a set_domain(), so introduce
a compiler barrier for that assembly.
The value of get_domain() must not be cached across a set_domain(), but
we still want to allow the compiler to optimise it away. Introduce a
dependency on current_thread_info()->cpu_domain to avoid this; the new
memory clobber in set_domain() should therefore cause the compiler to
re-load this. The other advantage of using this is we should have its
address in the register set already, or very soon after at most call
sites.
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Bug: 25672827
Patchset: PAN emulation
(cherry picked from commit 6e8f580d1fcc18e290713984c379cb97131c015a)
Signed-off-by: Kees Cook <keescook@google.com>
Change-Id: I44021c2e0af72a2f20bab4d5af7d67d20ca0a211
1 file changed