Messages in this thread | | | Date | Thu, 11 Jan 2018 10:47:59 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/retpoline: Fill return stack buffer on vmexit |
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On Thu, Jan 11, 2018 at 10:32:31AM +0100, Peter Zijlstra wrote: > can't you do lovely things like: > > volatile asm ("call __fill_rsb_thunk_%1" : : "r" (dummy)) > > which would still let gcc select the register ?
Calling a function from asm is nasty because you need to pay attention to clobbered registers as gcc doesn't see the function.
What one can do, I *think*, is do a non-inlined wrapping function and do all the alternative_call() fun inside. There you can do all the fun and have callee-clobbered regs which you can use.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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