Messages in this thread | | | From | Robert Jarzmik <> | Subject | Re: [PATCH 2/2] ARM: domains: add memory dependencies to get_domain/set_domain | Date | Fri, 11 Sep 2015 16:56:27 +0200 |
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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}
Cheers.
-- Robert
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