Messages in this thread | | | Date | Mon, 16 May 2022 22:37:23 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH v2 20/21] x86: Add support for CONFIG_CFI_CLANG |
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On Mon, May 16, 2022 at 12:39:19PM -0700, Sami Tolvanen wrote:
> > > With the current compiler patch, LLVM sets up function arguments after > > > the CFI check. if it's a problem, we can look into changing that. > > > > Yes, please fix that. Again see that same patch for why this is a > > problem. Objtool can trivially find retpoline calls, but finding this > > kCFI gadget is going to be hard work. If you ensure they're > > unconditionally stuck together, then the problem goes away find one, > > finds the other. > > You can use .kcfi_traps to locate the check right now, but I agree, > it's not quite ideal.
Oohh, indeed. Looking at that, I think .kcfi_traps would be better as relative offsets; eg. 'addr = (void*)s + *s' like. Halfs the amount of storage needed for it.
Also, that code can use a few {} extra.
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