Messages in this thread | | | Date | Tue, 20 Mar 2018 23:13:09 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 3/5] ARM: trusted_foundations: do not use naked function |
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On Wed, Mar 21, 2018 at 12:02:04AM +0100, Stefan Agner wrote: > As documented in GCC naked functions should only use Basic asm > syntax. The Extended asm or mixture of Basic asm and "C" code is > not guaranteed. Currently this works because it was hard coded > to follow and check GCC behavior for arguments and register > placement.
Those checks have nothing to do with that at all. The whole point of __asmeq() is to catch situations where you use register variables, specifying which register you want them in, and GCC then ends up passing them to assembly code in some other random register(s).
This was found with older GCCs, and the problem was fixed. It has nothing to do with naked functions per se.
In fact, as you're introducing further register variables, these checks become more important to have than they were with the previous code.
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