Messages in this thread | | | Date | Sat, 30 Oct 2021 20:02:49 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] static_call,x86: Robustify trampoline patching |
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On Sat, Oct 30, 2021 at 07:19:53PM +0200, Ard Biesheuvel wrote: > I just realized that arm64 has the exact same problem, which is not > being addressed by my v5 of the static call support patch.
Yeah, it would.
> As it turns out, the v11 Clang that I have been testing with is broken > wrt BTI landing pads, and omits them from the jump table entries. > Clang 12+ adds them properly, which means that both the jump table > entry and the static call trampoline may start with BTI C + direct > branch, and we also need additional checks to disambiguate.
I'm not sure, why would the static_call trampoline need a BTI C ? The whole point of static_call() is to be a direct call, we should never have an indirect call to the trampoline, that would defeat the whole purpose.
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