Messages in this thread | | | Date | Fri, 11 Sep 2015 16:10:17 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 2/2] ARM: domains: add memory dependencies to get_domain/set_domain |
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On Fri, Sep 11, 2015 at 04:56:27PM +0200, Robert Jarzmik wrote: > Russell King <rmk+kernel@arm.linux.org.uk> writes: > > 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. > > > > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> > Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> > > The test is failing without these 2 patches, while with them, an unaligned > access is fixed, and the generated code looks good : > 7ac: ee13cf10 mrc 15, 0, ip, cr3, cr0, {0} > 7b0: e3cc300c bic r3, ip, #12 > 7b4: e58dc014 str ip, [sp, #20] > 7b8: e3833004 orr r3, r3, #4 > 7bc: ee033f10 mcr 15, 0, r3, cr3, cr0, {0}
Thanks Robert, I've queued these as fixes now.
If you want to put the bug alignment patch in the patch system, I'll get that off to Linus this weekend too.
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