Messages in this thread | | | Date | Tue, 12 Nov 2019 08:57:46 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86/alternatives: Use C int3 selftest but disable KASAN |
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On Mon, Nov 11, 2019 at 01:51:16PM -0800, Kees Cook wrote: > Instead of using inline asm for the int3 selftest (which confuses the > Clang's ThinLTO pass),
What is that and why do we care?
> this restores the C function but disables KASAN > (and tracing for good measure) to keep the things simple and avoid > unexpected side-effects. This attempts to keep the fix from commit > ecc606103837 ("x86/alternatives: Fix int3_emulate_call() selftest stack > corruption") without using inline asm.
See, I don't much like that. The selftest basically does a naked CALL and hard relies on the callee saving everything if required, which is very much against the C calling convention.
Sure, by disabling KASAN and all the other crap the compiler probably does the right thing by accident, but it is still a C ABI violation.
We use ASM all over the kernel, why is this one a problem?
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